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Sample records for 252cf 254cf 256fm

  1. Graphite moderated (252)Cf source.

    PubMed

    Sajo-Bohus, Laszlo; Barros, Haydn; Greaves, Eduardo D; Vega-Carrillo, Hector Rene

    2015-06-01

    The Thorium molten-salt reactor is an attractive and affordable nuclear power option for developing countries with insufficient infrastructure and limited technological capability. In the aim of personnel training and experience gathering at the Universidad Simon Bolivar there is in progress a project of developing a subcritical thorium liquid-fuel reactor. The neutron source to run this subcritical reactor is a (252)Cf source and the reactor will use high-purity graphite as moderator. Using the MCNP5 code the neutron spectra of the (252)Cf in the center of the graphite moderator has been estimated along the channel where the liquid thorium salt will be inserted; also the ambient dose equivalent due to the source has been determined around the moderator.

  2. Level structure of sup 256 Fm: Experiment vs theory

    SciTech Connect

    Bunker, M.E.; Starner, J.W.

    1990-01-01

    The amount of experimental data on intrinsic states in the even-even isotopes of the transcurium elements is rather limited, providing only a few tests of theoretical models in this region. Thus, it is of interest to determine to what extent the recent results on levels in {sup 256}Fm compare with existing theoretical calculations, such as those of Ivanova et al. 4 refs., 1 fig., 1 tab.

  3. ANISOTROPY FACTORS FOR A 252Cf SOURCE

    SciTech Connect

    Veinot, K. G.; Bogard, James S

    2009-01-01

    A new 252Cf source has been procured for use at the Dosimetry Applications and Research (DOSAR) facility at the Oak Ridge National Laboratory (ORNL). This source was encapsulated by the Californium Facility at ORNL, however, the encapsulation differs from previous designs designated as SR-Cf-100. The new encapsulation, designated SR-Cf-3000, has a similar cylindrical radius to the previous generation, but is 1.6 cm longer. Since the encapsulation geometries differ the amount of internal scattering of neutrons will also differ leading to changes in anisotropy factors between the two designs. Additionally, the different encapsulations will affect the absorbed dose and dose equivalent delivered per neutron emitted by the source since both the quantity and energy distribution of the emitted neutrons will vary with irradiation angle. This work presents the fluence anisotropy factors for the SR-Cf-3000 series encapsulation as well as absorbed dose and dose equivalent values calculated for various angles of irradiation. The fluence anisotropy factors vary from a maximum of 1.037 to a minimum of 0.641 for irradiation angles perpendicular and parallel to the source axis, respectively. Anisotropy in absorbed dose varied from a maximum of 1.033 to a minimum of 0.676 while anisotropy of dose equivalent varied from 1.035 to 0.657.

  4. Reactor production of sup 252 Cf and transcurium isotopes

    SciTech Connect

    Alexander, C.W.; Halperin, J.; Walker, R.L.; Bigelow, J.E.

    1990-01-01

    Berkelium, californium, einsteinium, and fermium are currently produced in the High Flux Isotope Reactor (HFIR) and recovered in the Radiochemical Engineering Development Center (REDC) at the Oak Ridge National Laboratory (ORNL). All the isotopes are used for research. In addition, {sup 252}Cf, {sup 253}Es, and {sup 255}Fm have been considered or are used for industrial or medical applications. ORNL is the sole producer of these transcurium isotopes in the western world. A wide range of actinide samples were irradiated in special test assemblies at the Fast Flux Test Facility (FFTF) at Hanford, Washington. The purpose of the experiments was to evaluate the usefulness of the two-group flux model for transmutations in the special assemblies with an eventual goal of determining the feasibility of producing macro amounts of transcurium isotopes in the FFTF. Preliminary results from the production of {sup 254g}Es from {sup 252}Cf will be discussed. 14 refs., 5 tabs.

  5. Compound dual radiation action theory for 252Cf brachytherapy.

    PubMed

    Wang, C K; Zhang, X

    2004-01-01

    The existing dosimetry protocol that uses the concept of RBE for 252Cf brachytherapy contains large uncertainties. A new formula has been developed to correlate the biological effect (i.e. cell survival fraction) resulting from a mixed n + gamma radiation field with two physical quantities and two biological quantities. The formula is based on a pathway model evolved from that of the compound-dual-radiation-action (CDRA) theory, previously proposed by Rossi and Zaider. The new model employs the recently published data on radiation-induced DNA lesions. The new formula is capable of predicting quantitatively the synergistic effect caused by the interactions between neutron events and gamma ray events, and it is intended to be included into a new dosimetry protocol for future 252Cf brachytherapy.

  6. A pneumatic transfer system for special form {sup 252}Cf

    SciTech Connect

    Gehrke, R.J.; Berry, S.M.; Grafwallner, E.G.; Hoggan, J.M.

    1996-09-01

    A pneumatic transfer system has been developed for use with series 100 Special Form {sup 252}Cf. It was developed to reduce the exposure to personnel handling sources of {sup 252}Cf with masses up to 150 {micro}g by permitting remotely activated two-way transfer between the storage container and the irradiation position. The pneumatic transfer system also permits transfers for reproducible repetitive irradiation periods. In addition to the storage container equipped with quick-release fittings, the transfer system consists of an irradiation station, a control box with momentary contact switches to activate the air-pressure control valves and indicators to identify the location of the source, and connecting air hose and electrical wire. A source of 20 psig air and 110 volt electrical power are required for operation of the transfer system which can be easily moved and set up by one individual in 5 to 10 minutes. Tests have shown that rarely does a source become lodged in the transfer tubing, but two methods have been developed to handle incomplete transfers of the {sup 252}Cf source. The first method consists of closing one air vent to allow a pressure impulse to propel the source to the opposite side. The second method applies to those {sup 252}Cf capsules with a threaded or tapped end to which a small ferromagnetic piece can be attached; an incompletely transferred source in the transfer tube can then be guided to a position of safety by surrounding the transfer tubing containing the capsule with a horseshoe magnet attached to the end of a long pole.

  7. Interstitial /sup 252/Cf neutron therapy for glioblastoma multiforme

    SciTech Connect

    Maruyama, Y.; Chin, H.W.; Young, A.B.; Bean, J.; Tibbs, P.; Beach, J.L.

    1982-12-01

    /sup 252/Cf brachytherapy has been combined with whole brain photon beam therapy to 6000 rads in 5-7 weeks. In early phase I studies, all patients selected for study tolerated the procedure and the subsequent photon beam therapy. All showed improvement in performance status and decreased tumor size by CT scan evaluation, but it became clear that these tumors are of large size and bulk, produce marked adjacent brain edema, and require individualized implant therapy as well as high-dose external beam irradiation if response is to occur.

  8. Moderated 252Cf neutron energy spectra in brain tissue and calculated boron neutron capture dose.

    PubMed

    Rivard, Mark J; Zamenhof, Robert G

    2004-11-01

    While there is significant clinical experience using both low- and high-dose (252)Cf brachytherapy, combination therapy using (10)B for neutron capture therapy-enhanced (252)Cf brachytherapy has not been performed. Monte Carlo calculations were performed in a brain phantom (ICRU 44 brain tissue) to evaluate the dose enhancement predicted for a range of (10)B concentrations over a range of distances from a clinical (252)Cf source. These results were compared to experimental measurements and calculations published in the literature. For (10)B concentrations 252)Cf fast neutron dose.

  9. Measurement of the 250Cf component in a 252Cf neutron source at KRISS.

    PubMed

    Kim, Jungho; Park, Hyeonseo; Choi, Kil-Oung

    2014-10-01

    Neutron emission rate measurements have been carried out at the Korea Research Institute of Standards and Science using a manganese sulphate bath system for (252)Cf and (241)Am-Be sources since 2004. The relative measurement method was chosen in 2012, and the neutron emission rates agreed with those by the absolute measurement method within uncertainties. The neutron emission rate of an old (252)Cf source has been measured three times: in 2004, 2009 and 2012. The (250)Cf component was fitted to a double-exponential function of (252)Cf+(250)Cf, and the ratio of the (250)Cf component to the (252)Cf component was estimated to be 7.8 % in 2004 and 46.8 % in 2012. Underestimation of the neutron emission rates of old (252)Cf sources can be corrected if the neutron emission rate of the (250)Cf component is taken into account.

  10. A radiobiological model for the relative biological effectiveness of high-dose-rate 252Cf brachytherapy.

    PubMed

    Rivard, Mark J; Melhus, Christopher S; Zinkin, Heather D; Stapleford, Liza J; Evans, Krista E; Wazer, David E; Odlozilíková, Anna

    2005-09-01

    While there is significant clinical experience using both low- and high-dose-rate 252Cf brachytherapy, there are minimal data regarding values for the neutron relative biological effectiveness (RBE) with both modalities. The aim of this research was to derive a radiobiological model for 252Cf neutron RBE and to compare these results with neutron RBE values used clinically in Russia. The linear-quadratic (LQ) model was used as the basis to characterize cell survival after irradiation, with identical cell killing rates (S(N) = S(gamma)) between 252Cf neutrons and photons used for derivation of RBE. Using this equality, a relationship among neutron dose and LQ radiobiological parameter (i.e., alpha(N), beta(N), alpha(gamma), beta(gamma)) was obtained without the need to specify the photon dose. These results were used to derive the 252Cf neutron RBE, which was then compared with Russian neutron RBE values. The 252Cf neutron RBE was determined after incorporating the LQ radiobiological parameters obtained from cell survival studies with fast neutrons and teletherapy photons. For single-fraction high-dose-rate neutron doses of 0.5, 1.0, 1.5 and 2.0 Gy, the total biologically equivalent doses were 1.8, 3.4, 4.7 and 6.0 RBE Gy with 252Cf neutron RBE values of 3.2, 2.9, 2.7 and 2.5, respectively. Using clinical data for late-responding reactions from 252Cf, Russian investigators created an empirical model that predicted high-dose-rate 252Cf neutron RBE values ranging from 3.6 to 2.9 for similar doses and fractionation schemes and observed that 252Cf neutron RBE increases with the number of treatment fractions. Using these relationships, our results were in general concordance with high-dose-rate 252Cf RBE values obtained from Russian clinical experience.

  11. /sup 252/Cf-source-driven neutron noise analysis method

    SciTech Connect

    Mihalczo, J.T.; King, W.T.; Blakeman, E.D.

    1985-01-01

    The /sup 252/Cf-source-driven neutron noise analysis method has been tested in a wide variety of experiments that have indicated the broad range of applicability of the method. The neutron multiplication factor k/sub eff/ has been satisfactorily detemined for a variety of materials including uranium metal, light water reactor fuel pins, fissile solutions, fuel plates in water, and interacting cylinders. For a uranyl nitrate solution tank which is typical of a fuel processing or reprocessing plant, the k/sub eff/ values were satisfactorily determined for values between 0.92 and 0.5 using a simple point kinetics interpretation of the experimental data. The short measurement times, in several cases as low as 1 min, have shown that the development of this method can lead to a practical subcriticality monitor for many in-plant applications. The further development of the method will require experiments oriented toward particular applications including dynamic experiments and the development of theoretical methods to predict the experimental observables.

  12. Microscopic cold fission yields of {sup 252}Cf

    SciTech Connect

    Mirea, M.; Delion, D. S.; Sandulescu, A.

    2010-04-15

    We show that the sharp maximum corresponding to {sup 107}Mo in the fragment distribution of the {sup 252}Cf cold fission is actually a Sn-like radioactivity, similar to other decay processes in which magic nuclei are involved, namely alpha decay and heavy cluster emission, also called Pb-like radioactivity. It turns out that the mass asymmetry degree of freedom has a key role in connecting initial Sn with the final Mo isotopes along the fission path. We investigate the cold rearrangement of nucleons within the framework of the two-center shell model in order to compute the cold valleys in the charge equilibrated fragmentation potential. The fission yields are estimated by using the semiclassical penetration approach. We consider 5 degrees of freedom, namely the interfragment distance, the shapes of fragments, the neck parameter, and mass asymmetry. We found an isomeric minimum between the internal and external barriers. It turns out that the inner cold valley of the total potential energy is connected to the doubly magic isotope {sup 132}Sn.

  13. Attributes and templates from active measurements with {sup 252}Cf

    SciTech Connect

    Mihalczo, J.T.; Mattingly, J.K.

    2000-02-01

    Active neutron interrogation is useful for the detection of shielded HEU and could also be used for Pu. In an active technique, fissile material is stimulated by an external neutron source to produce fission with the emanation of neutrons and gamma rays. The time distribution of particles leaving the fissile material is measured with respect to the source emission in a variety of ways. A variety of accelerator and radioactive sources can be used. Active interrogation of nuclear weapons/components can be used in two ways: template matching or attribute estimation. Template matching compares radiation signatures with known reference signatures and for treaty applications has the problem of authentication of the reference signatures along with storage and retrieval of templates. Attribute estimation determines, for example, the fissile mass from various features of the radiation signatures and does not require storage of radiation signatures but does require calibration, which can be repeated as necessary. A nuclear materials identification system (NMIS) has been in use at the Oak Ridge Y-12 Plant for verification of weapons components being received and in storage by template matching and has been used with calibrations for attribute (fissile mass) estimation for HEU metal. NMIS employs a {sup 252}Cf source of low intensity (< 2 x 10{sup 6} n/sec) such that the dose at 1 m is approximately twice that on a commercial airline at altitude. The use of such a source presents no significant safety concerns either for personnel or nuclear explosive safety, and has been approved for use at the Pantex Plant on fully assembled weapons systems.

  14. A comparison of the expected costs of high dose rate brachytherapy using 252Cf versus 192Ir.

    PubMed

    Rivard, Mark J; Kirk, Bernadette L; Stapleford, Liza J; Wazer, David E

    2004-12-01

    A cost analysis to compare high dose rate (HDR) brachytherapy using either californium-252 (252Cf) or 192Ir was performed to determine the prospects of widespread clinical implementation of HDR 252Cf. Interest in the neutron-emitting 252Cf radioisotope as a radiotherapy nuclide has undergone a resurgence given recent efforts to fabricate HDR remotely afterloaded sources, and other efforts to create a miniature source for improved accessibility to a variety of anatomic sites. Therefore, HDR 252Cf brachytherapy may prove to be a potential rival to the use of HDR 192Ir remotely afterloaded brachytherapy--the current standard-of-care treatment modality using HDR brachytherapy. Considering the possible improvements in clinical efficacy using HDR 252Cf brachytherapy and the enormous costs of other high-LET radiation sources, the cost differences between 252Cf and 192Ir may be well-justified.

  15. AN INTERLABORATORY COMPARISON ON THE DETERMINATION OF 241Am, 244Cm AND 252Cf IN URINE.

    PubMed

    Gerstmann, Udo C; Taubner, Kerstin; Hartmann, Martina

    2016-09-01

    An intercomparison exercise on the determination of (241)Am, (244)Cm and (252)Cf in urine was performed. Since it was designed with regard to emergency preparedness, the detection limit for each nuclide was set to 0.1 Bq per 24-h urine sample. Most of the participating laboratories were established bioassay laboratories. However, some laboratories that routinely determine (241)Am only in environmental samples were also invited in order to explore their potential for emergency bioassay analysis. Another aspect of the intercomparison was to investigate the performance of all laboratories concerning the chemical yields of the (243)Am tracer in comparison with (244)Cm and (252)Cf. In summary, both types of laboratories showed good results. There was a negative bias for the results of (244)Cm and (252)Cf, which can be explained by slightly different radiochemical behaviours of americium, curium and californium and which is in agreement with results reported in the literature. PMID:26535001

  16. Fluence-to-dose equivalent conversion factors for polyethylene-moderated {sup 252}Cf

    SciTech Connect

    Tanner, J.E.; Soldat, K.L.; Stewart, R.D.; Casson, W.H.

    1994-04-01

    Neutron measurements and calculations were conducted to characterize the polyethylene-moderated {sup 252}Cf source at Oak Ridge National Laboratory`s Radiation Calibration Laboratory (RADCAL). The 12-inch-diameter polyethylene sphere produces a highly scattered neutron spectrum which is more representative of most radiation fields found in the workplace than the D{sub 2}O-moderated {sup 252}Cf neutron spectrum typically used for dosimeter calibration. However, the energy-dependent fluence and dose equivalent must be well known before using such a source for radiation protection purposes. The measurements and calculations were performed as independent checks of the desired quantities which were the flux, the absorbed dose rate, the dose equivalent rate, and the average energy. These quantities were determined for the polyethylene sphere with and without an outer cadmium shell and compared with a D{sub 2}O-moderated {sup 252}Cf source.

  17. Design of a setup for 252Cf neutron source for storage and analysis purpose

    NASA Astrophysics Data System (ADS)

    Hei, Daqian; Zhuang, Haocheng; Jia, Wenbao; Cheng, Can; Jiang, Zhou; Wang, Hongtao; Chen, Da

    2016-11-01

    252Cf is a reliable isotopic neutron source and widely used in the prompt gamma ray neutron activation analysis (PGNAA) technique. A cylindrical barrel made by polymethyl methacrylate contained with the boric acid solution was designed for storage and application of a 5 μg 252Cf neutron source. The size of the setup was optimized with Monte Carlo code. The experiments were performed and the results showed the doses were reduced with the setup and less than the allowable limit. The intensity and collimating radius of the neutron beam could also be adjusted through different collimator.

  18. Water-extended polyester neutron shield for a 252Cf neutron source.

    PubMed

    Vega-Carrillo, H R; Manzanares-Acuña, E; Hernández-Dávila, V M; Gallego, E; Lorente, A; Donaire, I

    2007-01-01

    A Monte Carlo study to determine the shielding features to neutrons of water-extended polyester was carried out. During calculations, (252)Cf and shielding were modelled and the neutron spectra as well as the H(10) were calculated in four sites. The calculation was extended to include a water shielding, the source in vacuum and in air. Besides neutron shielding characteristics, the Kerma in air due to gammas emitted by (252)Cf and due to capture gamma rays in the shielding were included.

  19. Stability of {sup 248–254}Cf isotopes against alpha and cluster radioactivity

    SciTech Connect

    Santhosh, K.P. Biju, R.K.

    2013-07-15

    Stability of {sup 248–254}Cf nuclei against alpha and cluster emissions is studied within our Coulomb and proximity potential model (CPPM). It is found that these nuclei are stable against light clusters (except alpha particles) and unstable against heavy cluster (A{sub 2}≥40) emissions. For heavy cluster emissions the daughter nuclei lead to doubly magic {sup 208}Pb or the neighbouring one. The effects of quadrupole and hexadecapole deformations of parent nuclei, daughter nuclei and emitted cluster on half lives are also studied. The computed alpha decay half life values (including quadrupole deformation β{sub 2}) are in close agreement with experimental data. Inclusion of quadrupole deformation reduces the height and width of the barrier (increases the barrier penetrability) and hence half life decreases. -- Highlights: •{sup 248–254}Cf parents are stable against light clusters (except alpha particles) and are unstable against heavy clusters ({sup 46}Ar, {sup 48,50}Ca etc.). •For the case of heavy cluster emissions the daughter nuclei are doubly magic {sup 208}Pb or neighbouring one. •The alpha decay half lives are in agreement with experimental data. •The cluster decay half lives decrease with the inclusion of quadrupole deformation.

  20. Light-charged-particle emission in the spontaneous fission of /sup 250/Cf, /sup 256/Fm, and /sup 257/Fm

    SciTech Connect

    Wild, J.F.; Baisden, P.A.; Dougan, R.J.; Hulet, E.K.; Lougheed, R.W.; Landrum, J.H.

    1985-08-01

    We have measured the energy spectra for the emission of long-range ..cap alpha.. particles from the spontaneous fission of /sup 250/Cf, /sup 256/Fm, and /sup 257/Fm, and for tritons and protons from the spontaneous fission of /sup 250/Cf and /sup 256/Fm. We have determined ..cap alpha.., triton, and proton emission probabilities and estimated total light-particle emission probabilities for these nuclides. We compare these and known emission probabilities for five other spontaneously fissioning nuclides with the deformation energy available at scission and show that there is a possible correlation that is consistent with a one-body dissipation mechanism for transferring release energy to particle clusters.

  1. On the use of a (252Cf-3He) assembly for landmine detection by the neutron back-scattering method.

    PubMed

    Elsheikh, N; Viesti, G; ElAgib, I; Habbani, F

    2012-04-01

    Experiments were carried out to optimize the performance of the neutron back-scattering (NBS) technique in landmine detection using an assembly consisting of three different layers placed above a (252)Cf neuron source, producing about 10(4)s(-1), in conjunction with a (3)He detector. The assembly was optimized experimentally. The selected assembly configuration was then examined against different (252)Cf stand-off distances and mine burial depths using dummy landmines. Furthermore, Monte Carlo simulations were performed to study the effect of the shield when a (252)Cf source in the range 10(4)-10(7)s(-1) was employed, and to optimize the geometry for future prototypes.

  2. Dynamics and energetics of a /sup 251/Cf-/sup 252/Cf power system

    SciTech Connect

    Harms, A.A. ); Cripps, G. )

    1988-06-01

    A combination fission-radioisotope compact power system involving the synergistic interaction of /sup 251/Cf and /sup 252/Cf is considered. Based on a nonlinear point kinetics formulation of the coupled reactions combined with the parametric incorporation of design and operational variables, it is shown that a stable autonomous power mode is readily attainable. This system appears particularly suitable for very long-life unattended operation for space and terrestrial applications.

  3. Brazilian gamma-neutron dosemeter: response to 241AmBe and 252Cf neutron sources.

    PubMed

    Souto, E B; Campos, L L

    2011-03-01

    With the aim of improving the monitoring of workers potentially exposed to neutron radiation in Brazil, the IPEN/CNEN-SP in association with PRO-RAD designed and developed a passive individual gamma-neutron mixed-field dosemeter calibrated to be used to (241)AmBe sources. To verify the dosimetry system response to different neutron spectra, prototypes were irradiated with a (252)Cf source and evaluated using the dose-calculation algorithm developed for (241)AmBe sources.

  4. Comparison of fission modes in {sup 252}Cf, {sup 257}Fm, and {sup 260}Md

    SciTech Connect

    Aarle, J. van; Siemon, K.; Patzelt, P.; Wild, J. F.; Lougheed, R. W.; Westmeier, W.

    1998-10-26

    Although the spontaneous-fission properties of heavy actinides have been studied for well over 35 years, many interesting and informative details continue to come into light. During the last decade, the spontaneous fission of {sup 252}Cf, {sup 257}Fm and {sup 260}Md has been extensively investigated at the Philipps University of Marburg, by means of a gadolinium-doped liquid scintillation tank for neutron counting and surface barrier detectors for fission fragment detection. The three nuclides represent the transition from the well-known asymmetric fission yield distribution, as it is characteristic for {sup 252}Cf, to a much more symmetrical one, found in the fission of {sup 260}Md. Therefore, trends in the dynamical changes of fission properties have been derived from these studies. For the spontaneous fission of {sup 252}Cf and {sup 260}Md, it was already shown that different fission modes, as proposed by theoretical calculations of Brosa et al. (5), could be separated, using the correlation between the neutrons emitted in a fission event and both the observed fission-fragment mass and the total kinetic energy (1, 2). In the case of {sup 257}Fm, no theoretical calculations for fission modes exist. However, from the fission properties of the two surrounding actinides, one can expect at least three different fission modes, namely two 'standard' and the 'supershort' mode. In this paper, results from the recent {sup 257}Fm experiment will be presented and compared to systematics extracted from the fission properties of other heavy actinides.

  5. Measured microdosimetric spectra and therapeutic potential of boron neutron capture enhancement of 252Cf brachytherapy.

    PubMed

    Burmeister, J; Kota, C; Maughan, R L

    2005-09-01

    Californium-252 is a neutron-emitting radioisotope used as a brachytherapy source for radioresistant tumors. Presented here are microdosimetric spectra measured as a function of simulated site diameter and distance from applicator tube 252Cf sources. These spectra were measured using miniature tissue-equivalent proportional counters (TEPCs). An investigation of the clinical potential of boron neutron capture (BNC) enhancement of 252Cf brachytherapy is also provided. The absorbed dose from the BNC reaction was measured using a boron-loaded miniature TEPC. Measured neutron, photon and BNC absorbed dose components are provided as a function of distance from the source. In general, the absorbed dose results show good agreement with results from other measurement techniques. A concomitant boost to 252Cf brachytherapy may be provided through the use of the BNC reaction. The potential magnitude of this BNC enhancement increases with increasing distance from the source and is capable of providing a therapeutic gain greater than 30% at a distance of 5 cm from the source, assuming currently achievable boron concentrations.

  6. The content of 250Cf and 248Cm in 252Cf neutron sources and the effect on the neutron emission rate.

    PubMed

    Roberts, N J; Jones, L N

    2007-01-01

    One of the most common radionuclide neutron sources used for the calibration of detectors is (252)Cf. However, these sources also contain (250)Cf, which is present in the material from which the sources are made, and (248)Cm, which is formed as the daughter of (252)Cf via alpha-decay. Both decay by spontaneous fission with longer half-lives than (252)Cf. Consequently, as the source becomes older, the emission rate does not follow the decay curve of (252)Cf. Fits have been made to emission rate measurements of (252)Cf sources at NPL spanning over 30 y to deduce their (250)Cf and (248)Cm content. The emission rate of a source can be significantly underestimated if the presence of (250)Cf and (248)Cm is not taken into account, and this has been investigated for a typical (252)Cf source. The importance of this problem to other calibration laboratories and users of (252)Cf sources is emphasised.

  7. 252Cf spectrum-averaged cross section for the 63Cu(n, p)63Ni reaction

    NASA Astrophysics Data System (ADS)

    Imamura, M.; Shibata, T.; Shibata, S.; Ohkubo, T.; Satoh, S.; Nogawa, N.

    1999-01-01

    The 63Ni produced by the 63Cu(n, p)63Ni reaction provides a unique measure to estimate the fast-neutron fluence of the Hiroshima/Nagasaki atomic bomb. In the similarity of the fission neutron spectrum of 252Cf to that of 235U, we have measured activation cross sections of the 63Cu(n, p)63Ni reaction averaged for the 252Cf fission spectrum.

  8. Comparison of fission modes in {sup 252}Cf, {sup 257}Fm, and {sup 260}Md

    SciTech Connect

    van Aarle, J.; Siemon, K.; Patzelt, P.; Wild, J.F.; Lougheed, R.W.; Westmeier, W.

    1998-10-01

    Although the spontaneous-fission properties of heavy actinides have been studied for well over 35 years, many interesting and informative details continue to come into light. During the last decade, the spontaneous fission of {sup 252}Cf, {sup 257}Fm and {sup 260}Md has been extensively investigated at the Philipps University of Marburg (1{endash}4), by means of a gadolinium-doped liquid scintillation tank for neutron counting and surface barrier detectors for fission fragment detection. The three nuclides represent the transition from the well-known asymmetric fission yield distribution, as it is characteristic for {sup 252}Cf, to a much more symmetrical one, found in the fission of {sup 260}Md. Therefore, trends in the dynamical changes of fission properties have been derived from these studies. For the spontaneous fission of {sup 252}Cf and {sup 260}Md, it was already shown that different fission modes, as proposed by theoretical calculations of Brosa et al. (5), could be separated, using the correlation between the neutrons emitted in a fission event and both the observed fission-fragment mass and the total kinetic energy (1, 2). In the case of {sup 257}Fm, no theoretical calculations for fission modes exist. However, from the fission properties of the two surrounding actinides, one can expect at least three different fission modes, namely two {open_quotes}standard{close_quotes} and the {open_quotes}supershort{close_quotes} mode. In this paper, results from the recent {sup 257}Fm experiment will be presented and compared to systematics extracted from the fission properties of other heavy actinides. {copyright} {ital 1998 American Institute of Physics.}

  9. Identification of high spin states in {sup 134}I from {sup 252}Cf fission

    SciTech Connect

    Liu, S. H.; Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Daniel, A. V.; Ter-Akopian, G. M.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.; Ma, W. C.

    2009-06-15

    High spin states in {sup 134}I were identified for the first time based on measurements of prompt {gamma} rays from the spontaneous fission of {sup 252}Cf at Gammasphere. Five excited levels with five deexciting transitions were observed. The mass number was assigned based on the intensity of transitions in the complementary Rh fragments. Angular correlations for the first two transitions in {sup 134}I and for high spin states in {sup 133,135,136}I were performed, but were not sufficient to firmly assign the spins and parities in {sup 134}I.

  10. Measurement and calculation of the emission anisotropy of an X1 252Cf neutron source.

    PubMed

    Hawkes, N P; Freedman, R; Tagziria, H; Thomas, D J

    2007-01-01

    The authors have measured the emission anisotropy from a (252)Cf spontaneous fission neutron source in an X1 encapsulation. The measurements were made in a large low-scatter laboratory using a long counter, and data were taken at angles varying in 10 degrees steps from 0 degrees to 180 degrees relative to the cylindrical axis of the source. Corrections were made for room scatter, loss of neutrons due to air scatter and detector dead time. Calculations corresponding to these measurements were subsequently carried out using the two Monte Carlo codes MCNP and MCBEND, and the results are compared with the measurements and with each other.

  11. A new facility for non-destructive assay using a 252Cf source.

    PubMed

    Stevanato, L; Caldogno, M; Dima, R; Fabris, D; Hao, Xin; Lunardon, M; Moretto, S; Nebbia, G; Pesente, S; Pino, F; Sajo-Bohus, L; Viesti, G

    2013-03-01

    A new laboratory facility for non-destructive analysis (NDA) using a time-tagged (252)Cf source is presented. The system is designed to analyze samples having maximum size of about 20 × 25 cm(2), the material recognition being obtained by measuring simultaneously total and energy dependent transmission of neutrons and gamma rays. The equipment technical characteristics and performances of the NDA system are presented, exploring also limits due to the sample thickness. Some recent applications in the field of cultural heritage are presented. PMID:23276691

  12. Test and evaluation results of the /sup 252/Cf shuffler at the Savannah River Plant

    SciTech Connect

    Crane, T.W.

    1981-03-01

    The /sup 252/Cf Shuffler, a nondestructive assay instrument employing californium neutron source irradiation and delayed-neutron counting, was developed for measuring /sup 235/U content of scrap and waste items generated at the Savannah River Plant (SRP) reactor fuel fabrication facility. The scrap and waste items include high-purity uranium-aluminum alloy ingots as well as pieces of castings, saw and lathe chips from machining operations, low-purity items such as oxides of uranium or uranium intermixed with flux materials found in recovery operations, and materials not recoverable at SRP such as floor sweepings or residues from the uranium scrap recovery operation. The uranium contains about 60% /sup 235/U with the remaining isotopes being /sup 236/U, /sup 238/U, and /sup 234/U in descending order. The test and evaluation at SRP concluded that the accuracy, safety, reliability, and ease of use made the /sup 252/Cf Shuffler a suitable instrument for routine use in an industrial, production-oriented plant.

  13. Bremsstrahlung emission of high energy accompanying spontaneous fission of {sup 252}Cf

    SciTech Connect

    Maydanyuk, S. P.; Olkhovsky, V. S.; Mandaglio, G.; Manganaro, M.; Fazio, G.; Giardina, G.

    2010-07-15

    The study of the bremsstrahlung photon emission accompanying fragments produced in the spontaneous fission of heavy nuclei by a fully quantum approach is presented for the first time. This kind of problem requires the knowledge of wave functions of the fissioning system leading to a wide distribution of couples of fragments that are the products of fission. With the aim of obtaining these wave functions, the interaction potential between the emitted fragment and residual nucleus is calculated by a standard approach. A new procedure was performed that allows an increase in the accuracy of calculations of radial integrals in the far asymptotic region and the achievement of the convenient convergence in calculations of the spectra. The total probability of the emitted photons in the spontaneous fission of {sup 252}Cf was calculated in such a way. We obtained good agreement between theory and experimental data up to 38 MeV for the bremsstrahlung spectrum of photons while the calculation of the total probability of photon emission accompanying fragments was performed up to an energy of 60 MeV. The analysis of contributions in the bremsstrahlung spectrum accompanying the emission of light, medium, and heavy fragments in the fission of {sup 252}Cf is presented.

  14. Brain tumour and infiltrations dosimetry of boron neutron capture therapy combined with 252Cf brachytherapy.

    PubMed

    Brandão, Sâmia F; Campos, Tarcísio P R

    2012-04-01

    This article presents a dosimetric investigation of boron neutron capture therapy (BNCT) combined with (252)Cf brachytherapy for brain tumour control. The study was conducted through computational simulation in MCNP5 code, using a precise and discrete voxel model of a human head, in which a hypothetical brain tumour was incorporated. A boron concentration ratio of 1:5 for healthy-tissue: tumour was considered. Absorbed and biologically weighted dose rates and neutron fluency in the voxel model were evaluated. The absorbed dose rate results were exported to SISCODES software, which generates the isodose surfaces on the brain. Analyses were performed to clarify the relevance of boron concentrations in occult infiltrations far from the target tumour, with boron concentration ratios of 1:1 up to 1:50 for healthy-tissue:infiltrations and healthy-tissue:tumour. The average biologically weighted dose rates at tumour area exceed up to 40 times the surrounding healthy tissue dose rates. In addition, the biologically weighted dose rates from boron have the main contribution at the infiltrations, especially far from primary tumour. In conclusion, BNCT combined with (252)Cf brachytherapy is an alternative technique for brain tumour treatment because it intensifies dose deposition at the tumour and at infiltrations, sparing healthy brain tissue.

  15. Radioactive Beams from 252Cf Fission Using a Gas Catcher and an ECR Charge Breeder at ATLAS

    SciTech Connect

    Savard, Guy; Pardo, Richard C.; Moore, E. Frank; Hecht, Adam A.; Baker, Sam

    2005-03-15

    A proposed upgrade to the radioactive beam capability of the ATLAS facility has been proposed using 252Cf fission fragments thermalized and collected into a low-energy particle beam using a helium gas catcher. In order to reaccelerate these beams the ATLAS ECR-I will be reconfigured as a charge breeder source. A 1Ci 252Cf source is expected to provide sufficient yield to deliver beams of up to {approx}103 far from stability ions per second on target. A brief facility description and the expected performance information are provided in this report.

  16. Application of 252Cf plasma desorption mass spectrometry in dental research

    NASA Astrophysics Data System (ADS)

    Fritsch, Hans-Walter; Schmidt, Lothar; Köhl, Peter; Jungclas, Hartmut; Duschner, Heins

    1993-07-01

    Topically applied fluorides introduced in dental hygiene products elevate the concentration levels of fluoride in oral fluids and thus also affect chemical reactions of enamel de- and remineralisation. The chemical reactions on the surface of tooth enamel still are a subject of controversy. Here 252Cf-plasma desorption mass spectrometry and argon ion etching are used to analyse the molecular structure of the upper layes of enamel. The mass spectrum of untreated enamel is characterised by a series of cluster ions containing phosphate. It is evident that under certain conditions the molecular structure of the surface enamel is completely transformed by treatment with fluorides. The result of the degradation and precipitation processes is reflected by a total replacement of the phosphate by fluoride in the measured cluster ion distribution. Stepwise etching of the upper layers by Ar+ ions reveals the transition from a nearly pure CaF2 structure to the unchanged composition of the enamel mineral.

  17. Relative Yields of 149-153Pr in Spontaneous Fission of 252Cf

    NASA Astrophysics Data System (ADS)

    Eldridge, Jonathan; Wang, Enhong; Hwang, J. K.; Hamilton, Joe; Ramayya, A. V.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.; Liu, S. H.; Ter-Akopian, G. M.; Oganessian, Yu. Ts.

    2013-10-01

    The relative yields of the fission partners of 149-153Pr, resulting from the spontaneous fission of 252Cf, were studied. This study was done by means of γ - γ - γ , and γ - γ - γ - γ coincidence data taken in 2000 by the multi-HPGe, Compton-suppressed, gamma detector array, Gammasphere, at Lawrence Berkeley National Lab. The coincidence data were analyzed by double- and triple-gating on transitions in 149-153Pr and obtaining the intensities of the 93-101Y transitions. For 150 , 151 , 152 , 153Pr the 3n channel was found to be the strongest. The 149Pr, however, was found to peak at the 4n channel. These results were used to verify the assignments of the level schemes of 151 , 152 , 153Pr. The data are found to be in agreement with Wahl's independent yield tables.

  18. Characteristics of the simulated workplace neutron fields using a 252Cf source surrounded with cylindrical moderators.

    PubMed

    Tsujimura, N; Yoshida, T

    2004-01-01

    The authors established the simulated workplace neutron fields using a 252Cf source surrounded with cylindrical moderators at the Japan Nuclear Cycle Development Institute (JNC), Tokai Works. The moderators are annular cylinders made of polymethyl methacrylate and steel. The neutron energy spectrum at the reference calibration point was evaluated from the calculations by MCNP-4B and the measurements by the Bonner multisphere spectrometer and the hydrogen-filled proportional counters. The calculated neutron spectra were in good agreements with the measured ones. These fields can provide the realistic neutron spectra similar to those encountered around the glove-boxes of the fabrication process of MOX (PuO2-UO2 mixed oxide) fuel.

  19. On the Effect of an Error in a Standard D2O-Moderated 252Cf Energy Spectrum

    SciTech Connect

    Frederick Cummings

    2009-12-01

    There appears to be an error in the neutron fluence for neutrons with energies between 9 and 10 MeV for the tabulated D2O-moderated 252Cf source in ISO 8529-1. The error contributes a total error to neutron dose values from this source of approximately 3%.

  20. A new facility for Non-Destructive Assay with a time-tagged {sup 252}Cf source

    SciTech Connect

    Stevanato, L.; Caldogno, M.; Hao Xin; Dima, R.; Fabris, D.; Nebbia, G.; Lunardon, M.; Moretto, S.; Pesente, S.; Viesti, G.; Sajo-Bohus, L.

    2010-08-04

    A new facility for non-destructive assay using a time-tagged {sup 252}Cf source is presented. The system is designed to analyze samples having maximum size of about 15x20 cm{sup 2}, the material recognition being obtained by measuring simultaneously transmission of neutrons and gamma rays.

  1. All possible ternary fragmentations of {sup 252}Cf in collinear configuration

    SciTech Connect

    Manimaran, K.; Balasubramaniam, M.

    2011-03-15

    All possible ternary fragmentations in fission of {sup 252}Cf are studied in collinear configuration within a spherical approximation using the recently proposed ''three cluster model.'' The potential energy surface of collinear configuration exhibits a strong valley around {sup 48}Ca and its neighboring nuclei {sup 50}Ca, {sup 54}Ti, and {sup 60}Cr. Such strong minima are not seen in the potential energy surface of an equatorial configuration. As a consequence of strong minima in the potential, the overall relative yield is higher for the ternary fragmentation with {sup 48}Ca, {sup 50}Ca, {sup 54}Ti, {sup 60}Cr, and {sup 82}Ge as the third fragment. The results of potential energy and relative yield calculations reveal that collinear configuration increases the probability of emission of heavy fragments like {sup 48}Ca (doubly magic nucleus) and its neighboring nuclei as the third fragment. The obtained results indicate that the collinear configuration is the preferred configuration for intermediate nuclei ({sup 48}Ca, {sup 50}Ca, {sup 54}Ti, and {sup 60}Cr) as the third fragment in particle accompanied fission while the equatorial configuration may be a preferred configuration for light nuclei ({sup 4}He, {sup 10}Be) as the third fragment.

  2. Structures of the neutron-rich nuclei observed in fission of {sup 252}Cf

    SciTech Connect

    Ramayya, A. V.; Hamilton, J. H.; Goodin, C. J.; Brewer, N. T.; Hwang, J. K.; Luo, Y. X.; Liu, S. H.; Stone, N. J.; Daniel, A. V.; Zhu, S. J.

    2014-08-14

    Analysis of high statistics triple coincidence fission γ data from {sup 252}Cf at Gammasphere including angular correlations yielded well-expanded high-spin level schemes with more complete and reliable spin/parity assignments for {sup 82}Ge, {sup 118,120,122}Cd and {sup 114,115}Rh. Both the quasi-particle/hole couplings and quasi-rotational degrees of freedom are implied to play roles in these Cd isotopes. Evidence for triaxial shapes and octupole components in the Cd isotopes is presented. These Cd isotopes may have triaxial deformations. High-spin level schemes of {sup 114,115}Rh have been established for the first time. The existence of a relatively large signature splitting and an yrare band shows typical features of a triaxially deformed nucleus. Possible excited deformed rotational bands are observed, for the first time, in {sup 82}Ge. From the multipole mixing ratio measurement, the ground state configurations of {sup 109,111}Ru, as well as excited states in {sup 103,107}Mo and {sup 111}Ru were determined.

  3. beta. -delayed fission from /sup 256/Es/sup m/ and the level scheme of /sup 256/Fm

    SciTech Connect

    Hall, H.L.; Gregorich, K.E.; Henderson, R.A.; Lee, D.M.; Hoffman, D.C.; Bunker, M.E.; Fowler, M.M.; Lysaght, P.; Starner, J.W.; Wilhelmy, J.B.; and others

    1989-05-01

    The 7.6-h isotope /sup 256/Es/sup m/ was produced from a 2.5-..mu..g/cm/sup 2/ target of /sup 254/Es by the (t,p) reaction. The reaction products were separated radiochemically, and the decay properties of /sup 256/Es/sup m/ were determined via ..beta..-..gamma.., ..gamma..-..gamma.., and ..beta..-fission correlation techniques. From these measurements we were able to assign 57 ..gamma.. rays to 26 levels in the daughter /sup 256/Fm. An isomeric level was observed at 1425 keV and assigned a spin and parity of 7/sup -/. This level has a t/sub 1/2/ of (70 +- 5) ns and we observed two ..beta..-delayed fissions with delay times in the proper time range to be associated with fission from this level. This gives a ..beta..-delayed fission probability of 2 x 10/sup -5/ for this level and a partial fission half-life of 0.8/sub -0.7//sup +8.8/ ms at the 95% confidence level.

  4. Absolute measurement of anti. nu. /sub p/ for /sup 252/Cf using the ORNL large liquid scintillator neutron detector

    SciTech Connect

    Spencer, R.R.; Gwin, R.; Ingle, R.

    1981-08-01

    The ORNL large liquid scintillator detector was used in a precise determination of anti ..nu../sub p/, the number of neutrons emitted promptly, for spontaneous fission of /sup 252/Cf. Measurements of the detector efficiency over a broad energy region were made by means of a proton-recoil technique employing the ORELA white neutron source. Monte Carlo calculation of the detector efficiency for a spectrum representative of /sup 252/Cf fission neutrons was calibrated with these elaborate measurements. The unusually flat response of the neutron detector resulted in elimination of several known sources of error. Experimental measurement was coupled with calculational methods to correct for other known errors. These measurements lead to an unusually small estimated uncertainty of 0.2% in the value obtained, anti ..nu../sub p/ = 3.773 +- 0.007.

  5. Fabrication of 50-mg /sup 252/Cf neutron sources for the FDA (Food and Drug Administration) activation analysis facility

    SciTech Connect

    Bigelow, J.E.; Cagle, E.B.; Knauer, J.B.

    1987-01-01

    The Transuranium Processing Plant (TPP) at ORNL has been requested by the Food and Drug Administration (FDA) to furnish 200 mg of /sup 252/Cf for use in their new activation analysis facility. This paper discusses the procedure to be employed in fabricating the californium into four neutron sources, each containing a nominal 50-mg of /sup 252/Cf. The ORNL Model LSD (Large, Stainless steel, Doubly encapsulated) neutron source consists of a 6.33-mm-diam aluminum pellet doubly encapsulated in Type 304L stainless steel. The pellet is comprised of an aluminum tube holding Cf/sub 2/O/sub 2/SO/sub 4/ microspheres confined by pressed aluminum powder. The microspheres are prepared in a separate vessel and then transferred into the specially designed aluminum tube prior to pressing.

  6. The sup 252 Cf(sf) neutron spectrum in the 5- to 20-MeV energy range

    SciTech Connect

    Marten, H.; Richter, D.; Seeliger, D. ); Fromm, W.D. ); Bottger, R.; Klein, H. )

    1990-11-01

    This paper reports on the {sup 252}Cf neutron spectrum measured at high energies with a miniature ionization chamber and two different NE-213 neutron detectors. The gamma-ray background and the main cosmic background caused by muons were suppressed by applying efficient pulse-shape discrimination. On the basis of two-dimensional spectroscopy of the neutron time-of-flight and scintillation pulse height, the sliding bias method is used to minimize experimental uncertainties. The experimental data, corrected for several systematic influences, confirm earlier results that show negative deviations from a reference Maxwellian distribution with a 1.42-MeV spectrum temperature for neutron energies above 6 MeV. Experimental results of this work are compared with various statistical model approaches to the {sup 252}Cf(sf) neutron spectrum.

  7. Evaluation of the characteristics of the neutron reference field using D2O-moderated 252Cf source.

    PubMed

    Kowatari, M; Fujii, K; Takahashi, M; Yoshizawa, M; Shimizu, S; Kawasaki, K; Yamaguchi, Y

    2007-01-01

    The ambient/personal dose equivalent per fluence for D(2)O moderated (252)Cf neutron source was determined by measurement. An appropriate subtraction of the scattered neutrons is required for the accurate measurement of direct neutrons. A cubic shadow object was used for the subtraction of the scattered neutrons from the surroundings. The scattered neutrons to be subtracted vary with the position of the shadow object due to the large volume of the source. Using the Monte Carlo code MCNP-4C, the optimum positions of the shadow object were surveyed for subtracting the scattered neutrons. The energy spectra of direct neutrons were measured in the optimum position. The dosimetric parameters for the D(2)O moderated (252)Cf neutron source were reasonable, taking into account the uncertainties of the parameters.

  8. A New Facility For Non-Destructive Assay With A Time-Tagged {sup 252}Cf Source

    SciTech Connect

    Stevanato, L.; Caldogno, M.; Hao, Xin; Dima, R.; Fabris, D.; Nebbia, G.; Lunardon, M.; Moretto, S.; Pesente, S.; Viesti, G.; Sajo-Bohus, L.

    2011-06-01

    A new facility for Non-Destructive Assay based on a time-tagged {sup 252}Cf spontaneous fission source is now in operation at the Padova University. The system is designed to analyze samples with dimensions on the order of 20x20 cm{sup 2}, the material recognition being obtained by measuring simultaneously transmission of neutrons and gamma rays as a function of energy.

  9. Intracavitary moderator balloon combined with 252Cf brachytherapy and boron neutron capture therapy, improving dosimetry in brain tumour and infiltrations

    PubMed Central

    Brandão, S F

    2015-01-01

    Objective: This article proposes a combination of californium-252 (252Cf) brachytherapy, boron neutron capture therapy (BNCT) and an intracavitary moderator balloon catheter applied to brain tumour and infiltrations. Methods: Dosimetric evaluations were performed on three protocol set-ups: 252Cf brachytherapy combined with BNCT (Cf-BNCT); Cf-BNCT with a balloon catheter filled with light water (LWB) and the same set-up with heavy water (HWB). Results: Cf-BNCT-HWB has presented dosimetric advantages to Cf-BNCT-LWB and Cf-BNCT in infiltrations at 2.0–5.0 cm from the balloon surface. However, Cf-BNCT-LWB has shown superior dosimetry up to 2.0 cm from the balloon surface. Conclusion: Cf-BNCT-HWB and Cf-BNCT-LWB protocols provide a selective dose distribution for brain tumour and infiltrations, mainly further from the 252Cf source, sparing the normal brain tissue. Advances in knowledge: Malignant brain tumours grow rapidly and often spread to adjacent brain tissues, leading to death. Improvements in brain radiation protocols have been continuously achieved; however, brain tumour recurrence is observed in most cases. Cf-BNCT-LWB and Cf-BNCT-HWB represent new modalities for selectively combating brain tumour infiltrations and metastasis. PMID:25927876

  10. True ternary fission, the collinear cluster tripartition (CCT) of {sup 252}Cf

    SciTech Connect

    Oertzen, W. von; Pyatkov, Y. V.; Kamanin, D.

    2012-10-20

    In systematic work over the last decade (see Pyatkov et al. [12] and refs therein), the ternary fission decay of heavy nuclei, in {sup 235}U(n,fff) and {sup 252}Cf(sf) has been studied in a collinear geometry. The name used for this process is (CCT), with three fragments of similar size in a collinear decay, it is the true ternary fission. This decay has been observed in spontaneous fission as well as in a neutron induced reaction. The measurements are based on different experimental set-ups, with binary coincidences containing TOF and energy determinations. With two detector telescopes placed at 180 Degree-Sign , the measurements of masses and energies of each of the registered two fragments, give complete kinematic solutions. Thus the missing mass events in binary coincidences can be determined, these events are obtained by blocking one of the lighter fragments on a structure in front of the detectors. The relatively high yield of CCT (more than 10{sup -3} per binary fission) is explained. It is due to the favourable Q-values (more positive than for binary) and the large phase space of the ternary CCT-decay, dominated by three (magic) clusters: e.g. isotopes of Sn, Ca and Ni, {sup 132}Sn+{sup 50}Ca+{sup 70}Ni. It is shown that the collinear (prolate) geometry has the favoured potential energy relative to the oblate shapes. The ternary fission is considered to be a sequential process. With this assumption the kinetic energies of the fragments have been calculated by Vijay et al.. The third fragments have very low kinetic energies (below 20 MeV) and have thus escaped their detection in previous work on 'ternary fission', where in addition an oblate shape and a triangle for the momentum vectors have been assumed.

  11. True ternary fission, the collinear cluster tripartition (CCT) of 252Cf

    NASA Astrophysics Data System (ADS)

    von Oertzen, W.; Pyatkov, Y. V.; Kamanin, D.

    2012-10-01

    In systematic work over the last decade (see Pyatkov et al. [12] and refs therein), the ternary fission decay of heavy nuclei, in 235U(n,fff) and 252Cf(sf) has been studied in a collinear geometry. The name used for this process is (CCT), with three fragments of similar size in a collinear decay, it is the true ternary fission. This decay has been observed in spontaneous fission as well as in a neutron induced reaction. The measurements are based on different experimental set-ups, with binary coincidences containing TOF and energy determinations. With two detector telescopes placed at 180°, the measurements of masses and energies of each of the registered two fragments, give complete kinematic solutions. Thus the missing mass events in binary coincidences can be determined, these events are obtained by blocking one of the lighter fragments on a structure in front of the detectors. The relatively high yield of CCT (more than 10-3 per binary fission) is explained. It is due to the favourable Q-values (more positive than for binary) and the large phase space of the ternary CCT-decay, dominated by three (magic) clusters: e.g. isotopes of Sn, Ca and Ni, 132Sn+50Ca+70Ni. It is shown that the collinear (prolate) geometry has the favoured potential energy relative to the oblate shapes. The ternary fission is considered to be a sequential process. With this assumption the kinetic energies of the fragments have been calculated by Vijay et al. [1]. The third fragments have very low kinetic energies (below 20 MeV) and have thus escaped their detection in previous work on "ternary fission", where in addition an oblate shape and a triangle for the momentum vectors have been assumed.

  12. Kinetic energy deficit in the symmetric fission of /sup 259/Md. [Light particle emission in /sup 256/Fm fission

    SciTech Connect

    Hulet, E.K.; Wild, J.F.; Lougheed, R.W.; Baisden, P.A.; Dougan, R.J.; Mustafa, M.G.

    1980-10-01

    The fragment energies of about 725 coincidence events have now been observed in the spontaneous fission (SF) decay of 105-min /sup 259/Md since its discovery in 1977. The fission of /sup 259/Md is characterized by a symmetric mass distribution, similar to those of /sup 258/Fm and /sup 259/Fm, but with a broad total kinetic energy (anti TKE) distribution which peaks at about 195 MeV, in contrast to those of /sup 258/Fm and /sup 259/Fm, for which the anti TKE is about 240 MeV. This kinetic energy deficit, approx. 40 MeV, has been postulated to be due to the emission of hydrogen-like particles by /sup 259/Md at the scission point in a large fraction of the fissions, leaving the residual fissioning nucleus with 100 protons. The residual nucleus would then be able to divide into two ultrastable tin-like fission fragments, but with less kinetic energy than that observed in the SF of /sup 258/Fm and /sup 259/Fm, because of binding-energy losses and a reduction in the Coulomb repulsion of the major fragments. To test this hypothesis, counter-telescope experiments aimed at detecting and identifying these light particles were performed. In 439 SF events 3 + 3 protons of the appropriate energy were observed, too few to account for the kinetic energy deficit in the fission of /sup 259/Md. There seems to be no explanation for this problem within the framework of current fission theory. These results are discussed along with preliminary measurements of light-particle emission in the SF of /sup 256/Fm. 5 figures.

  13. Determining the half-lives of /sup 253/Es, /sup 254/Es, /sup 254m/Es, /sup 255/Es, /sup 257/Es, /sup 256/Fm

    SciTech Connect

    Popov, Yu.S.; Timofeev, G.A.; Mishenev, V.B.; Kovantsev, V.N.; Elesin, A.A.

    1988-03-01

    Semiconductor alpha, gamma, and x-ray spectrometry has been used to identify einsteinium and fermium isotopes having mass numbers 253-257 in californium targets irradiated in the central channel of the high-flux SM-2 reactor. Half-life measurements have been made for /sup 253/Es, /sup 254/Es, /sup 254m/Es, /sup 255/Es, /sup 257/Es, /sup 256/Fm. The measurements are compared with published data.

  14. Coal liquefaction process streams characterization and evaluation: The application of {sup 252}Cf-plasma desorption mass spectrometry to analysis of direct coal liquefaction heavy products

    SciTech Connect

    Larsen, J.W.; Lapucha, A.R.

    1992-10-01

    This study demonstrated the feasibility of using {sup 252}Cf PDMS, GPC, and MPLC for the examination of the tetrahydrofuran (THF)-soluble portion of distillation resid materials derived from direct coal liquefaction. The {sup 252}Cf-PDMS technique was used to determine molecular weight distributions of twenty-five THF-soluble resids. In order to detemine if {sup 252}Cf-PDMS responds differently to different chemical classes of compounds, Lehigh separated five of the samples into chemically distinct fractions by MPLC, then analyzed the parent samples, their fractions, and the re-mixed fractions by {sup 252}Cf-PDMS and GPC. Irreversible alteration of the samples upon separation was noted by Lehigh. This was confirmed by use of gas chromatographic (GC) analyses. The noted irreversible alterations prevented a direct comparison of the remixed materials and the original samples. Thus, the selective response of {sup 252}Cf-PDMS to different chemical classes of compounds could not be confirmed or ruled out. The number average molecular weights (M{sub n}) obtained by {sup 252}Cf-PDMS and GPC agreed well. However, the weight average molecular weights (M{sub w}) obtained by GPC are always higher than the corresponding {sup 252}Cf-PDMS results. Number average molecular weights and weight average molecular weights obtained with {sup 252}Cf-PDMS and GPC were compared with those obtained by field ionization mass spectrometry (FIMS), previously reported by SRI International for the parent resid samples from which the Lehigh THF-soluble samples were derived.

  15. Coal liquefaction process streams characterization and evaluation: The application of [sup 252]Cf-plasma desorption mass spectrometry to analysis of direct coal liquefaction heavy products

    SciTech Connect

    Larsen, J.W.; Lapucha, A.R.

    1992-10-01

    This study demonstrated the feasibility of using [sup 252]Cf PDMS, GPC, and MPLC for the examination of the tetrahydrofuran (THF)-soluble portion of distillation resid materials derived from direct coal liquefaction. The [sup 252]Cf-PDMS technique was used to determine molecular weight distributions of twenty-five THF-soluble resids. In order to detemine if [sup 252]Cf-PDMS responds differently to different chemical classes of compounds, Lehigh separated five of the samples into chemically distinct fractions by MPLC, then analyzed the parent samples, their fractions, and the re-mixed fractions by [sup 252]Cf-PDMS and GPC. Irreversible alteration of the samples upon separation was noted by Lehigh. This was confirmed by use of gas chromatographic (GC) analyses. The noted irreversible alterations prevented a direct comparison of the remixed materials and the original samples. Thus, the selective response of [sup 252]Cf-PDMS to different chemical classes of compounds could not be confirmed or ruled out. The number average molecular weights (M[sub n]) obtained by [sup 252]Cf-PDMS and GPC agreed well. However, the weight average molecular weights (M[sub w]) obtained by GPC are always higher than the corresponding [sup 252]Cf-PDMS results. Number average molecular weights and weight average molecular weights obtained with [sup 252]Cf-PDMS and GPC were compared with those obtained by field ionization mass spectrometry (FIMS), previously reported by SRI International for the parent resid samples from which the Lehigh THF-soluble samples were derived.

  16. Detailed Study of the Angular Correlations in the Prompt Neutron Emission in Spontaneous Fission of 252Cf

    NASA Astrophysics Data System (ADS)

    Kopatch, Yu.; Chietera, A.; Stuttgé, L.; Gönnenwein, F.; Mutterer, M.; Gagarski, A.; Guseva, I.; Chernysheva, E.; Dorvaux, O.; Hambsch, F.-J.; Hanappe, F.; Mezentseva, Z.; Telezhnikov, S.

    An experiment has been performed at IPHC Strasbourg, aimed at the detailed investigation of angular correlations in the neutron emission from spontaneous fission of 252Cf. Fission fragments were measured by the angle-sensitive double ionization chamber CODIS while neutrons were detected by a set of 60 DEMON scintillator counters. The main aim of the experiment is the observation of the correlation between the fragment spins and neutron emission anisotropy. Preliminary results, based on the Monte-Carlo simulations, as well as the preliminary analysis of the experimental data are shown.

  17. Replacing a 252Cf source with a neutron generator in a shuffler - a conceptual design performed with MCNPX

    SciTech Connect

    Schear, Melissa A; Tobin, Stephen J

    2009-01-01

    The {sup 252}Cf shuffler has been widely used in nuclear safeguards and radioactive waste management to assay fissile isotopes, such as {sup 235}U or {sup 239}Pu, present in a variety of samples, ranging from small cans of uranium waste to metal samples weighing several kilograms. Like other non-destructive assay instruments, the shuffler uses an interrogating neutron source to induce fissions in the sample. Although shufflers with {sup 252}Cf sources have been reliably used for several decades, replacing this isotopic source with a neutron generator presents some distinct advantages. Neutron generators can be run in a continuous or pulsed mode, and may be turned off, eliminating the need for shielding and a shuffling mechanism in the shuffler. There is also essentially no dose to personnel during installation, and no reliance on the availability of {sup 252}Cf. Despite these advantages, the more energetic neutrons emitted from the neutron generator (141 MeV for D-T generators) present some challenges for certain material types. For example when the enrichment of a uranium sample is unknown, the fission of {sup 238}U is generally undesirable. Since measuring uranium is one of the main uses of a shuffler, reducing the delayed neutron contribution from {sup 238}U is desirable. Hence, the shuffler hardware must be modified to accommodate a moderator configuration near the source to tailor the interrogating spectrum in a manner which promotes sub-threshold fissions (below 1 MeV) but avoids the over-moderation of the interrogating neutrons so as to avoid self-shielding. In this study, where there are many material and geometry combinations, the Monte Carlo N-Particle eXtended (MCNPX) transport code was used to model, design, and optimize the moderator configuration within the shuffler geometry. The code is then used to evaluate and compare the assay performances of both the modified shuffler and the current {sup 252}Cf shuffler designs for different test samples. The

  18. Status of the electron cyclotron resonance charge breeder for the {sup 252}Cf fission source project at ATLAS

    SciTech Connect

    Vondrasek, R. C.; Scott, R.; Carr, J.; Pardo, R. C.

    2008-02-15

    The construction of the Californium Rare Ion Breeder Upgrade, a new radioactive beam facility for the Argonne tandem linac accelerator system (ATLAS), is in progress. The facility will use fission fragments from a 1 Ci {sup 252}Cf source, thermalized and collected into a low-energy particle beam by a helium gas catcher. In order to reaccelerate these beams, the existing ATLAS ECR1 ion source has been redesigned to function as a charge breeder source. The design features, initial results, and status of this charge breeder configuration are presented.

  19. 252Cf fission-neutron spectrum using a simplified time-of-flight setup: An advanced teaching laboratory experiment

    NASA Astrophysics Data System (ADS)

    Becchetti, F. D.; Febbraro, M.; Torres-Isea, R.; Ojaruega, M.; Baum, L.

    2013-02-01

    The removal of PuBe and AmBe neutron sources from many university teaching laboratories (due to heightened security issues) has often left a void in teaching various aspects of neutron physics. We have recently replaced such sources with sealed 252Cf oil-well logging sources (nominal 10-100 μCi), and developed several experiments using them as neutron sources. This includes a fission-neutron time-of-flight experiment using plastic scintillators, which utilizes the prompt γ rays emitted in 252Cf spontaneous fission as a fast timing start signal. The experiment can be performed with conventional nuclear instrumentation and a 1-D multi-channel pulse-height analyzer, available in most advanced teaching laboratories. Alternatively, a more sophisticated experiment using liquid scintillators and n/γ pulse-shape discrimination can be performed. Several other experiments using these neutron sources are also feasible. The experiments can introduce students to the problem of detecting the dark matter thought to dominate the universe and to the techniques used to detect contraband fissionable nuclear materials.

  20. The collinear cluster tri-partition (CCT) of 252Cf (sf): New aspects from neutron gated data

    NASA Astrophysics Data System (ADS)

    Pyatkov, Yu. V.; Kamanin, D. V.; von Oertzen, W.; Alexandrov, A. A.; Alexandrova, I. A.; Falomkina, O. V.; Jacobs, N.; Kondratjev, N. A.; Kuznetsova, E. A.; Lavrova, Yu. E.; Malaza, V.; Ryabov, Yu. V.; Strekalovsky, O. V.; Tyukavkin, A. N.; Zhuchko, V. E.

    2012-07-01

    Results of two different experiments for the study of fission of 252Cf (sf) events in coincidence with neutrons are reported. Two time-of-flight-energy (TOF- E detectors systems have been used. The fission fragment masses were obtained in a double arm coincidence set-up, where the missing mass in the binary decay is used to characterise ternary fission as a collinear cluster tri-partition (CCT). The 3He filled neutron counters have been arranged so as to detect principally neutrons emitted from an isotropic source in the laboratory frame. The fission events connected to the larger experimental neutron multiplicities show a wide range in the missing-mass spectrum, down to α -particles, carbon and oxygen isotopes. These are linked with magic nuclei in the binary mass-mass correlations of the fission fragments. These neutron gated data are virtually free from background events from scattered binary fission fragments. The ungated spectra are compared to those of the previous data from our previous article (Eur. Phys. J. A. 45, 29 (2010)), the observed structures agree well with the manifestations of the collinear cluster tri-partition of 252Cf (sf) observed earlier. Several new families of the CCT modes are observed.

  1. In-beam gamma-ray spectroscopy of {sup 248,250,252}Cf by neutron-transfer reactions using a Cf target

    SciTech Connect

    Takahashi, R.; Ishii, T.; Asai, M.; Nagae, D.; Makii, H.; Tsukada, K.; Toyoshima, A.; Ishii, Y.; Matsuda, M.; Makishima, A.; Shizuma, T.; Kohno, T.; Ogawa, M.

    2010-05-15

    The ground-state bands of {sup 248,250,252}Cf have been established up to the 10{sup +}, 12{sup +}, and 10{sup +} states, respectively, by in-beam gamma-ray spectroscopy using neutron-transfer reactions with a 153-MeV {sup 18}O beam and a highly radioactive Cf target. The deexcitation gamma rays in {sup 248,250,252}Cf were identified by taking coincidences with outgoing particles of {sup 16-19}O measured with Si DELTAE-E detectors, and by selecting their kinetic energies. Moments of inertia of {sup 248,250,252}Cf were discussed in terms of the N=152 deformed shell gap.

  2. Description of the /sup 252/Cf(sf) neutron spectrum in the framework of a generalized Madland-Nix model

    SciTech Connect

    Marten, H.; Seeliger, D.

    1986-08-01

    The Madland-Nix model (MNM) for the calculation of fission neutron spectra is modified considering the dependence on fragment mass number A. Further, an approximation of this generalized Madland-Nix model (GMNM) that takes into account the different center-of-mass system spectra for the light and heavy fragment groups is discussed. These new calculations are compared with two versions of the original MNM. In particular, the level density parameter, which was adjusted by fitting the calculated spectra to a Maxwellian distribution deduced from experimental data, becomes more reasonable in the framework of the GMNM. The results of the different model calculations are compared with experimental data on the /sup 252/Cf(sf) neutron spectrum in the 0.1- to 20-MeV energy range.

  3. Characterization of neutron fields from bare and heavy water moderated (252)Cf spontaneous fission source using Bonner Sphere Spectrometer.

    PubMed

    Atanackovic, Jovica; Yonkeu, Andre; Dubeau, Jacques; Witharana, Sampath Hakmana; Priest, Nicholas

    2015-05-01

    In this work a calibrated Bonner Sphere Spectrometer (BSS), together with ISO shadow cones, was used to quantify the total and scattered components of bare and heavy water moderated (252)Cf neutron fields. All measurements were performed with a BSS that was calibrated at the National Physical Laboratory (NPL), Teddington, UK, which is a global primary standard laboratory and world-leading facility for neutron metrology and neutron instruments calibration. The fields were characterized for source-spectrometer distances of 80, 100, 150 and 200cm; and at heights of 103 and 200cm from the facility floor. As expected, the scattered contribution was greatest at the farthest distance from the source and closer to the floor. Hence, at a distance of 200cm and a height of 103cm, the scatter added to the direct field up to 162% of the total neutron fluence and up to 61% of the ambient dose equivalent, while at the same distance and height of 200cm above the floor, these values were up to 146% and 52%, respectively. In the case of heavy water moderated (252)Cf neutron fields, a shadow cone subtraction technique could not be implemented, however Monte Carlo simulations were utilized in order to differentiate between the direct and scatter components of the neutron fields. In this case, at a source-detector distance of 200cm and a height of 103cm, the scatter added to the direct field up to 148% of the total neutron fluence and up to 45% of the ambient dose equivalent, while at the same distance and a height of 200cm above the floor, these values were up to 134% and 42%, respectively.

  4. A feasibility study of [sup 252]Cf neutron brachytherapy, cisplatin + 5-FU chemo-adjuvant and accelerated hyperfractionated radiotherapy for advanced cervical cancer

    SciTech Connect

    Murayama, Y.; Wierzbicki, J. Univ. of Kentucky Medical Center, Lexington, KY ); Bowen, M.G.; Van Nagell, J.R.; Gallion, H.H.; DePriest, P. )

    1994-06-15

    The purpose was to evaluate the feasibility and toxicity of [sup 252]Cf neutron brachytherapy combined with hyperaccelerated chemoradiotherapy for Stage III and IV cervical cancers. Eleven patients with advanced Stage IIIB-IVA cervical cancers were treated with [sup 252]Cf neutron brachytherapy in an up-front schedule followed by cisplatin (CDDP; 50 mg/m[sup 2]) chemotherapy and hyperfractionated accelerated (1.2 Gy bid) radiotherapy given concurrently with intravenous infusion of 5-Fluorouracil (5-FU) (1000 mg/m[sup 2]/day [times] 4 days) in weeks 1 and 4 with conventional radiation (weeks 2, 3, 5, and 6). Total dose at a paracervical point A isodose surface was 80-85 Gy-eq by external and intracavitary therapy and 60 Gy at the pelvic sidewalls. Patients tolerated the protocol well. There was 91% compliance with the chemotherapy and full compliance with the [sup 252]Cf brachytherapy and the external beam radiotherapy. There were no problems with acute chemo or radiation toxicity. One patient developed a rectovaginal fistula (Grade 3-4 RTOG criteria) but no other patients developed significant late cystitis, proctitis or enteritis. There was complete response (CR) observed in all cases. With mean follow-up to 26 months, local control has been achieved with 90% actuarial 3-year survival with no evidence of disease (NED). [sup 252]Cf neutrons can be combined with cisplatin and 5-FU infusion chemotherapy plus hyperaccelerated chemoradiotherapy without unusual side effects or toxicity and with a high local response and tumor control rate. Further study of [sup 252]Cf neutron-chemoradiotherapy for advanced and bulky cervical cancer are indicated. The authors found chemotherapy was more effective with the improved local tumor control. 18 refs., 2 tabs.

  5. Benchmark Experiments of Thermal Neutron and Capture Gamma-Ray Distributions in Concrete Using {sup 252}Cf

    SciTech Connect

    Asano, Yoshihiro; Sugita, Takeshi; Hirose, Hideyuki; Suzaki, Takenori

    2005-10-15

    The distributions of thermal neutrons and capture gamma rays in ordinary concrete were investigated by using {sup 252}Cf. Two subjects are considered. One is the benchmark experiments for the thermal neutron and the capture gamma-ray distributions in ordinary concrete. The thermal neutron and the capture gamma-ray distributions were measured by using gold-foil activation detectors and thermoluminescence detectors. These were compared with the simulations by using the discrete ordinates code ANISN with two different group structure types of cross-section library of a new Japanese version, JENDL-3.3, showing reasonable agreement with both fine and rough structure groups of thermal neutron energy. The other is a comparison of the simulations with two different cross-section libraries, JENDL-3.3 and ENDF/B-VI, for the deep penetration of neutrons in the concrete, showing close agreement in 0- to 100-cm-thick concrete. However, the differences in flux grow with an increase in concrete thickness, reaching up to approximately eight times near 4-m thickness.

  6. Shielding evaluation of a medical linear accelerator vault in preparation for installing a high-dose rate 252Cf remote afterloader.

    PubMed

    Melhus, C S; Rivard, M J; Kurkomelis, J; Liddle, C B; Massé, F X

    2005-01-01

    In support of the effort to begin high-dose rate 252Cf brachytherapy treatments at Tufts-New England Medical Center, the shielding capabilities of a clinical accelerator vault against the neutron and photon emissions from a 1.124 mg 252Cf source were examined. Outside the clinical accelerator vault, the fast neutron dose equivalent rate was below the lower limit of detection of a CR-39 etched track detector and below 0.14 +/- 0.02 muSv h(-1) with a proportional counter, which is consistent, within the uncertainties, with natural background. The photon dose equivalent rate was also measured to be below background levels (0.1 muSv h(-1)) using an ionisation chamber and an optically stimulated luminescence dosemeter. A Monte Carlo simulation of neutron transport through the accelerator vault was performed to validate measured values and determine the thermal-energy to low-energy neutron component. Monte Carlo results showed that the dose equivalent rate from fast neutrons was reduced by a factor of 100,000 after attenuation through the vault wall, and the thermal-energy neutron dose equivalent rate would be an additional factor of 1000 below that of the fast neutrons. Based on these findings, the shielding installed in this facility is sufficient for the use of at least 5.0 mg of 252Cf.

  7. Second malignancies following conventional or combined 252Cf neutron brachytherapy with external beam radiotherapy for breast cancer

    PubMed Central

    Valuckas, Konstantinas Povilas; Atkocius, Vydmantas; Kuzmickiene, Irena; Aleknavicius, Eduardas; Liukpetryte, Sarune; Ostapenko, Valerijus

    2013-01-01

    We retrospectively evaluated the risk of second malignancies among 832 patients with inner or central breast cancer treated with conventional external beam schedule (CRT group), or neutron brachytherapy using Californium-252 (252Cf) sources and hypofractionated external beam radiotherapy (HRTC group), between 1987 and 1996 at the Institute of Oncology, Vilnius University. Patients were observed until the occurrences of death or development of a second malignancy, or until 31 December 2009, whichever was earlier. Median follow-up time was 10.4 years (range, 1.2–24.1 years). Risk of second primary cancers was quantified using standardized incidence ratios (SIRs). Cox proportional hazards regression models were used to estimate hazard ratios (HRs). There was a significant increase in the risk of second primary cancers compared with the general population (SIR 1.3, 95% CI 1.1–1.5). The observed number of second primary cancers was also higher than expected for breast (SIR 1.8, 95% CI 1.3–2.4) and lung cancer (SIR 3.8, 95% CI 2.0–6.7). For second breast cancer, no raised relative risk was observed during the period ≥10 or more years after radiotherapy. Compared with the CRT group, HRTC patients had a not statistically significant higher risk of breast cancer. Increased relative risks were observed specifically for age at initial diagnosis of <50 years (HR 2.9, 95% CI 1.6–5.2) and for obesity (HR 2.8, 95% CI 1.1–7.2). PMID:23397075

  8. Microarray analysis of DNA damage repair gene expression profiles in cervical cancer cells radioresistant to 252Cf neutron and X-rays

    PubMed Central

    2010-01-01

    Background The aim of the study was to obtain stable radioresistant sub-lines from the human cervical cancer cell line HeLa by prolonged exposure to 252Cf neutron and X-rays. Radioresistance mechanisms were investigated in the resulting cells using microarray analysis of DNA damage repair genes. Methods HeLa cells were treated with fractionated 252Cf neutron and X-rays, with a cumulative dose of 75 Gy each, over 8 months, yielding the sub-lines HeLaNR and HeLaXR. Radioresistant characteristics were detected by clone formation assay, ultrastructural observations, cell doubling time, cell cycle distribution, and apoptosis assay. Gene expression patterns of the radioresistant sub-lines were studied through microarray analysis and verified by Western blotting and real-time PCR. Results The radioresistant sub-lines HeLaNR and HeLaXR were more radioresisitant to 252Cf neutron and X-rays than parental HeLa cells by detecting their radioresistant characteristics, respectively. Compared to HeLa cells, the expression of 24 genes was significantly altered by at least 2-fold in HeLaNR cells. Of these, 19 genes were up-regulated and 5 down-regulated. In HeLaXR cells, 41 genes were significantly altered by at least 2-fold; 38 genes were up-regulated and 3 down-regulated. Conclusions Chronic exposure of cells to ionizing radiation induces adaptive responses that enhance tolerance of ionizing radiation and allow investigations of cellular radioresistance mechanisms. The insights gained into the molecular mechanisms activated by these "radioresistance" genes will lead to new therapeutic targets for cervical cancer. PMID:20184742

  9. Results with the electron cyclotron resonance charge breeder for the 252Cf fission source project (Californium Rare Ion Breeder Upgrade) at Argonne Tandem Linac Accelerator System.

    PubMed

    Vondrasek, R; Kondrashev, S; Pardo, R; Scott, R; Zinkann, G P

    2010-02-01

    The construction of the Californium Rare Ion Breeder Upgrade, a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS), is nearing completion. The facility will use fission fragments from a 1 Ci (252)Cf source; thermalized and collected into a low-energy particle beam by a helium gas catcher. In order to reaccelerate these beams, an existing ATLAS electron cyclotron resonance (ECR) ion source was redesigned to function as an ECR charge breeder. Thus far, the charge breeder has been tested with stable beams of rubidium and cesium achieving charge breeding efficiencies of 9.7% into (85)Rb(17+) and 2.9% into (133)Cs(20+).

  10. QUALIFICATION OF THE SAVANNAH RIVER SITE 252CF SHUFFLER FOR RECEIPT VERIFICATION MEASUREMENTS OF MIXED U-PU OXIDES STORED IN 9975 SHIPPING CONTAINERS

    SciTech Connect

    Dubose, F.

    2011-05-26

    To extend their ability to perform accountability and verification measurements of {sup 235}U in a U-Pu oxide matrix, the K-Area Material Storage facility commissioned the development and construction of a Passive/Active {sup 252}Cf Shuffler. A series of {sup 252}Cf, PuO{sub 2}, and U-Pu oxide standards, in addition to a single U{sub 3}O{sub 8} standard, were measured to characterize and calibrate the shuffler. Accompanying these measurements were simulations using MCNP5/MCNPX, aimed at isolating the neutron countrate contributions for each of the isotopes present. Two calibration methods for determining the {sup 235}U content in mixed UPu oxide were then developed, yielding comparable results. The first determines the {sup 235}U mass by estimating the {sup 239}Pu/{sup 235}U ratio-dependent contributions from the primary delayed neutron contributors. The second defines an average linear response based on the {sup 235}U and {sup 239}Pu mass contents. In each case, it was observed that self-shielding due to {sup 235}U mass has a large influence on the observed rates, requiring bounds on the applicable limits of each calibration method.

  11. True ternary fission, the collinear decay into fragments of similar size in the 252Cf(sf) and 235U(nth, f) reactions

    NASA Astrophysics Data System (ADS)

    von Oertzen, W.; Nasirov, A. K.

    2014-06-01

    The collinear cluster decay in 252Cf(sf, fff), with three cluster fragments of different masses (e.g. 132Sn, 52-48Ca, 68-72Ni), which has been observed by the FOBOS group in JINR, has established a new decay mode of heavy nuclei, the collinear cluster tripartition (CCT). The same type of ternary fission decay has been observed in the reaction 235U(nth, fff). This kind of “true ternary fission” of heavy nuclei has been predicted many times in theoretical works during the last decades. In the present note we discuss true ternary fission (TFFF) into three nuclei of almost equal size (e.g. Z=98→Zi=32, 34, 32) in the same systems. The possible fission channels are predicted from potential-energy (PES) calculations. These PES's show pronounced minima for several ternary fragmentation decays, e.g. for 252Cf(sf) and for 235U(nth, f). They suggest the existence of a variety of collinear ternary fission modes. The TFFF-decays chosen in this letter have very similar dynamical features as the previously observed collinear CCT-decays. The data obtained in the above mentioned experiments allow us to extract the yield for these TFFF-decays in both systems by using specific gates on the measured parameters. These yields are a few 1.0ṡ10-6/(binary fission).

  12. Analysis of linear energy transfers and quality factors of charged particles produced by spontaneous fission neutrons from 252Cf and 244Pu in the human body.

    PubMed

    Endo, Akira; Sato, Tatsuhiko

    2013-04-01

    Absorbed doses, linear energy transfers (LETs) and quality factors of secondary charged particles in organs and tissues, generated via the interactions of the spontaneous fission neutrons from (252)Cf and (244)Pu within the human body, were studied using the Particle and Heavy Ion Transport Code System (PHITS) coupled with the ICRP Reference Phantom. Both the absorbed doses and the quality factors in target organs generally decrease with increasing distance from the source organ. The analysis of LET distributions of secondary charged particles led to the identification of the relationship between LET spectra and target-source organ locations. A comparison between human body-averaged mean quality factors and fluence-averaged radiation weighting factors showed that the current numerical conventions for the radiation weighting factors of neutrons, updated in ICRP103, and the quality factors for internal exposure are valid.

  13. Results with the electron cyclotron resonance charge breeder for the {sup 252}Cf fission source project (Californium Rare Ion Breeder Upgrade) at Argonne Tandem Linac Accelerator System

    SciTech Connect

    Vondrasek, R.; Kondrashev, S.; Pardo, R.; Scott, R.; Zinkann, G. P.

    2010-02-15

    The construction of the Californium Rare Ion Breeder Upgrade, a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS), is nearing completion. The facility will use fission fragments from a 1 Ci {sup 252}Cf source; thermalized and collected into a low-energy particle beam by a helium gas catcher. In order to reaccelerate these beams, an existing ATLAS electron cyclotron resonance (ECR) ion source was redesigned to function as an ECR charge breeder. Thus far, the charge breeder has been tested with stable beams of rubidium and cesium achieving charge breeding efficiencies of 9.7% into {sup 85}Rb{sup 17+} and 2.9% into {sup 133}Cs{sup 20+}.

  14. Comparative toxicity of /sup 226/Ra, /sup 239/Pu, /sup 241/Am, /sup 249/Cf, and /sup 252/Cf in C57BL/Do black and albino mice

    SciTech Connect

    Taylor, G.N.; Mays, C.W.; Lloyd, R.D.; Gardner, P.A.; TAlbot, L.R.; McFarland, S.S.; Pollard, T.A.; Atherton, D.R.; vanMoorhem, D.; Brammer, D.

    1983-09-01

    Groups of C57BL/Do (black and albino) mice were injected with graded activities of /sup 226/Ra, /sup 239/Pu, /sup 241/Am, /sup 249/Cf, or /sup 252/Cf and were followed throughout life. Bone sarcoma was the principal radiation-induced end point, and the risks associated with average skeletal doses of the four transuranium radionuclides, relative to radium, were determined. The relative biological effectiveness (RBE) was calculated for each emitter by dividing its risk coefficient (bone sarcomas per 10/sup 6/ mouse-rad) by the risk coefficient for /sup 226/Ra. Combined data for males and females in both black and albino mice gave the following values +- SD for the RBE relative to /sup 226/Ra = 1.0: /sup 239/Pu = 15.3 +- 3.9, /sup 241/Am = 4.9 +- 1.4, /sup 249/Cf = 5.0 +- 1.4, and /sup 252/Cf = 2.6 +- 0.8. About 70% of the tumors occurred in the axial skeleton, and the risk coefficient for females averaged about four times higher than for males when all five nuclides were included. The RBE of fission fragment irradiation from /sup 252/Cf for cancer induction, relative to ..cap alpha.. irradiation, for the combined data in all of the animals given /sup 252/Cf and /sup 249/Cf, was 0.02 +- 0.28, in agreement with the calculated theoretical value of 0.03, based on the ratio of summed track lengths in tissue.

  15. Comparative toxicity of /sup 226/Ra, /sup 239/Pu, /sup 241/Am, /sup 249/Cf, and /sup 252/Cf in C57BL/Do black and albino mice

    SciTech Connect

    Taylor, G.N.; Mays, C.W.; Lloyd, R.D.; Gardner, P.A.; Talbot, L.R.; McFarland, S.S.; Pollard, I.A.; Atherton, D.R.; VanMoorhem, D.; Brammer, D.

    1983-09-01

    Groups of C57BL/Do (black and albino) mice were injected with graded activities of /sup 226/Ra, /sup 239/Pu, /sup 241/Am, /sup 249/Cf, or /sup 252/Cf and were followed throughout life. Bone sarcoma was the principal radiation-induced end point, and the risks associated with average skeletal doses of the four transuranium radionuclides, relative to radium, were determined. The relative biological effectiveness (RBE) was calculated for each emitter by dividing its risk coefficient (bone sarcomas per 10(/sup 6/) mouse-rad) by the risk coefficient for /sup 226/Ra. Combined data for males and females in both black and albino mice gave the following values +/- SD for the RBE relative to /sup 226/Ra . 1.0: /sup 239/Pu . 15.3 +/- 3.9, /sup 241/Am . 4.9 +/- 1.4, /sup 249/Cf . 5.0 +/- 1.4, and /sup 252/Cf . 2.6 +/- 0.8. About 70% of the tumors occurred in the axial skeleton, and the risk coefficient for females averaged about four times higher than for males when all five nuclides were included. The RBE of fission fragment irradiation from /sup 252/Cf for cancer induction, relative to alpha irradiation, for the combined data in all of the animals given /sup 252/Cf and /sup 249/Cf, was 0.02 +/- 0.28, in agreement with the calculated theoretical value of 0.03, based on the ratio of summed track lengths in tissue.

  16. Fissible Deposit Characterization at the Former Oak Ridge K-25 Gaseous Diffusion Plant by {sup 252}CF-Source-Driven Measurements

    SciTech Connect

    Hannon, T.F.; Mihalczo, J.T.; Mullens, J.A.; Uckan, T.; Valentine, T.E.; Wyatt, M.S.

    1998-05-01

    largest deposits with the {sup 252}Cf-source-driven transmission (CFSDT) technique, an active neutron interrogation method developed for use at the Oak Ridge Y-12 Plant to identify nuclear weapons components in containers. The active CFSDT measurement technique uses CFSDT time-of-flight measurements of prompt neutrons and gamma rays from an externally introduced {sup 252}Cf source.

  17. A probe for neutron activation analysis in a drill hole using 252Cf, and a Ge(Li) detector cooled by a melting cryogen

    USGS Publications Warehouse

    Tanner, A.B.; Moxham, R.M.; Senftle, F.E.; Baicker, J.A.

    1972-01-01

    A sonde has been built for high-resolution measurement of natural or neutron-induced gamma rays in boreholes. The sonde is 7.3 cm in diameter and about 2.2 m in length and weighs about 16 kg. The lithium-compensated germanium semiconductor detector is stabilized at -185 to -188??C for as much as ten hours by a cryostatic reservoir containing melting propane. During periods when the sonde is not in use the propane is kept frozen by a gravity-fed trickle of liquid nitrogen from a reservoir temporarily attached to the cryostat section. A 252Cf source, shielded from the detector, may be placed in the bottom section of the sonde for anlysis by measurement of neutron-activation or neutron-capture gamma rays. Stability of the cryostat with changing hydrostatic pressure, absence of vibration, lack of need for power to the cryostat during operation, and freedom of orientation make the method desirable for borehole, undersea, space, and some laboratory applications. ?? 1972.

  18. Relative biological efficiency for the induction of various gene mutations in normal and enriched with 10B Tradescantia cells by neutrons from 252Cf source.

    PubMed

    Cebulska-Wasilewska, A; Schneider, K; Kim, J K

    2001-03-01

    The effectiveness of neutrons from a Californium-252 source in the induction of various abnormalities in the Tradescantia clone 4430 stamen hair cells (Trad-SH assay) were studied. A special attention was paid to check whether any enhancement in effects is visible in the cells enriched with boron ions. Inflorescences, normal or pretreated with chemicals containing boron, were irradiated in the air with neutrons from a 252Cf source at KAERI, Taejon, Korea. To estimate the relative biological effectiveness (RBE) of the beam under the study, numbers of Tradescantia inflorescence without chemical pretreatment were irradiated with various doses of X-rays. The ranges of radiation doses used for neutrons were 0-1.0Gy and for X-rays 0-0.5Gy. Following the culturing according to standard procedures screening of gene and lethal mutations in somatic cells of stamen hairs was done in the extended period, between days 7 and 19 after exposures. Maximal RBE values for the induction of pink, colorless and lethal mutations were evaluated from comparison of the slopes in linear parts of the dose response curves obtained after irradiation with X-rays and californium source. The RBE(max) value or the induction of gene mutation was estimated as 7.2 comparing the value 5.6 in the studies reported earlier. The comparison of dose-response curves and its alteration, due to changes in the cells and plants environment during and after irradiation, explains the observed differences. Inflorescence pretreated with borax responded to neutrons differently depending on the biological end points. Although, for the induction of pink mutations no significant difference was observed, though, in the case of cell lethality, pretreated with boron ion plants have shoved a statistically significant increase of the RBE value from 5.5 to 34.7, and in the case of colorless mutations from 1.6 to 5.6.

  19. Prompt neutron multiplicities for the transplutonium nuclides

    SciTech Connect

    Holden, N.E.; Zucker, M.S.

    1985-01-01

    The direct determination of the average prompt neutron emission values is reviewed, and a method of comparing different sites of neutron emission multiplicity distribution values is described. Measured and recommended values are tabulated for these nuclides: /sup 241/Am, /sup 242/Am, /sup 242/Cm, /sup 243/Cm, /sup 244/Cm, /sup 246/Cm, /sup 247/Cm, /sup 248/Cm, /sup 250/Cm, /sup 245/Cm, /sup 249/Bk, /sup 246/Cf, /sup 249/Cf, /sup 250/Cf, /sup 252/Cf, /sup 254/Cf, /sup 251/Cf, /sup 253/Es, /sup 254/Es, /sup 244/Fm, /sup 246/Fm, /sup 255/Fm, /sup 252/No, /sup 254/Fm, /sup 256/Fm, /sup 257/Fm. 59 refs., 24 tabs. (LEW)

  20. 1987 Neutron and gamma personnel dosimeter intercomparison study using a D/sub 2/O-moderated /sup 252/Cf source

    SciTech Connect

    Swaja, R.E.; West, L.E.; Sims, C.S.; Welty, T.J.

    1989-05-01

    The thirteenth Personnel Dosimetry Intercomparison Study (i.e., PDIS 13) was conducted during April 1987 as a joint effort by Oak Ridge National Laboratory's (ORNL) Dosimetry Applications Research Group and the Southwest Radiation Calibration Center at the University of Arkansas. A total of 48 organizations (34 from the US and 14 from abroad) participated in PDIS 13. Participants submitted a total of 1,113 neutron and gamma dosimeters for this mixed field study. The dosimeters were transferred by mail and were handled by experimental personnel at ORNL and the University of Arkansas. The type of neutron dosimeter and the percentage of participants submitting that type are as follows: TLD-albedo (49%), direct interaction TLD (31%), CR-39 (17%), film (3%). The type of gamma dosimeter and the percentage of participants submitting that type are as follows: Li/sub 2/B/sub 4/O/sub 7/, alone or in combination with CaSO/sub 4/, (69%), /sup 7/LiF (28%), natural LiF (3%). Radiation exposures in PDIS 13 were limited to 0.5 and 1.5 mSv from /sup 252/Cf moderated by 15-cm of D/sub 2/O. Traditional exposures using the Health Physics Research Reactor (HPRR) were not possible due to the fact that all reactors at ORNL, including the HPRR, were shutdown by order of the Department of Energy at the time the intercomparison was performed. Planned exposures using a /sup 238/PuBe source were negated by a faulty timing mechanism. Based on accuracy and precision, direct interaction TLD dosimeters exhibited the best performance in PDIS 13 neutron measurements. They were followed, in order of best performance, by CR-39, TLD albedo, and film. The Li/sub 2/B/sub 4/O/sub 7/ type TLD dosimeters exhibited the best performance in PDIS 13 gamma measurements. They were followed by natural LiF, /sup 7/LiF, and film. 12 refs., 1 fig., 5 tabs.

  1. Calibration of a Manganese Bath Relative to 252Cf Nu-Bar

    NASA Astrophysics Data System (ADS)

    Gilliam, David M.; Yue, Andrew T.; Scott Dewey, M.

    2009-08-01

    A large manganese sulfate bath is employed at the National Institute of Standards and Technology (NIST) to calibrate isotopic neutron sources relative to the national standard neutron source NBS-I. In the past few years many low-emission Cf-252 neutron sources have been calibrated for testing of neutron detectors for the U.S. Department of Homeland Security (DHS). The low-emission DHS sources are about a factor of 100 lower in emission rate than NBS-I, so that background fluctuations become more significant in making accurate calibrations. To verify and improve the calibrations relative to NBS-I, a new calibration for sealed Cf-252 neutron sources has been made by measuring the fission rate of a bare Cf-252 deposit and inferring its neutron emission rate from Cf-252 nu-bar, the well-established neutron multiplicity of spontaneous fission in Cf-252. The fission rate of the bare deposit was measured by counting fission fragments in vacuum with a surface barrier detector behind an aperture and spacer, which provided a well-defined solid angle for detection. A thin polyimide film was placed just above the Cf deposit to prevent contamination of the detector by self-sputtering of the Cf material in vacuum. Tests with additional layers of polyimide were performed to observe any perturbation in the detection efficiency due to scattering or absorption of alpha particles or fission fragments in the polyimide film. The increase in the background count rate due to accumulation of Cf on the polyimide film was less than 0.02% of the fission fragment count rate from the sample, at the end of all runs. It is estimated that this increase in background would have been about 150 times higher without the polyimide film. The sealed Cf source NIST-DHSA was compared to the bare source by relative neutron counting in an assembly of polyethylene moderator and He-3 detectors. The calibration via Cf-252 nu-bar gave a result that was 1.7% higher than the previous calibration relative to NBS-I in the large manganese sulfate bath. This discrepancy is about equal to the current uncertainty in either calibration. Improvement in the Cf-252 nu-bar method is expected by use of a recently acquired measuring microscope for source-aperture geometry characterization and by comparisons of the neutron emission of bare deposit and the sealed sources in a new reduced-volume manganese bath.

  2. Analusis by 252Cf plasma desorption mass spectrometry of Bordetella pertussis endotoxin after nitrous deamination

    NASA Astrophysics Data System (ADS)

    Deprun, C.; Karibian, D.; Caroff, M.

    1993-07-01

    Endotoxic lipopolysaccharides (LPSs) are the major components of Gram-negative bacterial outer membrane. Like many amphipathic molecules, they pose problems of heterogeneity, purity, solubility, and aggregation. Nevertheless, PDMS has recently have been applied to unmodified endotoxins composed of LPS having uip to five sugar units in their saccharide chain. The B. Pertussis LPSs, most of which have a dodecasaccharide domain, ahve been analysed by classical methods and the masses of the separate lipid and saccharide domains determined after rupture of the bond linking them. However, the acid treatment employed for these and most chemical analyses can also modify structures in the vicinity of the bond. In order to investigate this biologically-important region, the endotoxin was treated to nitrous deamination, which shortens the saccharide chain to five sugars, but preserves the acid-labile region of the LPS. The PDM spectrum of this derivative, which required new conditions for its desorption, confirmed the structure analysis and demonstrated the presence of at least four molecular species.

  3. Neutron multiplicity measurements of Cf and Fm isotopes

    SciTech Connect

    Hoffman, D.C.; Ford, G.P.; Balagna, J.P.; Veeser, L.R.

    1980-02-01

    Prompt neutrons in coincidence with the fission fragments from the spontaneous fission of /sup 250,252,254/Cf and /sup 257/Fm were measured inside a 75-cm-diameter, Gd-loaded liquid scintillation counter having a neutron-detection efficiency of about 78%. Measurements for /sup 256/Fm were done just outside the counter with an efficiency of 31%. The kinetic energies of both fission fragments and the number of neutrons for each fission event were recorded. From these data, the fragment kinetic energies and masses and the neutron multiplicity distributions were determined for /sup 250,252,254/Cf and /sup 257/Fm. Variances of neutron multiplicity distributions as a function of total fragment kinetic energy and the ratio of fragment masses have been calculated and are presented for all the nuclides studied.

  4. TYPE A PACKAGE LIMITS OF SPONTANEOUS FISSION RADIONUCLIDES

    SciTech Connect

    Rawl, R.R.

    2001-09-17

    The maxima value of the depth dose coefficient for fission neutrons in ICRP Publication 21 was a reasonable estimator of the effective dose coefficient recently tabulated in ICRP Publication 74. Thus the inflation of the coefficient in the 1996 Q-System analysis (IAEA 2000b) for the purpose of being consistent with respect to ICRP guidance on the neutron weighting factor was unnecessary from the standpoint of the effective dose. The consequence resulted in an unnecessarily restrictive value of A{sub 1} for {sup 248}Cm, {sup 252}Cf, and {sup 254}Cf. The calculations presented here support a relaxation of the A{sub 1} limits for these radionuclides.

  5. Calculation of Ambient (H*(10)) and Personal (Hp(10)) Dose Equivalent from a 252Cf Neutron Source

    SciTech Connect

    Traub, Richard J.

    2010-03-26

    The purpose of this calculation is to calculate the neutron dose factors for the Sr-Cf-3000 neutron source that is located in the 318 low scatter room (LSR). The dose factors were based on the dose conversion factors published in ICRP-21 Appendix 6, and the Ambient dose equivalent (H*(10)) and Personal dose equivalent (Hp(10)) dose factors published in ICRP Publication 74.

  6. Experimental determination of moisture distributions in fired clay brick using a 252Cf source: a neutron transmission study.

    PubMed

    El Abd, A; Abdel-Monem, A M; Kansouh, W A

    2013-04-01

    A neutron transmission method was proposed to study liquid transport in porous media. It was applied to study water penetration into two kinds of fired clay bricks. The results showed that the diffusion processes in the investigated samples are different. Water diffusivities and capillary absorption coefficients characterizing both the flow process and the brick samples were determined and compared. The proposed method is simple, accurate and reliable in studying water diffusion in porous media, in real time.

  7. Comparison of lipids A of several Salmonella and Escherichia strains by 252Cf plasma desorption mass spectrometry.

    PubMed Central

    Karibian, D; Deprun, C; Caroff, M

    1993-01-01

    Plasma desorption mass spectrometry has recently been used with success to characterize underivatized lipid A preparations: the major molecular species present give signals indicating their masses, from which probable compositions could be inferred by using the overall composition determined by chemical analyses. In the present study, plasma desorption mass spectrometry was used to compare structures in lipid A preparations isolated from several smooth and rough strains of Escherichia and Salmonella species. Preparations isolated from strains of both genera revealed considerable variation in degree of heterogeneity (number of fatty acids and presence or absence of hexadecanoic acid, phosphorylethanolamine, and aminoarabinose). Molecular species usually associated with Salmonella lipid A were found in preparations from Escherichia sp. In addition, preparations from three different batches of lipid A from one strain of Salmonella minnesota showed significant differences in composition. These results demonstrate that preparations used for biological and structural analyses should be defined in terms of their particular molecular constituents and that no generalizations based on analysis of a single preparation should be made. PMID:8491718

  8. On the effect of an error in a standard D2O-moderated 252Cf energy spectrum.

    PubMed

    Cummings, F M

    2009-12-01

    There appears to be an error in the neutron fluence for neutrons with energies between 9 and 10 MeV for the tabulated D2O-moderated Cf source in ISO 8529-1. If the referenced spectrum is used as tabulated, the error contributes a total error to neutron dose values from this source of approximately 3%.

  9. Determination of the multiplication factor and its bias by the {sup 252}Cf-source technique: A method for code benchmarking with subcritical configurations

    SciTech Connect

    Perez, R.B.; Valentine, T.E.; Mihalczo, J.T.; Mattingly, J.K.

    1997-08-01

    A brief discussion of the Cf-252 source driven method for subcritical measurements serves as an introduction to the concept and use of the spectral ratio, {Gamma}. It has also been shown that the Monte Carlo calculation of spectral densities and effective multiplication factors have as a common denominator the transport propagator. This commonality follows from the fact that the Neumann series expansion of the propagator lends itself to the Monte Carlo method. On this basis a linear relationship between the spectral ratio and the effective multiplication factor has been shown. This relationship demonstrates the ability of subcritical measurements of the ratio of spectral densities to validate transport theory methods and cross sections.

  10. Results with the electron cyclotron resonance charge breeder for the 252Cf fission source project (Californium Rare Ion Breeder Upgrade) at Argonne Tandem Linac Accelerator System

    NASA Astrophysics Data System (ADS)

    Vondrasek, R.; Kondrashev, S.; Pardo, R.; Scott, R.; Zinkann, G. P.

    2010-02-01

    The construction of the Californium Rare Ion Breeder Upgrade, a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS), is nearing completion. The facility will use fission fragments from a 1 Ci C252f source; thermalized and collected into a low-energy particle beam by a helium gas catcher. In order to reaccelerate these beams, an existing ATLAS electron cyclotron resonance (ECR) ion source was redesigned to function as an ECR charge breeder. Thus far, the charge breeder has been tested with stable beams of rubidium and cesium achieving charge breeding efficiencies of 9.7% into R85b17+ and 2.9% into C133s20+.

  11. Multimodal fission and neutron evaporation

    SciTech Connect

    Brosa, U.

    1988-10-01

    The average multiplicities nu-bar(A) of prompt neutrons emitted in the spontaneous fission of /sup 252/Cf and /sup 258/Fm are derived. Two new features are predicted: A simple sawtooth for /sup 258/Fm and a triple one for /sup 252/Cf. Experiments to check these predictions should be feasible now.

  12. Biomedical neutron research at the Californium User Facility for neutron science

    SciTech Connect

    Martin, R.C.; Byrne, T.E.; Miller, L.F.

    1997-04-01

    The Californium User Facility for Neutron Science has been established at Oak Ridge National Laboratory (ORNL). The Californium User Facility (CUF) is a part of the larger Californium Facility, which fabricates and stores compact {sup 252}Cf neutron sources for worldwide distribution. The CUF can provide a cost-effective option for research with {sup 252}Cf sources. Three projects at the CUF that demonstrate the versatility of {sup 252}Cf for biological and biomedical neutron-based research are described: future establishment of a {sup 252}Cf-based neutron activation analysis system, ongoing work to produce miniature high-intensity, remotely afterloaded {sup 252}Cf sources for tumor therapy, and a recent experiment that irradiated living human lung cancer cells impregnated with experimental boron compounds to test their effectiveness for boron neutron capture therapy.

  13. Shape trends and triaxiality in neutron-rich odd-mass Y and Nbisotopes

    SciTech Connect

    Luo, Y.X.; Rasmussen, J.O.; Gelberg, A.; Stefanescu, I.; Hamilton, J.H.; Ramayya, A.V.; Hwang, J.K.; Zhu, S.J.; Gore, P.M.; Fong,D.; Jones, E.F.; Wu, S.C.; Lee, I.Y.; Ginter, T.N.; Ma, W.C.; Ter-Akopian, G.M.; Daniel, A.V.; Stoyer, M.A.; Donangelo, R.

    2004-09-28

    New level schemes of Y and Nb isotopes are proposed based on measurements of prompt gamma rays from 252Cf fission at Gammasphere. Shape trends regarding triaxiality and quadrupole deformations are studied.

  14. Neutron dosimetry, moderated energy spectrum, and neutron capture therapy for californium-252 medical sources

    NASA Astrophysics Data System (ADS)

    Rivard, Mark Joseph

    Examination of neutron dosimetry for 252Cf has been conducted using calculative and experimental means. Monte Carlo N-Particle (MCNP) transport code was used in a distributed computing environment as a parallel virtual machine (PVM) to determine the absorbed neutron dose and neutron energy spectrum from 252Cf in a variety of clinically relevant materials. Herein, a Maxwellian spectrum was used to model the 252Cf neutron emissions within these materials. 252Cf mixed-field dosimetry of Applicator Tube (AT) type sources was measured using 1.0 and 0.05 cm3 tissue-equivalent ion chambers and a miniature GM counter. A dosimetry protocol was formulated similar that of ICRU 45. The 252Cf AT neutron dosimetry was determined in the cylindrical coordinate system formalism recommended by the AAPM Task Group 43. These results demonstrated the overwhelming dependence of dosimetry on the source geometry factor as there was no significant neutron attenuation within the source or encapsulation. Gold foils and TLDs were used to measure the thermal flux in the vicinity of 252Cf AT sources to compare with the results calculated using MCNP. As the fast neutron energy spectrum did not markedly changed at increasing distances from the AT source, neutron dosimetry results obtained with paired ion chambers using fixed sensitivity factors agreed well with MCNP results and those in the literature. Calculations of moderated 252Cf neutron energy spectrum with various loadings of 10B and 157Gd were performed, in addition to analysis of neutron capture therapy dosimetry with these isotopes. Radiological concerns such as personnel exposure and shielding of 252Cf emissions were examined. Feasibility of a high specific-activity 252Cf HDR source was investigated through radiochemical and metallurgical studies using stand-ins such as Tb, Gd and 249Cf. Issues such as capsule burst strength due to helium production for a variety of proposed HDR sources were addressed. A recommended 252Cf source

  15. Californium versus cobalt brachytherapy combined with external-beam radiotherapy for IIB stage cervical cancer: long-term experience of a single institute

    PubMed Central

    Janulionis, Ernestas; Valuckas, Konstantinas Povilas; Samerdokiene, Vitalija; Atkocius, Vydmantas

    2015-01-01

    Purpose The purpose of this paper was to observe and compare long-term curative effects and complications of FIGO stage IIB cervical cancer patients (n = 232) treated with high-dose-rate (HDR) californium (252Cf) neutron or cobalt (60Co) photon intracavitary brachytherapy (ICBT) combined with external-beam radiotherapy (EBRT). Material and methods The EBRT dose to the small pelvis was 50 Gy in both groups. The brachytherapy component of 252Cf or 60Co was added in the 3rd week of EBRT, 5 fractions were performed once per week resulting in a total ICBT dose of 40 Gy/Gyeq (point A). Results Overall survival (OS) at 5, 10 and 15 years was 63.6%, 50.4% and 38.8% in the 252Cf group and 62.2%, 50.5%, 39.9%, in the 60Co group, respectively (p = 0.74). The percentage of tumour recurrence was statistically significantly lower in the 252Cf group with 7.4% versus 17.1% in the 60Co group (p = 0.02). Second primary cancers have developed similarly 9.1% and 8.1% cases for 252Cf and 60Co groups, respectively. Conclusions Our long-term retrospective study comparing 252Cf and 60Co isotopes with brachytherapy in combined treatment of FIGO IIB stage cervix carcinoma patients shows, that overall survival in the both groups are similar. However, the recurrence of tumour was significantly lower in the 252Cf group. The incidence of second primary cancers was similar in both groups. PMID:26622239

  16. A New Simplified System for the Evaluation of BNCT Pharmaceuticals

    SciTech Connect

    Byrne, T.E.; Kabalka, G.W.; Martin, R.C.; Miller, L.F.

    1998-09-13

    A system for testing potential BNCT pharmaceuticals in cell cultures has been developed with the cooperation of Oak Ridge National Laboratory (ORNL), the University of Tennessee Chemistry Department and the University of Tennessee Nuclear Engineering Department. A BNCT test model has been established with the use of the human lung cancer cell line A 549. These cells were maintained in standard laboratory facilities and subjected to boronated chemicals. Following toxicity studies the human luug cancer cells were exposed to {sup 252}Cf neutron sources provided by the Radiochemical Engineering Development Center (REDC) at ORNL The isotope {sup 252}Cf performs effectively for BNCT applications. The neutron spectrum is similar to that of a reactor fission source with an average energy of 2.1 MeV. A 50 mg source of {sup 252}Cf moderated by water provides a source on the order of 1 x 10{sup 9} thermal neutrons/cm{sup 2}/sec at a distance of 3 cm. The half-life of {sup 252}Cf is 2.65 years, and thus may provide a simple and reliable source of neutrons for BNCT in locations without suitable nuclear reactors. The REDC of ORNL stores and processes the U.S. stockpile of {sup 252}Cf.

  17. Bimodal Fission in the Skyrme-Hartree-Fock Approach

    SciTech Connect

    Staszczak, A.; Dobaczewski, J.; Nazarewicz, Witold

    2007-01-01

    Spontaneous fission properties of 256Fm, 258Fm, and 260Fm isotopes are studied within the Skyrme-Hartree-Fock+BCS framework. In the particle-hole channel we take the Skyrme SkM* effective force, while in the particle-particle channel we employ the seniority pairing interaction. Three static fission paths for all investigated heavy fermium isotopes are found. The analysis of these fission modes allows to describe observed asymmetric fission of 256Fm, as well as bimodal fission of 258Fm and symmetric fission in 260Fm.

  18. DETECTORS AND EXPERIMENTAL METHODS: Equivalent properties of single event burnout induced by different sources

    NASA Astrophysics Data System (ADS)

    Yang, Shi-Yu; Cao, Zhou; Da, Dao-An; Xue, Yu-Xiong

    2009-05-01

    The experimental results of single event burnout induced by heavy ions and 252Cf fission fragments in power MOSFET devices have been investigated. It is concluded that the characteristics of single event burnout induced by 252Cf fission fragments is consistent to that in heavy ions. The power MOSFET in the “turn-off" state is more susceptible to single event burnout than it is in the “turn-on" state. The thresholds of the drain-source voltage for single event burnout induced by 173 MeV bromine ions and 252Cf fission fragments are close to each other, and the burnout cross section is sensitive to variation of the drain-source voltage above the threshold of single event burnout. In addition, the current waveforms of single event burnouts induced by different sources are similar. Different power MOSFET devices may have different probabilities for the occurrence of single event burnout.

  19. Screening of nanosatellite microprocessors using californium single-event latch-up test results

    NASA Astrophysics Data System (ADS)

    Tomioka, Takahiro; Okumura, Yuta; Masui, Hirokazu; Takamiya, Koichi; Cho, Mengu

    2016-09-01

    A single-event latch-up (SEL) test using a 252Cf radioisotope was carried out. The results were compared with those of a proton test and from observation in orbit. A radioisotope can reproduce phenomena observed in orbit that are caused by protons. Considering the inexpensive nature of the 252Cf test, it is more suitable for nanosatellites that require low cost and fast delivery. A SEL occurrence rate of a commercial-off-the-shelf microprocessor was derived from the ground test results. The 252Cf test provided a SEL rate approximately 1×106 times greater than that in orbit. This data can be used to derive the minimum SEL occurrence rate in orbit and help satellite designers to evaluate the risk of SEL and take measures if necessary.

  20. Californium-252: a remarkable versatile radioisotope

    SciTech Connect

    Osborne-Lee, I.W.; Alexander, C.W.

    1995-10-10

    A product of the nuclear age, Californium-252 ({sup 252}Cf) has found many applications in medicine, scientific research, industry, and nuclear science education. Californium-252 is unique as a neutron source in that it provides a highly concentrated flux and extremely reliable neutron spectrum from a very small assembly. During the past 40 years, {sup 252}Cf has been applied with great success to cancer therapy, neutron radiography of objects ranging from flowers to entire aircraft, startup sources for nuclear reactors, fission activation for quality analysis of all commercial nuclear fuel, and many other beneficial uses, some of which are now ready for further growth. Californium-252 is produced in the High Flux Isotope Reactor (HFIR) and processed in the Radiochemical Engineering Development Center (REDC), both of which are located at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. The REDC/HFIR facility is virtually the sole supplier of {sup 252}Cf in the western world and is the major supplier worldwide. Extensive exploitation of this product was made possible through the {sup 252}Cf Market Evaluation Program, sponsored by the United States Department of Energy (DOE) [then the Atomic Energy Commission (AEC) and later the Energy Research and Development Administration (ERDA)]. This program included training series, demonstration centers, seminars, and a liberal loan policy for fabricated sources. The Market Evaluation Program was instituted, in part, to determine if large-quantity production capability was required at the Savannah River Laboratory (SRL). Because of the nature of the product and the means by which it is produced, {sup 252}Cf can be produced only in government-owned facilities. It is evident at this time that the Oak Ridge research facility can meet present and projected near-term requirements. The production, shipment, and sales history of {sup 252}Cf from ORNL is summarized herein.

  1. NEUTRON ACTIVATION ANALYSIS APPLICATIONS AT THE SAVANNAH RIVER SITE USING AN ISOTOPIC NEUTRON SOURCE

    SciTech Connect

    Diprete, D; C Diprete, C; Raymond Sigg, R

    2006-08-14

    NAA using {sup 252}Cf is used to address important areas of applied interest at SRS. Sensitivity needs for many of the applications are not severe; analyses are accomplished using a 21 mg {sup 252}Cf NAA facility. Because NAA allows analysis of bulk samples, it offers strong advantages for samples in difficult-to-digest matrices when its sensitivity is sufficient. Following radiochemical separation with stable carrier addition, chemical yields for a number methods are determined by neutron activation of the stable carrier. In some of the cases where no suitable stable carriers exist, the source has been used to generate radioactive tracers to yield separations.

  2. Preliminary observations on californium-252 behaviour in sea water, sediments and zooplankton.

    PubMed

    Aston, S R; Fowler, S W

    1983-04-01

    We carried out radiotracer experiments on the behaviour of 252Cf in the marine environment. The particulate fraction of californium in sea water approached 45% after four days. Californium rapidly adsorbed onto marine coastal and deep-sea sediments with Kd values from 1.4 X 10(4) to greater than or equal to 1 X 10(5). The concentration of 252Cf in euphausiids reached near-equilibrium factors of 3 X 10(2) in water after one week; in contrast, the assimilation from food was very low. Excreted fecal pellets, molts and zooplankton carcasses are potentially important vectors for californium re-distribution in the oceans.

  3. NSDUAZ unfolding package for neutron spectrometry and dosimetry with Bonner spheres.

    PubMed

    Vega-Carrillo, H R; Ortiz-Rodríguez, J M; Martínez-Blanco, M R

    2012-12-01

    NSDUAZ (Neutron Spectrometry and Dosimetry from the Universidad Autónoma de Zacatecas) is a user friendly neutron unfolding package for Bonner sphere spectrometer with (6)LiI(Eu) developed under LabView(®) environment. Unfolding is carried out using a recursive iterative procedure with the SPUNIT algorithm, where the starting spectrum is obtained from a library initial guess spectra to start the iterations. The NSDUAZ performance was evaluated using (252)Cf, (252)Cf/D(2)O, (241)AmBe neutron sources and the neutrons outside the radial beam port of a TRIGA Mark III nuclear reactor running to 10 W. PMID:22578610

  4. Resonant tunneling and the bimodal symmetric fission of sup 258 Fm

    SciTech Connect

    Bhandari, B.S. )

    1991-02-25

    The concept of resonant tunneling is invoked to explain the sharp drop in the measured spontaneous-fission half-life when going from {sup 256}Fm to {sup 258}Fm. Various consequences of such a suggestion on the other observed characteristics of the bimodal symmetric fission of {sup 258}Fm are briefly discussed.

  5. Xe-135 Production from Cf-252

    SciTech Connect

    C. A. McGrath; T. P. Houghton; J. K. Pfeiffer; R. K. Hague

    2012-03-01

    135Xe is a good indicator that fission has occurred and is a valuable isotope that helps enforce the Comprehensive Test Ban Treaty. Due to its rather short half life and minimal commercial interest, there are no known sources where 135Xe can be purchased. Readily available standards of this isotope for calibrating collection and analytical techniques would be very useful. 135Xe can be produced in the fissioning of actinide isotopes, or by neutron capture on 134Xe. Since the neutron capture cross section of 134Xe is 3 mB, neutron capture is a low yield, though potentially useful, production route. 135Xe is also produced by spontaneous fission of 252Cf. 252Cf has a spontaneous fission rate of about 6 x 1011 s-1g-1. The cumulative yield from the spontaneous fission of 252Cf is 4.19%; and the competing neutron capture reaction that depletes 135Xe in thermal reactor systems is negligible because the neutron capture cross-section is low for fast fission neutrons. At the INL, scientists have previously transported fission products from an electroplated 252Cf thin source for the measurement of nuclear data of short-lived fission products using a technique called He-Jet collection. We have applied a similar system to the collection of gaseous 135Xe, in order to produce valuable standards of this isotope.

  6. Neutron interstitial brachytherapy for malignant gliomas: a pilot study

    SciTech Connect

    Patchell, R.A.; Maruyama, Y.; Tibbs, P.A.; Beach, J.L.; Kryscio, R.J.; Young, A.B.

    1988-01-01

    Fifty-six patients with malignant glioma were treated with implantation of the neutron-emitting element californium-252 (/sup 252/Cf) within 2 weeks after surgical debulking of the tumor. Implantation was performed using computerized tomography-guided placement of afterloading catheters, and the /sup 252/Cf sources were removed after approximately 300 neutron rads were delivered. Patients then received 6000 to 7000 conventional photon rads by external beam. The total photon-equivalent dose to the tumor ranged from 8100 to 9100 rads. The median survival time was 10 months, with 18-and 24-month survival rates of 28% and 19%, respectively. The results of reoperation or autopsy showed that patients had recurrence of the tumor but that radiation necrosis was restricted to the area of the original tumor. Serious complications occurred in five patients (9%) and consisted of wound infections in three, cerebral edema in one, and radiation necrosis beyond the original tumor margin in one. Previous studies using external-beam neutron radiation have shown that neutrons are capable of totally eradicating malignant gliomas; however, in most cases, unacceptable widespread radiation necrosis has resulted. Neutron implants are a logical way to increase the dose to the tumor and decrease the dose to normal brain. Interstitial neutron radiation can be given safely with /sup 252/Cf, and the survival results achieved by radiation alone using relatively low doses of interstitial neutron radiation from /sup 252/Cf implants plus conventional photon radiation were equal to the results attained with any currently available conventional therapy.

  7. Documentation and analysis for packaging for surface moisture measurement system 7A containers

    SciTech Connect

    Clem, D.K.

    1996-06-17

    This documentation and analysis for packaging documents that two, procured, carbon steel 5-gal drums meet all applicable U.S.Department of Transportation-7A requirements. One container will be used to transport a 0.009 Ci 252 Cf source and the other to transport a 1.7 Ci Am-Be source to and from various 200 Area tank farms.

  8. Nuclear Materials Identification System Operational Manual

    SciTech Connect

    Chiang, L.G.

    2001-04-10

    This report describes the operation and setup of the Nuclear Materials Identification System (NMIS) with a {sup 252}Cf neutron source at the Oak Ridge Y-12 Plant. The components of the system are described with a description of the setup of the system along with an overview of the NMIS measurements for scanning, calibration, and confirmation of inventory items.

  9. Experience in the separation and purification of transplutonium elements in the transuranium processing plant at the Oak Ridge National Laboratory

    SciTech Connect

    King, L.J.; Bigelow, J.E.; Collins, E.D.

    1980-01-01

    Since 1966, TRU has been the main center of production for transcurium elements in the US, producing 460 mg /sup 249/Bk, 4 g /sup 252/Cf, 18 mg /sup 253/Es, and 10 pg /sup 257/Fm. During the 14 years operation, 39 chemical processing campaigns were conducted to process 265 HFIR targets and 195 SRP production reactor targets. (DLC)

  10. Californium purification and electrodeposition

    DOE PAGESBeta

    Burns, Jonathan D.; Van Cleve, Shelley M.; Smith, Edward Hamilton; Boll, Rose Ann

    2014-11-30

    The staff at the Radiochemical Engineering Development Center, located at Oak Ridge National Laboratory, produced a 6.3 ± 0.4 GBq (1.7 ± 0.1 Ci) 252Cf source for the Californium Rare Isotope Breeder Upgrade (CARIBU) project at Argonne National Laboratory’s Argonne Tandem Linac Accelerator System. The source was produced by electrodeposition of a 252Cf sample onto a stainless steel substrate, which required material free from excess mass for efficient deposition. The resulting deposition was the largest reported 252Cf electrodeposition source ever produced. Several different chromatographic purification methods were investigated to determine which would be most effective for final purification of themore » feed material used for the CARIBU source. The separation of lanthanides from the Cf was of special concern. Furthermore, the separation, using 145Sm, 153Gd, and 249Cf as tracers, was investigated using BioRad AG 50X8 in α-hydroxyisobutyric acid, Eichrom LN resin in both HNO3 and HCl, and Eichrom TEVA resin in NH4SCN. The TEVA NH4SCN system was found to completely separate 145Sm and 153Gd from 249Cf and was adopted into the purification process used in purifying the 252Cf.« less

  11. [Use of time-of-flight mass spectrometry with ionization division fragments of californium-252 for studying the mechanisms of action of drugs on DNA and its components].

    PubMed

    Sukhodub, L F; Grebenik, L I; Chivanov, V D

    1994-01-01

    Using soft-ionization mass spectrometry (252-Cf particle desorption mass spectrometry, PDMS) a minor adduct of anticancer drug prospidine and deoxyguanosine-5-phosphate (pdG) has been found. It has been shown experimentally that PDMS is very useful for study of biological mixtures as well as mechanisms of interactions between drugs and biomolecules.

  12. [An improved method of preparing protein and peptide probes in mass spectrometry with ionization of division fragments by californium-252 (TOF-PDMS)].

    PubMed

    Chivanov, V D; Zubarev, R A; Aksenov, S A; Bordunova, O G; Eremenko, V I; Kabanets, V M; Tatarinova, V I; Mishnev, A K; Kuraev, V V; Knysh, A N; Eremenko, I A

    1996-08-01

    The addition of organic acids (picric, oxalic, citric, or tartaric) to peptide and protein samples was found to significantly increase the yield of their quasi-molecular ions (QMI) in time-of-flight 252Cf plasma desorption mass spectrometry. The yield of the ions depended on the pKa of the acid added.

  13. Production, distribution and applications of californium-252 neutron sources.

    PubMed

    Martin, R C; Knauer, J B; Balo, P A

    2000-01-01

    The radioisotope 252Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-yr half-life. A source the size of a person's little finger can emit up to 10(11) neutrons s(-1). Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement and minerals, as well as for detection and identification of explosives, land mines and unexploded military ordinance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 yr of experience and by US Bureau of Mines tests of source survivability during explosions. The production and distribution center for the US Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). DOE sells 252Cf to commercial reencapsulators domestically and internationally. Sealed 252Cf sources are also available for loan to agencies and subcontractors of the US government and to universities for educational, research and medical applications. The REDC has established the Californium User Facility (CUF) for Neutron Science to make its large inventory of 252Cf sources available to researchers for irradiations inside uncontaminated hot cells. Experiments at the CUF include a land mine detection system, neutron damage testing of solid-state detectors, irradiation of human cancer cells for boron neutron capture therapy experiments and irradiation of rice to induce genetic mutations.

  14. Remote afterloading for intracavitary and interstitial brachytherapy with californium-252

    NASA Astrophysics Data System (ADS)

    Tačev, Tačo; Grigorov, Grigor; Papírek, Tomáš; Kolařík, Vladimír.

    2004-01-01

    The authors present their design concept of remote afterloading for 252Cf brachytherapy with respect to characteristic peculiarities of 252Cf and the current worldwide development of remote afterloading devices. The afterloading device has been designed as a stationary radiator comprising three mutually interconnected units: (1) a control and drive unit, consisting of a control computer and a motor-driven Bowden system carrying the 252Cf source; (2) a source housed in a watertight, concrete vessel, which is stored in a strong room situated well beneath the patient's bed and (3) an afterloading application module installed in the irradiation room. As 252Cf is a nuclide with low specific activity, it was necessary to produce two independent devices for high dose rate intracavitary treatment and for low dose rate intestinal treatment. The sources may be moved arbitrarily during the treatment with a position accuracy of 0.5-1.0 mm within a distance of 520 cm from the source storage position in the strong room to the application position. The technical concept of the present automatic afterloading device for neutron brachytherapy represents one possible option of a range of conceivable design variants, which, while minimizing the technical and economic requirements, provides operating personnel with optimum protection and work safety, thus extending the applicability of high-LET radiation-based treatment methods in clinical practice.

  15. Synthesis of superheavy element 120 via {sup 50}Ti+{sup A}Cf hot fusion reactions

    SciTech Connect

    Liu, Z. H.; Bao Jingdong

    2009-11-15

    Synthesis of superheavy element 120 in terms of the {sup 50}Ti+{sup 249-252}Cf fusion-evaporation reactions is evaluated and discussed. It is found that the reactions of {sup 250,251}Cf({sup 50}Ti,3n){sup 297,298}120 and {sup 251,252}Cf({sup 50}Ti,4n){sup 297,298}120 are relatively favorable with the maximum evaporation-residue cross sections of 0.12, 0.09, 0.11, and 0.25 pb, respectively. However, {sup 252}Cf may be difficult to be target because its spontaneous fission will bring about serious background in the experiment. Fusion probabilities for different target-projectile combinations leading to the formation of surperheavy nucleus {sup 302}120 are estimated with the ''fusion-by-diffusion'' model and presented as a function of the Coulomb parameter Z{sub 1}Z{sub 2}/(A{sub 1}{sup 1/3}+A{sub 2}{sup 1/3}). Among the reactions {sup 50}Ti+{sup 252}Cf, {sup 54}Cr+{sup 248}Cm, {sup 58}Fe+{sup 244}Pu, and {sup 64}Ni+{sup 238}U, the reaction {sup 50}Ti+{sup 252}Cf has the largest fusion probability. Synthesis of superheavy element 120 is of essential importance for determining whether the magic proton shell should be at Z=114 or at higher proton numbers Z=120-126. Therefore, the experiment to produce isotopes with Z=120 in the fusion reactions {sup 50}Ti+{sup 250,251}Cf is of great interest.

  16. Spectroscopic studies beyond N = 152 neutron gap : decay of {sup 255 ovr sub 101}Md and {sup 256 ovr sub 101}Md.

    SciTech Connect

    Ahmad, I.; Chasman, R. R.; Fields, P. R.

    2000-01-01

    The isotopes {sup 255}Md and {sup 256}Md were produced by the irradiation of {sup 253}Es with 35-45 MeV {alpha} particles by ({alpha},n) and ({alpha},2n) reactions and were removed from the target by a helium jet system. {alpha}, {gamma}, and {alpha}-{gamma} coincidence spectra were measured with Si and Ge(Li) detectors. From the EC decays of {sup 255}Md and {sup 256}Md, levels in {sup 255}Fm and {sup 256}Fm were deduced. Favored {alpha} decay of {sup 255}Md was found to populate the 7/2{sup -}[514] single-particle state in {sup 251}Es, thus establishing the 7/2{sup -}[514] as the {sup 255}Md ground state. Several {gamma} rays were observed in the {sub 256}Md {alpha}-{gamma} coincidence spectrum. {sup 256}Fm is the heaviest nucleus in which excited intrinsic states have been identified.

  17. Spectroscopic studies beyond the N=152 neutron gap: Decay of {sub 101}{sup 255}Md and {sub 101}{sup 256}Md

    SciTech Connect

    Ahmad, I.; Chasman, R. R.; Fields, P. R.

    2000-04-01

    The isotopes {sup 255}Md and {sup 256}Md were produced by the irradiation of {sup 253}Es with 35-45 MeV {alpha} particles by ({alpha},n) and ({alpha},2n) reactions and were removed from the target by a helium jet system. {alpha}, {gamma}, and {alpha}-{gamma} coincidence spectra were measured with Si and Ge(Li) detectors. From the EC decays of {sup 255}Md and {sup 256}Md, levels in {sup 255}Fm and {sup 256}Fm were deduced. Favored {alpha} decay of {sup 255}Md was found to populate the 7/2{sup -}[514] single-particle state in {sup 251}Es, thus establishing the 7/2{sup -}[514] as the {sup 255}Md ground state. Several {gamma} rays were observed in the {sup 256}Md {alpha}-{gamma} coincidence spectrum. {sup 256}Fm is the heaviest nucleus in which excited intrinsic states have been identified. (c) 2000 The American Physical Society.

  18. Transuranium processing plant report of production, status, and plans for the period October 1, 1978-September 30, 1980

    SciTech Connect

    King, L.J.; Bigelow, J.E.; Collins, E.D.

    1981-08-01

    During this period, transuranium elements were obtained from 26 irradiated HFIT targets. The products included 86 mg of /sup 249/Bk, 686 mg of /sup 252/Cf, 3.1 mg of /sup 253/Es, and an estimated 1.4 pg of /sup 257/Fm. In addition, about 326 mg of high-purity /sup 248/ Cm was separated from previously purified /sup 252/Cf. One hundred seven product shipments were made from TRU; recipients and the amounts of nuclides shipped are listed in a table. Forty-two standard and two special HFIR targets were fabricated. During the next 18 months, production totals of 110 mg of /sup 249/ Bk, 1200 mg of /sup 252/Cf, 5.5 mg of /sup 253/Es, and 2 pg of /sup 257/Fm are anticipated. Also, a total of 225 mg of /sup 248/Cm is expected to be made available. During this report period, a charcoal adsorber system for radioiodine removal was installed, tested, and placed in service. This system serves as a backup to the Hopcalite-charcoal system for adsorption of /sup 131/I from the VOG stream. Seven /sup 252/Cf neutron sources were fabricated during this report period. A total of 100 neutron sources have been fabricated previously at TRU. The original and current contents (/sup 252/Cf and /sup 248/Cm) of the existing sources and the individuals to whom the sources are currently loaned are listed in a table. In addition to neutron sources, nine fission sources were prepared by electroplating /sup 252/Cf onto platinum disks or foils.Special projects during this report period included (1) purification of two batches of isotopically pure /sup 240/Pu, (2) fabrication of two special HFIR targets, (3) repurification of the residues of the einsteinium product from Campaign 56, (4) production of approx. 235 ..mu..g of /sup 250/Cf by irradiation of /sup 249/Bk, (5) radiography of 28 irradiated, stainless steel alloy, fracture-strain specimens, and (6) preparations for the production of 40 ..mu..g of /sup 245/Es by irradiation of /sup 253/Es.

  19. Microscopic Description of Scission Configurations

    SciTech Connect

    Dubray, N.; Goutte, H.; Berger, J. F.

    2007-02-26

    Properties of 226Th, 256Fm, 258Fm and 260Fm nuclei in the scission region are described using a full-microscopic Hartree-Fock-Bogoliubov approach with the effective Gogny nucleon-nucleon interaction. In a first step, the Potential Energy Surfaces are computed in the (q 20, q30) plane, the scission lines are found, fulfilling a given criterion on the density in the nuclear neck. Finally a few properties of the fragments along this line are presented.

  20. Prompt Fission Gamma-ray Studies at DANCE

    NASA Astrophysics Data System (ADS)

    Jandel, M.; Rusev, G.; Bond, E. M.; Bredeweg, T. A.; Chadwick, M. B.; Couture, A.; Fowler, M. M.; Haight, R. C.; Kawano, T.; Keksis, A. L.; Mosby, S. M.; O'Donnell, J. M.; Rundberg, R. S.; Stetcu, I.; Talou, P.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Stoyer, M. A.; Haslett, R. J.; Henderson, R. A.; Becker, J. A.; Wu, C. Y.

    Measurements of correlated data on prompt-fission γ-rays (PFG) have been carried out for various actinide isotopes in recent years using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory (LANL). We have developed a model that conveniently parametrizes the correlated data of γ-ray multiplicity and energy. New results on two- dimensional prompt-fission γ-ray multiplicity versus energy distributions from spontaneous fission on 252Cf and neutron-induced fission on 242mAm are presented together with previously obtained results on 233,235U and 239Pu. Correlated PFG data from 252Cf are also compared to results of the detailed theoretical model developed at LANL, for different thresholds of PFG energies. Future plans to measure correlated data on fission fragments, prompt fission neutrons and γ-rays at DANCE are presented.

  1. Unconventional neutron sources for oil well logging

    NASA Astrophysics Data System (ADS)

    Frankle, C. M.; Dale, G. E.

    2013-09-01

    Americium-Beryllium (AmBe) radiological neutron sources have been widely used in the petroleum industry for well logging purposes. There is strong desire on the part of various governmental and regulatory bodies to find alternate sources due to the high activity and small size of AmBe sources. Other neutron sources are available, both radiological (252Cf) and electronic accelerator driven (D-D and D-T). All of these, however, have substantially different neutron energy spectra from AmBe and thus cause significantly different responses in well logging tools. We report on simulations performed using unconventional sources and techniques to attempt to better replicate the porosity and carbon/oxygen ratio responses a well logging tool would see from AmBe neutrons. The AmBe response of these two types of tools is compared to the response from 252Cf, D-D, D-T, filtered D-T, and T-T sources.

  2. True ternary fission

    NASA Astrophysics Data System (ADS)

    Vijayaraghavan, K. R.; Balasubramaniam, M.; von Oertzen, W.

    2015-04-01

    The study of the ternary fission of nuclei has received new interest recently. It is of general interest for nuclear dynamics, although the process is very rare. In the present work, we discuss the possibilities of true ternary fission (fragment masses A >30 ) in 252Cf for different mass splits. These mass splits are strongly favored in a collinear geometry. Based on the three cluster model (TCM), it is shown that the true ternary fission into fragments with almost equal masses is one of the possible fission modes in 252Cf . For general decays it is shown that the formation of the lightest fragment at the center has the highest probability. Further the formation of tin isotopes and/or other closed shell fragments are favored. For the decay products the presence of closed shell nuclei among the three fragments enhances the decay probabilities.

  3. Neutron Calibration Facilities of the Irsn Research Laboratory in External Dosimetry

    NASA Astrophysics Data System (ADS)

    van Ryckeghem, L.; Lacoste, V.; Pelcot, G.; Pochat, J.-L.

    2003-06-01

    The Laboratory of Studies and Research in External Dosimetry (LRDE) associated to the National Office for Metrology (BNM) has to maintain the traceability of the French references for the calibration of neutron dosimeters. The LRDE owns a facility which provides some conventional neutron spectra from sources of 241Am-Be, 252Cf, and (252Cf + D2O)/Cd recommended by ISO standards. These ISO spectra appear not appropriated to simulate some kind of workplace spectra. In order to have similar radiation conditions between the calibration and the use of the device, LRDE has built facilities ("SIGMA" and "CANEL") providing some neutron spectra from thermal to fast energies reproducing those encountered in workplaces.

  4. Development of a new method for measurement of neutron detector efficiency up to 20 MeV

    DOE PAGESBeta

    Kornilov, N. V.; Grimes, S. M.; Massey, T. N.; Brient, C. E.; Carter, D. E.; O'Donnell, J. E.; Bateman, F. B.; Carlson, A. D.; Haight, R. C.; Boukharouba, N.

    2014-09-03

    A new approach to neutron detector efficiency has been taken. A neutron detector has been calibrated with a 252Cf source at low energy. The calibration can be extended to energies above 8 MeV based on the 252Cf results. The techniques uses the fact that the cross section for a symmetric reaction with nucleus of atomic number A yielding a final nucleus with atomic number (2A-1) and a neutron A + A → (2A – 1) + n. This reaction must be symmetric about 90° in the center-of-mass system. Furthermore, the laboratory energies for the neutrons at the paired energies differmore » substantially. Thus, an efficiency known at one of the two angles can be used to determine the efficiency to higher energies or, for a negative Q, to lower neutron energies.« less

  5. Performance of the electronic personal dosemeter for neutron 'Saphydose-N' at different workplaces of nuclear facilities.

    PubMed

    Lahaye, T; Chau, Q; Ménard, S; Lacoste, V; Muller, H; Luszik-Bhadra, M; Reginatto, M; Bruguier, P

    2006-01-01

    This paper mainly aims at presenting the measurements and the results obtained with the electronic personal neutron dosemeter Saphydose-N at different facilities. Three campaigns were led in the frame of the European contract EVIDOS ('Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields'). The first one consisted in the measurements at the IRSN French research laboratory in reference neutron fields generated by a thermal facility (SIGMA), radionuclide ISO sources ((241)AmBe; (252)Cf; (252)Cf(D(2)O)\\Cd) and a realistic spectrum (CANEL/T400). The second one was performed at the Krümmel Nuclear Power Plant (Germany) close to the boiling water reactor and to a spent fuel transport cask. The third one was realised at Mol (Belgium), at the VENUS Research Reactor and at Belgonucléaire, a fuel processing factory.

  6. French comparison exercise with the rotating neutron spectrometer, 'ROSPEC'.

    PubMed

    Crovisier, P; Asselineau, B; Pelcot, G; Van-Ryckeghem, L; Cadiou, A; Truffert, H; Groetz, J E; Benmosbah, M

    2005-01-01

    The French laboratories in charge of 'neutron' dosimetry using the spectrometer 'ROSPEC', formed a working group in 2001. The participants began to study the behaviour of the instrument with a comparison exercise in broad energy neutron fields recommended by the International Organisation for Standardisation (ISO) and available at the LMDN in Cadarache. The complete version of the ROSPEC is made up of six spherical proportional counters fixed to a rotating platform. These counters cover different energy ranges which overlap each other to provide a link between the detectors, within the energy range from thermal neutrons to 4.5 MeV. The irradiation configurations chosen were ISO standard sources (252Cf, (252Cf+D2O)(/Cd), 241Am-Be) and the SIGMA facility. The results show that the 'thermal and epithermal' neutron fluence was widely overestimated by the spectrometer in all configurations.

  7. An active drop counting device using condenser microphone for superheated emulsion detector

    SciTech Connect

    Das, Mala; Marick, C.; Kanjilal, D.; Saha, S.

    2008-11-15

    An active device for superheated emulsion detector is described. A capacitive diaphragm sensor or condenser microphone is used to convert the acoustic pulse of drop nucleation to electrical signal. An active peak detector is included in the circuit to avoid multiple triggering of the counter. The counts are finally recorded by a microprocessor based data acquisition system. Genuine triggers, missed by the sensor, were studied using a simulated clock pulse. The neutron energy spectrum of {sup 252}Cf fission neutron source was measured using the device with R114 as the sensitive liquid and compared with the calculated fission neutron energy spectrum of {sup 252}Cf. Frequency analysis of the detected signals was also carried out.

  8. Determining plutonium mass in spent fuel using Cf-252 interrogation with prompt neutron detection

    SciTech Connect

    Hu, Jianwei; Tobin, Stephen J; Menlove, Howard O; Croft, Stephen

    2010-01-01

    {sup 252}Cf Interrogation with Prompt Neutron (CIPN) detection is proposed as one of 14 NDA techniques to determine Pu mass in spent fuel assemblies (FAs). CIPN is a low-cost and portable instrument, and it looks like a modified fork detector combined with an active interrogation source. Fission chamber (FC) is chosen as neutron detector because of its insensitivity to {gamma} radiation. The CIPN assay is comprised of two measurements, a background count and an active count, without and with the {sup 252}Cf source next to the fuel respectively. The net signal above background is primarily due to the multiplication of Cf source neutrons caused by the fissile content. The capability of CIPN to detect diversion and to determine fissile content was quantified using MCNPX simulations. New schemes were proposed (such as burnup and cooling time correction, etc.) and the results show that the fissile content of a target spent fuel assembly can be determined using CIPN signal.

  9. Reflection Asymmetric Shapes in the Neutron-Rich 140,143Ba Isotopes

    NASA Astrophysics Data System (ADS)

    Zhu Sheng-jiang (S, J. Zhu; Wang, Mu-ge; J, H. Hamilton; A, V. Ramayya; B, R. S. Babu; W, C. Ma; Long, Gui-lu; Deng, Jing-kang; Zhu, Ling-yan; Li, Ming; T, N. Ginter; J, Komicki; J, D. Cole; R, Aryaeinejad; Y, K. Dardenne; M, W. Drigert; J, O. Rasmussen; Ts, Yu Oganessian; M, A. Stoyer; S, Y. Chu; K, E. Gregorich; M, F. Mohar; S, G. Prussin; I, Y. Lee; N, R. Johnson; F, K. McGowan

    1997-08-01

    Level schemes for the neutron-rich 140,143Ba nuclei have been determined by study of prompt γ-rays in spontaneous fission of 252Cf. The level pattern and enhanced E1 transitions between π = + and π = - bands show reflection asymmetric shapes with simplex quantum number s = +1 in 140Ba and s = ±i in 143Ba, respectively. The octupole deformation stability with spin variation has been discussed.

  10. Investigation of factors which lead to the background in the measurement of nitrogen by IVNAA.

    PubMed

    McNeill, K G; Borovnicar, D J; Krishnan, S S; Wang, H Y; Waana, C; Harrison, J E

    1989-01-01

    A major problem in the measurement of nitrogen in the body by in vivo neutron activation analysis is the size of the background. Investigations show that random summing of gamma rays in the range 4-7 MeV is a major contributor. By direct comparison, 252Cf is shown to be a better neutron source than Pu-Be in this regard. Data are presented on the contribution to the background of water and chloride in the body.

  11. Lifetimes in neutron-rich fission fragments using the differential recoil distance method

    SciTech Connect

    Kruecken, R.; Chou, W.-T.; Cooper, J. R.; Beausang, C. W.; Barton, C. J.; Caprio, M. A.; Casten, R. F.; Hecht, A. A.; Novak, J. R.; Pietralla, N.

    2001-07-01

    Lifetimes in the neutron-rich nuclei {sup 104}Mo, {sup 110}Ru, and {sup 144}Ba were measured using the differential recoil distance method. The experiment was performed with a {sup 252}Cf fission source inside the New Yale Plunger Device. {gamma} rays were detected by the SPEctrometer for Experiments with Doppler shifts at Yale (SPEEDY) while fission fragments with the appropriate kinematics were detected by an array of photocells.

  12. Calibration of neutron albedo dosemeters.

    PubMed

    Schwartz, R B; Eisenhauer, C M

    2002-01-01

    It is shown that by calibrating neutron albedo dosemeters under the proper conditions, two complicating effects will essentially cancel out, allowing accurate calibrations with no need for explicit corrections. The 'proper conditions' are: a large room (> or = 8 m on a side). use of a D2O moderated 252Cf source, and a source-to-phantom calibration distance of approximately 70 cm. PMID:12212898

  13. Detailed dose distribution prediction of Cf-252 brachytherapy source with boron loading dose enhancement.

    PubMed

    Ghassoun, J; Mostacci, D; Molinari, V; Jehouani, A

    2010-02-01

    The purpose of this work is to evaluate the dose rate distribution and to determine the boron effect on dose rate distribution for (252)Cf brachytherapy source. This study was carried out using a Monte Carlo simulation. To validate the Monte Carlo computer code, the dosimetric parameters were determined following the updated TG-43 formalism and compared with current literature data. The validated computer code was then applied to evaluate the neutron and photon dose distribution and to illustrate the boron loading effect.

  14. Digitized two-parameter spectrometer for neutron-gamma mixed field

    SciTech Connect

    Matej, Z.; Cvachovec, J.; Prenosil, V.; Cvachovec, F.; Zaritski, S.

    2011-07-01

    This paper shows the results of digital processing of output pulses from combined photon-neutron detector using a commercially available digitizer ACQUIRIS DP 210. The advantage of digital processing is reduction of the apparatus in weight and size, acceleration of measurement, and increased resistance to pile-up of pulses. The neutron and photon spectrum of radionuclide source {sup 252}Cf is presented. (authors)

  15. Basic results of investigations of scission neutrons in nuclear fission at low excitation energies

    SciTech Connect

    Petrov, G. A. Gagarski, A. M.; Guseva, I. S.; Sokolov, V. E.; Val'ski, G. V.; Vorobiev, A. S.; Krinitcin, D. O.; Shcherbakov, O. A.; Nikolaev, D. V.; Pleva, Yu. S.; Petrova, V. I.; Zavarukhina, T. A.

    2008-07-15

    To estimate the main characteristics of neutrons emitted shortly before the scission of a fissioning nucleus, various experiments sensitive to the presence of these scission neutrons in thermal-neutron-induced fission of {sup 235}U and spontaneous fission of {sup 252}Cf were performed. The results of the experiments were analyzed within theoretical calculations allowing for various possible neutron-emission mechanisms, including the possibility of the emergence of neutrons from the scission of a nucleus.

  16. Digital front-end electronics for a tagged neutron inspection system

    SciTech Connect

    Cester, D.; Stevanato, L.; Viesti, G.; Nebbia, G.

    2013-04-19

    In this paper, we shall present a simple VME front-end system that employs the FADC CAEN V1720 8- channel 12-bit 250-MS/s digitizer. This system produces coincidence spectra between the trigger particle and other detectors and it replaces the traditional technique of chaining analog electronics. Tests have been performed using a pulser working at different frequencies as well as employing a {sup 252}Cf source in concert with an array of detectors.

  17. Orientation of fission fragments and anisotropy of {gamma}-Quanta emission

    SciTech Connect

    Barabanov, A.L.

    1994-07-01

    Experimental data on angular distributions of {gamma}-quanta emitted by fragments of binary and ternary spontaneous fission of {sup 252}Cf are analyzed. Their difference indicates that the fragment alignment is higher in ternary fission than that in binary fission. Consequences of a possible relation between the ternary fission mechanism and the excitation of collective modes at the stage of descent from the barrier to the scission point are discussed. 19 refs., 5 figs.

  18. The SPIDER fission fragment spectrometer for fission product yield measurements

    DOE PAGESBeta

    Meierbachtol, K.; Tovesson, F.; Shields, D.; Arnold, C.; Blakeley, R.; Bredeweg, T.; Devlin, M.; Hecht, A. A.; Heffern, L. E.; Jorgenson, J.; et al

    2015-04-01

    The SPectrometer for Ion DEtermination in fission Research (SPIDER) developed for measuring mass yield distributions of fission products from spontaneous and neutron-induced fission. The 2E–2v method of measuring the kinetic energy (E) and velocity (v) of both outgoing fission products utilized, with the goal of measuring the mass of the fission products with an average resolution of 1 atomic mass unit (amu). The SPIDER instrument, consisting of detector components for time-of-flight, trajectory, and energy measurements, assembled and tested using 229Th and 252Cf radioactive decay sources. For commissioning, the fully assembled system measured fission products from spontaneous fission of 252Cf. Finally,more » individual measurement resolutions were met for time-of-flight (250 ps FWHM), spacial resolution (2 mm FHWM), and energy (92 keV FWHM for 8.376 MeV). These mass yield results measured from 252Cf spontaneous fission products are reported from an E–v measurement.« less

  19. Capture cross section measurement analysis in the Californium-252 spectrum with the Monte Carlo method.

    PubMed

    Manojlovič, Stanko; Trkov, Andrej; Žerovnik, Gašper; Snoj, Luka

    2015-07-01

    Absolute average capture cross sections of gold, thorium, tantalum, molybdenum, copper and strontium in (252)Cf spontaneous fission neutron spectrum were simulated for two types of experiment setups preformed by Z. Dezso and J. Csikai and by L. Green. The experiments were simulated with MCNP5 using cross section data from the ENDF/B-VII.0 library. The determination of neutron backscattering was calculated with the use of neutron flagging. Correction factors to experimentally measured values were determined to obtain average cross sections in a pure (252)Cf spontaneous fission spectrum. Influence of concrete wall thickness, air moisture and room size on the average cross section was analyzed. Correction factors amounted to about 30%. Corrected values corresponding to average cross sections in a pure (252)Cf spectrum were calculated for (197)Au, (232)Th, (181)Ta, (98)Mo, (65)Cu and (84)Sr. Average cross sections were also calculated with the RR_UNC software using IRDFF-v.1.05 and ENDF/B-VII.0 libraries. The revised average radiative capture cross sections are 75.5±0.1 mb for (197)Au, 87.0±1.6 mb for (232)Th , 98.0±4.5 mb for (181)Ta, 21.2±0.5 mb for (98)Mo, 10.3±0.3 mb for (63)Cu, and 34.9±6.5 mb for (84)Sr.

  20. MCNP SIMULATION OF THE HP(10) ENERGY RESPONSE OF A BRAZILIAN TLD ALBEDO NEUTRON INDIVIDUAL DOSEMETER, FROM THERMAL TO 20 MeV.

    PubMed

    Freitas, B M; Martins, M M; Pereira, W W; da Silva, A X; Mauricio, C L P

    2016-09-01

    The Brazilian Instituto de Radioproteção e Dosimetria (IRD) runs a neutron individual monitoring system with a home-made TLD albedo dosemeter. It has already been characterised and calibrated in some reference fields. However, the complete energy response of this dosemeter is not known, and the calibration factors for all monitored workplace neutron fields are difficult to be obtained experimentally. Therefore, to overcome such difficulties, Monte Carlo simulations have been used. This paper describes the simulation of the HP(10) neutron response of the IRD TLD albedo dosemeter using the MCNPX transport code, for energies from thermal to 20 MeV. The validation of the MCNPX modelling is done comparing the simulated results with the experimental measurements for ISO standard neutron fields of (241)Am-Be, (252)Cf, (241)Am-B and (252)Cf(D2O) and also for (241)Am-Be source moderated with paraffin and silicone. Bare (252)Cf are used for normalisation. PMID:26276807

  1. Use of GEANT4 vs. MCNPX for the characterization of a boron-lined neutron detector

    NASA Astrophysics Data System (ADS)

    van der Ende, B. M.; Atanackovic, J.; Erlandson, A.; Bentoumi, G.

    2016-06-01

    This work compares GEANT4 with MCNPX in the characterization of a boron-lined neutron detector. The neutron energy ranges simulated in this work (0.025 eV to 20 MeV) are the traditional domain of MCNP simulations. This paper addresses the question, how well can GEANT4 and MCNPX be employed for detailed thermal neutron detector characterization? To answer this, GEANT4 and MCNPX have been employed to simulate detector response to a 252Cf energy spectrum point source, as well as to simulate mono-energetic parallel beam source geometries. The 252Cf energy spectrum simulation results demonstrate agreement in detector count rate within 3% between the two packages, with the MCNPX results being generally closer to experiment than are those from GEANT4. The mono-energetic source simulations demonstrate agreement in detector response within 5% between the two packages for all neutron energies, and within 1% for neutron energies between 100 eV and 5 MeV. Cross-checks between the two types of simulations using ISO-8529 252Cf energy bins demonstrates that MCNPX results are more self-consistent than are GEANT4 results, by 3-4%.

  2. Degrader foils for the CARIBU project

    NASA Astrophysics Data System (ADS)

    Greene, John P.; Savard, Guy; Pardo, Richard C.; Baker, Samuel I.; Levand, Anthony F.; Zabransky, Bruce J.

    2011-11-01

    The Californium Rare Ion Breeder Upgrade (CARIBU) project was conceived to provide neutron rich beams originating from the 3% fission decay branch of a 252Cf source to be accelerated by the Argonne Tandem Linear Accelerator System (ATLAS). This 1Ci 252Cf source will be housed in a movable shielded cask, from which it can be directly transferred into a large helium gas stopper cell. Within the gas stopper, the CARIBU 252Cf source is positioned behind an aluminum degrader foil where the radioactive recoils of interest lose most of their energy before being stopped in the helium gas. To stop recoils over the full fission mass range effectively, three degraders of increasing thickness are required, one to cover the light fission peak and two for the isotopes in the heavy fission peak. The geometry of the source within the gas cell would ideally require a hemispherically shaped degrader foil for uniform energy loss of the fission products. The fabrication of a thin foil of such a shape proved to be exceedingly difficult and, therefore, a compromise "top hat" arrangement was designed. In addition, the ultra-high vacuum (UHV) environment necessary for the gas cell to function properly prevented the use of any epoxy due to vacuum outgassing. Handling, assembling of the foils and mounting must be done under clean room conditions. Details of early attempts at producing these foils as well as handling and mounting will be discussed.

  3. Design of a californium-based epithermal neutron beam for neutron capture therapy.

    PubMed

    Yanch, J C; Kim, J K; Wilson, M J

    1993-08-01

    The potential of the spontaneously fissioning isotope, 252Cf, to provide epithermal neutrons for use in boron neutron capture therapy (BNCT) has been investigated using Monte Carlo simulation. The Monte Carlo code MCNP was used to design an assembly composed of a 26 cm long, 11 cm radius cylindrical D2O moderator followed by a 64 cm long Al filter. Lithium filters are placed between the moderator and the filter and between the Al and the patient. A reflector surrounding the moderator/filter assembly is required in order to maintain adequate therapy flux at the patient position. An ellipsoidal phantom composed of skull- and brain-equivalent material was used to determine the dosimetric effect of this beam. It was found that both advantage depths and advantage ratios compare very favourably with reactor and accelerator epithermal neutron sources. The dose rate obtainable, on the other hand, is 4.1 RBE cGy min-1, based on a very large (1.0 g) source of 252Cf. This dose rate is two to five times lower than those provided by existing reactor beams and can be viewed as a drawback of using 252Cf as a neutron source. Radioisotope sources, however, do offer the advantage of in-hospital installation.

  4. Correction and verification of AECL Bonner Sphere response matrix based on mono-energetic neutron calibration performed at NPL.

    PubMed

    Atanackovic, J; Thomas, D J; Roberts, N J; Witharana, S; Dubeau, J; Yonkeu, A

    2014-10-01

    The AECL Bonner Sphere Spectrometer (BSS) was taken to National Physical Laboratory (NPL) for calibration in mono-energetic neutron fields and bare (252)Cf neutron fields. The mono-energetic radiations were performed using ISO-8529 prescribed neutron energies: 0.071, 0.144, 0.565, 1.2, 5 and 17 MeV. A central SP9 proportional counter was also evaluated at the NPL thermal neutron calibration facility in order to assess an effective pressure of (3)He inside the counter, i.e. number density of (3)He atoms. Based on these measurements and methods outlined by Thomas and Soochak, a new BSS response matrix was generated. The response matrix is then verified by unfolding spectra corresponding to various neutron fields. Those are NPL bare (252)Cf source, National Institute of Standards and Technology bare and heavy water moderated (252)Cf source and (241)AmBe calibration source located at National Research Council. A good agreement was observed with expected neutron fluence rates, as well as derived dosimetric quantities, such as International Commission on Radiological Protection-74 ambient dose equivalent.

  5. The analysis of complex mixed-radiation fields using near real-time imaging.

    PubMed

    Beaumont, Jonathan; Mellor, Matthew P; Joyce, Malcolm J

    2014-10-01

    A new mixed-field imaging system has been constructed at Lancaster University using the principles of collimation and back projection to passively locate and assess sources of neutron and gamma-ray radiation. The system was set up at the University of Manchester where three radiation sources: (252)Cf, a lead-shielded (241)Am/Be and a (22)Na source were imaged. Real-time discrimination was used to find the respective components of the neutron and gamma-ray fields detected by a single EJ-301 liquid scintillator, allowing separate images of neutron and gamma-ray emitters to be formed. (252)Cf and (22)Na were successfully observed and located in the gamma-ray image; however, the (241)Am/Be was not seen owing to surrounding lead shielding. The (252)Cf and (241)Am/Be neutron sources were seen clearly in the neutron image, demonstrating the advantage of this mixed-field technique over a gamma-ray-only image where the (241)Am/Be source would have gone undetected.

  6. Production, Distribution, and Applications of Californium-252 Neutron Sources

    SciTech Connect

    Balo, P.A.; Knauer, J.B.; Martin, R.C.

    1999-10-03

    The radioisotope {sup 252}Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-year half-life. A source the size of a person's little finger can emit up to 10{sup 11} neutrons/s. Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement, and minerals, as well as for detection and identification of explosives, laud mines, and unexploded military ordnance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards, and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 years of experience and by U.S. Bureau of Mines tests of source survivability during explosions. The production and distribution center for the U. S Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). DOE sells The radioisotope {sup 252}Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6- year half-life. A source the size of a person's little finger can emit up to 10 neutrons/s. Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement, and minerals, as well as for detection and identification of explosives, laud mines, and unexploded military ordnance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards, and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 years of experience and by U.S. Bureau of Mines tests of source survivability during explosions. The production and distribution center for the U. S Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory(ORNL). DOE sells {sup 252}Cf to commercial

  7. Low-Dose-Rate Californium-252 Neutron Intracavitary Afterloading Radiotherapy Combined With Conformal Radiotherapy for Treatment of Cervical Cancer

    SciTech Connect

    Zhang Min; Xu Hongde; Pan Songdan; Lin Shan; Yue Jianhua; Liu Jianren

    2012-07-01

    Purpose: To study the efficacy of low-dose-rate californium-252 ({sup 252}Cf) neutron intracavitary afterloading radiotherapy (RT) combined with external pelvic RT for treatment of cervical cancer. Methods and Materials: The records of 96 patients treated for cervical cancer from 2006 to 2010 were retrospectively reviewed. For patients with tumors {<=}4 cm in diameter, external beam radiation was performed (1.8 Gy/day, five times/week) until the dose reached 20 Gy, and then {sup 252}Cf neutron intracavitary afterloading RT (once/week) was begun, and the frequency of external beam radiation was changed to four times/week. For patients with tumors >4 cm, {sup 252}Cf RT was performed one to two times before whole-pelvis external beam radiation. The tumor-eliminating dose was determined by using the depth limit of 5 mm below the mucosa as the reference point. In all patients, the total dose of the external beam radiation ranged from 46.8 to 50 Gy. For {sup 252}Cf RT, the dose delivered to point A was 6 Gy/fraction, once per week, for a total of seven times, and the total dose was 42 Gy. Results: The mean {+-} SD patient age was 54.7 {+-} 13.7 years. Six patients had disease assessed at stage IB, 13 patients had stage IIA, 49 patients had stage IIB, 3 patients had stage IIIA, 24 patients had stage IIIB, and 1 patient had stage IVA. All patients obtained complete tumor regression (CR). The mean {+-} SD time to CR was 23.5 {+-} 3.4 days. Vaginal bleeding was fully controlled in 80 patients within 1 to 8 days. The mean {+-} SD follow-up period was 27.6 {+-} 12.7 months (range, 6-48 months). Five patients died due to recurrence or metastasis. The 3-year survival and disease-free recurrence rates were 89.6% and 87.5 %, respectively. Nine patients experienced mild radiation proctitis, and 4 patients developed radiocystitis. Conclusions: Low-dose-rate {sup 252}Cf neutron RT combined with external pelvic RT is effective for treating cervical cancer, with a low incidence of

  8. Quadrupole Collective Inertia in Nuclear Fission: Cranking Approximation

    SciTech Connect

    Baran, A.; Sheikh, J. A.; Dobaczewski, J.; Nazarewicz, Witold

    2011-01-01

    Collective mass tensor derived from the cranking approximation to the adiabatic time-dependent Hartree-Fock-Bogoliubov (ATDHFB) approach is compared with that obtained in the Gaussian Overlap Approximation (GOA) to the generator coordinate method. Illustrative calculations are carried out for one-dimensional quadrupole fission pathways in ^{256}Fm. It is shown that the collective mass exhibits strong variations with the quadrupole collective coordinate. These variations are related to the changes in the intrinsic shell structure. The differences between collective inertia obtained in cranking and perturbative cranking approximations to ATDHFB, and within GOA, are discussed.

  9. Improving the safety of a body composition analyser based on the PGNAA method.

    PubMed

    Miri-Hakimabad, Hashem; Izadi-Najafabadi, Reza; Vejdani-Noghreiyan, Alireza; Panjeh, Hamed

    2007-12-01

    The 252Cf radioisotope and 241Am-Be are intense neutron emitters that are readily encapsulated in compact, portable and sealed sources. Some features such as high flux of neutron emission and reliable neutron spectrum of these sources make them suitable for the prompt gamma neutron activation analysis (PGNAA) method. The PGNAA method can be used in medicine for neutron radiography and body chemical composition analysis. 252Cf and 241Am-Be sources generate not only neutrons but also are intense gamma emitters. Furthermore, the sample in medical treatments is a human body, so it may be exposed to the bombardments of these gamma-rays. Moreover, accumulations of these high-rate gamma-rays in the detector volume cause simultaneous pulses that can be piled up and distort the spectra in the region of interest (ROI). In order to remove these disadvantages in a practical way without being concerned about losing the thermal neutron flux, a gamma-ray filter made of Pb must be employed. The paper suggests a relatively safe body chemical composition analyser (BCCA) machine that uses a spherical Pb shield, enclosing the neutron source. Gamma-ray shielding effects and the optimum radius of the spherical Pb shield have been investigated, using the MCNP-4C code, and compared with the unfiltered case, the bare source. Finally, experimental results demonstrate that an optimised gamma-ray shield for the neutron source in a BCCA can reduce effectively the risk of exposure to the 252Cf and 241Am-Be sources. PMID:18268376

  10. Moderator design studies for a new neutron reference source based on the D-T fusion reaction

    NASA Astrophysics Data System (ADS)

    Mozhayev, Andrey V.; Piper, Roman K.; Rathbone, Bruce A.; McDonald, Joseph C.

    2016-06-01

    The radioactive isotope Californium-252 (252Cf) is relied upon internationally as a neutron calibration source for ionizing radiation dosimetry because of its high specific activity. The source may be placed within a heavy-water (D2O) moderating sphere to produce a softened spectrum representative of neutron fields common to commercial nuclear power plant environments, among others. Due to termination of the U.S. Department of Energy loan/lease program in 2012, the expense of obtaining 252Cf sources has undergone a significant increase, rendering high output sources largely unattainable. On the other hand, the use of neutron generators in research and industry applications has increased dramatically in recent years. Neutron generators based on deuteriumtritium (D-T) fusion reaction provide high neutron fluence rates and, therefore, could possibly be used as a replacement for 252Cf. To be viable, the 14 MeV D-T output spectrum must be significantly moderated to approximate common workplace environments. This paper presents the results of an effort to select appropriate moderating materials and design a configuration to reshape the primary neutron field toward a spectrum approaching that from a nuclear power plant workplace. A series of Monte-Carlo (MCNP) simulations of single layer high- and low-Z materials are used to identify initial candidate moderators. Candidates are refined through a similar series of simulations involving combinations of 2-5 different materials. The simulated energy distribution using these candidate moderators are rated in comparison to a target spectrum. Other properties, such as fluence preservation and/or enhancement, prompt gamma production and other characteristics are also considered.

  11. Improving the safety of a body composition analyser based on the PGNAA method.

    PubMed

    Miri-Hakimabad, Hashem; Izadi-Najafabadi, Reza; Vejdani-Noghreiyan, Alireza; Panjeh, Hamed

    2007-12-01

    The 252Cf radioisotope and 241Am-Be are intense neutron emitters that are readily encapsulated in compact, portable and sealed sources. Some features such as high flux of neutron emission and reliable neutron spectrum of these sources make them suitable for the prompt gamma neutron activation analysis (PGNAA) method. The PGNAA method can be used in medicine for neutron radiography and body chemical composition analysis. 252Cf and 241Am-Be sources generate not only neutrons but also are intense gamma emitters. Furthermore, the sample in medical treatments is a human body, so it may be exposed to the bombardments of these gamma-rays. Moreover, accumulations of these high-rate gamma-rays in the detector volume cause simultaneous pulses that can be piled up and distort the spectra in the region of interest (ROI). In order to remove these disadvantages in a practical way without being concerned about losing the thermal neutron flux, a gamma-ray filter made of Pb must be employed. The paper suggests a relatively safe body chemical composition analyser (BCCA) machine that uses a spherical Pb shield, enclosing the neutron source. Gamma-ray shielding effects and the optimum radius of the spherical Pb shield have been investigated, using the MCNP-4C code, and compared with the unfiltered case, the bare source. Finally, experimental results demonstrate that an optimised gamma-ray shield for the neutron source in a BCCA can reduce effectively the risk of exposure to the 252Cf and 241Am-Be sources.

  12. Californium-252 Brachytherapy Combined With External-Beam Radiotherapy for Cervical Cancer: Long-Term Treatment Results

    SciTech Connect

    Lei Xin; Qian Chengyuan; Qing Yi; Zhao Kewei; Yang Zhengzhou; Dai Nan; Zhong Zhaoyang; Tang Cheng; Li Zheng; Gu Xianqing; Zhou Qian; Feng Yan; Xiong Yanli; Shan Jinlu; Wang Dong

    2011-12-01

    Purpose: To observe, by retrospective analysis, the curative effects and complications due to californium-252 ({sup 252}Cf) neutron intracavitary brachytherapy (ICBT) combined with external-beam radiotherapy (EBRT) in the treatment of cervical cancer. Methods and Materials: From February 1999 to December 2007, 696 patients with cervical cancer (Stages IB to IIIB) were treated with {sup 252}Cf-ICBT in combination of EBRT. Of all, 31 patients were at Stage IB, 104 at IIA, 363 at IIB, 64 at IIIA, and 134 at IIIB. Californium-252 ICBT was delivered at 7-12 Gy per insertion per week, with a total dose of 29-45 Gy to reference point A in three to five insertions. The whole pelvic cavity was treated with 8-MV X-ray external irradiation at 2 Gy per fraction, four times per week. After 16-38 Gy of external irradiation, the center of the whole pelvic field was blocked with a 4-cm-wide lead shield, with a total external irradiation dose of 44-56 Gy. The total treatment course was 5 to 6 weeks. Results: Overall survival rate at 3 and 5 years for all patients was 76.0% and 64.9%, respectively. Disease-free 3- and 5-year survival rates of patients were 71.2% and 58.4%, respectively. Late complications included vaginal contracture and adhesion, radiation proctitis, radiation cystitis, and inflammatory bowel, which accounted for 5.8%, 7.1%, 6.2%, and 4.9%, respectively. Univariate analysis results showed significant correlation of stage, age, histopathologic grade, and lymph node status with overall survival. Cox multiple regression analysis showed that the independent variables were stage, histopathologic grade, tumor size, and lymphatic metastasis in all patients. Conclusion: Results of this series suggest that the combined use of {sup 252}Cf-ICBT with EBRT is an effective method for treatment of cervical cancer.

  13. Analysis of the scintillation mechanism in a pressurized {sup 4}He fast neutron detector using pulse shape fitting

    SciTech Connect

    Kelley, R.P. Ray, H.; Jordan, K.A.; Murer, D.

    2015-03-15

    An empirical investigation of the scintillation mechanism in a pressurized {sup 4}He gas fast neutron detector was conducted using pulse shape fitting. Scintillation signals from neutron interactions were measured and averaged to produce a single generic neutron pulse shape from both a {sup 252}Cf spontaneous fission source and a (d,d) neutron generator. An expression for light output over time was then developed by treating the decay of helium excited states in the same manner as the decay of radioactive isotopes. This pulse shape expression was fitted to the measured neutron pulse shape using a least-squares optimization algorithm, allowing an empirical analysis of the mechanism of scintillation inside the {sup 4}He detector. A further understanding of this mechanism in the {sup 4}He detector will advance the use of this system as a neutron spectrometer. For {sup 252}Cf neutrons, the triplet and singlet time constants were found to be 970 ns and 686 ns, respectively. For neutrons from the (d,d) generator, the time constants were found to be 884 ns and 636 ns. Differences were noted in the magnitude of these parameters compared to previously published data, however the general relationships were noted to be the same and checked with expected trends from theory. Of the excited helium states produced from a {sup 252}Cf neutron interaction, 76% were found to be born as triplet states, similar to the result from the neutron generator of 71%. The two sources yielded similar pulse shapes despite having very different neutron energy spectra, validating the robustness of the fits across various neutron energies.

  14. RBE-LET relationships of high-LET radiations in Drosophila mutations.

    PubMed

    Yoshikawa, I; Takatsuji, T; Nagano, M; Takada, J; Endo, S; Hoshi, M

    1999-12-01

    The relative biological effectiveness (RBE) of 252Cf neutrons and synchrotron-generated high-energy charged particles for mutation induction was evaluated as a function of linear energy transfer (LET), using the loss of heterozygosity for wing-hair mutations and the reversion of the mutant white-ivory eye-color in Drosophila melanogaster. Loss of heterozygosity for wing-hair mutations results predominantly from mitotic crossing over induced in wing anlage cells of larvae, while the reverse mutation of eye-color is due to an intragenic structural change (2.96 kb-DNA excision) in the white locus on the X-chromosome. The measurements were performed in a combined mutation assay system so that induced mutant wing-hair clones as well as revertant eye-color clone can be detected simultaneously in the same individual. Larvae were irradiated at the age of 3 days post oviposition with 252Cf neutrons, carbon beam or neon beam. For the neutron irradiation, the RBE values for wing-hair mutations were larger than that for eye-color mutation by about 7 fold. The RBE of carbon ions for producing the wing-hair mutations increased with increase in LET. The estimated RBE values were found to be in the range 2 to 6.5 for the wing-hair. For neon beam irradiation, the RBE values for wing-hair mutations peak near 150 keV/micron and decrease with further increase in LET. On the other hand, the RBE values for the induction of the eye-color mutation are nearly unity in 252Cf neutrons and both ions throughout the LET range irradiated. We discuss the relationships between the initial DNA damage and LET in considering the mechanism of somatic mutation induction. PMID:10804999

  15. Preliminary calibration of the ACP safeguards neutron counter

    NASA Astrophysics Data System (ADS)

    Lee, T. H.; Kim, H. D.; Yoon, J. S.; Lee, S. Y.; Swinhoe, M.; Menlove, H. O.

    2007-10-01

    The Advanced Spent Fuel Conditioning Process (ACP), a kind of pyroprocess, has been developed at the Korea Atomic Energy Research Institute (KAERI). Since there is no IAEA safeguards criteria for this process, KAERI has developed a neutron coincidence counter to make it possible to perform a material control and accounting (MC&A) for its ACP materials for the purpose of a transparency in the peaceful uses of nuclear materials at KAERI. The test results of the ACP Safeguards Neutron Counter (ASNC) show a satisfactory performance for the Doubles count measurement with a low measurement error for its cylindrical sample cavity. The neutron detection efficiency is about 21% with an error of ±1.32% along the axial direction of the cavity. Using two 252Cf neutron sources, we obtained various parameters for the Singles and Doubles rates for the ASNC. The Singles, Doubles, and Triples rates for a 252Cf point source were obtained by using the MCNPX code and the results for the ft8 cap multiplicity tally option with the values of ɛ, fd, and ft measured with a strong source most closely match the measurement results to within a 1% error. A preliminary calibration curve for the ASNC was generated by using the point model equation relationship between 244Cm and 252Cf and the calibration coefficient for the non-multiplying sample is 2.78×10 5 (Doubles counts/s/g 244Cm). The preliminary calibration curves for the ACP samples were also obtained by using an MCNPX simulation. A neutron multiplication influence on an increase of the Doubles rate for a metal ingot and UO2 powder is clearly observed. These calibration curves will be modified and complemented, when hot calibration samples become available. To verify the validity of this calibration curve, a measurement of spent fuel standards for a known 244Cm mass will be performed in the near future.

  16. RBE-LET relationships of high-LET radiations in Drosophila mutations.

    PubMed

    Yoshikawa, I; Takatsuji, T; Nagano, M; Takada, J; Endo, S; Hoshi, M

    1999-12-01

    The relative biological effectiveness (RBE) of 252Cf neutrons and synchrotron-generated high-energy charged particles for mutation induction was evaluated as a function of linear energy transfer (LET), using the loss of heterozygosity for wing-hair mutations and the reversion of the mutant white-ivory eye-color in Drosophila melanogaster. Loss of heterozygosity for wing-hair mutations results predominantly from mitotic crossing over induced in wing anlage cells of larvae, while the reverse mutation of eye-color is due to an intragenic structural change (2.96 kb-DNA excision) in the white locus on the X-chromosome. The measurements were performed in a combined mutation assay system so that induced mutant wing-hair clones as well as revertant eye-color clone can be detected simultaneously in the same individual. Larvae were irradiated at the age of 3 days post oviposition with 252Cf neutrons, carbon beam or neon beam. For the neutron irradiation, the RBE values for wing-hair mutations were larger than that for eye-color mutation by about 7 fold. The RBE of carbon ions for producing the wing-hair mutations increased with increase in LET. The estimated RBE values were found to be in the range 2 to 6.5 for the wing-hair. For neon beam irradiation, the RBE values for wing-hair mutations peak near 150 keV/micron and decrease with further increase in LET. On the other hand, the RBE values for the induction of the eye-color mutation are nearly unity in 252Cf neutrons and both ions throughout the LET range irradiated. We discuss the relationships between the initial DNA damage and LET in considering the mechanism of somatic mutation induction.

  17. Acoustic response of superheated droplet detectors to neutrons

    NASA Astrophysics Data System (ADS)

    Gao, Size; Zhang, Guiying; Ni, Bangfa; Zhao, Changjun; Zhang, Huanqiao; Guan, Yongjing; Chen, Zhe; Xiao, Caijin; Liu, Chao; Liu, Cunxiong

    2012-03-01

    The search for dark matter (DM) is a hot field nowadays, a number of innovative techniques have emerged. The superheated droplet technique is relatively mature; however, it is recently revitalized in a number of frontier fields including the search for DM. In this work, the acoustic response of Superheated Droplet Detectors (SDDs) to neutrons was studied by using a 252Cf neutron source, SDDs developed by the China Institute of Atomic Energy, a sound sensor, a sound card and a PC. Sound signals were filtered. The characteristics of FFT spectra, power spectra and time constants were used to determine the authenticity of the bubbles analyzed.

  18. A modular large-area lithium foil multi-wire proportional counter neutron detector

    NASA Astrophysics Data System (ADS)

    Nelson, Kyle A.; Edwards, Nathaniel S.; Kusner, Michael R.; Mayhugh, Michael R.; Montag, Benjamin W.; Schmidt, Aaron J.; Wayant, Clayton D.; McGregor, Douglas S.

    2015-11-01

    Several Li foil multi-wire proportional counters were constructed with five layers of 75 μm thick 6Li foils spaced 1.63 cm apart. Each detector had 1250 cm2 of active area and was backfilled with 1.0 atm of P-10 gas. Two of these detectors were positioned back-to-front with 5.0 cm of high-density polyethylene (HDPE) positioned between the two detectors and on the front and back. Additional 2.54 cm thick HDPE sheets were added to the remaining sides. The detectors were operated with a single electronics unit and were delivered to a test facility where multiple neutron and gamma-ray sensitivity experiments were completed. First, a 252Cf neutron source was positioned at various distances from the front of the detector and the absolute detection efficiency (cps ng-1) was recorded at each distance. Second, a transient test was completed by moving the neutron source in front of the detector at a constant rate while recording the change in count rate (cps). Third, the lateral sensitivity and symmetry of the detection system was investigated by positioning a 252Cf source up to 5.0 m away from the centerline of the arrayed detectors in 1.0 m increments in both outward directions. The angular response was investigated by positioning the 252Cf source 2.0 m from the center of the device and recording the count rate at each stationary position in 15° increments from 0° to 360°. The count rate varied 15% from minimum to maximum during the angular response test. Additionally, the arrayed system was modeled in MCNP6 and had an intrinsic neutron detection efficiency of 12.6% for a bare 252Cf source, less than the experimentally determined efficiency of 13.9±0.03%, as expected. The gamma-ray sensitivity of the detection system was also investigated and pulse-height spectra were collected and plotted against a neutron response spectrum for comparison.

  19. TEPC performance for a reference standard.

    PubMed

    Zhang, Weihua; Wang, Zhiqiang; Liu, Yina; Li, Chunjuan; Xiao, Xuefu; Luo, Hailong; Chen, Jun; Li, Wei

    2014-01-01

    A portable tissue-equivalent proportional counter (TEPC)-based system was developed, which will be used as a reference standard in the neutron mixed field for radiation protection. In this paper, microdosimetry of the TEPC system was studied both in neutron ((252)Cf and (241)Am-Be sources) and gamma ((137)Cs and (60)Co sources) reference radiation fields. The measured neutron and gamma-dose equivalent rates were, respectively, compared with those of the reference ambient dose equivalent rate H(*)(10). And the measured microdosimetric spectra were compared with the Monte Carlo code FLUKA simulated results. All of the comparisons primarily agreed well. PMID:24036657

  20. Collective Band Structures in the Neutron-Rich 107,109Ru Nuclei

    NASA Astrophysics Data System (ADS)

    Zhu, Sheng-jiang; Gan, Cui-yun; J, Hamilton H.; A, Ramayya V.; B, Babu R. S.; M, Sakhaee; W, Ma C.; Long, Gui-lu; Deng, Jing-kang; Zhu, Ling-yan; Li, Ming; Yang, Li-ming; J, Komicki; J, Cole D.; R, Aryaeinejad; Y, Dardenne K.; M, Drigert W.; J, Rasmussen O.; M, Stoyer A.; S, Chu Y.; K, Gregorich E.; M, Mohar F.; S, Prussin G.; I, Lee Y.; N, Johnson R.; F, McGowan K.

    1998-11-01

    The levels in neutron-rich odd-A 107,109Ru nuclei have been investigated by using γ-γ- and γ-γ-γ-coincidence studies of the prompt γ-rays from the spontaneous fission of 252Cf. The ground state bands and the negative parity bands are identified and expanded in both nuclei. Triaxial rotor plus particle model calculations indicate the ground state bands originate from ν(d5/2 + g7/2) quasiparticle configurations and the negative parity bands are from νh11/2 orbital.

  1. Octupole Deformation Bands of πh11/2 in Neutron-Rich 145,147La Nuclei

    NASA Astrophysics Data System (ADS)

    Zhu, Sheng-jiang; S, Zhu J.; Wang, Mu-ge; J, Hamilton H.; A, Ramayya V.; B, Babu R. S.; W, Ma C.; Long, Gui-lu; Zhu, Ling-yan; Li, Ming; A, Sakhaee; Gan, Cui-yun; Yang, Li-ming; J, Komicki; J, Cole D.; R, Aryaeinejad; M, Drigert W.; J, Rasmussen O.; M, Stoyer A.; S, Chu Y.; K, Gregorich E.; M, Mohar F.; S, Prussin G.; I, Lee Y.; Yu, Oganessian Ts; G, Ter-Akopian M.; A, Daniel V.

    1999-03-01

    Octupole deformation bands built on πh11/2 orbital in neutron-rich odd-Z 145,147La nuclei have been investigated by measuring the prompt γ-rays emitted from the 252Cf source. The alternating parity band structures and strong E1 transitions observed between negative- and positive-parity bands in both nuclei indicate the octupole deformation enhanced by the h11/2 single proton coupling. According to observed energy displacements the octupole deformation becomes stable at the intermediate spin states.

  2. Combined liquid chromatography-mass spectrometry for trace analysis of pharmaceuticals

    NASA Astrophysics Data System (ADS)

    Schmidt, Lothar; Danigel, Harald; Jungclas, Hartmut

    1982-07-01

    A 252Cf-plasma desorption mass spectrometer (PDMS) for the analysis of thin layers from nonvolatile organic samples has been set up to be combined with a liquid chromatograph. A novel interface performs the direct inlet of the liquid sample through a capillary into the vacuum system of the spectrometer. Samples of drugs are periodically collected, transferred to the ion source and analysed using a rotating disk. This on-line sample preparation has been tested for three antiarrhythmic drugs using various solvents and mixtures.

  3. A Fission Time Projection Chamber for High Precision Cross Section Measurements

    NASA Astrophysics Data System (ADS)

    Snyder, Lucas; Greife, Uwe

    2010-11-01

    The design of next generation nuclear reactors and other nuclear applications are increasingly dependent on advanced simulations. Sensitivity studies have shown a need for high precision nuclear data to improve the predictive capabilities of these simulations. The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration has constructed and is currently testing a prototype Time Projection Chamber (TPC) designed to measure fission cross sections to a higher accuracy than is capable with existing technology. In this talk, I will discuss the status of the fission TPC and progress on collecting the first set of data from ^252Cf spontaneous fission.

  4. Experimental validation of the new nanodosimetry-based cell survival model for mixed neutron and gamma-ray irradiation.

    PubMed

    Wang, C-K Chris; Zhang, Xin; Gifford, Ian; Burgett, Eric; Adams, Vince; Al-Sheikhly, Mohamad

    2007-09-01

    The new nanodosimetry-based linear-quadratic (LQ) formula has been reviewed for mixed-LET irradiation. V-79 Chinese hamster cells have been irradiated with a mixed-LET field of fission neutrons and gamma rays at the University of Maryland Training Reactor (MUTR). The results show that the experimental survival curve agrees well with that predicted by the new nanodosimetry-based LQ model. The experimental study described in this note, therefore, serves as a validation for the new model to be used for mixed-LET radiotherapies, e.g. 252Cf brachytherapy.

  5. Experimental validation of the new nanodosimetry-based cell survival model for mixed neutron and gamma-ray irradiation

    NASA Astrophysics Data System (ADS)

    Wang, C.-K. Chris; Zhang, Xin; Gifford, Ian; Burgett, Eric; Adams, Vince; Al-Sheikhly, Mohamad

    2007-09-01

    The new nanodosimetry-based linear-quadratic (LQ) formula has been reviewed for mixed-LET irradiation. V-79 Chinese hamster cells have been irradiated with a mixed-LET field of fission neutrons and gamma rays at the University of Maryland Training Reactor (MUTR). The results show that the experimental survival curve agrees well with that predicted by the new nanodosimetry-based LQ model. The experimental study described in this note, therefore, serves as a validation for the new model to be used for mixed-LET radiotherapies, e.g. 252Cf brachytherapy.

  6. Production of microgram amounts of einsteinium 253 by irradiating californium in a reactor

    SciTech Connect

    Kulyukhin, S.A.; Averman, L.N.; Mikheev, N.B.; Novichenko, V.L.; Rumer, I.A.

    1986-07-01

    /sup 253/Es has been made by irradiating 250 microg of /sup 252/Cf in a neutron flux of 5.10/sup 14/ n/cm/sup 2/.sec for 500 h. The product, about 1 microg of einsteinium, was separated chromatographically on Aminex resin of particle size 20-25 microm. The eluent was ammonium alpha-hydroxyisobutyrate (0.14 mole/liter) at pH 4.95. The purification coefficient for Es from Cf was about 1.10/sup 5/. More extensive purification can be provided by repeating the process on another column with the same parameters.

  7. Status of transuranium element production

    SciTech Connect

    King, L.J.

    1985-01-01

    The Transuranium Processing Plant at Oak Ridge National Laboratory has been the production, storage, and distribution center for the heavy-element research program of the US Department of Energy since 1966. During the past four years, annual production rates of transcurium elements have been relatively stable, averaging 34 mg of /sup 249/Bk, 369 mg of /sup 252/Cf, 1.4 mg of /sup 253/Es, and 0.7 pg of /sup 257/Fm. The extensive provisions for changing and modifying equipment have allowed continual updating of the plant to include new concepts in chemical processes and equipment design. 21 refs., 4 figs., 2 tabs.

  8. Optimization of source-sample-detector geometries for bulk hydrogen analysis using epithermal neutrons.

    PubMed

    Csikai, J; Dóczi, R

    2009-01-01

    The advantages and limitations of epithermal neutrons in qualification of hydrocarbons via their H contents and C/H atomic ratios have been investigated systematically. Sensitivity of this method and the dimensions of the interrogated regions were determined for various types of hydrogenous samples. Results clearly demonstrate the advantages of direct neutron detection, e.g. by BF(3) counters as compared to the foil activation method in addition to using the hardness of the spectral shape of Pu-Be neutrons to that from a (252)Cf source.

  9. Improvement in the practical implementation of neutron source strength calibration using prompt gamma rays.

    PubMed

    Khabaz, Rahim; Rene Vega-Carrillo, Hector

    2013-08-01

    In this study, the neutron emission rate from neutron sources using prompt gamma rays in hydrogen was determined, and several improvements were applied. Using Monte Carlo calculations, the best positions for the source, moderator and detector relative to each other were selected. For (241)Am-Be and (252)Cf sources, the sizes for polyethylene spheres with the highest efficiency were 12- and 10-inch, respectively. In addition, a new shielding cone was designed to account for scattered neutrons and gamma rays. The newly designed shielding cone, which is 45 cm in length, provided suitable attenuation for the source radiation.

  10. Neutron radiative capture methods for surface elemental analysis

    USGS Publications Warehouse

    Trombka, J.I.; Senftle, F.; Schmadebeck, R.

    1970-01-01

    Both an accelerator and a 252Cf neutron source have been used to induce characteristic gamma radiation from extended soil samples. To demonstrate the method, measurements of the neutron-induced radiative capture and activation gamma rays have been made with both Ge(Li) and NaI(Tl) detectors, Because of the possible application to space flight geochemical analysis, it is believed that NaI(Tl) detectors must be used. Analytical procedures have been developed to obtain both qualitative and semiquantitative results from an interpretation of the measured NaI(Tl) pulse-height spectrum. Experiment results and the analytic procedure are presented. ?? 1970.

  11. Advanced development of the spectrum sciences Model 5005-TF, single-event test fixture

    SciTech Connect

    Ackermann, M.R.; Browning, J.S. ); Hughlock, B.W. ); Lum, G.K. ); Tsacoyeanes, W.C. Lab., Inc., Cambridge, MA ); Weeks, M.D. )

    1990-09-01

    This report summarizes the advanced development of the Spectrum Sciences Model 5005-TF, Single-Event Test Fixture. The Model 5005-TF uses a Californium-252 (Cf-252) fission-fragment source to test integrated circuits and other devices for the effects of single-event phenomena. Particle identification methods commonly used in high-energy physics research and nuclear engineering have been incorporated into the Model 5005-TF for estimating the particle charge, mass, and energy parameters. All single-event phenomena observed in a device under test (DUT) are correlated with an identified fission fragment, and its linear energy transfer (LET) and range in the semiconductor material of the DUT.

  12. Evaluation of Savannah River Plant shuffler calibration standards

    SciTech Connect

    Meier, M.M.; Crane, T.W.; Nachtsheim, C.J.

    1981-03-01

    Six chemistry and three nondestructive assay (NDA) measurements have been made to provide information on the /sup 235/U content of twelve standards cut from a cylinder of uranium-aluminum alloy to be used in calibrating the /sup 252/Cf shuffler. These data have been evaluated to produce a set of uranium mass estimates and associated uncertainties for the standards by means of least squares techniques. Longitudinal fluctuation in uranium density is modeled, both by linear splines and by polynomials, and the two methods are compared. Also, a method is given for assessing the accuracy of the measurement uncertainties initially provided.

  13. Borehole field calibration and measurement of low-concentration manganese by decay gamma rays ( Maryland, USA).

    USGS Publications Warehouse

    Mikesell, J.L.; Senftle, F.E.; Lloyd, T.A.; Tanner, A.B.; Merritt, C.T.; Force, E.R.

    1986-01-01

    The Mn concentration in the Arundel clay formation, Prince Georges County, Maryland, was determined from a borehole by using delayed neutron activation. Then neutrons were produced by a 100 mu g 252Cf source. The 847 keV gamma ray of Mn was detected continuously, and its counting rate was measured at intervals of 15 s as the measuring sonde was moved at a rate of 0.5 cm/s. The borehole measurements compared favourably with a chemical core analysis and were unaffected by water in the borehole.-from Authors

  14. Piezonuclear battery

    DOEpatents

    Bongianni, Wayne L.

    1992-01-01

    A piezonuclear battery generates output power arising from the piezoelectric voltage produced from radioactive decay particles interacting with a piezoelectric medium. Radioactive particle energy may directly create an acoustic wave in the piezoelectric medium or a moderator may be used to generate collision particles for interacting with the medium. In one embodiment a radioactive material (.sup.252 Cf) with an output of about 1 microwatt produced a 12 nanowatt output (1.2% conversion efficiency) from a piezoelectric copolymer of vinylidene fluoride/trifluorethylene.

  15. Reinvestigation of two-phonon γ-vibrational band in neutron-rich 114Pd

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Zhu, S. J.; Hamilton, J. H.; Ramayya, A. V.; Wang, E. H.; Liu, Y. X.; Sun, Y.; Hwang, J. K.; Xiao, Z. G.; Li, H. J.; Luo, Y. X.; Rasmussen, J. O.; Ter-Akopian, G. M.; Oganessian, Yu. Ts.

    2016-08-01

    The level structure in neutron-rich 114Pd nucleus has been reinvestigated by measuring prompt γ rays emitted in the spontaneous fission of 252Cf. A two-phonon γ-vibrational band built on the 1639.3keV level is observed, which confirms the previous suggestion from a β-decay experiment. Systematical comparison supports the assignment for a two-phonon γ-vibrational band in 114Pd. Triaxial projected shell model calculations for the multi-phonon γ bands of 114Pd are in good agreement with the experimental data.

  16. Characterization of a 6Li-loaded liquid organic scintillator for fast neutron spectrometry and thermal neutron detection.

    PubMed

    Bass, C D; Beise, E J; Breuer, H; Heimbach, C R; Langford, T J; Nico, J S

    2013-07-01

    The characterization of a liquid scintillator incorporating an aqueous solution of enriched lithium chloride to produce a scintillator with 0.40% (6)Li is presented, including the performance of the scintillator in terms of its optical properties and neutron response. The scintillator was incorporated into a fast neutron spectrometer, and the light output spectra from 2.5 MeV, 14.1 MeV, and (252)Cf neutrons were measured using capture-gated coincidence techniques. The spectrometer was operated without coincidence to perform thermal neutron measurements. Possible improvements in spectrometer performance are discussed.

  17. Development and testing of an active area neutron dosemeter.

    PubMed

    Brushwood, J M; Gow, J P D; Beeley, P A; Spyrou, N M

    2004-01-01

    This paper describes the design, development and testing of an active area neutron dosemeter (AAND). The classic moderator and central detector is retained but in AAND this arrangement is augmented by small thermal neutron detectors positioned within the moderating body. The outputs from these detectors are combined using an appropriately weighted linear superposition to fit both the ambient dose equivalent and the radiation weighting factor. Experimental verifications of both the modelled detector energy reponses and the overall AAND response are given. In the relatively soft D2O moderated 252Cf spectra, the AAND determined both the H*(10) and mean radiation weighting factor to better than +10%.

  18. Use of Neutron Benchmark Fields for the Validation of Dosimetry Cross Sections

    NASA Astrophysics Data System (ADS)

    Griffin, Patrick

    2016-02-01

    The evolution of validation metrics for dosimetry cross sections in neutron benchmark fields is explored. The strength of some of the metrics in providing validation evidence is examined by applying them to the 252Cf spontaneous fission standard neutron benchmark field, the 235U thermal neutron fission reference benchmark field, the ACRR pool-type reactor central cavity reference benchmark fields, and the SPR-III fast burst reactor central cavity. The IRDFF dosimetry cross section library is used in the validation study and observations are made on the amount of coverage provided to the library contents by validation data available in these benchmark fields.

  19. IDENTIFICATION OF HIGH-SPIN STATES IN NEUTRON-RICH 88,90,92Kr AND 86Se

    SciTech Connect

    J. D. Cole

    2011-08-01

    Level schemes of even-even neutron-rich {sup 88-92}Kr and {sup 86}Se have been investigated by measuring triple-{gamma} coincidence data from the spontaneous fission of {sup 252}Cf with the Gammasphere detector array. The level scheme of {sup 88}Kr has been extended up to 7169 keV state. Several new excited states with new transitions have been identified in {sup 90,92}Kr and {sup 86}Se. Spins and parities have been assigned to levels in these nuclei by following regional systematics and angular correlation measurements. The level structures of the N = 52, 54, Se, Kr, and Sr isotones are discussed.

  20. Collinear cluster tripartition channel in the reaction {sup 235}U(n{sub th}, f)

    SciTech Connect

    Pyatkov, Yu. V.; Kamanin, D. V.; Kopach, Yu. N.; Alexandrov, A. A.; Alexandrova, I. A.; Borzakov, S. B.; Voronov, Yu. N.; Zhuchko, V. E.; Kuznetsova, E. A. Panteleev, Ts.; Tyukavkin, A. N.

    2010-08-15

    Investigation of the {sup 235}U(n{sub th}, f) reaction using the miniFOBOS double-arm time-of-flight spectrometer of fission fragments confirmed manifestations of the earlier unknown many-body, at least ternary, decay involving almost collinear decay-product escape, which were first observed in the spontaneous fission of {sup 252}Cf(sf). The use of variables sensitive to the nuclear charge of fission fragments allowed the reliability of identification of decay events to be increased and new decay modes to be revealed.

  1. Fast neutron spectrometry and dosimetry using a spherical moderator with position-sensitive detectors.

    PubMed

    Li, Taosheng; Yang, Lianzhen; Ma, Jizeng; Fang, Dong

    2007-01-01

    A neutron spectrometry and dosimetry measurement system has been developed based on a different design of the divided regions for a sphere, with three position-sensitive counters. The characteristics of the measurement system have been investigated in the reference radiation fields of Am-Be and (252)Cf sources. When realistic input spectra are used for the unfolding, the overall deviations of the calculated results for four dosimetric quantities are less than +/-10%. The results of other input spectra are also discussed in this report.

  2. Evidence for octupole excitations in the odd-odd neutron-rich nucleus {sup 142}Cs

    SciTech Connect

    Liu, S. H.; Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.; Ma, W. C.; Daniel, A. V.; Ter-Akopian, G. M.

    2010-05-15

    High-spin states in the neutron-rich nucleus {sup 142}Cs are reinvestigated from a study of the spontaneous fission of {sup 252}Cf with the Gammasphere detector array. A new level scheme is built and spin-parities are assigned to levels based on angular correlation measurements and systematics. The new structure of {sup 142}Cs is proposed to be related to octupole correlations. The electric dipole moment of {sup 142}Cs is measured and a dramatic decrease of the dipole moments with increasing neutron numbers in the Cs isotopic chain is found.

  3. Performance of the Argonne National Laboratory electron cyclotron resonance charge breeder

    NASA Astrophysics Data System (ADS)

    Vondrasek, R.; Kolomiets, A.; Levand, A.; Pardo, R.; Savard, G.; Scott, R.

    2011-05-01

    An electron cyclotron resonance charge breeder for the Californium rare ion breeder upgrade (CARIBU), a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS), has been constructed and commissioned. Charge breeding efficiencies up to 15.6% have been realized for stable beams with a typical breeding time of 10 ms/charge state. The CARIBU system has been undergoing commissioning tests utilizing a 100 mCi 252Cf fission source. A charge breeding efficiency of 14.8 ± 5% has been achieved for the first radioactive beam of 143Cs27+.

  4. An alternative calibration method for counting P-32 reactor monitors

    SciTech Connect

    Quirk, T.J.; Vehar, D.W.

    2011-07-01

    Radioactivation of sulfur is a common technique used to measure fast neutron fluences in test and research reactors. Elemental sulfur can be pressed into pellets and used as monitors. The {sup 32}S(n, p) {sup 32}P reaction has a practical threshold of about 3 MeV and its cross section and associated uncertainties are well characterized [1]. The product {sup 32P} emits a beta particle with a maximum energy of 1710 keV [2]. This energetic beta particle allows pellets to be counted intact. ASTM Standard Test Method for Measuring Reaction Rates and Fast-Neutron Fluences by Radioactivation of Sulfur-32 (E265) [3] details a method of calibration for counting systems and subsequent analysis of results. This method requires irradiation of sulfur monitors in a fast-neutron field whose spectrum and intensity are well known. The resultant decay-corrected count rate is then correlated to the known fast neutron fluence. The Radiation Metrology Laboratory (RML) at Sandia has traditionally performed calibration irradiations of sulfur pellets using the {sup 252}Cf spontaneous fission neutron source at the National Inst. of Standards and Technology (NIST) [4] as a transfer standard. However, decay has reduced the intensity of NIST's source; thus lowering the practical upper limits of available fluence. As of May 2010, neutron emission rates have decayed to approximately 3 e8 n/s. In practice, this degradation of capabilities precludes calibrations at the highest fluence levels produced at test reactors and limits the useful range of count rates that can be measured. Furthermore, the reduced availability of replacement {sup 252}Cf threatens the long-term viability of the NIST {sup 252}Cf facility for sulfur pellet calibrations. In lieu of correlating count rate to neutron fluence in a reference field the total quantity of {sup 32}P produced in a pellet can be determined by absolute counting methods. This offers an attractive alternative to extended {sup 252}Cf exposures because it

  5. Toward an Automated Analysis of Slow Ions in Nuclear Track Emulsion

    NASA Astrophysics Data System (ADS)

    Mamatkulov, K. Z.; Kattabekov, R. R.; Ambrozova, I.; Artemenkov, D. A.; Bradnova, V.; Kamanin, D. V.; Majling, L.; Marey, A.; Ploc, O.; Rusakova, V. V.; Stanoeva, R.; Turek, K.; Zaitsev, A. A.; Zarubin, P. I.; Zarubina, I. G.

    Application of the nuclear track emulsion technique (NTE) in radioactivity and nuclear fission studies is discussed. It is suggested to use a HSP-1000 automated microscope for searching for a collinear cluster tri-partition of heavy nuclei implanted in NTE. Calibrations of α-particles and ion ranges in a novel NTE are carried out. Surface exposures of NTE samples to a 252Cf source started. Planar events containing fragments and long-range α-particles as well as fragment triples only are studied. NTE samples are calibrated by ions Kr and Xe of energy of 1.2 and 3 A MeV.

  6. Nuclear structure of the odd-odd N=85 neutron-rich nucleus {sup 140}Cs

    SciTech Connect

    Liu, S. H.; Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Luo, Y. X.; Rasmussen, J. O.; Daniel, A. V.; Ter-Akopian, G. M.; Zhu, S. J.; Ma, W. C.

    2010-03-15

    High-spin excited states in the neutron-rich nucleus {sup 140}Cs were re-investigated from the spontaneous fission of {sup 252}Cf with the Gammasphere detector array. Seven new transitions at low and moderate spin and 13 at high spin were observed in {sup 140}Cs and the level scheme of {sup 140}Cs was extended to 3794 keV with a new sideband. Spins and parities were assigned to levels based on angular correlation measurements and the systematics in the N=85 isotones.

  7. Collinear Cluster Tripartition as a Neutron Source--Evaluation of the Setup Parameters

    SciTech Connect

    Kamanin, D. V.; Kuznetsova, E. A.; Aleksandrov, A. A.; Aleksandrova, I. A.; Borzakov, S. B.; Chelnokov, M. L.; Pham Minh, D.; Kondratyev, N. A.; Kopach, Yu. N.; Panteleev, Ts.; Penionzhkevich, Yu. E.; Svirikhin, A. I.; Sokol, E. A.; Testov, D. A.; Zhuchko, V. E.; Yeremin, A. V.; Pyatkov, Yu. V.; Jacobs, N.; Ryabov, Yu. V.

    2010-04-30

    Forthcoming experiments aimed at studying the mechanism of collinear cluster tripartition are planning to be performed with the new facility. Charged products will be registered with the double arm time-of-flight spectrometer composed of mosaics of PIN -diodes and MCP (micro channel plates) based timing detectors. Several tens of {sup 3}He-filled counters will be gathered round the {sup 252}Cf source. In order to choose an optimal configuration of the neutron detector and other parameters of the experiment special modeling has performed using both 'neutron barrel' and known MCNP code. The first test run of the new facility is in progress also its 'neutron skin' in under construction.

  8. Project Plan 7930 Cell G PaR Remote Handling System Replacement

    SciTech Connect

    Kinney, Kathryn A

    2009-10-01

    For over 40 years the US Department of Energy (DOE) and its predecessors have made Californium-252 ({sup 252}Cf) available for a wide range of industries including medical, nuclear fuels, mining, military and national security. The Radiochemical Engineering Development Center (REDC) located within the Oak Ridge National Laboratory (ORNL) processes irradiated production targets from the High Flux Isotope Reactor (HFIR). Operations in Building 7930, Cell G provide over 70% of the world's demand for {sup 252}Cf. Building 7930 was constructed and equipped in the mid-1960s. Current operations for {sup 252}Cf processing in Building 7930, Cell G require use of through-the-wall manipulators and the PaR Remote Handling System. Maintenance and repairs for the manipulators is readily accomplished by removal of the manipulator and relocation to a repair shop where hands-on work can be performed in glove boxes. Contamination inside cell G does not currently allow manned entry and no provisions were created for a maintenance area inside the cell. There has been no maintenance of the PaR system or upgrades, leaving operations vulnerable should the system have a catastrophic failure. The Cell G PaR system is currently being operated in a run to failure mode. As the manipulator is now 40+ years old there is significant risk in this method of operation. In 2006 an assessment was completed that resulted in recommendations for replacing the manipulator operator control and power centers which are used to control and power the PaR manipulator in Cell G. In mid-2008 the chain for the bridge drive failed and subsequent examinations indicated several damaged links (see Figure 1). To continue operations the PaR manipulator arm is being used to push and pull the bridge as a workaround. A retrieval tool was fabricated, tested and staged inside Cell G that will allow positioning of the bridge and manipulator arm for removal from the cell should the PaR system completely fail. A fully

  9. A multiple parallel-plate avalanche counter for fission-fragment detection

    NASA Astrophysics Data System (ADS)

    Wu, C. Y.; Henderson, R. A.; Haight, R. C.; Lee, H. Y.; Taddeucci, T. N.; Bucher, B.; Chyzh, A.; Devlin, M.; Fotiades, N.; Kwan, E.; O'Donnell, J. M.; Perdue, B. A.; Ullmann, J. L.

    2015-09-01

    A new low-mass multiple gas-filled parallel-plate avalanche counter for the fission-fragment detection has been developed to mark the fission occurrence in measurements of the prompt fission neutron energy spectrum as a function of incident neutron energy. It was used successfully for the neutron-induced fission of 235U and 239Pu with a total mass near 100 mg each and the spontaneous fission of 252Cf. Both the incident neutron energy and the prompt fission neutron energy are measured by using the time-of-flight method. The design and performance of this avalanche counter are described.

  10. Californium-252 Neutron Therapy in China

    SciTech Connect

    Sharwin X. Zeng; Jian H. Gu

    2000-11-12

    Californium-252 brachytherapy, believed to be the most successful source for neutron therapy, gives most of the cures as well as long-term and complication-free survivals. Chinese radiation oncologists were interested in californium neutron therapy (Cf-NT) in the early 1980s, but {sup 252}Cf sources for medical use were not available in China until 1992 when a californium joint venture was established by the China Institute of Atomic Energy (Beijing) and the Research Institute for Nuclear Reactors (Dimitrovgrad) of Russia. In 1995, 25 seeds of {sup 252}Cf with a strength of 3 {mu}g each were sent to China for preclinical investigation. Three years later, a high dose rate (HDR) {sup 252}Cf source was imported and transferred into a home-made remote after-loader for intracavitary treatment in Chongqing, and a clinical trail was started in February 1999. This is the first time that Cf-NT was performed for cancer patients in China. Since then, Cf-NT in China has developed rapidly. It is estimated that one-tenth of those radiation oncology centers with brachytherapy practice will be equipped with californium units in 5 yr. That means more than 30 units will be in use in hospitals. That is significant compared with other countries, but it is just one, on average, for each province or one per 40 million people in China. Progress also has been achieved in the {sup 252}Cf treatment delivery equipment. Preliminary clinical trails showed complete response observed in all cases treated, with a rapid clearance of tumors and mild reactions in normal tissues. The short-term results are quite encouraging. To deal with problems due to the demand for Cf-NT in China, attention should be paid to the following particulars: (1) A high-strength miniature source is needed for HDR/MDR interstitial therapy to extend the Cf-NT coverage. (2) Basic work on radiophysics and radiobiology needs to be done, including source calibration, clinical dosimetry, clinical RBE determination, and Cf

  11. Simulating Makrofol as a detector for neutron-induced recoils.

    PubMed

    Zhang, G; Becker, F; Urban, M; Xuan, Y

    2011-03-01

    The response of solid-state nuclear track detector is extremely dependent on incident angles of neutrons, which determine the angular distribution of secondary particles. In this paper, the authors present a method to investigate the angular response of Makrofol detectors. Using the C++-based Monte-Carlo tool-kit Geant4 in combination with SRIM and our MATLAB codes, we simulated the angular response of Makrofol. The simulations were based on the restricted energy loss model, and the concept of energy threshold and critical angle. Experiments were carried out with (252)Cf neutrons to verify the simulation results.

  12. On replacing Am-Be neutron sources in compensated porosity logging tools.

    PubMed

    Peeples, Cody R; Mickael, Medhat; Gardner, Robin P

    2010-01-01

    Authors explored the direct replacement of Am-Be neutron sources in neutron porosity logging tools through Monte Carlo simulations using MCNP5. (252)Cf and electronic accelerator neutron sources based on the Deuterium-Tritium fusion reaction were considered. Between the sources, a tradeoff was noted between sensitivity to the presence of hydrogen and uncertainty due to counting statistics. It was concluded that both replacement sources as well as accelerator sources based on the Deuterium-Deuterium fusion reaction warrant further consideration as porosity log sources.

  13. Neutron detector characterization for SCINTIA array

    SciTech Connect

    Matei, C.; Hambsch, F. J.; Oberstedt, S.

    2011-07-01

    SCINTIA is a new detector array of organic scintillators under development at the Inst. for Reference Materials and Measurements (IRMM). The present design of SCINTIA includes NE213, p-terphenyl and Li glass neutron detectors positioned in a spherical configuration around the target. The properties of a novel p-terphenyl neutron detector to be used with SCINTIA have been investigated using photon sources and neutrons from a time tagged {sup 252}Cf(sf) source. The results show that the p-terphenyl crystal has better energy resolution, increased proton light output and neutron efficiency when compared to a similar size NE213 equivalent neutron detector. (authors)

  14. Neutron detection in a high gamma ray background with liquid scintillators

    SciTech Connect

    Stevanato, L.; Cester, D.; Viesti, G.; Nebbia, G.

    2013-04-19

    The capability of liquid scintillator (namely 2'' Multiplication-Sign 2'' cells of EJ301 and EJ309) of detecting neutrons in a very high gamma ray background is explored. A weak {sup 252}Cf source has been detected in a high {sup 137}Cs gamma ray background corresponding to a dose rate of 100 {mu}Sv/h with probability of detection in compliance with IEC requirements for hand held instruments. Tests were performed with new generation of CAEN digitizers, in particular the V1720 (8 Channel 12bit 250 MS/s) one.

  15. TEPC performance for a reference standard.

    PubMed

    Zhang, Weihua; Wang, Zhiqiang; Liu, Yina; Li, Chunjuan; Xiao, Xuefu; Luo, Hailong; Chen, Jun; Li, Wei

    2014-01-01

    A portable tissue-equivalent proportional counter (TEPC)-based system was developed, which will be used as a reference standard in the neutron mixed field for radiation protection. In this paper, microdosimetry of the TEPC system was studied both in neutron ((252)Cf and (241)Am-Be sources) and gamma ((137)Cs and (60)Co sources) reference radiation fields. The measured neutron and gamma-dose equivalent rates were, respectively, compared with those of the reference ambient dose equivalent rate H(*)(10). And the measured microdosimetric spectra were compared with the Monte Carlo code FLUKA simulated results. All of the comparisons primarily agreed well.

  16. Pre-experiment testing of the Multi Channel Systems 16-channel preamplifier CPA16

    SciTech Connect

    Patin, J B; Stoyer, M A; Moody, K J; Friensehner, A V

    2003-11-03

    The 16-channel preamplifier model CPA16 from Multi Channel Systems was studied. The CPA16 preamplifier/amplifier module is a candidate to be used as the preamplifiers and amplifiers for the focal plane detectors of the Mass Analyzer of Super Heavy Atoms (MASHA). The equipment used to test the CPA16, the results of testing the CPA16 with a pulser, a mixed {sup 229}Th/{sup 148}Gd source and a {sup 252}Cf source, and a summary of the results will be presented.

  17. Potential Energy Calculations for Collinear Cluster Tripartition Fission Events

    NASA Astrophysics Data System (ADS)

    Unzhakova, A. V.; Pashkevich, V. V.; Pyatkov, Y. V.

    2014-09-01

    Strutinsky shell correction calculations were performed to describe the recent experimental results on collinear ternary fission. Collinear Cluster Tripartion fission events were studied experimentally in neutron induced fission of 235U, where the missing mass in the detected binary decay was suggested to characterize fission event as a collinear tripartition; and in spontaneous fission of 252Cf, where the direct detection of the three fission fragments has been used to confirm the existence of the Collinear Cluster Tripartition channel with a probability of 4.7×10-3 relative to the binary fission events.

  18. Performance of the Argonne National Laboratory electron cyclotron resonance charge breeder

    SciTech Connect

    Vondrasek, R.; Kolomiets, A.; Levand, A.; Pardo, R.; Savard, G.; Scott, R.

    2011-05-15

    An electron cyclotron resonance charge breeder for the Californium rare ion breeder upgrade (CARIBU), a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS), has been constructed and commissioned. Charge breeding efficiencies up to 15.6% have been realized for stable beams with a typical breeding time of 10 ms/charge state. The CARIBU system has been undergoing commissioning tests utilizing a 100 mCi {sup 252}Cf fission source. A charge breeding efficiency of 14.8 {+-} 5% has been achieved for the first radioactive beam of {sup 143}Cs{sup 27+}.

  19. Study of PIN diode energy traps created by neutrons

    NASA Astrophysics Data System (ADS)

    Sopko, V.; Sopko, B.; Chren, D.; Dammer, J.

    2013-03-01

    Characterization of radiation defects is still ongoing and finds greater application in the increasing radiation doses on semiconductor detectors in experiments. Studying the changes of silicon PIN diode for high doses of radiation is the fundamental motivation for our measurements. In this article we describe the behavior of the PIN diode and development of the disorder caused by neutrons from a 252Cf and doses up to 8 Gy. The calibration curve for PIN diode shows the effect of disorders as the changes of the voltampere characteristics depending on the dose of neutron irradiation. The measured values for defects are in good agreement with created energy traps.

  20. Preliminary evaluation of the /sup 235/U(n,f) cross-section from 100 keV to 20 MeV

    SciTech Connect

    Bhat, M.R.

    1983-01-01

    A preliminary evaluation of the fission cross-section of /sup 235/U from 100 keV to 20 MeV is described. Variance-covariance matrices for a number of experimental data sets were constructed and used to evaluate the fission cross-section following a Bayesian procedure. The evaluated fission cross-section is compared with experimental data including the /sup 252/Cf fission neutron spectrum averages and some of the problems encountered in carrying out the fit are discussed.

  1. What happened to the moon? A lunar history mission using neutrons

    SciTech Connect

    Breitkreutz, H.; Li, X.; Burfeindt, J.; Bernhardt, H. G.; Hoffmann, P.; Trieloff, M.; Schwarz, W. H.; Hopp, J.; Jessberger, E. K.; Hiesinger, H.

    2011-07-01

    The ages of lunar rocks can be determined using the {sup 40}Ar -{sup 39}Ar technique that can be used in-situ on the moon if a neutron source, a noble gas mass spectrometer and a gas extraction and purification system are brought to the lunar surface. A possible instrument for such a task is ISAGE, which combines a strong {sup 252}Cf neutron source and a compact spectrometer for in-situ dating of e.g. the South Pole Aitken impact basin or the potentially very young basalts south of the Aristachus Plateau. In this paper, the design of the neutron source will be discussed. The source is assumed to be a hollow sphere surrounded by a reflector, a geometry that provides a very homogeneous flux at the irradiation position inside the sphere. The optimal source geometry depending on the experimental conditions, the costs of transportation for the reflector and the costs of the source itself are calculated. A minimum {sup 252}Cf mass of 1.5 mg is determined. (authors)

  2. Spectral correction factors for conventional neutron dosemeters used in high-energy neutron environments.

    PubMed

    Lee, K W; Sheu, R J

    2015-04-01

    High-energy neutrons (>10 MeV) contribute substantially to the dose fraction but result in only a small or negligible response in most conventional moderated-type neutron detectors. Neutron dosemeters used for radiation protection purpose are commonly calibrated with (252)Cf neutron sources and are used in various workplace. A workplace-specific correction factor is suggested. In this study, the effect of the neutron spectrum on the accuracy of dose measurements was investigated. A set of neutron spectra representing various neutron environments was selected to study the dose responses of a series of Bonner spheres, including standard and extended-range spheres. By comparing (252)Cf-calibrated dose responses with reference values based on fluence-to-dose conversion coefficients, this paper presents recommendations for neutron field characterisation and appropriate correction factors for responses of conventional neutron dosemeters used in environments with high-energy neutrons. The correction depends on the estimated percentage of high-energy neutrons in the spectrum or the ratio between the measured responses of two Bonner spheres (the 4P6_8 extended-range sphere versus the 6″ standard sphere).

  3. Benchmark test of neutron transport calculations: indium, nickel, gold, europium, and cobalt activation with and without energy moderated fission neutrons by iron simulating the Hiroshima atomic bomb casing.

    PubMed

    Iwatani, K; Hoshi, M; Shizuma, K; Hiraoka, M; Hayakawa, N; Oka, T; Hasai, H

    1994-10-01

    A benchmark test of the Monte Carlo neutron and photon transport code system (MCNP) was performed using a bare- and energy-moderated 252Cf fission neutron source which was obtained by transmission through 10-cm-thick iron. An iron plate was used to simulate the effect of the Hiroshima atomic bomb casing. This test includes the activation of indium and nickel for fast neutrons and gold, europium, and cobalt for thermal and epithermal neutrons, which were inserted in the moderators. The latter two activations are also to validate 152Eu and 60Co activity data obtained from the atomic bomb-exposed specimens collected at Hiroshima and Nagasaki, Japan. The neutron moderators used were Lucite and Nylon 6 and the total thickness of each moderator was 60 cm or 65 cm. Measured activity data (reaction yield) of the neutron-irradiated detectors in these moderators decreased to about 1/1,000th or 1/10,000th, which corresponds to about 1,500 m ground distance from the hypocenter in Hiroshima. For all of the indium, nickel, and gold activity data, the measured and calculated values agreed within 25%, and the corresponding values for europium and cobalt were within 40%. From this study, the MCNP code was found to be accurate enough for the bare- and energy-moderated 252Cf neutron activation calculations of these elements using moderators containing hydrogen, carbon, nitrogen, and oxygen. PMID:8083048

  4. Implementation of the Fissile Mass Flow Monitor Source Verification and Confirmation

    SciTech Connect

    Uckan, Taner; March-Leuba, Jose A; Powell, Danny H; Nelson, Dennis; Radev, Radoslav

    2007-12-01

    This report presents the verification procedure for neutron sources installed in U.S. Department of Energy equipment used to measure fissile material flow. The Fissile Mass Flow Monitor (FMFM) equipment determines the {sup 235}U fissile mass flow of UF{sub 6} gas streams by using {sup 252}Cf neutron sources for fission activation of the UF{sub 6} gas and by measuring the fission products in the flow. The {sup 252}Cf sources in each FMFM are typically replaced every 2 to 3 years due to their relatively short half-life ({approx} 2.65 years). During installation of the new FMFM sources, the source identity and neutronic characteristics provided by the manufacturer are verified with the following equipment: (1) a remote-control video television (RCTV) camera monitoring system is used to confirm the source identity, and (2) a neutron detection system (NDS) is used for source-strength confirmation. Use of the RCTV and NDS permits remote monitoring of the source replacement process and eliminates unnecessary radiation exposure. The RCTV, NDS, and the confirmation process are described in detail in this report.

  5. DOSE PROFILE MODELING OF IDAHO NATIONAL LABORATORY’S ACTIVE NEUTRON INTERROGATION TEST FACILITY

    SciTech Connect

    D. L. Chichester; E. H. Seabury; J. M. Zabriskie; J. Wharton; A. J. Caffrey

    2009-06-01

    A new research and development laboratory has been commissioned at Idaho National Laboratory for performing active neutron interrogation research and development. The facility is designed to provide radiation shielding for DT fusion (14.1 MeV) neutron generators (2 x 108 neutrons per second), DD fusion (2.5 MeV) neutron generators (up to 2 x 106 neutrons per second), and 252Cf spontaneous fission neutron sources (6.7 x 107 neutrons per second, 30 micrograms). Shielding at the laboratory is comprised of modular concrete shield blocks 0.76 m thick with tongue-in-groove features to prevent radiation streaming, arranged into one small and one large test vault. The larger vault is designed to allow operation of the DT generator and has walls 3.8 m tall, an entrance maze, and a fully integrated electrical interlock system; the smaller test vault is designed for 252Cf and DD neutron sources and has walls 1.9 m tall and a simple entrance maze. Both analytical calculations and numerical simulations were used in the design process for the building to assess the performance of the shielding walls and to ensure external dose rates are within required facility limits. Dose rate contour plots have been generated for the facility to visualize the effectiveness of the shield wall and entrance maze and to illustrate the spatial profile of the radiation dose field above the facility and the effects of skyshine around the vaults.

  6. Fast-neutron spectrometry using a ³He ionization chamber and digital pulse shape analysis.

    PubMed

    Chichester, D L; Johnson, J T; Seabury, E H

    2012-08-01

    Digital pulse shape analysis (dPSA) has been used with a Cuttler-Shalev type (3)He ionization chamber to measure the fast-neutron spectra of a deuterium-deuterium electronic neutron generator, a bare (252)Cf spontaneous fission neutron source, and of the transmitted fast neutron spectra of a (252)Cf source attenuated by water, graphite, liquid nitrogen, and magnesium. Rise-time dPSA has been employed using the common approach for analyzing n +(3)He→(1)H+(3)H ionization events and improved to account for wall-effect and pile-up events, increasing the fidelity of these measurements. Simulations have been performed of the different experimental arrangements and compared with the measurements, demonstrating general agreement between the dPSA-processed fast-neutron spectra and predictions. The fast-neutron resonance features of the attenuation cross sections of the attenuating materials are clearly visible within the resolution limits of the electronics used for the measurements, and the potential applications of high-resolution fast-neutron spectrometry for nuclear nonproliferation and safeguards measurements are discussed.

  7. Benchmark test of neutron transport calculations: Indium, nickel, gold, europium, and cobalt activation with and without energy moderated fission neutrons by iron simulating the Hiroshima atomic bomb casing

    SciTech Connect

    Iwatani, Kazuo; Shizuma, Kiyoshi; Hasai, Hiromi; Hoshi, Masaharu; Hiraoka, Masayuki; Hayakawa, Norihiko; Oka, Takamitsu

    1994-10-01

    A benchmark test of the Monte Carlo neutron and photon transport code system (MCNP) was performed using a bare- and energy-moderated {sup 252}Cf fission neutron source which was obtained by transmission through 10-cm-thick iron. An iron plate was used to simulate the effect of the Hiroshima atomic bomb casing. This test includes the activation of indium and nickel for fast neutrons and gold, europium, and cobalt for thermal and epithermal neutrons, which were inserted in the moderators. The latter two activations are also to validate {sup 152}Eu and {sup 60}Co activity data obtained from the atomic bomb-exposed specimens collected at Hiroshima and Nagasaki, Japan. The neutron moderators used were Lucite and Nylon 6 and the total thickness of each moderator was 60 cm or 65 cm. Measured activity data (reaction yield) of the neutron-irradiated detectors in these moderators decreased to about 1/1,000th or 1/10,000th, which corresponds to about 1,500 m ground distance from the hypocenter in Hiroshima. For all of the indium, nickel, and gold activity data, the measured and calculated values agreed within 25%, and the corresponding values for europium and cobalt were within 40%. From this study, the MCNP code was found to be accurate enough for the bare- and energy-moderated {sup 252}Cf neutron activation calculations of these elements using moderators containing hydrogen, carbon, nitrogen, and oxygen. 18 refs., 10 figs., 4 tabs.

  8. Benchmark test of neutron transport calculations: indium, nickel, gold, europium, and cobalt activation with and without energy moderated fission neutrons by iron simulating the Hiroshima atomic bomb casing.

    PubMed

    Iwatani, K; Hoshi, M; Shizuma, K; Hiraoka, M; Hayakawa, N; Oka, T; Hasai, H

    1994-10-01

    A benchmark test of the Monte Carlo neutron and photon transport code system (MCNP) was performed using a bare- and energy-moderated 252Cf fission neutron source which was obtained by transmission through 10-cm-thick iron. An iron plate was used to simulate the effect of the Hiroshima atomic bomb casing. This test includes the activation of indium and nickel for fast neutrons and gold, europium, and cobalt for thermal and epithermal neutrons, which were inserted in the moderators. The latter two activations are also to validate 152Eu and 60Co activity data obtained from the atomic bomb-exposed specimens collected at Hiroshima and Nagasaki, Japan. The neutron moderators used were Lucite and Nylon 6 and the total thickness of each moderator was 60 cm or 65 cm. Measured activity data (reaction yield) of the neutron-irradiated detectors in these moderators decreased to about 1/1,000th or 1/10,000th, which corresponds to about 1,500 m ground distance from the hypocenter in Hiroshima. For all of the indium, nickel, and gold activity data, the measured and calculated values agreed within 25%, and the corresponding values for europium and cobalt were within 40%. From this study, the MCNP code was found to be accurate enough for the bare- and energy-moderated 252Cf neutron activation calculations of these elements using moderators containing hydrogen, carbon, nitrogen, and oxygen.

  9. Determination of the optimum-size californium-252 neutron source for borehole capture gamma-ray analysis

    USGS Publications Warehouse

    Senftle, F.E.; Macy, R.J.; Mikesell, J.L.

    1979-01-01

    The fast- and thermal-neutron fluence rates from a 3.7 ??g 252Cf neutron source in a simulated borehole have been measured as a function of the source-to-detector distance using air, water, coal, iron ore-concrete mix, and dry sand as borehole media. Gamma-ray intensity measurements were made for specific spectral lines at low and high energies for the same range of source-to-detector distances in the iron ore-concrete mix and in coal. Integral gamma-ray counts across the entire spectrum were also made at each source-to-detector distance. From these data, the specific neutron-damage rate, and the critical count-rate criteria, we show that in an iron ore-concrete mix (low hydrogen concentration), 252Cf neutron sources of 2-40 ??g are suitable. The source size required for optimum gamma-ray sensitivity depends on the energy of the gamma ray being measured. In a hydrogeneous medium such as coal, similar measurements were made. The results show that sources from 2 to 20 ??g are suitable to obtain the highest gamma-ray sensitivity, again depending on the energy of the gamma ray being measured. In a hydrogeneous medium, significant improvement in sensitivity can be achieved by using faster electronics; in iron ore, it cannot. ?? 1979 North-Holland Publishing Co.

  10. Isotopic yield in cold binary fission of even-even 244-258Cf isotopes

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Cyriac, Annu; Krishnan, Sreejith

    2016-05-01

    The cold binary fission of even-even 244-258Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. The favorable fragment combinations are obtained from the cold valley plot (plot of driving potential vs. mass number of fragments) and by calculating the yield for charge minimized fragments. It is found that for 244,246,248Cf isotopes highest yield is for the fragments with isotope of Pb (Z = 82) as one fragment, whereas for 250Cf and 252Cf isotopes the highest yield is for the fragments with isotope of Hg (Z = 80) as one fragment. In the case of 254,256,258Cf isotopes the highest yield is for the fragments with Sn (Z = 50) as one fragment. Thus, the fragment combinations with maximum yield reveal the role of doubly magic and near doubly magic nuclei in binary fission. It is found that asymmetric splitting is favored for Cf isotopes with mass number A ≤ 250 and symmetric splitting is favored for Cf isotopes with A > 252. In the case of Cf isotope with A = 252, there is an equal probability for asymmetric and symmetric splitting. The individual yields obtained for the cold fission of 252Cf isotope are compared with the experimental data taken from the γ- γ- γ coincidences technique using Gammasphere.

  11. Confinement Vessel Assay System: Design and Implementation Report

    SciTech Connect

    Frame, Katherine C.; Bourne, Mark M.; Crooks, William J.; Evans, Louise; Mayo, Douglas R.; Gomez, Cipriano D.; Miko, David K.; Salazar, William R.; Stange, Sy; Vigil, Georgiana M.

    2012-07-18

    Los Alamos National Laboratory has a number of spherical confinement vessels remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1- to 2-inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the vessels. We have developed a neutron assay system for the purposes of Materials Control and Accountability (MC&A) measurements of the vessel prior to and after cleanout. We present our approach to confronting the challenges in designing, building, and testing such a system. The system was designed to meet a set of functional and operational requirements. A Monte Carlo model was developed to aid in optimizing the detector design as well as to predict the systematic uncertainty associated with confinement vessel measurements. Initial testing was performed to optimize and determine various measurement parameters, and then the system was characterized using {sup 252}Cf placed a various locations throughout the measurement system. Measurements were also performed with a {sup 252}Cf source placed inside of small steel and HDPE shells to study the effect of moderation. These measurements compare favorably with their MCNPX model equivalent, making us confident that we can rely on the Monte Carlo simulation to predict the systematic uncertainty due to variations in response to material that may be localized at different points within a vessel.

  12. Investigation and optimisation of mobile NaI(Tl) and 3He-based neutron detectors for finding point sources

    NASA Astrophysics Data System (ADS)

    Nilsson, Jonas M. C.; Finck, Robert R.; Rääf, Christopher

    2015-06-01

    Neutron radiation produces high-energy gamma radiation through (n,γ) reactions in matter. This can be used to detect neutron sources indirectly using gamma spectrometers. The sensitivity of a gamma spectrometer to neutrons can be amplified by surrounding it with polyvinyl chloride (PVC). The hydrogen in the PVC acts as a moderator and the chlorine emits prompt gammas when a neutron is captured. A 4.7-l 3He-based mobile neutron detector was compared to a 4-l NaI(Tl)-detector covered with PVC using this principle. Methods were also developed to optimise the measurement parameters of the systems. The detector systems were compared with regard to their ability to find 241AmBe, 252Cf and 238Pu-13C neutron sources. Results from stationary measurements were used to calculate optimal integration times as well as minimum detectable neutron emission rates. It was found that the 3He-based detector was more sensitive to 252Cf sources whereas the NaI(Tl) detector was more sensitive to 241AmBe and 238Pu-13C sources. The results also indicated that the sensitivity of the detectors to sources at known distances could theoretically be improved by 60% by changing from fixed integration times to list mode in mobile surveys.

  13. Neutron noise measurements at the Delphi subcritical assembly

    SciTech Connect

    Szieberth, M.; Klujber, G.; Kloosterman, J. L.; De Haas, D.

    2012-07-01

    The paper presents the results and evaluations of a comprehensive set of neutron noise measurements on the Delphi subcritical assembly of the Delft Univ. of Technology. The measurements investigated the effect of different source distributions (inherent spontaneous fission and {sup 252}Cf) and the position of the detectors applied (both radially and vertically). The evaluation of the measured data has been performed by the variance-to-mean ratio (VTMR, Feynman-{alpha}), the autocorrelation (ACF, Rossi-{alpha}) and the cross-correlation (CCF) methods. The values obtained for the prompt decay constant show a strong bias, which depends both on the detector position and on the source distribution. This is due to the presence of higher modes in the system. It has been observed that the {alpha} value fitted is higher when the detector is close to the boundary of the core or to the {sup 252}Cf point-source. The higher alpha-modes have also been observed by fitting functions describing two alpha-modes. The successful set of measurement also provides a good basis for further theoretical investigations including the Monte Carlo simulation of the noise measurements and the calculation of the alpha-modes in the Delphi subcritical assembly. (authors)

  14. Radioisotopic neutron transmission spectrometry: Quantitative analysis by using partial least-squares method.

    PubMed

    Kim, Jong-Yun; Choi, Yong Suk; Park, Yong Joon; Jung, Sung-Hee

    2009-01-01

    Neutron spectrometry, based on the scattering of high energy fast neutrons from a radioisotope and slowing-down by the light hydrogen atoms, is a useful technique for non-destructive, quantitative measurement of hydrogen content because it has a large measuring volume, and is not affected by temperature, pressure, pH value and color. The most common choice for radioisotope neutron source is (252)Cf or (241)Am-Be. In this study, (252)Cf with a neutron flux of 6.3x10(6)n/s has been used as an attractive neutron source because of its high flux neutron and weak radioactivity. Pulse-height neutron spectra have been obtained by using in-house built radioisotopic neutron spectrometric system equipped with (3)He detector and multi-channel analyzer, including a neutron shield. As a preliminary study, polyethylene block (density of approximately 0.947g/cc and area of 40cmx25cm) was used for the determination of hydrogen content by using multivariate calibration models, depending on the thickness of the block. Compared with the results obtained from a simple linear calibration model, partial least-squares regression (PLSR) method offered a better performance in a quantitative data analysis. It also revealed that the PLSR method in a neutron spectrometric system can be promising in the real-time, online monitoring of the powder process to determine the content of any type of molecules containing hydrogen nuclei.

  15. Facilitating Precision Mass Measurements at CARIBU

    NASA Astrophysics Data System (ADS)

    Lascar, Daniel; van Schelt, Jon; Savard, Guy; Segel, Ralph; Clark, Jason; Sharma, Kumar; Caldwell, Shane; Gang, Li; Sternberg, Matthew; Greene, John; Levand, Anthony; Zabransky, Bruce

    2011-10-01

    The Canadian Penning Trap Mass Spectrometer (CPT) has begun a campaign of precision mass measurements of neutron-rich nuclei produced via spontaneous fission of 252Cf as part of the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) to the ATLAS facility at Argonne National Laboratory. As of the time of submission of this abstract, we have measured neutron rich isotopes of Cs, I, Te, Sb, and Sn. CARIBU is currently running with a 60 mCi source of 252Cf which will be upgraded to a 1 Ci source in the future. In order to make this campaign possible, several upgrades to the CARIBU and CPT system were required including a new Radio Frequency Quadrupole (RFQ) ion buncher to CARIBU's low energy beamline, cryogenic cooling of the RFQ Paul trap below the CPT, and an electrostatic elevator to allow for transport of ion bunches from a 50 kV platform to the CPT system's 2 kV beamline. Construction and commissioning of the buncher and modified Paul Trap will be discussed as well as their impact on the measurements in this campaign. Support from U.S. DOE, Nucl Phys Div and NSERC Canada.

  16. Evaluation of H*(10) using the developed spherical type neutron dose monitor.

    PubMed

    Bhuiya, S H; Yamanishi, H; Uda, T

    2010-10-01

    An instrument for evaluating the neutron ambient dose equivalent has been developed. It has the characteristic of uniform response to wide energy of neutrons. The monitor is four-layered spherically shaped, based on moderation and absorption of neutrons. Neutron dose can be evaluated from the linear combination of three specific responses of thermoluminescent dosimeters (TLDs), which are located at three depths in the moderator. TLDs were arranged between layers of two consecutive depths on 12 radial axes at even intervals so that the monitor is equally sensitive to all directions of neutrons. In order to verify the usefulness of dose evaluation by the monitor, irradiation experiments were conducted at the FRS, JAEA. The D2O-moderated 252Cf was used for the calibration of the monitor. Experiments were also conducted by using two neutron sources of 252Cf bare and 241Am-Be. As a result, the evaluated dose for each irradiation was obtained close to the actual irradiated dose. It was confirmed that the method of dose evaluation by the developed monitor can be applied to practical neutron fields where the distance of neutron source is unknown.

  17. Radioluminescence of solid neodymium-doped laser materials excited by {alpha}-particles and fission fragments

    SciTech Connect

    Seregina, E A; Seregin, A A

    2013-02-28

    The characteristics of radioluminescence of Nd{sup 3+} : Y{sub 3}Al{sub 5}O{sub 12} crystals and laser glasses under excitation by plutonium-239 ({sup 239}Pu) {alpha}-particles, as well as by {alpha}-particles and spontaneous fission fragments of californium-252 ({sup 252}Cf), are studied. The radioluminescence branching ratios {beta}{sub ij} for the transition from the {sup 2}F2{sub 5/2} level to the {sup 2S+1}L{sub J} levels in Nd{sup 3+} : Y{sub 3}Al{sub 5}O{sub 12} crystals are measured. Radioluminescence from the {sup 2}P{sub 3/2} level to low-lying levels is observed. The {beta}{sub ij} ratios for transitions from the high-lying {sup 2}F2{sub 5/2}, {sup 4}D{sub 3/2}, and {sup 2}P{sub 3/2} levels are theoretically calculated. The lifetimes of metastable levels of Nd{sup 3+} excited by {sup 252}Cf fission fragments are measured. The efficiency of the conversion of energy of {alpha}-particles and fission fragments to the energy of optical radiation of Nd{sup 3+} : Y{sub 3}Al{sub 5}O{sub 12} crystals and laser glasses is determined. (active media)

  18. Radioluminescence of solid neodymium-doped laser materials excited by α-particles and fission fragments

    NASA Astrophysics Data System (ADS)

    Seregina, E. A.; Seregin, A. A.

    2013-02-01

    The characteristics of radioluminescence of Nd3+ : Y3Al5O12 crystals and laser glasses under excitation by plutonium-239 (239Pu) α-particles, as well as by α-particles and spontaneous fission fragments of californium-252 (252Cf), are studied. The radioluminescence branching ratios βij for the transition from the 2F25/2 level to the 2S+1LJ levels in Nd3+ : Y3Al5O12 crystals are measured. Radioluminescence from the 2P3/2 level to low-lying levels is observed. The βij ratios for transitions from the high-lying 2F25/2, 4D3/2, and 2P3/2 levels are theoretically calculated. The lifetimes of metastable levels of Nd3+ excited by 252Cf fission fragments are measured. The efficiency of the conversion of energy of α-particles and fission fragments to the energy of optical radiation of Nd3+ : Y3Al5O12 crystals and laser glasses is determined.

  19. A New Method of Prompt Fission Neutron Energy Spectrum Unfolding

    SciTech Connect

    Zeynalova, O. V.; Zeynalov, Sh.; Hambsch, F.-J.; Oberstedt, S.

    2010-11-25

    The prompt neutron emission in spontaneous fission of {sup 252}Cf has been investigated applying digital signal electronics along with associated digital signal processing algorithms. The goal was to find out the reasons of a long time existing discrepancy between theoretical calculations and the measurements of prompt fission neutron (PFN) emission dependence on the total kinetic energy (TKE) of fission fragments (FF). On the one hand the {sup 252}Cf(sf) reaction is one of the main references for nuclear data, on the other hand the understanding of PFN emission mechanism is very important for nuclear fission theory. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 10{sup 7} fission fragment-neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. For the first time the dependence of the number of emitted neutrons as a function of total kinetic energy (TKE) of the fragments is in very good agreement with theoretical calculations in the range of TKE from 140-220 MeV.

  20. A Sensitive, Selective, and Portable Detector for Contraband: The Compact Integrated Narcotics Detection Instrument

    SciTech Connect

    T. O. Tuemer; L. Doan; C. W. Su; J. Baritelle; B. Rhoton

    2000-06-04

    This paper describes the design and operation of a Compact Integrated Narcotics Detection Instrument (CINDI), which utilizes neutrons emitted from {sup 252}Cf. Neutrons emitted from the front face of CINDI penetrate dense compartment barrier materials with little change in energy but are backscattered by hydrogen-rich materials such as drugs. CINDI has led to a new technology that shows promise for identifying the concealed contraband. Carriers such as vehicles, marine vessels, airplanes, containers, cargo, and luggage will be scanned using both neutron and gamma-ray sources. The signal from both the neutron and gamma-ray backscattering and/or transmission can be used simultaneously to detect and possibly identify the contrabands it has been trained for.

  1. Mass measurements near the r-process path using the Canadian Penning Trap mass spectrometer

    NASA Astrophysics Data System (ADS)

    Van Schelt, J.; Lascar, D.; Savard, G.; Clark, J. A.; Caldwell, S.; Chaudhuri, A.; Fallis, J.; Greene, J. P.; Levand, A. F.; Li, G.; Sharma, K. S.; Sternberg, M. G.; Sun, T.; Zabransky, B. J.

    2012-04-01

    The masses of 40 neutron-rich nuclides from Z=51 to 64 were measured at an average precision of δm/m=10-7 using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. The measurements, of fission fragments from a 252Cf spontaneous fission source in a helium gas catcher, approach the predicted path of the astrophysical r process. Where overlap exists, this data set is largely consistent with previous measurements from Penning traps, storage rings, and reaction energetics, but large systematic deviations are apparent in β-endpoint measurements. Differences in mass excess from the 2003 Atomic Mass Evaluation of up to 400 keV are seen, as well as systematic disagreement with various mass models.

  2. Fission Measurements with Dance

    NASA Astrophysics Data System (ADS)

    Jandel, M.; Bredeweg, T. A.; Fowler, M. M.; Bond, E. M.; Chadwick, M. B.; Clement, R. R.; Couture, A.; O'Donnell, J. M.; Haight, R. C.; Keksis, A. L.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Agvaanluvsan, U.; Dashdorj, D.; Macri, R. A.; Parker, W. E.; Wilk, P. A.; Wu, C. Y.; Becker, J. A.; Angell, C. T.; Tonchev, A. P.; Baker, J. D.

    2008-08-01

    Neutron capture cross section measurements on actinides are complicated by the presence of neutron-induced fission. An efficient fission tagging detector used in coincidence with the Detector for Advanced Neutron Capture Experiments (DANCE) provides a powerful tool in undertaking simultaneous measurements of (n,γ) and (n,f) cross sections. Preliminary results on 235U(n,γ) and (n,f) and 242mAm(n,f) cross sections measured with DANCE and a custom fission-tagging parallel plate avalanche counter (PPAC) are presented. Additional measurements of γ-ray cluster multiplicity distributions for neutron-induced fission of 235U and 242mAm and spontaneous fission of 252Cf are shown, as well as γ-ray energy and average γ-ray energy distributions.

  3. Liquid sample shuffler

    SciTech Connect

    Crane, T.W.

    1985-01-01

    A method for measuring either the uranium or plutonium content of solutions has been developed and tested on natural uranium solution. The method involves using an isotopic, /sup 252/Cf, neutron source to induce fissions and then counting delayed neutrons once the source is withdrawn. The neutron source is inserted into a port in the center of the solution tank to improve the chance of a source neutron inducing a fission. Delayed neutrons are counted with high efficiency by detectors placed in ports surrounding the irradiation position. Because neutrons are counted, instead of gamma rays, radioactive solutions such as those found in reprocessing plants can be measured. The ultimate detection limit of this technique is better than 1 mg/l of the fissile isotope.

  4. Scintillation and optical properties of Pb-doped YCa 4O(BO 3) 3 crystals

    NASA Astrophysics Data System (ADS)

    Fujimoto, Yutaka; Yanagida, Takayuki; Yokota, Yuui; Kawaguchi, Noriaki; Fukuda, Kentaro; Totsuka, Daisuke; Watanabe, Kenichi; Yamazaki, Atsushi; Chani, Valery; Yoshikawa, Akira

    2011-10-01

    This communication reports optical properties and radiation responses of Pb 2+ 0.5 and 1.0 mol%-doped YCa 4O(BO 3) 3 (YCOB) single crystals grown by the micro-pulling-down (μ-PD) method for neutron scintillator applications. The crystals had no impurity phases according to the results of X-ray powder diffraction. These Pb 2+-doped crystals demonstrated blue-light luminescence at 330 nm because of Pb 2+1S 0- 3P 0,1 transition in the photoluminescence spectra. The main emission decay component was determined to be about 250-260 ns under 260 nm excitation wavelength. When irradiated by a 252Cf source, the relative light yield of 0.5% Pb 2+-doped crystal was about 300 ph/n that was determined using the light yield of a reference Li-glass scintillator.

  5. Demonstration of a TODGA/TBP process for recovery of trivalent actinides and lanthanides from a PUREX raffinate

    SciTech Connect

    Modolo, G.; Asp, H.; Vijgen, H.; Malmbeck, R.; Magnusson, D.; Sorel, C.

    2007-07-01

    The efficiency of the partitioning of trivalent actinides from a PUREX raffinate has been demonstrated with a TODGA + TBP extractant mixture dissolved in an industrial aliphatic solvent TPH. Based on the results coming from cold and hot batch extraction studies and with the aid of computer code calculations a continuous counter current process have been developed and two flowsheets were tested using miniature centrifugal contactors. The feed solutions was a synthetic PUREX raffinate, spiked with {sup 241}Am, {sup 244}Cm, {sup 252}Cf, {sup 152}Eu and {sup 134}Cs. More than 99.9 % of the trivalent actinides and lanthanides were extracted and back-extracted and very high decontamination factors to most fission products were obtained. Co-extraction of zirconium, molybdenum and palladium was prevented using oxalic acid and HEDTA. However 10% of ruthenium was extracted and only 3 % could be back extracted using diluted nitric acid. (authors)

  6. Characterization and testing of EJ-309 and Stilbene scintillation detectors

    NASA Astrophysics Data System (ADS)

    Baramsai, B.; Jandel, M.; Bredeweg, T. A.; Couture, A.; Mosby, S.; Rusev, G.; Ullmann, J. L.; Walker, C. L.

    2015-09-01

    A new neutron detector array (NEUANCE) is under development at the Los Alamos Neutron Science Center (LANSCE). After completion, NEUANCE will be installed in the central cavity of the 3.6π Υ-ray detector array DANCE located at the Lujan Center of LANSCE. The detector system, with simultaneous neutron and -ray detection capability, will be used to study neutron-induced capture and session reactions. The response of a EJ-309 scintillation detector to Υ-ray and neutron radiation was measured using the standard Υ-ray and 252Cf sources. The light from the detector was collected using a Hamamatsu photomultiplier tube or a Silicon photomultiplier GEANT4 was used to understand the light output and the optical photon transport in the scintillation. The detector geometry and optimum parameters for the data acquisition system were determined based on the test results and the simulations.

  7. A compact gas-filled avalanche counter for DANCE

    NASA Astrophysics Data System (ADS)

    Wu, C. Y.; Chyzh, A.; Kwan, E.; Henderson, R. A.; Gostic, J. M.; Carter, D.; Bredeweg, T. A.; Couture, A.; Jandel, M.; Ullmann, J. L.

    2012-12-01

    A compact gas-filled avalanche counter for the detection of fission fragments was developed for a highly segmented 4π γ-ray calorimeter, namely the Detector for Advanced Neutron Capture Experiments located at the Lujan Center of the Los Alamos Neutron Science Center. It has been used successfully for experiments with 235U, 238Pu, 239Pu, and 241Pu isotopes to provide a unique signature to differentiate the fission from the competing neutron-capture reaction channel. It was also used to study the spontaneous fission in 252Cf. The design and performance of this avalanche counter for targets with extreme α-decay rate up to ˜2.4×108/s are described.

  8. Fast neutron flux analyzer with real-time digital pulse shape discrimination

    NASA Astrophysics Data System (ADS)

    Ivanova, A. A.; Zubarev, P. V.; Ivanenko, S. V.; Khilchenko, A. D.; Kotelnikov, A. I.; Polosatkin, S. V.; Puryga, E. A.; Shvyrev, V. G.; Sulyaev, Yu. S.

    2016-08-01

    Investigation of subthermonuclear plasma confinement and heating in magnetic fusion devices such as GOL-3 and GDT at the Budker Institute (Novosibirsk, Russia) requires sophisticated equipment for neutron-, gamma- diagnostics and upgrading data acquisition systems with online data processing. Measurement of fast neutron flux with stilbene scintillation detectors raised the problem of discrimination of the neutrons (n) from background cosmic particles (muons) and neutron-induced gamma rays (γ). This paper describes a fast neutron flux analyzer with real-time digital pulse-shape discrimination (DPSD) algorithm FPGA-implemented for the GOL-3 and GDT devices. This analyzer was tested and calibrated with the help of 137Cs and 252Cf radiation sources. The Figures of Merit (FOM) calculated for different energy cuts are presented.

  9. Development of a thermal neutron sensor for Humanitarian Demining.

    PubMed

    Cinausero, M; Lunardon, M; Nebbia, G; Pesente, S; Viesti, G; Filippini, V

    2004-07-01

    A thermal neutron sensor prototype for Humanitarian Demining has been developed, trying to minimize cost and complexity of the system as required in such application. A (252)Cf source or a sealed-tube neutron generator is employed to produce primary fast neutrons that are thermalized in a moderator designed to optimize the neutron capture reaction yield in buried samples. A description of the sensor, including the performances of the acquisition system based on a Flash ADC card and final tests with explosive simulants are reported. A comparison of the sensor performance when using a radioactive source to that when employing a sealed-tube neutron generator is presented. Limitations and possible applications of this technique are discussed. PMID:15145439

  10. Development of 300 °C heat resistant boron-loaded resin for neutron shielding

    NASA Astrophysics Data System (ADS)

    Morioka, Atsuhiko; Sakurai, Shinji; Okuno, Koichi; Sato, Satoshi; Verzirov, Yury; Kaminaga, Atsushi; Nishitani, Takeo; Tamai, Hiroshi; Kudo, Yusuke; Yoshida, Shigeru; Matsukawa, Makoto

    2007-08-01

    A new neutron shielding material resistant to temperatures up to 300 °C is developed, consisting of a phenol-based resin with 6 wt% boron. The resin will be applied around the vacuum vessel of the DD plasma device to suppress the streaming neutrons and to reduce the nuclear heating of the superconducting coils. The neutron shielding performance of the newly developed resin, examined by the 252Cf neutron source, is almost the same as that of polyethylene, which is not effective above 100 °C. The new resin maintains its mechanical strength in the high temperature region. The outgas of CO 2, NH 3 and H 2O from the resin have been measured, however, the neutron shielding performance of the resin after 200 °C baking was almost the same as that before baking. Thirteen kinds of organic gases have been observed at ˜300 °C.

  11. Solid phase synthesis of somatostatin-28 II. A new biologically active octacosapeptide from anglerfish pancreatic islets.

    PubMed

    Nicolas, P; Delfour, A; Boussetta, H; Morel, A; Rholam, M; Cohen, P

    1986-10-30

    Somatostatin-28 II, an octacosapeptide recently isolated from anglerfish pancreatic islets, was synthetized by the solid phase method along with its somatostatin-14 II and somatostatin-28 II-(1-12) corresponding domains. Homogeneity of the synthetic peptides was demonstrated by analytical RP-HPLC, thin layer chromatography and electrophoresis. The peptides were further characterized by amino acids analysis, fast atomic bombarding mass spectrometry and/or 252Cf plasma desorption mass spectrometry. Synthetic somatostatin-28 II and somatostatin-14 II displace equally well the potent agonist (Tyr0,D-Trp8)-somatostatin-14 from its specific binding sites on anterior pituitary cells membranes. Both peptides activate adenylate cyclase from dispersed rat anterior pituitary cells. PMID:2877662

  12. Passive neutron assay of heterogeneous waste drums using the segmented Add-a-Source method

    SciTech Connect

    Menlove, H.O.

    1995-07-01

    We have developed passive neutron detectors that include the Add-a-Source (AS) technique to improve the accuracy of the nondestructive assay of plutonium in large waste containers. We have improved the AS by incorporating multiple positions for the {sup 252}Cf source on the exterior of a 200-L drum. The multiple positions give a better coverage of the drum and have the effect of segmenting the matrix as a function of fill height. We have applied the multiposition AS to the assay of drums with heterogeneous matrix combinations of concrete, polyethylene, wood, paper, and metal. The measurement errors caused by the matrix significantly reduced by the AS technique and anomalous shielding material in the drum can be flagged for more detailed investigation.

  13. Neutron and Gamma Ray Pulse Shape Discrimination with Polyvinyltoluene

    SciTech Connect

    Lintereur, Azaree T.; Ely, James H.; Stave, Jean A.; McDonald, Benjamin S.

    2012-03-01

    The goal of this was research effort was to test the ability of two poly vinyltoluene research samples to produce recordable, distinguishable signals in response to gamma rays and neutrons. Pulse shape discrimination was performed to identify if the signal was generated by a gamma ray or a neutron. A standard figure of merit for pulse shape discrimination was used to quantify the gamma-neutron pulse separation. Measurements were made with gamma and neutron sources with and without shielding. The best figure of merit obtained was 1.77; this figure of merit was achieved with the first sample in response to an un-moderated 252Cf source shielded with 5.08 cm of lead.

  14. β-delayed neutron spectroscopy using trapped radioactive ions.

    PubMed

    Yee, R M; Scielzo, N D; Bertone, P F; Buchinger, F; Caldwell, S; Clark, J A; Deibel, C M; Fallis, J; Greene, J P; Gulick, S; Lascar, D; Levand, A F; Li, G; Norman, E B; Pedretti, M; Savard, G; Segel, R E; Sharma, K S; Sternberg, M G; Van Schelt, J; Zabransky, B J

    2013-03-01

    A novel technique for β-delayed neutron spectroscopy has been demonstrated using trapped ions. The neutron-energy spectrum is reconstructed by measuring the time of flight of the nuclear recoil following neutron emission, thereby avoiding all the challenges associated with neutron detection, such as backgrounds from scattered neutrons and γ rays and complicated detector-response functions. (137)I(+) ions delivered from a (252)Cf source were confined in a linear Paul trap surrounded by radiation detectors, and the β-delayed neutron-energy spectrum and branching ratio were determined by detecting the β(-) and recoil ions in coincidence. Systematic effects were explored by determining the branching ratio three ways. Improvements to achieve higher detection efficiency, better energy resolution, and a lower neutron-energy threshold are proposed. PMID:23496704

  15. Chromatographic cation exchange separation of decigram quantities of californium and other transplutonium elements

    SciTech Connect

    Benker, D.E.; Chattin, F.R.; Collins, E.D.; Knauer, J.B.; Orr, P.B.; Ross, R.G.; Wiggins, J.T.

    1981-01-01

    Decigram quantities of highly radioactive transplutonium elements are routinely partitioned at TRU by chromatographic elution from cation resin using AHIB eluents. Batch runs containing up to 200 mg of /sup 252/Cf can be made in about 5 h (2 h to load the feed and 3 h for the elution), with two high-pressure ion exchange columns, a small one for the initial loading of the feed and a large one for the elution. The separations achieved in the column are preserved by routing the column effluent through an alpha detector and using the response from the detector to select appropriate product fractions. The high-pressure ion exchange process has been reliable and relatively easy to operate; therefore it will continue to be used for partitioning transplutonium elements at TRU. 3 figures, 1 table.

  16. Chromatographic cation exchange separation of decigram quantities of californium and other transplutonium elements

    SciTech Connect

    Benker, D.E.; Chattin, F.R.; Collins, E.D.; Knauer, J.B.; Orr, P.B.; Ross, R.G.; Wiggins, J.T.

    1980-01-01

    Decigram quantities of highly radioactive transplutonium elements are routinely partitioned at TRU by chromatographic elution from cation resin using AHIB eluent. By using two high-pressure ion exchange columns, a small one for the initial loading of the feed and a large one for the elution, batch runs containing up to 200 mg of /sup 252/Cf can be made in about 5 hours (2 hours to load the feed and 3 hours for the elution). The number of effluent product fractions and the amount of actinides that must be collected in intermediate fractions are minimized by monitoring response from a flow-through alpha-detector. This process has been reliable and relatively easy to operate, and will continue to be used for partitioning transplutonium elements at TRU.

  17. RPC as Thermal Neutron Detector for Humanitarian De-Mining

    NASA Astrophysics Data System (ADS)

    Arnaldi, R.; Colla, A.; de Marco, N.; Ferretti, A.; Gallio, M.; Musso, A.; Oppedisano, C.; Piccotti, A.; Poggio, F.; Scomparin, E.; Sigaudo, F.; Travaglia, G.; Vercellin, E.; Cortese, P.; Dellacasa, G.

    2003-12-01

    The possibility of detecting thermal neutrons with single gap Resistive Plate Chambers has been investigated. The development of the detector has been performed in the framework of the DIAMINE European Project for Humanitarian De-mining. To convert neutrons the inner surface of one RPC electrode has been coated with a thin layer of 10B4C. The RPC detects the charged particles generated by neutrons via the (n,α) reaction on Boron. Tests of converter samples have been performed with a thermalized 252Cf source in order to evaluate the conversion efficiency: a good agreement between experimental results and simulation has been achieved. Futhermore a detailed description of a first detector prototype together with the results of a test on low energy neutron beams are presented.

  18. RPC for thermal neutron detection

    NASA Astrophysics Data System (ADS)

    Arnaldi, R.; Chiavassa, E.; Colla, A.; Cortese, P.; Dellacasa, G.; DeMarco, N.; Ferretti, A.; Gagliardi, M.; Gallio, M.; Gemme, R.; Musso, A.; Oppedisano, C.; Piccotti, A.; Poggio, F.; Scomparin, E.; Vercellin, E.

    2006-05-01

    The possibility to detect thermal neutrons with single gap Resistive Plate Chambers has been investigated. To detect neutrons a 10B4C thin coating on the inner surface of one RPC electrode is used as thermal neutron converter. The RPC detects the charged particles generated by neutrons via the (n, α) reaction on Boron. Tests on converter samples have been performed with a thermalized 252Cf source in order to evaluate the conversion efficiency: a good agreement between experimental results and simulation has been achieved. A detector prototype has been developed and tested on a low energy neutron beam at the European laboratories JRC in Belgium. A detailed description of the detector and the experimental test results are presented.

  19. Apparatus for irradiating a continuously flowing stream of fluid

    DOEpatents

    Speir, Leslie G.; Adams, Edwin L.

    1984-01-01

    An apparatus for irradiating a continuously flowing stream of fluid is diosed. The apparatus consists of a housing having a spherical cavity and a spherical moderator containing a radiation source positioned within the spherical cavity. The spherical moderator is of lesser diameter than the spherical cavity so as to define a spherical annular volume around the moderator. The housing includes fluid intake and output conduits which open onto the spherical cavity at diametrically opposite positions. Fluid flows through the cavity around the spherical moderator and is uniformly irradiated due to the 4.pi. radiation geometry. The irradiation source, for example a .sup.252 CF neutron source, is removable from the spherical moderator through a radial bore which extends outwardly to an opening on the outside of the housing. The radiation source may be routinely removed without interrupting the flow of fluid or breaching the containment of the fluid.

  20. Apparatus for irradiating a continuously flowing stream of fluid. [For neutron activation analysis

    DOEpatents

    Speir, L.G.; Adams, E.L.

    1982-05-13

    An apparatus for irradiating a continuously flowing stream of fluid is disclosed. The apparatus consists of a housing having a spherical cavity and a spherical moderator containing a radiation source positioned within the spherical cavity. The spherical moderator is of lesser diameter than the spherical cavity so as to define a spherical annular volume around the moderator. The housing includes fluid intake and output conduits which open onto the spherical cavity at diametrically opposite positions. Fluid flows through the cavity around the spherical moderator and is uniformly irradiated due to the 4..pi.. radiation geometry. The irradiation source, for example a /sup 252/Cf neutron source, is removable from the spherical moderator through a radial bore which extends outwardly to an opening on the outside of the housing. The radiation source may be routinely removed without interrupting the flow of fluid or breaching the containment of the fluid.

  1. Stochastic image reconstruction for a dual-particle imaging system

    NASA Astrophysics Data System (ADS)

    Hamel, M. C.; Polack, J. K.; Poitrasson-Rivière, A.; Flaska, M.; Clarke, S. D.; Pozzi, S. A.; Tomanin, A.; Peerani, P.

    2016-02-01

    Stochastic image reconstruction has been applied to a dual-particle imaging system being designed for nuclear safeguards applications. The dual-particle imager (DPI) is a combined Compton-scatter and neutron-scatter camera capable of producing separate neutron and photon images. The stochastic origin ensembles (SOE) method was investigated as an imaging method for the DPI because only a minimal estimation of system response is required to produce images with quality that is comparable to common maximum-likelihood methods. This work contains neutron and photon SOE image reconstructions for a 252Cf point source, two mixed-oxide (MOX) fuel canisters representing point sources, and the MOX fuel canisters representing a distributed source. Simulation of the DPI using MCNPX-PoliMi is validated by comparison of simulated and measured results. Because image quality is dependent on the number of counts and iterations used, the relationship between these quantities is investigated.

  2. A gamma/neutron-discriminating, Cooled, Optically Stimulated Luminescence (COSL) dosemeter

    SciTech Connect

    Eschbach, P.A.; Miller, S.D.

    1992-07-01

    The Cooled Optically Stimulated Luminescence (COSL) of CaF{sub 2}:Mn (grain sizes from 0.1 to 100 microns) powder embedded in a hydrogenous matrix is reported as a function of fast-neutron dose. When all the CaF{sub 2}:Mn grains are interrogated at once, the COSL plastic dosemeters have a minimum detectable limit of 1 cSv fast neutrons; the gamma component from the bare {sup 252}cf exposure was determined with a separate dosemeter. We report here on a proton-recoil-based dosemeter that generates pulse height spectra, much like the scintillator of Hornyak, (2) to provide information on both the neutron and gamma dose.

  3. Prompt Fission γ-ray Spectra Characteristics - A First Summary

    NASA Astrophysics Data System (ADS)

    Oberstedt, S.; Billnert, R.; Gatera, A.; Geerts, W.; Halipré, P.; Hambsch, F.-J.; Lebois, M.; Oberstedt, A.; Marini, P.; Vidali, M.; Wilson, J. N.

    In this work we give an overview of our investigations of prompt γ-ray emission in nuclear fission. This work was conducted during the last five years in response to a high priority nuclear data request formulated by the OECD/NEA. The aim was to reveal data deficiencies responsible for a severe under-prediction of the prompt γ heating in nuclear reactor cores. We obtained new prompt fission γ-ray spectral (PFGS) data for 252Cf(SF) as well as for thermal-neutron induced fission on 235U(nth,f) and 241Pu(nth,f). In addition, first PFGS measurements with a fast-neutron beam were accomplished, too. The impact of the new data and future data needs are discussed.

  4. Novel Scintillation Detectors for Prompt Fission γ-Ray Measurements

    NASA Astrophysics Data System (ADS)

    Billnert, R.; Andreotti, E.; Hambsch, F.-J.; Hult, M.; Karlsson, J.; Marissens, G.; Oberstedt, A.; Oberstedt, S.

    In this work we present first results from measurements of prompt fission γ-rays from the spontaneous fission in 252Cf. New and accurate data on corresponding γ-rays from the reactions 235U(nth,f) and 239Pu(nth,f) are highly demanded for the modeling of new Generation-IV nuclear reactor systems. For these experiments we employed scintillation detectors made out of new materials (LaBr3, LaCl3 and CeBr3), whose properties were necessary to know in order to obtain reliable results. Hence, we have characterized these detectors. In all the important properties these detectors outshine sodium-iodine detectors that where used in the 1970s, when the existing data had been acquired. Our finding is that the new generation of scintillation detectors is indeed promising, as far as an improved precision of the demanded data is concerned.

  5. Triaxial and Triaxial Softness in Neutron Rich ru and pd Nuclei

    NASA Astrophysics Data System (ADS)

    Luo, Y. X.; Hamilton, J. H.; Ramaya, A. V.; Hwang, J. K.; Liu, S. H.; Rasmussen, J. O.; Frauendorf, S.; Ter-Akopian, G. M.; Daniel, A. V.; Oganessian, Yu. Ts.; Zhu, S. J.

    2013-06-01

    The level structures of 108,110,112Ru (Z=44) and 112,114,115,116,117,118Pd (Z=46) have been significantly expanded through studies of prompt γ-γ-γ coincidences observed with Gammasphere following the spontaneous fission of 252Cf. The softness to triaxiality perturbs the band structures of 108Ru and even-N Pd isotopes. Two sets of odd-parity bands are identified in 112,114,116Pd similar to but different from those in 110,112Ru. These differences can be accounted for by interferences of the chiral doubling and softness to triaxiality. Also in 112Ru, evidence for wobbling motion is found in the behavior of the γ vibrational band. Similar evidence for wobbling motion is found in 114Pd, the N = 68 isotone of 112Ru.

  6. Measurement of 56Fe activity produced in inelastic scattering of neutrons created by cosmic muons in an iron shield.

    PubMed

    Krmar, M; Jovančević, N; Nikolić, D

    2012-01-01

    We report on the study of the intensities of several gamma lines emitted after the inelastic scattering of neutrons in (56)Fe. Neutrons were produced via nuclear processes induced by cosmic muons in the 20tons massive iron cube placed at the Earth's surface and used as a passive shield for the HPGe detector. Relative intensities of detected gamma lines are compared with the results collected in the same iron shield by the use of the (252)Cf neutrons. Assessment against the published data from neutron scattering experiments at energies up to 14MeV is also provided. It allowed us to infer the qualitative information about the average energy of muon-created neutrons in the iron shield.

  7. Status of neutron diagnostics on the experimental advanced superconducting tokamak

    NASA Astrophysics Data System (ADS)

    Zhong, G. Q.; Hu, L. Q.; Pu, N.; Zhou, R. J.; Xiao, M.; Cao, H. R.; Zhu, Y. B.; Li, K.; Fan, T. S.; Peng, X. Y.; Du, T. F.; Ge, L. J.; Huang, J.; Xu, G. S.; Wan, B. N.

    2016-11-01

    Neutron diagnostics have become a significant means to study energetic particles in high power auxiliary heating plasmas on the Experimental Advanced Superconducting Tokamak (EAST). Several kinds of neutron diagnostic systems have been implemented for time-resolved measurements of D-D neutron flux, fluctuation, emission profile, and spectrum. All detectors have been calibrated in laboratory, and in situ calibration using 252Cf neutron source in EAST is in preparation. A new technology of digitized pulse signal processing is adopted in a wide dynamic range neutron flux monitor, compact recoil proton spectrometer, and time of flight spectrometer. Improvements will be made continuously to the system to achieve better adaptation to the EAST's harsh γ-ray and electro-magnetic radiation environment.

  8. A molecular fraction method for measuring personnel radiation doses

    NASA Astrophysics Data System (ADS)

    Fadel, M. A.; Khalil, W. A.; Krodja, R. P.; Sheta, N.; Abd El-Baset, M. S.

    1987-02-01

    This work represents a development in fast and albedo neutron and gamma ray dosimetry, using cellulose nitrate, as a tissue equivalent material, in which radiation damage was registered. The changes in molecular fractions of the polymer were measured after irradiation with neutron fluences from a 252Cf source in the range 10 5-10 10 n/cm 2 and gamma doses in the range 10 -4-10 -1 Gy through the use of gel filtration chromatography. Effects of irradiation on phantom, phantom to dosimeter distance, phantom thickness and storage at extreme environmental conditions were studied on the detector response and readout. The results showed that main chain scission followed by formation of new molecular configurations is the predominant effect of radiation on the polymer. The method enables measurements of neutron fluences and gamma doses in mixed radiation fields. Empirical formulae for calculating the absorbed dose from the measured changes in molecular fraction intensities are given.

  9. Advanced modeling of prompt fission neutrons

    SciTech Connect

    Talou, Patrick

    2009-01-01

    Theoretical and numerical studies of prompt fission neutrons are presented. The main results of the Los Alamos model often used in nuclear data evaluation work are reviewed briefly, and a preliminary assessment of uncertainties associated with the evaluated prompt fission neutron spectrum for n (0.5 MeV)+{sup 239}Pu is discussed. Advanced modeling of prompt fission neutrons is done by Monte Carlo simulations of the evaporation process of the excited primary fission fragments. The successive emissions of neutrons are followed in the statistical formalism framework, and detailed information, beyond average quantities, can be inferred. This approach is applied to the following reactions: {sup 252}Cf (sf), n{sub th} + {sup 239}Pu, n (0.5 MeV)+{sup 235}U, and {sup 236}Pu (sf). A discussion on the merits and present limitations of this approach concludes this presentation.

  10. Canister cryogenic system for cooling germanium semiconductor detectors in borehole and marine probes

    USGS Publications Warehouse

    Boynton, G.R.

    1975-01-01

    High resolution intrinsic and lithium-drifted germanium gamma-ray detectors operate at about 77-90 K. A cryostat for borehole and marine applications has been designed that makes use of prefrozen propane canisters. Uses of such canisters simplifies cryostat construction, and the rapid exchange of canisters greatly reduces the time required to restore the detector to full holding-time capability and enhances the safety of a field operation where high-intensity 252Cf or other isotopic sources are used. A holding time of 6 h at 86 K was achieved in the laboratory in a simulated borehole probe in which a canister 3.7 cm diameter by 57 cm long was used. Longer holding times can be achieved by larger volume canisters in marine probes. ?? 1975.

  11. Detection of buried explosives using portable neutron sources with nanosecond timing.

    PubMed

    Kuznetsov, A V; Evsenin, A V; Gorshkov, I Yu; Osetrov, O I; Vakhtin, D N

    2004-07-01

    Significant reduction of time needed to identify hidden explosives and other hazardous materials by the "neutron in, gamma out" method has been achieved by introducing timed (nanosecond) neutron sources-the so-called nanosecond neutron analysis technique. Prototype mobile device for explosives' detection based on a timed (nanosecond) isotopic (252)Cf neutron source has been created. The prototype is capable of identifying 400 g of hidden explosives in 10 min. Tests have been also made with a prototype device using timed (nanosecond) neutron source based on a portable D-T neutron generator with built-in segmented detector of accompanying alpha-particles. The presently achieved intensity of the neutron generator is 5x10(7)n/s into 4pi, with over 10(6) of these neutrons being correlated with alpha-particles detected by the built-in alpha-particle detector. Results of measurements with an anti-personnel landmine imitator are presented. PMID:15145438

  12. Final report on Seed Money Project 3210-0346: Feasibility study for californium cold neutron source

    SciTech Connect

    Alsmiller, R.G.; Henderson, D.L.; Montgomery, B.H.

    1988-10-01

    A study has been completed of the feasibility and cost of building a cold neutron source that is not dependent on a reactor or accelerator. The neutron source is provided by up to ten /sup 252/Cf capsules, each containing 50 mg of the isotope produced in the High-Flux Isotope Reactor. The neutrons are moderated by heavy water and liquid deuterium to attain, in practice, a peak cold neutron flux of 1.4 /times/ 10/sup 13/ neutrons/(m/sup 2//center dot/s). The new facility would be located in the TURF Californium Facility. The estimated cost of the Californium Cold Neutron Source Facility is $6.5 million. 6 figs., 1 tab.

  13. A compact gas-filled avalanche counter for DANCE

    DOE PAGESBeta

    Wu, C. Y.; Chyzh, A.; Kwan, E.; Henderson, R. A.; Gostic, J. M.; Carter, D.; Bredeweg, T. A.; Couture, A.; Jandel, M.; Ullmann, J. L.

    2012-08-04

    A compact gas-filled avalanche counter for the detection of fission fragments was developed for a highly segmented 4π γ-ray calorimeter, namely the Detector for Advanced Neutron Capture Experiments located at the Lujan Center of the Los Alamos Neutron Science Center. It has been used successfully for experiments with 235U, 238Pu,239Pu, and 241Pu isotopes to provide a unique signature to differentiate the fission from the competing neutron-capture reaction channel. We also used it to study the spontaneous fission in 252Cf. The design and performance of this avalanche counter for targets with extreme α-decay rate up to ~2.4×108/s are described.

  14. A compact gas-filled avalanche counter for DANCE

    SciTech Connect

    Wu, C. Y.; Chyzh, A.; Kwan, E.; Henderson, R. A.; Gostic, J. M.; Carter, D.; Bredeweg, T. A.; Couture, A.; Jandel, M.; Ullmann, J. L.

    2012-08-04

    A compact gas-filled avalanche counter for the detection of fission fragments was developed for a highly segmented 4π γ-ray calorimeter, namely the Detector for Advanced Neutron Capture Experiments located at the Lujan Center of the Los Alamos Neutron Science Center. It has been used successfully for experiments with 235U, 238Pu,239Pu, and 241Pu isotopes to provide a unique signature to differentiate the fission from the competing neutron-capture reaction channel. We also used it to study the spontaneous fission in 252Cf. The design and performance of this avalanche counter for targets with extreme α-decay rate up to ~2.4×108/s are described.

  15. An analyzer for the determination of protein concentration in corn

    SciTech Connect

    Nazarov, V.M.; Ostrovnaya, T.M.; Pavlov, S.S.; Sysoev, V.P. )

    1992-01-01

    A neutron capture gamma-ray analyzer has been constructed for rapid determination of protein concentration in corn. In contrast to the well-known methods of protein determination (e.g., chemical method of Kjeldahl, infrared method), the present method uses large volume samples and does not require special sample preparation, thereby achieving a measurement time reduction by several times. The neutron capture gamma-ray analysis is based on the determination of nitrogen because the protein concentration is directly proportional to the nitrogen concentration with different proportionality constant for different types of corn. Fast neutrons from a [sup 252]Cf neutron source are moderated by the corn itself to thermal energies. The measurement chamber is a sphere with double walls. The spherical annulus is filled with a biological shield. The sample is placed inside the inner sphere, and the neutron source is placed at the center of the sample sphere.

  16. Neutron Capture and Fission Measurements on Actinides at DANCE

    NASA Astrophysics Data System (ADS)

    Chyzh, Andrii; Wu, Ching-Yen; Kwan, Elaine; Henderson, Rodger; Gostic, Julie; Ullmann, John; Jandel, Marian; Bredeweg, Todd; Couture, Aaron; Lee, Hye Young; Haight, Robert; O'Donnell, John

    2011-10-01

    Neutron capture and fission measurements on actinides are important in nuclear engineering and physics. DANCE (Detector for Advanced Neutron Capture Measurement build at LANL) together with PPAC (avalanche technique based fission tagging detector designed and fabricated at LLNL) were used to measure the prompt γ-ray energy and multiplicity distributions in the spontaneous fission of 252Cf. These measured spectra together with the unfolded ones will be presented. The unfolding technique will be described. In addition the 238Pu(n , γ) cross section will be presented, which was measured using DANCE alone and also is the first such measurement in a laboratory environment. This work was performed under the auspices of the US Department of Energy by Los Alamos National Laboratory under Contract DE-AC52-06NA25396 and Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  17. Passive neutron design study for 200-L waste drums

    SciTech Connect

    Menlove, H.O.; Beddingfield, D.B.; Pickrell, M.M.

    1997-09-01

    We have developed a passive neutron counter for the measurement of plutonium in 200-L drums of scrap and waste. The counter incorporates high efficiency for the multiplicity counting in addition to the traditional coincidence counting. The {sup 252}Cf add-a-source feature is used to provide an accurate assay over a wide range of waste matrix materials. The room background neutron rate is reduced by using 30 cm of external polyethylene shielding and the cosmic-ray background is reduced by statistical filtering techniques. Monte Carlo Code calculations were used to determine the optimum detector design, including the gas pressure, size, number, and placement of the {sup 3}He tubes in the moderator. Various moderators, including polyethylene, plastics, teflon, and graphite, were evaluated to obtain the maximum efficiency and minimum detectable mass of plutonium.

  18. CHARACTERIZATION OF A THIN SILICON SENSOR FOR ACTIVE NEUTRON PERSONAL DOSEMETERS.

    PubMed

    Takada, M; Nunomiya, T; Nakamura, T; Matsumoto, T; Masuda, A

    2016-09-01

    A thin silicon sensor has been developed for active neutron personal dosemeters for use by aircrews and first responders. This thin silicon sensor is not affected by the funneling effect, which causes detection of cosmic protons and over-response to cosmic neutrons. There are several advantages to the thin silicon sensor: a decrease in sensitivity to gamma rays, an improvement of the energy detection limit for neutrons down to 0.8 MeV and an increase in the sensitivity to fast neutrons. Neutron response functions were experimentally obtained using 2.5 and 5 MeV monoenergy neutron beams and a (252)Cf neutron source. Simulation results using the Monte Carlo N-Particle transport code agree quite well with the experimental ones when an energy deposition region shaped like a circular truncated cone is used in place of a cylindrical region. PMID:27150515

  19. Dounreay Shuffler diagnostic software operations manual

    SciTech Connect

    Eccleston, G.W.; Stuewe, B.; Klosterbuer, S.; Van Lyssel, T.

    1985-07-01

    This operations manual describes the test software for the Dounreay Shuffler. The Shuffler is an assay system, controlled by a Commodore PET computer, that measures the plutonium content in leached hulls at the fuel reprocessing plant in Dounreay, Scotland. The Shuffler contains a /sup 252/Cf neutron source that is moved between storage and irradiation locations to obtain measurement data. A stepping motor control (SMC) module operates the Shuffler and accepts commands from the PET to move the source. This manual briefly describes the Shuffler and provides details on running and using the diagnostic software program. The communications protocol for message transmittal between the PET and SMC is defined and a detailed example of message sending is presented in an appendix.

  20. Proposed s =±1 octupole bands in 140Xe

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Zhu, S. J.; Hamilton, J. H.; Wang, E. H.; Ramayya, A. V.; Xiao, Z. G.; Li, H. J.; Luo, Y. X.; Rasmussen, J. O.; Ter-Akopian, G. M.; Oganessian, Yu. Ts.

    2016-06-01

    Level structures of neutron-rich 140Xe nucleus have been reinvestigated by using a triple γ coincidence study from the spontaneous fission of 252Cf. Several new levels and transitions are identified. The previously observed s =+1 octupole band structure is confirmed and expanded. Another set of the Δ I =2 positive and negative parity bands connected by strong E 1 transitions is proposed as the s =-1 octupole band structure. Thus, the s =±1 doublet octupole bands are completed in 140Xe. The experimental B (E 1 )/B (E 2 ) branching ratios indicate that the octupole correlations in 140Xe are weak. The other characteristics of the s =±1 octupole bands have been discussed.

  1. Evidence for Chiral Doublet Bands in 110,112Ru

    NASA Astrophysics Data System (ADS)

    Luo, Y. X.; Zhu, S. J.; Hamilton, J. H.; Rasmussen, J. O.; Ramayya, A. V.; Goodin, C.; Li, K.; Hwang, J. K.; Che, X. L.; Jang, Z.; Frauendorf, S.; Dimitrov, V.; Zhang, Jing-Ye; Stefanescu, I.; Gelberg, A.; Ter-Akopian, G. M.; Daniel, A. V.; Stoyer, M. A.; Donangelo, R.; Cole, J. D.; Stone, N. J.

    2008-08-01

    From γ-γ-γ coincidence studies of prompt γ rays in the spontaneous fission from 252Cf with Gammasphere, two sets of ΔI = 1 doublet bands assigned odd-parities were identified in 108,110,112Ru. γ-γ (θ) angular correlation data were analyzed to assign multipolarities of the depopulating transitions and spins of the bandheads. The above assignments and the decay pattern of the levels uniquely support the odd-parity assignment of the doublet bands. By checking characteristic conditions for generating chiral symmetry breaking and the fingerprints as expected for observations of chiral doublet bands in the nuclei, and based on the Tilted Axis Cranking calculations, the Δ I = 1 odd-parity doublet bands identified in 110,112Ru are assigned zero and one phonon chiral vibration bands built on υ h11/2 × (d5/2g7/2)-1 configuration.

  2. High-spin states in {sup 91,92,93}Rb and {sup 155,156}Pm

    SciTech Connect

    Hwang, J. K.; Ramayya, A. V.; Hamilton, J. H.; Liu, S. H.; Li, K.; Crowell, H. L.; Goodin, C.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.

    2009-09-15

    The excited states of the neutron-rich nuclei {sup 155,156}Pm and {sup 91,92,93}Rb were studied from the spontaneous fission of {sup 252}Cf. The {gamma}-{gamma}-{gamma} and x(Pm)-{gamma}-{gamma} triple coincidence relations were applied to identify the {gamma} transitions. Fourteen, six, three, twelve, and twelve new {gamma} transitions from high-spin states were observed in {sup 155,156}Pm, {sup 91,92}Rb, and {sup 93}Rb (first levels), respectively. The {pi}5/2[532] rotational band in {sup 155}Pm was extended up to 23/2{sup -}. The {pi}g{sub 9/2} particle states and {pi}f{sub 5/2} particle states in {sup 91,93}Rb weakly coupled to {sup 90,92}Kr, respectively, are reported.

  3. Luminescent and scintillating properties of lanthanum fluoride nanocrystals in response to gamma/neutron irradiation: codoping with Ce activator, Yb wavelength shifter, and Gd neutron captor

    NASA Astrophysics Data System (ADS)

    Vargas, J. M.; Blostein, J. J.; Sidelnik, I.; Rondón Brito, D.; Rodríguez Palomino, L. A.; Mayer, R. E.

    2016-09-01

    A novel concept for gamma radiation detection and spectroscopy, and detection of thermal neutrons based on co-doped lanthanum fluoride nanocrystals containing gadolinium is presented. The trends of colloidal synthesis of the mentioned material, LaF3 co-doped with Ce3+ as the activator, Yb3+ as the wavelength-shifter and Gd3+ as the neutron captor, is reported. Nanocrystals of the mentioned material were characterized by transmission electron microscopy, X ray diffraction, energy dispersive X ray spectroscopy, optical absorption, and photoluminescence spectroscopy. Gamma detection and its potential spectroscopy feature have been confirmed. The neutron detection capability has been confirmed by experiments performed using a 252Cf neutron source.

  4. Determining the 6Li doped side of a glass scintillator for ultra cold neutrons

    NASA Astrophysics Data System (ADS)

    Jamieson, Blair; Rebenitsch, Lori Ann

    2015-08-01

    Ultracold neutron (UCN) detectors using two visually very similar, to the microscopic level, pieces of optically contacted cerium doped lithium glasses have been proposed for high rate UCN experiments. The chief difference between the two glass scintillators is that one side is 6Li depleted and the other side 6Li doped. This note outlines a method to determine which side of the glass stack is doped with 6Li using AmBe and 252Cf neutron sources, and a Si surface barrier detector. The method sees an excess of events around the α and triton energies of neutron capture on 6Li when the enriched side is facing the Si surface barrier detector.

  5. Simulation of response functions of fast neutron sensors and development of thin neutron silicon sensor.

    PubMed

    Takada, Masashi; Nakamura, Takashi; Matsuda, Mikihiko; Nunomiya, Tomoya

    2014-10-01

    On radiation detection using silicon sensor, signals are produced from collected charges in a depletion layer; however, for high-energy particles, this depletion layer is extended due to funnelling phenomenon. The lengths of charge collection were experimentally obtained from proton peak energies in measured pulse-heights. The length is extended with increasing proton energy of up to 6 MeV, and then, is constant over 6 MeV. The response functions of fast neutron sensors were simulated for 5- and 15-MeV monoenergetic and (252)Cf neutron sources using the Monte Carlo N-Particle eXtended code. The simulation results agree well with the experimental ones, including the effect of funnelling phenomenon. In addition, a thin silicon sensor was developed for a new real-time personal neutron dosemeter. Photon sensitivity is vanishingly smaller than neutron one by a factor of 5×10(-4). PMID:24516186

  6. Measurements of the neutron source strength at DIII-D

    SciTech Connect

    Heidbrink, W.W.; Taylor, P.L.; Phillips, J.A.

    1997-01-01

    A set of neutron counters and a pair of scintillators measure the 2.5 MeV neutron emission produced by the DIII-D tokamak. The neutron counter set provides a large dynamic range ({approximately}7 orders of magnitude) while the scintillators provide the very fast resolution needed for studying transient events. The counters are absolutely calibrated {ital in situ} with a {sup 252}Cf source and the scintillators are cross calibrated to the counters. The historic variations in the emission measured by the various detectors have been compared and are consistent within the estimated accuracy of the absolute calibration (15{percent}). In the discharges with the highest emission levels (2.4{times}10{sup 16} n/s), the signals from the neutron counters and the scintillators agree well. Comparisons with other diagnostics also corroborate the neutron measurements.{copyright} {ital 1997 American Institute of Physics.}

  7. Hazards control progress report No. 58, April-September 1979

    SciTech Connect

    Griffith, R.V.

    1980-02-22

    Progress is reported on research in the areas of radiation protection and industrial hygiene. Subject areas include: (1) basic computer programs for counting room automation; (2) a computing portable neutron spectrometer; (3) preliminary measurements of the neutron energy response of CR-39 carbonate plastic; (4) effect of high-expansion foam on self-1 contained breathing apparatuses; (5) permeation of organic solvents through glove samples; (6) determining neutron dose rates and 9-to-3 in. sphere ratios from a moderated 252Cf source in the LLL Calibration Facility; (7) application of the AERIN computer code to two americium inhalation exposures; and (8) air- and soil-sampling program at Site 300's high-explosive test bombers. (ACR)

  8. Beta-Delayed Neutron Spectroscopy Using VANDLE at CARIBU

    NASA Astrophysics Data System (ADS)

    Taylor, S.; Kolos, K.; Grzywacz, R.; Paulauskas, S. V.; Madurga, M.; Savard, G.; Brewer, N. T.; Vandle Collaboration

    2015-10-01

    Measurement of spectroscopic information on beta-delayed neutrons of neutron rich fission fragments is of interest to the areas of astrophysics, reactor design, nuclear structure and stockpile stewardship. Using the Time of Flight (TOF) method, the Versatile Array of Neutron Detectors at Low Energy(VANDLE)[1,2,3] measured fission fragments of 252Cf provided by CARIBU at Argonne National Lab. 135,136Sb and 85As isotopes were measured to explore the nuclear structure around doubly magic nuclei 132Sn and 78Ni. A new TOF start detector was developed for this experiment using new Silicon Photo-Multipliers from SensL to allow for a lower beta particle energy detection threshold and better timing resolution compared to previous VANDLE experiments. This work is funded by the U.S. Department of Energy NNSA under the Stewardship Science Academic Alliance program through DOE Cooperative Agreement No. DE-FG52-08NA28552.

  9. Applications of Event-by-Event Fission Modeling with FREYA

    SciTech Connect

    Vogt, R; Randrup, J

    2011-09-16

    The recently developed code FREYA (Fission Reaction Event Yield Algorithm) generates large samples of complete fission events, consisting of two receding product nuclei as well as a number of neutrons and photons, all with complete kinematic information. Thus it is possible to calculate arbitrary correlation observables whose behavior may provide unique insight into the fission process. We first discuss the present status of FREYA, which has now been extended to include spontaneous fission. Concentrating on {sup 239}Pu(n{sub th},f), {sup 240}Pu(sf) and {sup 252}Cf(sf), we discuss the neutron multiplicity correlations, the dependence of the neutron energy spectrum on the neutron multiplicity, and the relationship between the fragment kinetic energy and the number of neutrons and their energies. We also suggest novel fission observables that could be measured with modern detectors.

  10. Neutron-induced fission: properties of prompt neutron and γ rays as a function of incident energy

    NASA Astrophysics Data System (ADS)

    Stetcu, I.; Talou, P.; Kawano, T.

    2016-06-01

    We have applied the Hauser-Feshbach statistical theory, in a Monte-Carlo implementation, to the de-excitation of fission fragments, obtaining a reasonable description of the characteristics of neutrons and gamma rays emitted before beta decays toward stability. Originally implemented for the spontaneous fission of 252Cf and the neutroninduced fission of 235U and 239Pu at thermal neutron energy, in this contribution we discuss the extension of the formalism to incident neutron energies up to 20 MeV. For the emission of pre-fission neutrons, at incident energies beyond second-chance fission, we take into account both the pre-equilibrium and statistical pre-fission components. Phenomenological parameterizations of mass, charge and TKE yields are used to obtain the initial conditions for the fission fragments that subsequently decay via neutron and emissions. We illustrate this approach for 239Pu(n,f).

  11. Study of a gold-foil-based multisphere neutron spectrometer.

    PubMed

    Wang, Z; Hutchinson, J D; Hertel, N E; Burgett, E; Howell, R M

    2008-01-01

    Multisphere neutron spectrometers with active thermal neutron detectors cannot be used in high-intensity radiation fields due to pulse pile-up and dead-time effects. Thus, a multisphere spectrometer using a passive detection system, specifically gold foils, has been investigated in this work. The responses of a gold-foil-based Bonner sphere neutron spectrometer were studied for two different gold-foil holder designs; an aluminium-polyethylene holder and a polyethylene holder. The responses of the two designs were calculated for four incident neutron beam directions, namely, parallel, perpendicular and at +/-45 degrees relative to the flat surface of the foil. It was found that the use of polyethylene holder resulted in a more isotropic response to neutrons for the four incident directions considered. The computed responses were verified by measuring the neutron spectrum of a 252Cf source with known strength.

  12. Set-up of a passive Bonner sphere system for neutron spectrometry at mixed fields with predominant photon component based on activation detector.

    PubMed

    Amgarou, K; Lacoste, V; Muller, H; Fernández, F

    2007-01-01

    A passive Bonner sphere system (BSS), based on thermal neutron activation detectors, was developed to perform neutron spectrometry in pulsed and very intense (n-gamma) fields with predominant photon component, as those produced by high energy (>10 MV) medical linear electron accelerators. In this paper, a description of the new system is presented together with an experimental characterisation of a portable Sodium Iodide (NaI) detector and a fixed high-purity Germanium one, both used to measure the induced gamma-activity of the activated materials, respectively, in situ and in the laboratory. The choice of the activated materials is justified according to pre-established practical considerations and physical criteria. The response functions of the entire passive BSS were calculated using the MCNPX code. A preliminary experimental validation with a bare (252)Cf source is given as well.

  13. Thermal neutron analysis (TNA) explosive detection based on electronic neutron generators

    SciTech Connect

    Lee, W.; Mahood, D.B.; Ryge, P.

    1994-12-31

    Thermal neutron analysis explosive detection systems have been developed and demonstrated for inspection of checked airline baggage and for detection of buried land mines. Thermal neutrons from a moderated neutron source impinge on the inspected object and the resulting capture gamma ray signatures provide detection information. Isotopic neutron sources, e.g. {sup 252}Cf, are compact, economical and reliable, but they are subject to the licensing requirements, safety concerns and public perception problems associated with radioactive material. These are mitigated by use of an electronic neutron generator - an ion accelerator with a target producing neutrons by a nuclear reaction such as D(d,n){sup 3}He or {sup 9}Be(d,n){sup 10}B. With suitable moderator designs based on neutron transport codes, operational explosive detection systems can be build and would provide effective alternatives to radioactive neutron sources. Calculations as well as laboratory and field experience with three generator types will be presented.

  14. Pulse shape discrimination in helium-4 scintillation detectors

    NASA Astrophysics Data System (ADS)

    Kelley, Ryan P.; Enqvist, Andreas; Jordan, Kelly A.

    2016-09-01

    Three algorithms were investigated for discriminating between neutrons and gamma rays in a pressurized 4He gas fast neutron detector: charge comparison, weighted integration, and neutron-gamma model analysis (NGMA). For each algorithm, a comprehensive pulse shape discrimination study was conducted using time-of-flight measurements, receiver operator characteristic curves, figure of merit performance measures, and a comparison of performance between 252Cf and PuBe mixed neutron/gamma sources. The NGMA method was found to have the best overall performance by both the figure of merit and the receiver operator characteristic curve. The results also illustrated the high gamma rejection efficiency of these detectors, which is desirable in a variety of neutron monitoring applications.

  15. In-situ calibration of TFTR (Tokamak Fusion Test Reactor) neutron detectors

    SciTech Connect

    Hendel, H.W.; Palladino, R.W.; Barnes, C.W.; Diesso, M.; Felt, J.S.; Jassby, D.L.; Johnson, L.C.; Ku, L.P.; Liu, Q.P.; Motley, R.W.; Murphy, H.B.; Murphy, J.; Nieschmidt, E.B.; Roberts, J.A.; Saito, T.; Strachan, J.D.; Waszazak, R.J.; Young, K.

    1990-03-01

    We report results of the TFTR fission detector calibration performed in December 1988. A NBS-traceable, remotely controlled {sup 252}Cf neutron source was moved toroidally through the TFTR vacuum vessel. Detection efficiencies for two {sup 235}U detectors were measured for 930 locations of the neutron point source in toroidal scans at 16 different major radii and vertical heights. These scans effectively simulated the volume-distributed plasma neutron source, and the volume-integrated detection efficiency was found to be insensitive to plasma position. The Campbell mode is useful due to its large overlap with the count rate mode and large dynamic range. The resulting absolute plasma neutron source calibration has an uncertainty of {plus minus} 13%. 21 refs., 23 figs., 4 tabs.

  16. A double-Bragg detector with digital signal processing for the event-by-event study of fission in actinide nuclei

    NASA Astrophysics Data System (ADS)

    Frost, R. J. W.; Smith, A. G.

    2016-09-01

    In the current paper, a windowless double-Bragg chamber incorporating full signal digitisation has been developed for the purpose of studying the energy (E), mass (A), charge (Z) and angular distributions (θ, Φ) of nuclei generated by fission. This device measures E for each fission fragment by collection of the charge produced during ionisation of the fill gas. Subsequent digitisation of the signals from each of two anodes yields information on dE/dx, as well as electron collection time, which can be further used for polar angle (θ) determination. Frisch-grid and cathode signals are also digitised and are used both for anode signal correction and to produce further information on θ. To verify the operation of this detector, three angular determination techniques from the literature were implemented, and the results were found to be consistent with the referenced paper. Current results from the spontaneous fission of 252Cf are presented.

  17. In-plant experience with passive-active shufflers at Los Alamos

    SciTech Connect

    Hurd, J.R.; Hsue, F.; Rinard, P.M.

    1995-09-01

    Two Canberra-built passive-active {sup 252}Cf shufflers of Los Alamos hardware and software design have been installed at Los Alamos National Laboratory, one at the Chemistry and Metallurgy Research (CMR) Facility at TA-3 and the other at the Plutonium Facility (PF-4) at TA-55. These instruments fulfill important safeguards and accountability measurement requirements for special nuclear material (SNM) in matrices too dense or otherwise not appropriate for typical gamma-ray or other neutron counting techniques. They support many programmatic requirements including measurements of transuranic (TRU) waste and inventory verification. This paper describes the instrument performance under plant conditions with various background radiations on well-characterized standards to determine long-term stability and establish a calibration. Results are also reported on verification measurements of previously unmeasured inventory items in various matrices and geometric distributions. Preliminary investigative measurements are presented on standards of mixed uranium and plutonium oxide (MOX).

  18. Phase I-II clinical trial of Californium-252. Treatment of stage IB carcinoma of the cervix.

    PubMed

    Maruyama, Y; VanNagell, J R; Yoneda, J; Donaldson, E; Gallion, H; Rowley, K; Kryscio, R; Beach, J L

    1987-04-15

    Intracavitary Californium-252 combined with whole-pelvis photon radiotherapy was tested as the sole form of treatment for 22 patients with Stage IB carcinoma of the cervix. Californium-252 (Cf) is a fast neutron-emitting radioisotope currently being tested in trials of neutron brachytherapy (NT). The outcomes of the treated group of patients were traced for local tumor control, survival, patterns of failure, and complications. The Cf intracavitary therapy combined with whole-pelvis photon radiotherapy resulted in 95% 2-year and 91% 5-year actuarial survival. There were 9% Grade II-III complications by the Stockholm scale and 4% local failures. These results were obtained in an early clinical trial with a group of largely poor-risk patients with tumors of mean diameter of 4.3 cm.

  19. Identification of a quasiparticle band in very neutron-rich {sup 104}Zr

    SciTech Connect

    Yeoh, E. Y.; Wang, J. G.; Ding, H. B.; Gu, L.; Xu, Q.; Xiao, Z. G.; Zhu, S. J.; Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Liu, S. H.; Liu, Y. X.; Sun, Y.; Luo, Y. X.; Rasmussen, J. O.; Lee, I. Y.

    2010-08-15

    The high spin levels of a very neutron-rich {sup 104}Zr nucleus have been reinvestigated by measuring the prompt {gamma} rays in the spontaneous fission of {sup 252}Cf. The ground-state band has been confirmed. A new sideband has been identified with a band-head energy at 1928.7 keV. The projected shell model is employed to investigate the band structure of {sup 104}Zr. The results of calculated levels are in good agreement with the experimental data, and suggest that the new band in {sup 104}Zr may be based on the neutron {nu}5/2{sup -}[532] x {nu}3/2{sup +}[411] configuration.

  20. Characteristics of the Neutron Irradiation Facilities of the PSI Calibration Laboratory

    SciTech Connect

    Hoedlmoser, H.; Schuler, Ch.; Butterweck, G.; Mayer, S.

    2011-12-13

    The neutron radiation fields of the Calibration Laboratory at Paul Scherrer Institute (PSI) are traceable to the national standards of the Physikalisch-Technische Bundesanstalt (PTB) in Germany. A Berthold LB6411 neutron dose rate meter for neutron radiation is used as a secondary standard. Recently, a thorough characterization of the neutron irradiation fields of the {sup 241}Am-Be and {sup 252}Cf sources by means of reference measurements and a detailed MCNPX simulation of the irradiation facility has been initiated. In this work, the characteristics of the neutron radiation fields are summarized and presented together with model equations and an uncertainty analysis. MCNPX results are shown for the {sup 241}Am-Be source. A comparison of measured and simulated data shows an excellent agreement. From the simulation, valuable information about the neutron fields like the contribution of scattered neutrons in the fields and the energy spectra could be obtained.

  1. Commissioning a Tape Transport System for Decay Studies and Beam Diagnostics at CARIBU

    NASA Astrophysics Data System (ADS)

    Bertone, P. F.; Digiovine, B.; Lister, C. J.; Teh, K.; Kondev, F. G.; Nair, C.; Chowdhury, P.; Deo, A. Y.; Lakshmi, S.

    2011-10-01

    The CAlifornium Rare Isotope Breeder Upgrade (CARIBU) to the ATLAS facility at Argonne utilizes the spontaneous fission of 252 Cf for producing neutron-rich radioactive nuclei. CARIBU will be used for a wide variety of experiments, involving both reaccelerated and stopped beams, in nuclear structure, nuclear astrophysics and applications. Many of these experiments will require a means of transporting radioactivity to and from detector counting stations for the purpose of assaying beam content, measuring half-lives, β- γ spectroscopy and determining Gamow-Teller strength distributions. We have commissioned the first of several tape transport systems that will perform these functions. An overview of the design and deployment of the system will be given along with preliminary test results. Supported by the U.S. DOE Office of Nuclear Physics DE-AC02-06CH11357.

  2. A Comparison of Neutron-Based Non-Destructive Assessment Methods for Chemical Warfare Material and High Explosives

    SciTech Connect

    Seabury, E. H.; Chichester, D. L.; Wharton, C. J.; Caffrey, A. J.

    2009-03-10

    Prompt Gamma Neutron Activation Analysis (PGNAA) systems employ neutrons as a probe to interrogate items, e.g. chemical warfare materiel-filled munitions. The choice of a neutron source in field-portable systems is determined by its ability to excite nuclei of interest, operational concerns such as radiological safety and ease-of-use, and cost. Idaho National Laboratory's PINS Chemical Assay System has traditionally used a {sup 252}Cf isotopic neutron source, but recently a deuterium-tritium (DT) electronic neutron generator (ENG) has been tested as an alternate neutron source. This paper presents the results of using both of these neutron sources to interrogate chemical warfare materiel (CWM) and high explosive (HE) filled munitions.

  3. A compact neutron beam generator system designed for prompt gamma nuclear activation analysis.

    PubMed

    Ghassoun, J; Mostacci, D

    2011-08-01

    In this work a compact system was designed for bulk sample analysis using the technique of PGNAA. The system consists of (252)Cf fission neutron source, a moderator/reflector/filter assembly, and a suitable enclosure to delimit the resulting neutron beam. The moderator/reflector/filter arrangement has been optimised to maximise the thermal neutron component useful for samples analysis with a suitably low level of beam contamination. The neutron beam delivered by this compact system is used to irradiate the sample and the prompt gamma rays produced by neutron reactions within the sample elements are detected by appropriate gamma rays detector. Neutron and gamma rays transport calculations have been performed using the Monte Carlo N-Particle transport code (MCNP5).

  4. Possible excited deformed rotational bands in {sup 82}Ge

    SciTech Connect

    Hwang, J. K.; Hamilton, J. H.; Ramayya, A. V.; Brewer, N. T.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.

    2011-08-15

    Excited states of neutron-rich nucleus {sup 82}Ge were studied from the spontaneous fission of {sup 252}Cf. Eleven new transitions and seven new levels in {sup 82}Ge were identified by using X(Dy)-{gamma}-{gamma} and {gamma}-{gamma}-{gamma} triple coincidences. Possible excited deformed rotational bands are observed, for the first time, in this nuclear region. Coexistence of the spherical ground and deformed excited shapes is proposed in {sup 82}Ge. These deformed rotational bands can be formed by two-particle, two-hole excitations with the 0{sup +} pairing energy states of the {nu}9/2[404]{sup -2} x 1/2[431]{sup 2} configuration across the N=50 closed shell.

  5. Feasibility study of Californium-252 for the therapy of stage IV cervical cancer.

    PubMed

    Maruyama, Y; Van Nagell, J R; Yoneda, J; Donaldson, E; Gallion, H; Patel, P; Kryscio, R J

    1988-06-15

    Twenty patients with Stage IVA and IVB cervic cancers were treated with Californium-252 (Cf) neutron brachytherapy (NT) in a feasibility trial between 1976 and 1986. Eleven patients had Stage IVA disease; nine patients had Stage IVB disease. Patient compliance with therapy was poor in four of nine patients with Stage IVB disease, and the 50% survival time was 6 months. In Stage IVA disease there were 18% 3-year survivals. For those that failed, the 50% survival time was 7.5 months. Because of the frequency of disseminated metastases, effective adjuvant therapy needs to be developed to use after the tumor debulking therapy, especially for Stage IVB disease. A single early Cf-NT implant followed by 6000 cGy of whole-pelvis fractionated radiation would accomplish this adequately for local tumor control and palliation.

  6. High-spin level structure of {sup 115}Rh: Evolution of triaxiality in odd-even Rh isotopes

    SciTech Connect

    Liu, S. H.; Gelberg, A.; Gu, L.; Yeoh, E. Y.; Zhu, S. J.; Luo, Y. X.; Rasmussen, J. O.; Ma, W. C.; Daniel, A. V.; Oganessian, Yu. Ts.; Ter-Akopian, G. M.

    2011-07-15

    High-spin excited states in the neutron-rich nucleus {sup 115}Rh have been identified for the first time by studying prompt {gamma} rays from the spontaneous fission of {sup 252}Cf with the Gammasphere detector array. A new yrast band and a sideband are built in {sup 115}Rh. This level scheme is proposed to be built on the 7/2{sup +} ground state. The existence of a large signature splitting and an yrare band in {sup 115}Rh shows typical features of a triaxially deformed nucleus. The rigid triaxial rotor plus particle model is used to interpret the level structure of {sup 115}Rh. The level energies, the {gamma} branching ratios, the large signature splitting in the yrast band, and the inverted signature splitting in the yrare band in {sup 115}Rh are reproduced very well. Strong K mixing occurs in {sup 115}Rh at high spin.

  7. New Band Structures in Aapprox110 Neutron-Rich Nuclei

    SciTech Connect

    Zhu, S. J.; Wang, J. G.; Ding, H. B.; Gu, L.; Xu, Q.; Yeoh, E. Y.; Xiao, Z. G.; Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Liu, S. H.; Li, K.; Luo, Y. X.; Rasmussen, J. O.; Lee, I. Y.; Qi, B.; Meng, J.

    2010-05-12

    The high spin states of neutron-rich nuclei in Aapprox110 region have been carefully investigated by measuring prompt gamma-gamma-gamma coincident measurements populated in the spontaneous fission of {sup 252}Cf with the Gammasphere detector array. Many new collective bands have been discovered. In this proceeding paper, we introduce some interesting new band structures recently observed by our cooperative groups, that is, the one-phonon- and two-phonon gamma-vibrational bands in odd-A {sup 103}Nb, {sup 105}Mo and {sup 107}Tc, the chiral doublet bands in even-even {sup 106}Mo, {sup 110}Ru and {sup 112}Ru, and the pseudospin partner bands with in {sup 108}Tc. The characteristics of these band structures have been discussed.

  8. Structure of the yrast band in the odd-odd deformed nucleus {sup 156}Pm

    SciTech Connect

    Sood, P. C.; Sai, K. Vijay; Gowrishankar, R.; Sainath, M.

    2011-05-15

    The six-level sequence deduced for the odd-odd nucleus {sup 156}Pm in the high-spin studies following spontaneous fission of {sup 252}Cf is shown to constitute the K{sup {pi}=}4{sup +} yrast band having the two-quasiparticle configuration {l_brace}p:5/2[532]+ n:3/2[521]{r_brace}. Spin parities I{sup {pi}=}4{sup +} through 9{sup +} are assigned to the earlier suggested six levels. The location and the decay {gamma}'s of the 10{sup +} level of this band are indicated. It is also pointed out that there are no {gamma} rays common to these postfission high-spin spectra and those seen in the {sup 156}Nd {beta}-decay studies.

  9. Isospin effects on neutrons as a probe of nuclear dissipation

    SciTech Connect

    Ye, W.

    2009-03-15

    Based on a dynamical Langevin equation coupled with a statistical decay model, we calculate the excess of the precision neutron multiplicity of the heavy nuclei {sup 240}Cf, {sup 246}Cf, {sup 252}Cf, and {sup 240}U over that predicted by the standard statistical model as a function of the postsaddle dissipation strength. We find that with increasing isospin of the system, the sensitivity of the excess to the dissipation strength decreases substantially. Moreover, for {sup 240}U, this excess is no longer sensitive to the nuclear dissipation. These results suggest that, on the experimental side, to accurately obtain information of the postsaddle dissipation strength by measuring the neutron multiplicity evaporated during the fission process of heavy nuclei, it is best to populate those compound systems with low isospin.

  10. The CARIBU gas catcher

    NASA Astrophysics Data System (ADS)

    Savard, G.; Levand, A. F.; Zabransky, B. J.

    2016-06-01

    The CARIBU upgrade of the ATLAS facility provides radioactive beams of neutron-rich isotopes for experiments at low and Coulomb barrier energies. It creates these beam using a large RF gas catcher that collects and cools fission fragments from an intense 252 Cf fission source and transforms them into a low-emittance monoenergetic beam. This beam can then be purified, reaccelerated and delivered to experiments. This technique is fast and universal, providing access to all fission fragment species independently of their chemical properties. The CARIBU gas catcher has been built to operate at high ionization density and in the presence of the contamination from the source. A brief overview of the CARIBU concept is given below, together with a more detailed description of the CARIBU gas catcher and the performance it has now achieved.

  11. Simulation of response functions of fast neutron sensors and development of thin neutron silicon sensor.

    PubMed

    Takada, Masashi; Nakamura, Takashi; Matsuda, Mikihiko; Nunomiya, Tomoya

    2014-10-01

    On radiation detection using silicon sensor, signals are produced from collected charges in a depletion layer; however, for high-energy particles, this depletion layer is extended due to funnelling phenomenon. The lengths of charge collection were experimentally obtained from proton peak energies in measured pulse-heights. The length is extended with increasing proton energy of up to 6 MeV, and then, is constant over 6 MeV. The response functions of fast neutron sensors were simulated for 5- and 15-MeV monoenergetic and (252)Cf neutron sources using the Monte Carlo N-Particle eXtended code. The simulation results agree well with the experimental ones, including the effect of funnelling phenomenon. In addition, a thin silicon sensor was developed for a new real-time personal neutron dosemeter. Photon sensitivity is vanishingly smaller than neutron one by a factor of 5×10(-4).

  12. Long counter and its application for the calibration of the neutron irradiators.

    PubMed

    Park, Hyeonseo; Kim, Jungho; Choi, Kil-Oung

    2014-10-01

    The Korea Research Institute of Standards and Science (KRISS) has constructed a new long counter that can be disassembled in parts and reassembled. This counter can be easily transported and used as a transfer standard instrument for neutron fluence measurements. The response function and the effective centre of the counter are investigated by calculating neutron energies from thermal to 30 MeV using MCNPX. By carrying out measurements using a (252)Cf source in the KRISS irradiation room, the accuracy of the evaluated effective centre position is confirmed. The 'distance variation method' is adopted to eliminate the effect of inscatter neutrons. This method is effective and used for the experimental determination of the effective centre. The neutron emission rates determined by the neutron fluence measurements using the long counter developed are compared with those measured by a manganese sulphate bath, and show good agreement within 3 %.

  13. Sputtering yield of Pu bombarded by fission Fragments from Cf

    SciTech Connect

    Danagoulian, Areg; Klein, Andreas; Mcneil, Wendy V; Yuan, Vincent W

    2008-01-01

    We present results on the yield of sputtering of Pu atoms from a Pu foil, bombarded by fission fragments from a {sup 252}Cf source in transmission geometry. We have found the number of Pu atoms/incoming fission fragments ejected to be 63 {+-} 1. In addition, we show measurements of the sputtering yield as a function of distance from the central axis, which can be understood as an angular distribution of the yield. The results are quite surprising in light of the fact that the Pu foil is several times the thickness of the range of fission fragment particles in Pu. This indicates that models like the binary collision model are not sufficient to explain this behavior.

  14. Dose estimations of fast neutrons from a nuclear reactor by micronuclear yields in onion seedlings.

    PubMed

    Fujikawa, K; Endo, S; Itoh, T; Yonezawa, Y; Hoshi, M

    1999-12-01

    Irradiations of onion seedlings with fission neutrons from bare, Pb-moderated, and Fe-moderated 252Cf sources induced micronuclei in the root-tip cells at similar rates. The rate per cGy averaged for the three sources, , was 19 times higher than rate induced by 60Co gamma-rays. When neutron doses, Dn, were estimated from frequencies of micronuclei induced in onion seedlings after exposure to neutron-gamma mixed radiation from a 1 W nuclear reactor, using the reciprocal of as conversion factor, resulting Dn values agreed within 10% with doses measured with paired ionizing chambers. This excellent agreement was achieved by the high sensitivity of the onion system to fast neutrons relative to gamma-rays and the high contribution of fast neutrons to the total dose of mixed radiation in the reactor's field.

  15. Detection of fast neutrons from shielded nuclear materials using a semiconductor alpha detector.

    PubMed

    Pöllänen, R; Siiskonen, T

    2014-08-01

    The response of a semiconductor alpha detector to fast (>1 MeV) neutrons was investigated by using measurements and simulations. A polyethylene converter was placed in front of the detector to register recoil protons generated by elastic collisions between neutrons and hydrogen nuclei of the converter. The developed prototype equipment was tested with shielded radiation sources. The low background of the detector and insensitivity to high-energy gamma rays above 1 MeV are advantages when the detection of neutron-emitting nuclear materials is of importance. In the case of a (252)Cf neutron spectrum, the intrinsic efficiency of fast neutron detection was determined to be 2.5×10(-4), whereas three-fold greater efficiency was obtained for a (241)AmBe neutron spectrum.

  16. The angular dependence of an Si energy deposition spectrometer response at several radiation sources.

    PubMed

    Spurný, Frantisek; Trompier, François; Bottollier-Depois, Jean-François

    2005-06-01

    An MDU-Liulin spectrometer based on an Si-diode was mainly used during the last few years with the goal to use them for measurements onboard aircraft. To investigate its ability to obtain such measurements, the detector was tested in some radiation reference fields, like 60Co and other photon beams, neutrons of an AmBe and 252Cf sources and in high-energy radiation fields at CERN. Due to the high geometrical asymmetry of the Si-diode semiconductor, an angular dependence of the response would be expected. This work presents analyses and discusses the results of angular dependence studies obtained at the different radiation sources mentioned. It was found that these angular dependences vary with the type and energy of radiation. The influence of these variations on the use as a dosimeter onboard aircraft is also studied and discussed.

  17. Matrix and position correction of shuffler assays by application of the alternating conditional expectation algorithm to shuffler data

    SciTech Connect

    Pickrell, M M; Rinard, P M

    1992-01-01

    The {sup 252}Cf shuffler assays fissile uranium and plutonium using active neutron interrogation and then counting the induced delayed neutrons. Using the shuffler, we conducted over 1700 assays of 55-gal. drums with 28 different matrices and several different fissionable materials. We measured the drums to dispose the matrix and position effects on {sup 252}Cf shuffler assays. We used several neutron flux monitors during irradiation and kept statistics on the count rates of individual detector banks. The intent of these measurements was to gauge the effect of the matrix independently from the uranium assay. Although shufflers have previously been equipped neutron monitors, the functional relationship between the flux monitor sepals and the matrix-induced perturbation has been unknown. There are several flux monitors so the problem is multivariate, and the response is complicated. Conventional regression techniques cannot address complicated multivariate problems unless the underlying functional form and approximate parameter values are known in advance. Neither was available in this case. To address this problem, we used a new technique called alternating conditional expectations (ACE), which requires neither the functional relationship nor the initial parameters. The ACE algorithm develops the functional form and performs a numerical regression from only the empirical data. We applied the ACE algorithm to the shuffler-assay and flux-monitor data and developed an analytic function for the matrix correction. This function was optimized using conventional multivariate techniques. We were able to reduce the matrix-induced-bias error for homogeneous samples to 12.7%. The bias error for inhomogeneous samples was reduced to 13.5%. These results used only a few adjustable parameters compared to the number of available data points; the data were not over fit,'' but rather the results are general and robust.

  18. A physics investigation of deadtime losses in neutron counting at low rates with Cf252

    SciTech Connect

    Evans, Louise G; Croft, Stephen

    2009-01-01

    {sup 252}Cf spontaneous fission sources are used for the characterization of neutron counters and the determination of calibration parameters; including both neutron coincidence counting (NCC) and neutron multiplicity deadtime (DT) parameters. Even at low event rates, temporally-correlated neutron counting using {sup 252}Cf suffers a deadtime effect. Meaning that in contrast to counting a random neutron source (e.g. AmLi to a close approximation), DT losses do not vanish in the low rate limit. This is because neutrons are emitted from spontaneous fission events in time-correlated 'bursts', and are detected over a short period commensurate with their lifetime in the detector (characterized by the system die-away time, {tau}). Thus, even when detected neutron events from different spontaneous fissions are unlikely to overlap in time, neutron events within the detected 'burst' are subject to intrinsic DT losses. Intrinsic DT losses for dilute Pu will be lower since the multiplicity distribution is softer, but real items also experience self-multiplication which can increase the 'size' of the bursts. Traditional NCC DT correction methods do not include the intrinsic (within burst) losses. We have proposed new forms of the traditional NCC Singles and Doubles DT correction factors. In this work, we apply Monte Carlo neutron pulse train analysis to investigate the functional form of the deadtime correction factors for an updating deadtime. Modeling is based on a high efficiency {sup 3}He neutron counter with short die-away time, representing an ideal {sup 3}He based detection system. The physics of dead time losses at low rates is explored and presented. It is observed that new forms are applicable and offer more accurate correction than the traditional forms.

  19. Shielding Calculations for the BDMS UF6 Mass Flow Meter

    SciTech Connect

    Radev, R; Hall, J

    2001-09-13

    We performed Monte Carlo calculations of the neutron and gamma ray spectra and neutron and gamma dose rates outside the shielding of the UF{sub 6} mass flowmeter. The UF{sub 6} mass flowmeter and the UF{sub 6} mass flowmeter are the two main components of the Blend Down Monitoring System (BDMS) equipment. The BDMS equipment is designed to continuously monitor the UF{sub 6} enrichment and mass flow rates in processing pipes at uranium facilities. The UF{sub 6} mass flowmeter incorporates four {sup 252}Cf neutron sources, surrounded by a polyethylene shielding block. The uranium fission products generated by the {sup 252}Cf neutrons are detected down the pipe, thus confirming the UF{sub 6} mass flow rate. The dose calculations used both U.S. and Russian gamma and neutron fluence-to-dose conversion coefficients. The purpose of these calculations was to facilitate proper interpretation of the neutron dose rate measurements from rem meters (e.g., rem balls) outside of BDMS shielding. An accurate determination of the dose rate is particular interest in that it enables dose rates to be compared with the applicable regulatory limit. The calculations show that neutrons outside of BDMS shielding are significantly reduced in energy, i.e., the spectrum is shifted (i.e., moderated) towards lower energies and contains significantly larger amount of neutrons in the energy range below 100 keV. Results of the calculations indicate that neutron dose rate measurements taken outside of BDMS shielding are overestimated by 25% to 55%, depending on the location around BDMS, when using either Russian or U.S. dose conversion coefficients. For an accurate neutron dose rate evaluation, application of an appropriate correction factor to the neutron dose rate measurements is necessary.

  20. Gas-phase chemistry of technetium carbonyl complexes.

    PubMed

    Wang, Yang; Qin, Zhi; Fan, Fang-Li; Haba, Hiromitsu; Komori, Yukiko; Cao, Shi-Wei; Wu, Xiao-Lei; Tan, Cun-Min

    2015-05-28

    Gas-phase chemical behaviors of short-lived technetium carbonyl complexes were studied using a low temperature isothermal chromatograph (IC) coupled with a (252)Cf spontaneous fission (SF) source. Fission products recoiled from the (252)Cf SF source were thermalized in a mixed gas containing CO, and then technetium carbonyl complexes were formed from reactions between CO gas and various technetium isotopes. A gas-jet system was employed to transport the volatile carbonyl complexes from a recoil chamber to the IC. Short IC columns made of Fluorinated Ethylene Propylene (FEP) Teflon and quartz were used to obtain chemical information about the technetium carbonyl complexes. The results for the (104)Tc-(106)Tc carbonyl complexes were found to be strongly influenced by the precursors, and showed the chemical behaviors of (104)Mo-(106)Mo carbonyl complexes, respectively. However, (107)Tc and (108)Tc could represent the chemical information of the element technetium due to their high independent yields and the very short half-lives of their precursors (107)Mo and (108)Mo. An adsorption enthalpy of about ΔHads = -43 kJ mol(-1) was determined for the Tc carbonyl complexes on both the Teflon and quartz surfaces by fitting the breakthrough curves of the (107)Tc and (108)Tc carbonyl complexes with a Monte Carlo simulation program. Chemical yields of around 25% were measured for the Tc carbonyl complexes relative to the transport yields obtained with the gas-jet transport of KCl aerosol particles with Ar carrier gas. Furthermore, the influence of a small amount of O2 gas on the yields of the Mo and Tc carbonyl complexes was studied.

  1. Benchmark test of transport calculations of gold and nickel activation with implications for neutron kerma at Hiroshima.

    PubMed

    Hoshi, M; Hiraoka, M; Hayakawa, N; Sawada, S; Munaka, M; Kuramoto, A; Oka, T; Iwatani, K; Shizuma, K; Hasai, H

    1992-11-01

    A benchmark test of the Monte Carlo neutron and photon transport code system (MCNP) was performed using a 252Cf fission neutron source to validate the use of the code for the energy spectrum analyses of Hiroshima atomic bomb neutrons. Nuclear data libraries used in the Monte Carlo neutron and photon transport code calculation were ENDF/B-III, ENDF/B-IV, LASL-SUB, and ENDL-73. The neutron moderators used were granite (the main component of which is SiO2, with a small fraction of hydrogen), Newlight [polyethylene with 3.7% boron (natural)], ammonium chloride (NH4Cl), and water (H2O). Each moderator was 65 cm thick. The neutron detectors were gold and nickel foils, which were used to detect thermal and epithermal neutrons (4.9 eV) and fast neutrons (> 0.5 MeV), respectively. Measured activity data from neutron-irradiated gold and nickel foils in these moderators decreased to about 1/1,000th or 1/10,000th, which correspond to about 1,500 m ground distance from the hypocenter in Hiroshima. For both gold and nickel detectors, the measured activities and the calculated values agreed within 10%. The slopes of the depth-yield relations in each moderator, except granite, were similar for neutrons detected by the gold and nickel foils. From the results of these studies, the Monte Carlo neutron and photon transport code was verified to be accurate enough for use with the elements hydrogen, carbon, nitrogen, oxygen, silicon, chlorine, and cadmium, and for the incident 252Cf fission spectrum neutrons. PMID:1399639

  2. The neutron-gamma Feynman variance to mean approach: Gamma detection and total neutron-gamma detection (theory and practice)

    NASA Astrophysics Data System (ADS)

    Chernikova, Dina; Axell, Kåre; Avdic, Senada; Pázsit, Imre; Nordlund, Anders; Allard, Stefan

    2015-05-01

    Two versions of the neutron-gamma variance to mean (Feynman-alpha method or Feynman-Y function) formula for either gamma detection only or total neutron-gamma detection, respectively, are derived and compared in this paper. The new formulas have particular importance for detectors of either gamma photons or detectors sensitive to both neutron and gamma radiation. If applied to a plastic or liquid scintillation detector, the total neutron-gamma detection Feynman-Y expression corresponds to a situation where no discrimination is made between neutrons and gamma particles. The gamma variance to mean formulas are useful when a detector of only gamma radiation is used or when working with a combined neutron-gamma detector at high count rates. The theoretical derivation is based on the Chapman-Kolmogorov equation with the inclusion of general reactions and corresponding intensities for neutrons and gammas, but with the inclusion of prompt reactions only. A one energy group approximation is considered. The comparison of the two different theories is made by using reaction intensities obtained in MCNPX simulations with a simplified geometry for two scintillation detectors and a 252Cf-source. In addition, the variance to mean ratios, neutron, gamma and total neutron-gamma are evaluated experimentally for a weak 252Cf neutron-gamma source, a 137Cs random gamma source and a 22Na correlated gamma source. Due to the focus being on the possibility of using neutron-gamma variance to mean theories for both reactor and safeguards applications, we limited the present study to the general analytical expressions for Feynman-alpha formulas.

  3. Fission Fragment Yield, Cross Section and Prompt Neutron and Gamma Emission Data from Actinide Isotopes

    NASA Astrophysics Data System (ADS)

    Hambsch, F.-J.; Oberstedt, S.; Al-Adili, A.; Brys, T.; Billnert, R.; Matei, C.; Oberstedt, A.; Salvador-Castiñeira, P.; Tudora, A.; Vidali, M.

    2014-05-01

    Recent experimental investigations on major and minor actinides at the JRC-IRMM are presented. Fission-fragment distributions of isotopes with vibrational resonances in the sub-threshold fission cross section, i. e. 234,238U, have been measured. For 234U, the impact of an increased neutron multiplicity for the heavy fragments with higher incident neutron energies has been studied as observed in experiment and also recently theoretically predicted. The impact is found to be noticeable on post-neutron mass yields, which are the relevant quantities for a-priori waste assessments. The fission cross sections for 240,242Pu at threshold and in the plateau region are being investigated within the ANDES project. The results show some discrepancies to the ENDF/B-VII.1 evaluation mainly for 242Pu around 1 MeV, where the evaluation exhibits a resonance-like structure not observed so clearly in the present work. The requested target accuracy in design studies of innovative reactor concepts like Gen-IV is in the range of a few percent. In order to be able to respond to requests for measurements of prompt neutron and γ-ray emission in fission JRC-IRMM has also invested in setting up a neutron and γ-ray detector array. The neutron array is called SCINTIA and has so far been tested with 252Cf(SF). For γ-ray multiplicity and spectrum measurements of 252Cf(SF) and 235U(nth, f) lanthanum- and cerium-halide detectors were successfully used.

  4. Future research program on prompt γ-ray emission in nuclear fission

    NASA Astrophysics Data System (ADS)

    Oberstedt, S.; Billnert, R.; Hambsch, F.-J.; Lebois, M.; Oberstedt, A.; Wilson, J. N.

    2015-12-01

    In recent years the measurement of prompt fission γ-ray spectra (PFGS) has gained renewed interest, after about forty years since the first comprehensive studies of the reactions 235U(n th , f), 239Pu(n th ,f) and 252Cf(sf). The renaissance was initiated by requests for new values especially for γ-ray multiplicity and average total energy release per fission in neutron-induced fission of 235U and 239Pu. Both isotopes are considered the most important ones with respect to the modeling of innovative cores required for the Generation-IV reactors, the majority working with fast neutrons. During the last 5 years we have conducted a systematic study of spectral data for thermal-neutron-induced fission on 235U and 241Pu as well as for the spontaneous fission of 252Cf with unprecedented accuracy. From the new data we conclude that those reactions do not considerably contribute to the observed heat excess and suspect other reactions playing a significant role. Possible contributions may originate from fast-neutron-induced reactions on 238U, which is largely present in the fuel, or from γ-induced fission from neutron capture in the construction material. A first experiment campaign on prompt γ-ray emission from fast-neutron-induced fission on 235,238U was successfully performed in order to test our assumptions. In the following we attempt to summarize, what has been done in the field to date, and to motivate future measurement campaigns exploiting dedicated neutron and photon beams as well as upcoming highly efficient detector assemblies.

  5. Active neutron interrogation for verification of storage of weapons components at the Oak Ridge Y-12 Plant

    SciTech Connect

    Mihalczo, J.T.; Valentine, T.E.; Mattingly, J.K.; Mullens, J.A.; Hughes, S.S.

    1998-02-23

    A nuclear weapons identification system (NWIS), under development since 1984 at the Oak Ridge Y-12 Plant and presently in use there, uses active neutron interrogation with low-intensity {sup 252}Cf sources in ionization chambers to provide a timed source of fission neutrons from the spontaneous fission of {sup 252}Cf. To date, measurements have been performed on {approximately}15 different weapons systems in a variety of configurations both in and out of containers. Those systems included pits and fully assembled systems ready for deployment at the Pantex Plant in Amarillo, Texas, and weapons components at the Oak Ridge Y-12 Plant. These measurements have shown that NWIS can identify nuclear weapons and/or components; nuclear weapons/components can be distinguished from mockups where fissile material has been replaced by nonfissile material; omissions of small amounts (4%) of fissile material can be detected; changes in internal configurations can be determined; trainer parts can be identified as was demonstrated by verification of 512 containers with B33 components at the Y-12 Plant (as many as 32 in one 8-hour shift); and nonfissile components can be identified. The current NWIS activities at the Oak Ridge Y-12 Plant include: (1) further development of the system for more portability and lower power consumption, (2) collection of reference signatures for all weapons components in containers, and (3) confirmation of a particular weapons component in storage and confirmation of receipts. This paper describes the recent measurements with NWIS for a particular weapons component in storage that have resolved an Inspector General (IG`s) audit finding with regard to performance of confirmation of inventory.

  6. Radioactivity in atomic-bomb samples from exposure to environmental neutrons.

    PubMed

    Endo, S; Shizuma, K; Tanaka, K; Ishikawa, M; Rühm, W; Egbert, S D; Hoshi, M

    2007-12-01

    For about one decade, activation measurements performed on environmental samples from a distance larger than 1 km from the hypocenter of the atomic-bomb explosion over Hiroshima suggested much higher thermal neutron fluences to the survivors than predicted. This caused concern among the radiation protection community and prompted a complete re-evaluation of all aspects of survivor dosimetry. While it was shown recently that secondary neutrons from cosmic radiation and other sources have probably been the reason for the high measured concentrations of the long-lived radioisotope 36Cl in these samples, the source for high measured concentrations of the short-lived radionuclides 152Eu and 60Co has not yet been investigated in detail. In order to quantify the production of 152Eu and 60Co in environmental samples by secondary neutrons from cosmic radiation, thermal neutron fluxes were measured by means of a He gas proportional counter in various buildings where these samples had been and still are being stored. Because a 252Cf neutron source has been operated occasionally close to one of the sample storage rooms, additional neutron flux measurements were carried out when the neutron source was in operation. The thermal neutron fluxes measured ranged from 0.00017 to 0.00093 n cm(-2) s(-1) and depended on the floor number of the investigated building. Based on the measured neutron fluxes, the specific activities from the reactions 151Eu(n,gamma)152Eu and 59Co(n,gamma)60Co in the atomic-bomb samples were estimated to be 7.9 mBq g(-1) Eu and 0.27 mBq g(-1) Co, respectively, in saturation. These activities are much lower than those recently measured in samples that had been exposed to atomic-bomb neutrons. It is therefore concluded that environmental and moderated 252Cf neutrons are not the source for the high activities that had been measured in these samples.

  7. Benchmark test of transport calculations of gold and nickel activation with implications for neutron kerma at Hiroshima.

    PubMed

    Hoshi, M; Hiraoka, M; Hayakawa, N; Sawada, S; Munaka, M; Kuramoto, A; Oka, T; Iwatani, K; Shizuma, K; Hasai, H

    1992-11-01

    A benchmark test of the Monte Carlo neutron and photon transport code system (MCNP) was performed using a 252Cf fission neutron source to validate the use of the code for the energy spectrum analyses of Hiroshima atomic bomb neutrons. Nuclear data libraries used in the Monte Carlo neutron and photon transport code calculation were ENDF/B-III, ENDF/B-IV, LASL-SUB, and ENDL-73. The neutron moderators used were granite (the main component of which is SiO2, with a small fraction of hydrogen), Newlight [polyethylene with 3.7% boron (natural)], ammonium chloride (NH4Cl), and water (H2O). Each moderator was 65 cm thick. The neutron detectors were gold and nickel foils, which were used to detect thermal and epithermal neutrons (4.9 eV) and fast neutrons (> 0.5 MeV), respectively. Measured activity data from neutron-irradiated gold and nickel foils in these moderators decreased to about 1/1,000th or 1/10,000th, which correspond to about 1,500 m ground distance from the hypocenter in Hiroshima. For both gold and nickel detectors, the measured activities and the calculated values agreed within 10%. The slopes of the depth-yield relations in each moderator, except granite, were similar for neutrons detected by the gold and nickel foils. From the results of these studies, the Monte Carlo neutron and photon transport code was verified to be accurate enough for use with the elements hydrogen, carbon, nitrogen, oxygen, silicon, chlorine, and cadmium, and for the incident 252Cf fission spectrum neutrons.

  8. Effect of diameter of nanoparticles and capture cross-section library on macroscopic dose enhancement in boron neutron capture therapy

    PubMed Central

    Farhood, Bagher

    2014-01-01

    Purpose The aim of this study is evaluation of the effect of diameter of 10B nanoparticles and various neutron capture cross-section libraries on macroscopic dose enhancement in boron neutron capture therapy (BNCT). Material and methods MCNPX Monte Carlo code was used for simulation of a 252Cf source, a soft tissue phantom and a tumor containing 10B nanoparticles. Using 252Cf as a neutron source, macroscopic dose enhancement factor (MDEF) and total dose rate in tumor in the presence of 100, 200, and 500 ppm of 10B nanoparticles with 25 nm, 50 nm, and 100 nm diameters were calculated. Additionally, the effect of ENDF, JEFF, JENDL, and CENDL neutron capture cross-section libraries on MDEF was evaluated. Results There is not a linear relationship between the average MDEF value and nanoparticles’ diameter but the average MDEF grows with increased concentration of 10B nanoparticles. There is an increasing trend for average MDEF with the tumor distance. The average MDEF values were obtained the same for various neutron capture cross-section libraries. The maximum and minimum doses that effect on the total dose in tumor were neutron and secondary photon doses, respectively. Furthermore, the boron capture related dose component reduced in some extent with increase of diameter of 10B nanoparticles. Conclusions Based on the results of this study, it can be concluded that from physical point of view, various nanoparticle diameters have no dominant effect on average MDEF value in tumor. Furthermore, it is concluded that various neutron capture cross-section libraries are resulted to the same macroscopic dose enhancements. However, it is predicted that taking into account the biological effects for various nanoparticle diameters will result in different dose enhancements. PMID:25834582

  9. Intercomparison study on (152)Eu gamma ray and (36)Cl AMS measurements for development of the new Hiroshima-Nagasaki Atomic Bomb Dosimetry System 2002 (DS02).

    PubMed

    Hoshi, M; Endo, S; Tanaka, K; Ishikawa, M; Straume, T; Komura, K; Rühm, W; Nolte, E; Huber, T; Nagashima, Y; Seki, R; Sasa, K; Sueki, K; Fukushima, H; Egbert, S D; Imanaka, T

    2008-07-01

    In the process of developing a new dosimetry system for atomic bomb survivors in Hiroshima and Nagasaki (DS02), an intercomparison study between (152)Eu and (36)Cl measurements was proposed, to reconcile the discrepancy previously observed in the Hiroshima data between measurements and calculations of thermal neutron activation products. Nine granite samples, exposed to the atomic-bomb radiation in Hiroshima within 1,200 m of the hypocenter, as well as mixed standard solutions containing known amounts of europium and chlorine that were neutron-activated by a (252)Cf source, were used for the intercomparison. Gamma-ray spectrometry for (152)Eu was carried out with ultra low-background Ge detectors at the Ogoya Underground Laboratory, Kanazawa University, while three laboratories participated in the (36)Cl measurement using accelerator mass spectrometry (AMS): The Technical University of Munich, Germany, the Lawrence Livermore National Laboratory, USA and the University of Tsukuba, Japan. Measured values for the mixed standard solutions showed good agreement among the participant laboratories. They also agreed well with activation calculations, using the neutron fluences monitored during the (252)Cf irradiation, and the corresponding activation cross-sections taken from the JENDL-3.3 library. The measured-to-calculated ratios obtained were 1.02 for (152)Eu and 0.91-1.02 for (36)Cl, respectively. Similarly, the results of the granite intercomparison indicated good agreement with the DS02 calculation for these samples. An average measured-to-calculated ratio of 0.98 was obtained for all granite intercomparison measurements. The so-called neutron discrepancy that was previously observed and that which included increasing measured-to-calculated ratios for thermal neutron activation products for increasing distances beyond 1,000 m from the hypocenter was not seen in the results of the intercomparison study. The previously claimed discrepancy could be explained by

  10. Gas-phase chemistry of technetium carbonyl complexes.

    PubMed

    Wang, Yang; Qin, Zhi; Fan, Fang-Li; Haba, Hiromitsu; Komori, Yukiko; Cao, Shi-Wei; Wu, Xiao-Lei; Tan, Cun-Min

    2015-05-28

    Gas-phase chemical behaviors of short-lived technetium carbonyl complexes were studied using a low temperature isothermal chromatograph (IC) coupled with a (252)Cf spontaneous fission (SF) source. Fission products recoiled from the (252)Cf SF source were thermalized in a mixed gas containing CO, and then technetium carbonyl complexes were formed from reactions between CO gas and various technetium isotopes. A gas-jet system was employed to transport the volatile carbonyl complexes from a recoil chamber to the IC. Short IC columns made of Fluorinated Ethylene Propylene (FEP) Teflon and quartz were used to obtain chemical information about the technetium carbonyl complexes. The results for the (104)Tc-(106)Tc carbonyl complexes were found to be strongly influenced by the precursors, and showed the chemical behaviors of (104)Mo-(106)Mo carbonyl complexes, respectively. However, (107)Tc and (108)Tc could represent the chemical information of the element technetium due to their high independent yields and the very short half-lives of their precursors (107)Mo and (108)Mo. An adsorption enthalpy of about ΔHads = -43 kJ mol(-1) was determined for the Tc carbonyl complexes on both the Teflon and quartz surfaces by fitting the breakthrough curves of the (107)Tc and (108)Tc carbonyl complexes with a Monte Carlo simulation program. Chemical yields of around 25% were measured for the Tc carbonyl complexes relative to the transport yields obtained with the gas-jet transport of KCl aerosol particles with Ar carrier gas. Furthermore, the influence of a small amount of O2 gas on the yields of the Mo and Tc carbonyl complexes was studied. PMID:25920667

  11. Neutron counting and gamma spectroscopy with PVT detectors.

    SciTech Connect

    Mitchell, Dean James; Brusseau, Charles A.

    2011-06-01

    Radiation portals normally incorporate a dedicated neutron counter and a gamma-ray detector with at least some spectroscopic capability. This paper describes the design and presents characterization data for a detection system called PVT-NG, which uses large polyvinyl toluene (PVT) detectors to monitor both types of radiation. The detector material is surrounded by polyvinyl chloride (PVC), which emits high-energy gamma rays following neutron capture reactions. Assessments based on high-energy gamma rays are well suited for the detection of neutron sources, particularly in border security applications, because few isotopes in the normal stream of commerce have significant gamma ray yields above 3 MeV. Therefore, an increased count rate for high-energy gamma rays is a strong indicator for the presence of a neutron source. The sensitivity of the PVT-NG sensor to bare {sup 252}Cf is 1.9 counts per second per nanogram (cps/ng) and the sensitivity for {sup 252}Cf surrounded by 2.5 cm of polyethylene is 2.3 cps/ng. The PVT-NG sensor is a proof-of-principal sensor that was not fully optimized. The neutron detector sensitivity could be improved, for instance, by using additional moderator. The PVT-NG detectors and associated electronics are designed to provide improved resolution, gain stability, and performance at high-count rates relative to PVT detectors in typical radiation portals. As well as addressing the needs for neutron detection, these characteristics are also desirable for analysis of the gamma-ray spectra. Accurate isotope identification results were obtained despite the common impression that the absence of photopeaks makes data collected by PVT detectors unsuitable for spectroscopic analysis. The PVT detectors in the PVT-NG unit are used for both gamma-ray and neutron detection, so the sensitive volume exceeds the volume of the detection elements in portals that use dedicated components to detect each type of radiation.

  12. Charge breeding results and future prospects with electron cyclotron resonance ion source and electron beam ion source (invited)a)

    NASA Astrophysics Data System (ADS)

    Vondrasek, R.; Levand, A.; Pardo, R.; Savard, G.; Scott, R.

    2012-02-01

    The Californium Rare Ion Breeder Upgrade (CARIBU) of the Argonne National Laboratory ATLAS facility will provide low-energy and reaccelerated neutron-rich radioactive beams for the nuclear physics program. A 70 mCi 252Cf source produces fission fragments which are thermalized and collected by a helium gas catcher into a low-energy particle beam with a charge of 1+ or 2+. An electron cyclotron resonance (ECR) ion source functions as a charge breeder in order to raise the ion charge sufficiently for acceleration in the ATLAS linac. The final CARIBU configuration will utilize a 1 Ci 252Cf source to produce radioactive beams with intensities up to 106 ions/s for use in the ATLAS facility. The ECR charge breeder has been tested with stable beam injection and has achieved charge breeding efficiencies of 3.6% for 23Na8+, 15.6% for 84Kr17+, and 13.7% for 85Rb19+ with typical breeding times of 10 ms/charge state. For the first radioactive beams, a charge breeding efficiency of 11.7% has been achieved for 143Cs27+ and 14.7% for 143Ba27+. The project has been commissioned with a radioactive beam of 143Ba27+ accelerated to 6.1 MeV/u. In order to take advantage of its lower residual contamination, an EBIS charge breeder will replace the ECR charge breeder in the next two years. The advantages and disadvantages of the two techniques are compared taking into account the requirements of the next generation radioactive beam facilities.

  13. Monte Carlo N-particle simulation of neutron-based sterilisation of anthrax contamination

    PubMed Central

    Liu, B; Xu, J; Liu, T; Ouyang, X

    2012-01-01

    Objective To simulate the neutron-based sterilisation of anthrax contamination by Monte Carlo N-particle (MCNP) 4C code. Methods Neutrons are elementary particles that have no charge. They are 20 times more effective than electrons or γ-rays in killing anthrax spores on surfaces and inside closed containers. Neutrons emitted from a 252Cf neutron source are in the 100 keV to 2 MeV energy range. A 2.5 MeV D–D neutron generator can create neutrons at up to 1013 n s−1 with current technology. All these enable an effective and low-cost method of killing anthrax spores. Results There is no effect on neutron energy deposition on the anthrax sample when using a reflector that is thicker than its saturation thickness. Among all three reflecting materials tested in the MCNP simulation, paraffin is the best because it has the thinnest saturation thickness and is easy to machine. The MCNP radiation dose and fluence simulation calculation also showed that the MCNP-simulated neutron fluence that is needed to kill the anthrax spores agrees with previous analytical estimations very well. Conclusion The MCNP simulation indicates that a 10 min neutron irradiation from a 0.5 g 252Cf neutron source or a 1 min neutron irradiation from a 2.5 MeV D–D neutron generator may kill all anthrax spores in a sample. This is a promising result because a 2.5 MeV D–D neutron generator output >1013 n s−1 should be attainable in the near future. This indicates that we could use a D–D neutron generator to sterilise anthrax contamination within several seconds. PMID:22573293

  14. Search for instantaneous radiation near the instant of break momentum of various fissioning nuclear systems at low excitation energies

    SciTech Connect

    Vorobyev, A. S. Val'ski, G. V.; Gagarskii, A. M.; Guseva, I. S.; Petrov, G. A.; Petrova, V. I.; Serebrin, A. Yu.; Sokolov, V. E.; Shcherbakov, O. A.

    2011-12-15

    The main results of studying the properties of 'instantaneous' neutrons and {gamma} photons during the fission of {sup 233,235}U(n{sub th}, f) and {sup 239}Pu(n{sub th}, f) nuclei and spontaneous fission of {sup 252}Cf, which were performed on the WWR-M reactor at the St. Petersburg Nuclear Physics Institute, Russian Academy of Sciences, are presented. Along with obtaining the main characteristics of the instantaneous radiation from fission fragments, these studies were also aimed at gaining deeper insight into such exotic processes as the emission of break neutrons and {gamma} photons from a fissioning nucleus near the break point. These investigations were performed on different experimental setups using different analytical methods. This approach allowed us not only to find but also to reduce to minimum possible systematic effects. The yields of break neutrons were found to be about (5-7) Multiplication-Sign 10{sup -2} of the total number of neutrons per {sup 233,235}U(n, f) fission event and approximately twice as much for {sup 239}Pu(n, f) and {sup 252}Cf. The coefficient of T-odd asymmetry for {gamma} photons is in agreement with the estimate obtained on the assumption that the observed effect is mainly related to the {gamma} photons emitted by excited fragments with highly oriented angular momenta. This fact gave grounds to conclude that the desired break {gamma} photons cannot be reliably selected (within the obtained experimental accuracy) against the much larger background of {gamma} photons from fission fragments.

  15. Theoretical study of the almost sequential mechanism of true ternary fission

    NASA Astrophysics Data System (ADS)

    Tashkhodjaev, R. B.; Muminov, A. I.; Nasirov, A. K.; von Oertzen, W.; Oh, Yongseok

    2015-05-01

    We consider the collinear ternary fission which is a sequential ternary decay with a very short time between the ruptures of two necks connecting the middle cluster of the ternary nuclear system and outer fragments. In particular, we consider the case where the Coulomb field of the first massive fragment separated during the first step of the fission produces a lower pre-scission barrier in the second step of the residual part of the ternary system. In this case, we obtain a probability of about 10-3 per binary fission for the yield of massive clusters such as 70Ni,Ge-8280,86Se, and 94Kr in the ternary fission of 252Cf. These products appear together with the clusters having mass numbers of A =132 -140 . The results show that the yield of a heavy cluster such as Ni-7068 would be followed by a product of A =138 -148 with a large probability as observed in the experimental data obtained with the FOBOS spectrometer at the Joint Institute for Nuclear Research. The third product is not observed. The landscape of the potential-energy surface shows that the configuration of the Ni +Ca +Sn decay channel is lower by about 12 MeV than that of the Ca +Ni +Sn channel. This leads to the fact that the yield of Ni and Sn is large. The analysis on the dependence of the velocity of the middle fragment on mass numbers of the outer products leads to the conclusion that, in the collinear tripartition channel of 252Cf, the middle cluster has a very small velocity, which does not allow it to be found in experiments.

  16. Charge breeding results and future prospects with electron cyclotron resonance ion source and electron beam ion source (invited)

    SciTech Connect

    Vondrasek, R.; Levand, A.; Pardo, R.; Savard, G.; Scott, R.

    2012-02-15

    The Californium Rare Ion Breeder Upgrade (CARIBU) of the Argonne National Laboratory ATLAS facility will provide low-energy and reaccelerated neutron-rich radioactive beams for the nuclear physics program. A 70 mCi {sup 252}Cf source produces fission fragments which are thermalized and collected by a helium gas catcher into a low-energy particle beam with a charge of 1+ or 2+. An electron cyclotron resonance (ECR) ion source functions as a charge breeder in order to raise the ion charge sufficiently for acceleration in the ATLAS linac. The final CARIBU configuration will utilize a 1 Ci {sup 252}Cf source to produce radioactive beams with intensities up to 10{sup 6} ions/s for use in the ATLAS facility. The ECR charge breeder has been tested with stable beam injection and has achieved charge breeding efficiencies of 3.6% for {sup 23}Na{sup 8+}, 15.6% for {sup 84}Kr{sup 17+}, and 13.7% for {sup 85}Rb{sup 19+} with typical breeding times of 10 ms/charge state. For the first radioactive beams, a charge breeding efficiency of 11.7% has been achieved for {sup 143}Cs{sup 27+} and 14.7% for {sup 143}Ba{sup 27+}. The project has been commissioned with a radioactive beam of {sup 143}Ba{sup 27+} accelerated to 6.1 MeV/u. In order to take advantage of its lower residual contamination, an EBIS charge breeder will replace the ECR charge breeder in the next two years. The advantages and disadvantages of the two techniques are compared taking into account the requirements of the next generation radioactive beam facilities.

  17. Development of Two-Dimensional Fitting and Application to Prompt Gamma-Rays of CALIFORNIUM-252 Fission

    NASA Astrophysics Data System (ADS)

    Chemaly, Mike Georges

    We have developed a method for the direct two -dimensional decomposition of complex coincidence matrices in order to extract gamma-gamma coincidence intensities at the statistical limits. The algorithms written to analyze the gamma-gamma coincidence data were developed first while working on unidimensional spectra from the decay of ^ {65}Ni, ^{65} Zn and ^{rm 108m} Ag. They were then extended to work in two dimensions in order to obtain a general method that could be used for extracting information from data sets having different dimensions. We successfully modeled the continuum and the ridges over the entire coincidence matrix. The continuum is described by the simple product of two vectors while the ridges are reproduced from a centroid based on gamma -rays in the total projection and a vector giving the height as a function of position. The peaks found by a two-dimensional zero-area transform are fitted with a Singular Value Decomposition --Levenberg Marquardt code extended to two dimensions. We applied the technique to the analysis of the coincidences involving the prompt gammas from the spontaneous fission of ^{252}Cf. The information from the 20,000 coincidence peaks obtained from the fit was manipulated through a computer program. The built-in database constructed from NNDC nuclear structure data files provided access to literature schemes. A graphical interface allowed the interactive building and extension of level schemes. Newly placed transitions were checked by comparing predicted coincidences to those observed. In the even-even nuclides, models like the Variable-Moment -of-Inertia and the product of valence protons and neutrons (NpNn scheme) are used to guide placements based on systematics. We take advantage of the cross-coincidences between fission partners to determine the atomic number and mass of the nuclide in which a transition occurred. Fifty-eight level schemes from ^{252}Cf fission have been constructed and seventeen of them have been

  18. Development of a modular directional and spectral neutron detection system using solid-state detectors

    NASA Astrophysics Data System (ADS)

    Weltz, A.; Torres, B.; McElwain, L.; Dahal, R.; Huang, J.; Bhat, I.; Lu, J.; Danon, Y.

    2015-08-01

    A detection system using room-temperature, microstructured solid-state thermal neutron detectors with very low leakage current has been developed at Rensselaer Polytechnic Institute (RPI) with the ability to provide positional and spectral information about an unknown neutron source. The Directional and Spectral Neutron Detection System (DSNDS) utilizes a set of small-but-scalable, zero-bias solid-state thermal neutron detectors which have demonstrated high thermal neutron efficiency and adequate gamma insensitivity. The DSNDS can gather spectral information about an unknown neutron source with a relatively small number of detectors, simplifying the detector electronics and minimizing cost; however, the DSNDS is modular in design, providing the capability to increase the detection efficiency and angular resolution. The system used in this paper was comprised of a stack of five high-density polyethylene (HDPE) disks with a thickness of 5 cm and a diameter of 30 cm, the middle disk containing 16 detectors positioned as one internal (moderated) and one external (unmoderated) ring of solid-state neutron detectors. These two detector rings provide the ability to determine the directionality of a neutron source. The system gathers spectral information about a neutron source in two ways: by measuring the relative responses of the internal ring of detectors as well as measuring the ratio of the internal-to-external detector responses. Experiments were performed with variable neutron spectra: a 252Cf spontaneous fission neutron source which was HDPE moderated, HDPE reflected, lead (Pb) shielded, and bare in order to benchmark the system for spectral sensitivity. Simulations were performed in order to characterize the neutron spectra corresponding to each of the source configurations and showed agreement with experimental measurements. The DSNDS demonstrates the ability to determine the relative angle of the source and the hardness of the neutron spectrum. By using the

  19. Monte-Carlo Hauser-Feshbach simulations of prompt fission gamma-ray properties

    NASA Astrophysics Data System (ADS)

    Stetcu, Ionel; Talou, Patrick; Kawano, Toshihiko; Jandel, Marian

    2014-09-01

    Properties of prompt fission neutrons and γ rays, emitted before the weak decays of the fission fragments toward stability, are important for both nuclear technologies and a better understanding of the fission process. In the present work, we use the Hauser-Feshbach model to simulate the de-excitation of the fully accelerated fission fragments treated as compound nuclei. Our Monte-Carlo implementation of the Hauser-Feshbach statistical model, which takes into account the competition between the neutron and γ emissions, allows the description of both average quantities, like in the Los Alamos model, and correlations between the emitted particles. Our simulations will be compared against available experimental data and current evaluations. In particular, we will compare our average γ-ray spectrum with recent measurements at the research reactor KFKI in Budapest for the 235U(nth , f) and 252Cf(sf) reactions, as well as multiplicity-dependent distributions obtained at the DANCE facility at LANSCE. Properties of prompt fission neutrons and γ rays, emitted before the weak decays of the fission fragments toward stability, are important for both nuclear technologies and a better understanding of the fission process. In the present work, we use the Hauser-Feshbach model to simulate the de-excitation of the fully accelerated fission fragments treated as compound nuclei. Our Monte-Carlo implementation of the Hauser-Feshbach statistical model, which takes into account the competition between the neutron and γ emissions, allows the description of both average quantities, like in the Los Alamos model, and correlations between the emitted particles. Our simulations will be compared against available experimental data and current evaluations. In particular, we will compare our average γ-ray spectrum with recent measurements at the research reactor KFKI in Budapest for the 235U(nth , f) and 252Cf(sf) reactions, as well as multiplicity-dependent distributions obtained at the

  20. Verification of threshold activation detection (TAD) technique in prompt fission neutron detection using scintillators containing 19F

    NASA Astrophysics Data System (ADS)

    Sibczynski, P.; Kownacki, J.; Moszyński, M.; Iwanowska-Hanke, J.; Syntfeld-Każuch, A.; Gójska, A.; Gierlik, M.; Kaźmierczak, Ł.; Jakubowska, E.; Kędzierski, G.; Kujawiński, Ł.; Wojnarowicz, J.; Carrel, F.; Ledieu, M.; Lainé, F.

    2015-09-01

    In the present study ⌀ 5''× 3'' and ⌀ 2''× 2'' EJ-313 liquid fluorocarbon as well as ⌀ 2'' × 3'' BaF2 scintillators were exposed to neutrons from a 252Cf neutron source and a Sodern Genie 16GT deuterium-tritium (D+T) neutron generator. The scintillators responses to β- particles with maximum endpoint energy of 10.4 MeV from the n+19F reactions were studied. Response of a ⌀ 5'' × 3'' BC-408 plastic scintillator was also studied as a reference. The β- particles are the products of interaction of fast neutrons with 19F which is a component of the EJ-313 and BaF2 scintillators. The method of fast neutron detection via fluorine activation is already known as Threshold Activation Detection (TAD) and was proposed for photofission prompt neutron detection from fissionable and Special Nuclear Materials (SNM) in the field of Homeland Security and Border Monitoring. Measurements of the number of counts between 6.0 and 10.5 MeV with a 252Cf source showed that the relative neutron detection efficiency ratio, defined as epsilonBaF2 / epsilonEJ-313-5'', is 32.0% ± 2.3% and 44.6% ± 3.4% for front-on and side-on orientation of the BaF2, respectively. Moreover, the ⌀ 5'' EJ-313 and side-on oriented BaF2 were also exposed to neutrons from the D+T neutron generator, and the relative efficiency epsilonBaF2 / epsilonEJ-313-5'' was estimated to be 39.3%. Measurements of prompt photofission neutrons with the BaF2 detector by means of data acquisition after irradiation (out-of-beam) of nuclear material and between the beam pulses (beam-off) techniques were also conducted on the 9 MeV LINAC of the SAPHIR facility.

  1. Further Investigations of NIST Water Sphere Discrepancies

    SciTech Connect

    Broadhead, B.L.

    2001-01-11

    Measurements have been performed on a family of water spheres at the National Institute of Standards and Technology (NIST) facilities. These measurements are important for criticality safety studies in that, frequently, difficulties have arisen in predicting the reactivity of individually subcritical components assembled in a critical array. It has been postulated that errors in the neutron leakage from individual elements in the array could be responsible for these problems. In these NIST measurements, an accurate determination of the leakage from a fission spectrum, modified by water scattering, is available. Previously, results for 3-, 4-, and 5-in. diam. water-filled spheres, both with and without cadmium covers over the fission chambers, were presented for four fissionable materials: {sup 235}U, {sup 238}U, {sup 237}Np, and {sup 239}Pu. Results were also given for ''dry'' systems, in which the water spheres were drained of water, with the results corresponding to essentially measurements of unmoderated {sup 252}Cf spontaneous-fission neutrons. The calculated-to-experimental (C/E) values ranged from 0.94 to 1.01 for the dry systems and 0.93 to 1.05 for the wet systems, with experimental uncertainties ranging from 1.5 to 1.9%. These results indicated discrepancies that were clearly outside of the experimental uncertainties, and further investigation was suggested. This work updates the previous calculations with a comparison of the predicted C/E values with ENDF/B-V and ENDF/B-VI transport cross sections. Variations in the predicted C/E values that arise from the use of ENDF/B-V, ENDF/B-VI, ENDL92, and LLLDOS for the response fission cross sections are also tabulated. The use of both a 45-group NIST fission spectrum and a continuous-energy fission spectrum for {sup 252}Cf are evaluated. The use of the generalized-linear-least-squares (GLLSM) procedures to investigate the reported discrepancies in the water sphere results for {sup 235}U, {sup 238}U, {sup 239}Pu

  2. Neutron spectrum unfolding using artificial neural network and modified least square method

    NASA Astrophysics Data System (ADS)

    Hosseini, Seyed Abolfazl

    2016-09-01

    MLSQR and ANN methods for 252Cf and 241Am-9Be source are validated against the ISO spectrum. The unfolded neutron energy spectra from both MLSQR and ANN methods show a good agreement with the actual spectrum of 252Cf and 241Am-9Be source.

  3. Optimization and Characterization of a Novel Self Powered Solid State Neutron Detector

    NASA Astrophysics Data System (ADS)

    Clinton, Justin

    There is a strong interest in detecting both the diversion of special nuclear material (SNM) from legitimate, peaceful purposes and the transport of illicit SNM across domestic and international borders and ports. A simple solid-state detector employs a planar solar-cell type p-n junction and a thin conversion layer that converts incident neutrons into detectable charged particles, such as protons, alpha-particles, and heavier ions. Although simple planar devices can act as highly portable, low cost detectors, they have historically been limited to relatively low detection efficiencies; ˜10% and ˜0.2% for thermal and fast detectors, respectively. To increase intrinsic detection efficiency, the incorporation of 3D microstructures into p-i-n silicon devices was proposed. In this research, a combination of existing and new types of detector microstructures were investigated; Monte Carlo models, based on analytical calculations, were constructed and characterized using the GEANT4 simulation toolkit. The simulation output revealed that an array of etched hexagonal holes arranged in a honeycomb pattern and filled with either enriched (99% 10B) boron or parylene resulted in the highest intrinsic detection efficiencies of 48% and 0.88% for thermal and fast neutrons, respectively. The optimal parameters corresponding to each model were utilized as the basis for the fabrication of several prototype detectors. A calibrated 252Cf spontaneous fission source was utilized to generate fast neutrons, while thermal neutrons were created by placing the 252Cf in an HDPE housing designed and optimized using the MCNP simulation software. Upon construction, thermal neutron calibration was performed via activation analysis of gold foils and measurements from a 6Li loaded glass scintillator. Experimental testing of the prototype detectors resulted in maximum intrinsic efficiencies of 4.5 and 0.12% for the thermal and fast devices, respectively. The prototype thermal device was filled

  4. A new method to calculate the response of the WENDI-II rem counter using the FLUKA Monte Carlo Code

    NASA Astrophysics Data System (ADS)

    Jägerhofer, Lukas; Feldbaumer, Eduard; Theis, Christian; Roesler, Stefan; Vincke, Helmut

    2012-11-01

    The FHT-762 WENDI-II is a commercially available wide range neutron rem counter which uses a 3He counter tube inside a polyethylene moderator. To increase the response above 10 MeV of kinetic neutron energy, a layer of tungsten powder is implemented into the moderator shell. For the purpose of the characterization of the response, a detailed model of the detector was developed and implemented for FLUKA Monte Carlo simulations. In common practice Monte Carlo simulations are used to calculate the neutron fluence inside the active volume of the detector. The resulting fluence is then folded offline with the reaction rate of the 3He(n,p)3H reaction to yield the proton-triton production rate. Consequently this approach does not consider geometrical effects like wall effects, where one or both reaction products leave the active volume of the detector without triggering a count. This work introduces a two-step simulation method which can be used to determine the detector's response, including geometrical effects, directly, using Monte Carlo simulations. A "first step" simulation identifies the 3He(n,p)3H reaction inside the active volume of the 3He counter tube and records its position. In the "second step" simulation the tritons and protons are started in accordance with the kinematics of the 3He(n,p)3H reaction from the previously recorded positions and a correction factor for geometrical effects is determined. The three dimensional Monte Carlo model of the detector as well as the two-step simulation method were evaluated and tested in the well-defined fields of an 241Am-Be(α,n) source as well as in the field of a 252Cf source. Results were compared with measurements performed by Gutermuth et al. [1] at GSI with an 241Am-Be(α,n) source as well as with measurements performed by the manufacturer in the field of a 252Cf source. Both simulation results show very good agreement with the respective measurements. After validating the method, the response values in terms of

  5. Nuclear Data Sheets for A = 93

    SciTech Connect

    Baglin, Coral M.

    2011-05-15

    Nuclear structure data pertaining to all nuclei with mass number A=93 (Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag) have been compiled and evaluated and incorporated into the ENSDF data file. This publication for A=93 supersedes the previous publication by C.M. Baglin, Nuclear Data Sheets80, 1 (1997) (literature cutoff date November 1996) and subsequent revisions by C.M. Baglin of the ENSDF files for 93Br and {sup 93}Kr (literature cutoff 26 February 2001) and for {sup 93}Rh (literature cutoff 27 February 2001); it includes all data available prior to 15 December 2010. Significant changes since prior evaluations include the following: 2010Hw03 identified several high-spin states in {sup 93}Kr in {sup 252}Cf SF decay; in addition to the many low-spin levels already known in {sup 93}Rb from {beta}{sup -} decay, several higher-spin states have now been identified in a {sup 252}Cf SF decay study (2009Hw03); this SF decay has also been used to identify additional states in {sup 93}Sr (2003Hw01) and the {sup 238}U({sup 82}Se,X{gamma}) reaction (2007Bu35) has provided new information on {sup 93}Y. (HI,xn{gamma}) reaction studies have expanded our knowledge of the structure of {sup 93}Zr (2002Fo03, 2005Pa48), {sup 93}Nb (2007Wa45), {sup 93}Mo (2005Fu01), {sup 93}Tc (2003Ha22) and {sup 93}Pd (2004So04,2004Ru02). Considerable information on {sup 93}Nb was provided by a (p,2n{gamma}) study (2010Or01, 2006Or09, 2007Or01). The level schemes of {sup 93}Ru, {sup 93}Rh and {sup 93}Pd have undergone the most extensive revision thanks to studies of {sup 93}Rh {epsilon} decay (2004De40), {sup 94}Ag {epsilon}p decay (2004Mu30) and {sup 94}Ag p decay (2005Mu15, 2005Mu30), respectively. The half-life of the Zr member of this chain is of particular interest because of {sup 93}Zr's large contribution to long-term activity of nuclear reactor waste and also due to its potential as a supernova chronometer. During 2010, two new well-documented measurements of T{sub 1/2}({sup 93}Zr

  6. Significant disparity in base and sugar damage in DNA resulting from neutron and electron irradiation

    PubMed Central

    Pang, Dalong; Nico, Jeffrey S.; Karam, Lisa; Timofeeva, Olga; Blakely, William F.; Dritschilo, Anatoly; Dizdaroglu, Miral; Jaruga, Pawel

    2014-01-01

    In this study, a comparison of the effects of neutron and electron irradiation of aqueous DNA solutions was investigated to characterize potential neutron signatures in DNA damage induction. Ionizing radiation generates numerous lesions in DNA, including base and sugar lesions, lesions involving base–sugar combinations (e.g. 8,5′-cyclopurine-2′-deoxynucleosides) and DNA–protein cross-links, as well as single- and double-strand breaks and clustered damage. The characteristics of damage depend on the linear energy transfer (LET) of the incident radiation. Here we investigated DNA damage using aqueous DNA solutions in 10 mmol/l phosphate buffer from 0–80 Gy by low-LET electrons (10 Gy/min) and the specific high-LET (∼0.16 Gy/h) neutrons formed by spontaneous 252Cf decay fissions. 8-hydroxy-2′-deoxyguanosine (8-OH-dG), (5′R)-8,5′-cyclo-2′-deoxyadenosine (R-cdA) and (5′S)-8,5′-cyclo-2′-deoxyadenosine (S-cdA) were quantified using liquid chromatography–isotope-dilution tandem mass spectrometry to demonstrate a linear dose dependence for induction of 8-OH-dG by both types of radiation, although neutron irradiation was ∼50% less effective at a given dose compared with electron irradiation. Electron irradiation resulted in an exponential increase in S-cdA and R-cdA with dose, whereas neutron irradiation induced substantially less damage and the amount of damage increased only gradually with dose. Addition of 30 mmol/l 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS), a free radical scavenger, to the DNA solution before irradiation reduced lesion induction to background levels for both types of radiation. These results provide insight into the mechanisms of DNA damage by high-LET 252Cf decay neutrons and low-LET electrons, leading to enhanced understanding of the potential biological effects of these types of irradiation. PMID:25034731

  7. CARIBU: a new facility for the study of neutron-rich isotopes

    NASA Astrophysics Data System (ADS)

    Savard, G.; Pardo, R. C.; Baker, S.; Davids, C. N.; Levand, A.; Peterson, D.; Phillips, D. G.; Sun, T.; Vondrasek, R.; Zabransky, B. J.; Zinkann, G. P.

    2011-07-01

    The Californium Rare Ion Breeder Upgrade (CARIBU) to the ATLAS superconducting linac facility is currently being commissioned. It provides low-energy and re-accelerated beams of neutron-rich isotopes obtained from 252Cf fission. The fission products from a 252Cf source are stopped in a large high-intensity gas catcher, thermalized and extracted through an RFQ cooler, accelerated to 50 kV and mass separated in a high-resolution separator before being sent to either an ECR charge breeder for post-acceleration through the ATLAS linac or to a low-energy experimental area. This approach gives access to beams of very neutron-rich isotopes, many of which have not been available at low or Coulomb barrier energies previously. These beams provide unique opportunities for measurements along the r-process path. To take advantage of these unique possibility, the reaccelerated beams from CARIBU will be made available at the experimental stations of ATLAS to serve equipment such as Gammasphere, HELIOS and the reaction spectrometers. In addition, the Canadian Penning Trap (CPT) mass spectrometer has been moved to the CARIBU low-energy experimental area and a new injection line has been built. The new injection line consists of a RFQ buncher sitting on a 50 kV high-voltage platform that will accumulate the mass separated 50 kV radioactive beams, cool and extract them as a pulsed beam of 3 keV. This beam can be sent either to a tape station for diagnostics and tuning, or a cryogenic linear trap for preparation before transfer to the high-precision Penning trap where the mass measurements will take place. Initial CARIBU commissioning is proceeding with a 2 mCi source that will be replaced by a 100 mCi source as the commissioning proceeds. Final operation will use a 1 Ci source and attain yield in excess of 107 ions/sec for the most intense beams at low energy, an order of magnitude less for reaccelerated beams.

  8. Effect of pre-equilibrium emission on probing postsaddle nuclear dissipation with neutrons

    NASA Astrophysics Data System (ADS)

    Tian, Jian; Ye, Wei

    2016-09-01

    Using the stochastic Langevin model coupled with a statistical decay model, we study the influence of pre-equilibrium (PE) emission on probing postsaddle friction (β) with neutrons. A postsaddle friction value of (14 ‑ 16.5) × 1021 s‑1 and (11 ‑ 13) × 1021 s‑1 is obtained from comparing calculated and measured prescission neutron multiplicities of heavy fissioning systems 248Fm and 256Fm in the absence and presence of the deformation factor. Moreover, it is found that a larger β is required to fit multiplicity data after the PE effect is accounted for, and that the effect becomes stronger when more energy is removed by PE particles. Our findings suggest that, to more accurately determine the postsaddle friction strength through the measurement of prescission neutrons, in addition to incorporating the contribution of PE evaporation source into the experimental multi-source analysis for particle energy spectra in coincidence with fission fragments, on the theoretical side, it is very important to make a precise evaluation of the energy that PE emission carries away from excited compound systems produced in heavy-ion fusion reactions. Supported by National Nature Science Foundation of China (11575044)

  9. New fission valley for /sup 258/Fm and nuclei beyond

    SciTech Connect

    Moeller, P.; Nix, J.R.; Swiatecki, W.J.

    1986-01-01

    Experimental results on the fission properties of nuclei close to /sup 264/Fm show sudden and large changes with a change of only one or two neutrons or protons. The nucleus /sup 258/Fm, for instance, undergoes symmetric fission with a half-life of about 0.4 ms and a kinetic energy peaked at about 235 MeV whereas /sup 256/Fm undergoes asymmetric fission with a half-life of about 3 h and a kinetic energy peaked at about 200 MeV. Qualitatively, these sudden changes hve been postulated to be due to the emergence of fragment shells in symmetric fission products close to /sup 132/Sn. A quantitative calculation that shows where high-kinetic-energy symmetric fission occurs and why it is associated with a sudden and large decrease in fission half-lives. The study is based on calculations of potential-energy surfaces in the macroscopic-microscopic model and a semi-empirical model for the nuclear inertia. The implications of the new fission valley on the stability of the heaviest elements is discussed. 33 refs., 12 figs.

  10. Effect of pre-equilibrium emission on probing postsaddle nuclear dissipation with neutrons

    NASA Astrophysics Data System (ADS)

    Tian, Jian; Ye, Wei

    2016-09-01

    Using the stochastic Langevin model coupled with a statistical decay model, we study the influence of pre-equilibrium (PE) emission on probing postsaddle friction (β) with neutrons. A postsaddle friction value of (14 - 16.5) × 1021 s-1 and (11 - 13) × 1021 s-1 is obtained from comparing calculated and measured prescission neutron multiplicities of heavy fissioning systems 248Fm and 256Fm in the absence and presence of the deformation factor. Moreover, it is found that a larger β is required to fit multiplicity data after the PE effect is accounted for, and that the effect becomes stronger when more energy is removed by PE particles. Our findings suggest that, to more accurately determine the postsaddle friction strength through the measurement of prescission neutrons, in addition to incorporating the contribution of PE evaporation source into the experimental multi-source analysis for particle energy spectra in coincidence with fission fragments, on the theoretical side, it is very important to make a precise evaluation of the energy that PE emission carries away from excited compound systems produced in heavy-ion fusion reactions. Supported by National Nature Science Foundation of China (11575044)

  11. Dynamical interpretation of average fission-fragment kinetic energy systematics and nuclear scission

    SciTech Connect

    Nadtochy, P.N.; Adeev, G.D.

    2005-11-01

    A dynamical interpretation of the well-known systematics for average total kinetic energy of fission fragments over a wide range of the Coulomb parameter (600 on the Coulomb parameter. The results of dynamical calculations of within three-dimensional Langevin dynamics show that the mean distance between the centers of mass of nascent fragments at the scission configuration increases linearly with the parameter Z{sup 2}/A{sup 1/3}. This distance changes approximately from 2.35R{sub 0} for {sup 119}Xe to 2.6R{sub 0} for {sup 256}Fm. In spite of this increase in mean distance between future fragments at scission, the linear dependence of on the parameter Z{sup 2}/A{sup 1/3} remains approximately valid over a wide range of the Coulomb parameter Z{sup 2}/A{sup 1/3}.

  12. 12. 3-min /sup 256/Cf and 43-min /sup 258/Md and systematics of the spontaneous fission propertiesof heavy nuclides

    SciTech Connect

    Hoffman, D.C.; Wilhelmy, J.B.; Weber, J.; Daniels, W.R.; Hulet, E.K.; Lougheed, R.W.; Landrum, J.H.; Wild, J.F.; Dupzyk, R.J.

    1980-03-01

    The new isotope 12.3-min /sup 256/Cf was produced via the /sup 254/Cf(t,p) reaction, and a new 43-min isomer of /sup 258/Md was produced via the /sup 255/Es(..cap alpha..,n) reaction. The fragment mass and kinetic energy distributions from the spontaneous fission of /sup 256/Cf were found to be very similar to those from the spontaneous fission of lighter Cf isotopes. The mass division is primarily asymmetric, and the average total kinetic energy is 189.8 +- 0.9 MeV. The 43-min /sup 258/Md presumably decays by electron capture and provides an opportunity to study the mass and kinetic energy distributions from the spontaneous fission of the 380-..mu..s /sup 258/Fm daughter. The observed narrow, symmetric mass distribution and the most probable total kinetic energy of 238 +- 3 MeV are similar to those reported for the spontaneous fission of /sup 259/Fm but show a sharp increase in symmetric mass division and total kinetic energy compared to /sup 257/Fm and the lighter Fm isotopes. No such abrupt change in properties was observed for /sup 256/Cf, which, like /sup 258/Fm, has 158 neutrons. The marked difference between the spontaneous fission properties of the heavier Fm isotopes and those of other spontaneously fissioning nuclides is compared to some theoretical predictions.

  13. A Combined Neutron and Gamma-Ray Multiplicity Counter Based on Liquid Scintillation Detectors

    SciTech Connect

    Andreas Enqvist; Marek Flaska; Jennifer Dolan; David L. Chichester; Sara A. Pozzi

    2011-10-01

    Multiplicity counters for neutron assay have been extensively used in materials control and accountability for nonproliferation and nuclear safeguards. Typically, neutron coincidence counters are utilized in these fields. In this work, we present a measurement system that makes use not only of neutron (n) multiplicity counting but also of gamma-ray (g) multiplicity counting and the combined higher-order multiples containing both neutrons and gamma rays. The benefit of this approach is in using both particle types available from the sample, leading to a reduction in measurement times needed when using more measurables. We present measurement results of n, g, nn, ng, gg, nnn, nng, ngg, and ggg multiples emitted by Mixed-Oxide (MOX) samples measured at Idaho National Laboratory (INL). The MOX measurement is compared to initial validation of the detection system done using a 252Cf source. The dual radiation measuring system proposed here uses extra measurables to improve the statistics when compared to a neutron-only system and allows for extended analysis and interpretation of sample parameters. New challenges such as the effect of very high intrinsic gamma-ray sources in the case of MOX samples is discussed. Successful measurements of multiples rates can be performed also when using high-Z shielding.

  14. Experiments and Simulations of the Use of Time-Correlated Thermal Neutron Counting to Determine the Multiplication of an Assembly of Highly Enriched Uranium

    SciTech Connect

    David L. Chichester; Mathew T. Kinlaw; Scott M. Watson; Jeffrey M. Kalter; Eric C. Miller; William A. Noonan

    2014-11-01

    A series of experiments and numerical simulations using thermal-neutron time-correlated measurements has been performed to determine the neutron multiplication, M, of assemblies of highly enriched uranium available at Idaho National Laboratory. The experiments used up to 14.4 kg of highly-enriched uranium, including bare assemblies and assemblies reflected with high-density polyethylene, carbon steel, and tungsten. A small 252Cf source was used to initiate fission chains within the assembly. Both the experiments and the simulations used 6-channel and 8-channel detector systems, each consisting of 3He proportional counters moderated with polyethylene; data was recorded in list mode for analysis. 'True' multiplication values for each assembly were empirically derived using basic neutron production and loss values determined through simulation. A total of one-hundred and sixteen separate measurements were performed using fifty-seven unique measurement scenarios, the multiplication varied from 1.75 to 10.90. This paper presents the results of these comparisons and discusses differences among the various cases.

  15. Microstructure damage of thin aluminum films by irradiation with alpha particles and fission fragments

    SciTech Connect

    Sadi, S.; Paulenova, A.; Loveland, W.D.; Watson, P.R.

    2007-07-01

    The atomic force microscopy (AFM) has been used to study the microstructure damage of thin aluminum film surfaces induced by bombardment of alpha particles and fission fragments from {sup 252}Cf source. Different types of defects (dislocations lines, loops, voids, and blisters) and their complex morphologies appeared under both the beam of alpha particles and a mix of alpha particles and fission fragments. The first surface damage became clearly visible only after 250 hr irradiation of a mix of alpha particles and fission fragments (8.65 x 10{sup 8} ff/cm{sup 2} and 1.36 x 10{sup 10} {alpha}/cm{sup 2}). The number of voids and dislocation lines created on the aluminum surface were (3.8 {+-} 0.8) x 10{sup 7} cm{sup -2} and (2.1 {+-} 0.8) x 10{sup 6} cm{sup -2}, respectively. Single blisters were observed with the mean diameter of (933 {+-} 22) nm and the mean height of (102 {+-} 15) nm. The first ellipsoidal dislocation loops appeared at the fluence of (1.03 x 10{sup 9} ff/cm{sup 2} and 1.62 x 10{sup 10} {alpha}/cm{sup 2}). However, these ellipsoidal loops were not seen with low energetic alpha particles at the same fluence. Our results suggest that the fission fragments might maximize large voids and dislocations and increase the degradation in depth resolution. (authors)

  16. Properties of true quaternary fission of nuclei with allowance for its multistep and sequential character

    SciTech Connect

    Kadmensky, S. G. Titova, L. V.; Bulychev, A. O.

    2015-07-15

    An analysis of basicmechanisms of binary and ternary fission of nuclei led to the conclusion that true ternary and quaternary fission of nuclei has a sequential two-step (three-step) character, where, at the first step, a fissile nucleus emits a third light particle (third and fourth light particles) under shakeup effects associated with a nonadiabatic character of its collective deformation motion, whereupon the residual nucleus undergoes fission to two fission fragments. Owing to this, the formulas derived earlier for the widths with respect to sequential two- and three-step decays of nuclei in constructing the theory of two-step twoproton decays and multistep decays in chains of genetically related nuclei could be used to describe the relative yields and angular and energy distributions of third and fourth light particles emitted in (α, α), (t, t), and (α, t) pairs upon the true quaternary spontaneous fission of {sup 252}Cf and thermal-neutron-induced fission of {sup 235}U and {sup 233}U target nuclei. Mechanisms that explain a sharp decrease in the yield of particles appearing second in time and entering into the composition of light-particle pairs that originate from true quaternary fission of nuclei in relation to the yields of analogous particles in true ternary fission of nuclei are proposed.

  17. A Radiation Laboratory Curriculum Development at Western Kentucky University

    SciTech Connect

    Barzilov, Alexander P.; Novikov, Ivan S.; Womble, Phil C.

    2009-03-10

    We present the latest developments for the radiation laboratory curriculum at the Department of Physics and Astronomy of Western Kentucky University. During the last decade, the Applied Physics Institute (API) at WKU accumulated various equipment for radiation experimentation. This includes various neutron sources (computer controlled d-t and d-d neutron generators, and isotopic 252 Cf and PuBe sources), the set of gamma sources with various intensities, gamma detectors with various energy resolutions (NaI, BGO, GSO, LaBr and HPGe) and the 2.5-MeV Van de Graaff particle accelerator. XRF and XRD apparatuses are also available for students and members at the API. This equipment is currently used in numerous scientific and teaching activities. Members of the API also developed a set of laboratory activities for undergraduate students taking classes from the physics curriculum (Nuclear Physics, Atomic Physics, and Radiation Biophysics). Our goal is to develop a set of radiation laboratories, which will strengthen the curriculum of physics, chemistry, geology, biology, and environmental science at WKU. The teaching and research activities are integrated into real-world projects and hands-on activities to engage students. The proposed experiments and their relevance to the modern status of physical science are discussed.

  18. Characterization of a prototype neutron portal monitor detector

    NASA Astrophysics Data System (ADS)

    Nakhoul, Nabil

    The main objective of this thesis is to provide characterization measurements on a prototype neutron portal monitor (NPM) detector constructed at the University of Massachusetts Lowell. NPM detectors are deployed at all United States border crossings and shipping ports to stop the illicit transfer of weapons-grade plutonium (WGPu) into our country. This large prototype detector with its 0.93 square meter face area is based on thermal neutron capture in 6Li as an alternate technology to the current, very expensive, 3He-based NPM. A neutron detection efficiency of 27.5 % is measured with a 252Cf source which has a spontaneous fission neutron spectrum very similar to that of 240Pu in WGPu. Measurements with an intense 137Cs source establish the extreme insensitivity of the prototype NPM to gamma-ray backgrounds with only one additional count registered for 1.1 million incident gamma rays. This detector also has the ability to locate neutron sources to within an angle of a few degrees. Its sensitivity is further demonstrated by discovering in a few-second measurement the presence of a 2 curie PuBe neutron source even at a distance of 95.5 feet. This thesis also covers in considerable detail the design features that give rise to both a high intrinsic neutron detection efficiency and an extreme gamma-ray insensitivity.

  19. Initiation of a Nuclear Research Program at Fisk University in Cooperation with the Nuclear Physics Group at Vanderbilt University, August 15, 1997 - January 14, 2000

    SciTech Connect

    Collins, W.E.; Hamilton, J.H.

    2002-10-01

    Carrying a spirit of a long history of cooperation in physics education and research between Fisk University and Vanderbilt University, the Nuclear Research Program in the Department of Physics at Fisk University was proposed in 1996 in cooperation with the Nuclear Physics Group at Vanderbilt University. An initial NRP program was commissioned in 1997 with the financial support from DOE. The program offers a great opportunity for students and faculty at Fisk University to directly access experimental nuclear data and analyzing facilities within the Nuclear Physics Group at Vanderbilt University for a quick start. During the program Fisk Faculty and students (along with the colleagues at Vanderbilt University) have achieved progress in a few areas. We have (a) established an in-house nuclear data processing and analysis program at Fisk University, (b) conducted hands-on nuclear physics experiments for a Fisk undergraduate student at Vanderbilt University, (c) participated in the UNIRIB research with radioactive ion beam and Recoil Mass Spectrometer at Oak Ridge National Laboratory, and (d) studied {sup 252}Cf spontaneous fission and in-beam nuclear reactions for exotic nuclei. Additionally, this work has produced publication in conference proceedings as well as referred journals. [2-7].

  20. Effect of irradiation of wheat grains with fast neutrons on the grain yield and other characteristics of the plants.

    PubMed

    Hanafy, Magda S; Mohamed, Hanan A

    2014-04-01

    The effects of fast neutrons from a (252)Cf source in the fluence range 10(5)-10(8)n/cm(2) on the Egyptian wheat cultivar (Sakha 92) were studied. The experiment was conducted for three successive seasons (2008/2009, 2009/2010, and 2010/2011) to study the effect of the irradiation on the plant growth, grain yield, and physiological changes of three generations of plants produced by irradiated moisturized grains. A low fast-neutron fluence 2 × 10(6)n/cm(2) increased the yield throughout the three mutagenic generations considerably. It also increased concentrations of the total chlorophyll, sugars, and crude protein. These changes improve the quantity and quality of the grain. Also, a study of the effect of salinity of the irrigation water on the characteristics of the third-generation grains produced by neutron-irradiated grains was performed. With increasing concentration of sodium chloride in the irrigation water in the range 0.5-1.5%, concentrations of osmoprotectants, namely, reducing sugars and proline amino acids, increased. The concentration of Na(+) in the grains increased in parallel with the salinity of the irrigation water regardless of irradiation, while the concentrations of Ca(2+) and K(+) decreased. PMID:24509363

  1. Dose coefficients for intakes of radionuclides via contaminated wounds.

    PubMed

    Toohey, R E; Bertelli, L; Sugarman, S L; Wiley, A L; Christensen, D M

    2011-05-01

    The NCRP Wound Model, which describes the retention of selected radionuclides at the site of a contaminated wound and their uptake into the transfer compartment, has been combined with the ICRP element-specific systemic models for those radionuclides to derive dose coefficients for intakes via contaminated wounds. These coefficients can be used to generate derived regulatory guidance (i.e., the activity in a wound that would result in an effective dose of 20 or 50 mSv, or in some cases, a organ-equivalent dose of 500 mSv) and clinical decision guidance (i.e., activity levels that would indicate the need for consideration of medical intervention to remove activity from the wound site, administration of decorporation therapy or both). Data are provided for 38 radionuclides commonly encountered in various activities such as nuclear weapons, fuel fabrication or recycling, waste disposal, medicine, research, and nuclear power. These include 3H, 14C, 32P, 35S, 59Fe, 57,58,60Co, 85,89,90Sr, 99mTc, 106Ru, 125,129,131I, 134,137Cs, 192Ir, 201Tl, 210Po, 226,228Ra, 228,230,232Th, 234,235,238U, 237Np, 238,239,240,241Pu, 241Am, 242,244Cm, and 252Cf.

  2. Signature inversion in odd-odd {sup 114}Rh: First identification of high-spin states in very neutron-rich {sup 114}Rh and application of the triaxial projected shell model

    SciTech Connect

    Liu, S. H.; Chen, Y. S.; Gao, Z. C.; Zhu, S. J.; Gu, L.; Yeoh, E. Y.; Luo, Y. X.; Rasmussen, J. O.; Ma, W. C.; Batchelder, J. C.; Ter-Akopian, G. M.; Oganessian, Yu. Ts.; Gelberg, A.

    2011-06-15

    High-spin excited states in the very neutron-rich nucleus {sup 114}Rh have been studied by examining the prompt {gamma} rays emitted in the spontaneous fission of {sup 252}Cf with the Gammasphere detector array. A high-spin level scheme of {sup 114}Rh has been established for the first time with 13 new levels. The level scheme is proposed to be built on a 7{sup -} state. The existence of a relatively large signature splitting and an yrare band show features which may indicate triaxial deformation. The phenomenon of signature inversion has been observed in {sup 114}Rh at I=12 ({h_bar}/2{pi}). The observed signature inversion of {sup 114}Rh is interpreted successfully in terms of the triaxial projected shell model. Theoretical calculations suggest that the negative-parity, yrast band of {sup 114}Rh has the two-quasi-particle configuration of {pi}g{sub 9/2} x {nu}h{sub 11/2}, consistent with the systematics of odd-odd Rh isotopes. The signature inversion at spin 12 ({h_bar}/2{pi}) may be attributed to the change of rotational mode, from quasi-particle aligned rotation at low spins to collective rotation at high spins.

  3. Simultaneous measurement of (n,γ) and (n,fission) cross sections with the DANCE array

    NASA Astrophysics Data System (ADS)

    Bredeweg, T. A.; Jandel, M.; Fowler, M. M.; Bond, E. M.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Macri, R. A.; Wu, C. Y.; Becker, J. A.

    2006-10-01

    We have recently begun a program of high precision measurements of the key production and destruction reactions of important radiochemical diagnostic isotopes, including several isotopes of uranium, plutonium and americium. The Detector for Advanced Neutron Capture Experiments (DANCE), a 4π BaF2 array located at the Los Alamos Neutron Science Center, will be used to measure the neutron capture cross sections for most of the isotopes of interest. Since neutron capture measurements on many of the actinides are complicated by the presence of γ-rays arising from low-energy neutron-induced fission, we are currently using a dual parallel-plate avalanche counter with the target material electro-deposited directly on the center cathode foil. This design provides a high efficiency for detecting fission fragments and allows loading of pre-assembled target/detector assemblies into the neutron beam line at DANCE. An outline of the current experimental program will be presented as well as results from measurements on ^235U and ^252Cf that utilized the fission-tag detector.

  4. Neutron Capture and Fission Measurements on Actinides at Dance

    NASA Astrophysics Data System (ADS)

    Chyzh, A.; Wu, C. Y.; Kwan, E.; Henderson, R. A.; Gostic, J. M.; Ullmann, J. L.; Bredeweg, T. A.; Jandel, M.; Couture, A. J.; O'Donnell, J. M.; Haight, R. C.; Lee, H. Y.

    2013-03-01

    The prompt γ-ray energy and multiplicity distributions in the spontaneous fission of 252Cf have been measured using a highly granular 4π γ-ray calorimeter. Corrections were made for both energy and multiplicity distributions according to the detector response, which is simulated numerically using a model validated with the γ-ray calibration sources. A comparison of the total γray energy distribution was made between the measurement and a simulation by random sampling of the corrected γ-ray energy and multiplicity distributions through the detector response. A reasonable agreement is achieved between the measurement and simulation, indicating weak correlations between γ-ray energy and multiplicity. Moreover, the increasing agreement with increasing multiplicity manifests the stochastic aspect of the prompt γ decay in spontaneous fission. This calorimeter was designed for the study of neutron capture reactions and an example is given, where the238Pu(n, γ) measurement was carried out in the laboratory environment for the first time.

  5. Development of a thin scintillation films fission-fragment detector and a novel neutron source

    NASA Astrophysics Data System (ADS)

    Rusev, G.; Jandel, M.; Baramsai, B.; Bond, E. M.; Bredeweg, T. A.; Couture, A.; Daum, J. K.; Favalli, A.; Ianakiev, K. D.; Iliev, M. L.; Mosby, S.; Roman, A. R.; Springs, R. K.; Ullmann, J. L.; Walker, C. L.

    2015-08-01

    Investigation of prompt fission and neutron-capture Υ rays from fissile actinide samples at the Detector for Advanced Neutron Capture Experiments (DANCE) requires use of a fission-fragment detector to provide a trigger or a veto signal. A fission-fragment detector based on thin scintillating films and silicon photomultipliers has been built to serve as a trigger/veto detector in neutron-induced fission measurements at DANCE. The fissile material is surrounded by scintillating films providing a 4π detection of the fission fragments. The scintillations were registered with silicon photomultipliers. A measurement of the 235U(n,f) reaction with this detector at DANCE revealed a correct time-of-flight spectrum and provided an estimate for the efficiency of the prototype detector of 11.6(7)%. Design and test measurements with the detector are described. A neutron source with fast timing has been built to help with detector-response measurements. The source is based on the neutron emission from the spontaneous fission of 252Cf and the same type of scintillating films and silicon photomultipliers. Overall time resolution of the source is 0.3 ns. Design of the source and test measurements with it are described. An example application of the source for determining the neutron/gamma pulse-shape discrimination by a stilbene crystal is given.

  6. Development and characterization of a high sensitivity segmented Fast Neutron Spectrometer (FaNS-2)

    NASA Astrophysics Data System (ADS)

    Langford, T. J.; Beise, E. J.; Breuer, H.; Heimbach, C. R.; Ji, G.; Nico, J. S.

    2016-01-01

    We present the development of a segmented fast neutron spectrometer (FaNS-2) based upon plastic scintillator and 3He proportional counters. It was designed to measure both the flux and spectrum of fast neutrons in the energy range of few MeV to 1 GeV. FaNS-2 utilizes capture-gated spectroscopy to identify neutron events and reject backgrounds. Neutrons deposit energy in the plastic scintillator before capturing on a 3He nucleus in the proportional counters. Segmentation improves neutron energy reconstruction while the large volume of scintillator increases sensitivity to low neutron fluxes. A main goal of its design is to study comparatively low neutron fluxes, such as cosmogenic neutrons at the Earth's surface, in an underground environment, or from low-activity neutron sources. In this paper, we present details of its design and construction as well as its characterization with a calibrated 252Cf source and monoenergetic neutron fields of 2.5 MeV and 14 MeV. Detected monoenergetic neutron spectra are unfolded using a Singular Value Decomposition method, demonstrating a 5% energy resolution at 14 MeV. Finally, we discuss plans for measuring the surface and underground cosmogenic neutron spectra with FaNS-2.

  7. Spontaneous Partitioning of Californium from Curium: Curious Cases from the Crystallization of Curium Coordination Complexes

    SciTech Connect

    Cary, Samantha K.; Silver, Mark A.; Liu, Guokui; Wang, Jamie C.; Bogart, Justin A.; Stritzinger, Jared T.; Arico, Alexandra A.; Hanson, Kenneth; Schelter, Eric J.; Albrecht-Schmitt, Thomas E.

    2015-12-07

    The reaction of 248CmCl3 with excess 2,6-pyridinedicarboxylic acid (DPA) under mild solvothermal conditions results in crystallization of the tris-chelate complex Cm(HDPA)3·H2O. Approximately half of the curium remains in solution at the end of this process, and evaporation of the mother liquor results in crystallization of the bis-chelate complex [Cm(HDPA)- (H2DPA)(H2O)2Cl]Cl·2H2O. 248Cm is the daughter of the α decay of 252Cf and is extracted in high purity from this parent. However, trace amounts of 249,250,251Cf are still present in all samples of 248Cm. During the crystallization of Cm(HDPA)3·H2O and [Cm(HDPA)(H2DPA)(H2O)2Cl]Cl·2H2O, californium(III) spontaneously separates itself from the curium complexes and is found doped within crystals of DPA in the form of Cf(HDPA)3. These results add to the growing body of evidence that the chemistry of californium is fundamentally different from that of earlier actinides.

  8. In situ capture gamma-ray analysis of coal in an oversize borehole

    USGS Publications Warehouse

    Mikesell, J.L.; Dotson, D.W.; Senftle, F.E.; Zych, R.S.; Koger, J.; Goldman, L.

    1983-01-01

    In situ capture gamma-ray analysis in a coal seam using a high resolution gamma-ray spectrometer in a close-fitting borehole has been reported previously. In order to check the accuracy of the method under adverse conditions, similar measurements were made by means of a small-diameter sonde in an oversize borehole in the Pittsburgh seam, Greene County, Pennsylvania. The hole was 5 times the diameter of the sonde, a ratio that substantially increased the contribution of water (hydrogen) to the total spectral count and reduced the size of the sample measured by the detector. The total natural count, the 40K,count, and the intensities of capture gamma rays from Si, Ca, H, and Al were determined as a function of depth above, through, and below the coal seam. From these logs, the depth and width of the coal seam and its partings were determined. Spectra were accumulated in the seam for 1 h periods by using neutron sources of different strengths. From the spectra obtained by means of several 252Cf neutron sources of different sizes, the ultimate elemental analysis and ash content were determined. The results were not as good as those obtained previously in a close-fitting borehole. However, the results did improve with successively larger source-to-detector distances, i.e.,as the count contribution due to hydrogen in the water decreased. It was concluded that in situ borehole analyses should be made in relatively close-fitting boreholes. ?? 1983.

  9. First results from the new double velocity-double energy spectrometer VERDI

    NASA Astrophysics Data System (ADS)

    Frégeau, M. O.; Oberstedt, S.; Gamboni, Th.; Geerts, W.; Hambsch, F.-J.; Vidali, M.

    2016-05-01

    The VERDI spectrometer (VElocity foR Direct mass Identification) is a two arm time-of-flight spectrometer built at the European Commission Joint Research Centre IRMM. It determines fragment masses and kinetic energy distributions produced in nuclear fission by means of the double velocity and double energy (2v-2E) method. The simultaneous measurement of pre- and post neutron fragment characteristics allows studying the share of excitation energy between the two fragments. In particular, the evolution of fission modes and neutron multiplicity may be studied as a function of the available excitation energy. Both topics are of great importance for the development of models used in the evaluation of nuclear data, and also have important implications for the fundamental understanding of the fission process. The development of VERDI focus on maximum geometrical efficiency while striving for highest possible mass resolution. An innovative transmission start detector, using electrons ejected from the target itself, was developed. Stop signal and kinetic energy of both fragments are provided by two arrays of silicon detectors. The present design provides about 200 times higher geometrical efficiency than that of the famous COSI FAN TUTTE spectrometer [Nuclear Instruments and Methods in Physics Research 219 (1984) 569]. We report about a commissioning experiment of the VERDI spectrometer, present first results from a 2v-2E measurement of 252Cf spontaneous fission and discuss the potential of this instrument to contribute to the investigation prompt fission neutron characteristics as a function of fission fragment properties.

  10. Measurement of {sup 235}U content and flow of UF{sub 6} using delayed neutrons or gamma rays following induced fission

    SciTech Connect

    Stromswold, D.C.; Peurrung, A.J.; Reeder, P.L.; Perkins, R.W.

    1996-06-01

    Feasibility experiments conducted at Pacific Northwest National Laboratory demonstrate that either delayed neutrons or energetic gamma rays from short-lived fission products can be used to monitor the blending of UF{sub 6} gas streams. A {sup 252}Cf neutron source was used to induce {sup 235}U fission in a sample, and delayed neutrons and gamma rays were measured after the sample moved {open_quotes}down-stream.{close_quotes} The experiments used a UO{sub 2} powder that was transported down the pipe to simulate the flowing UF{sub 6} gas. Computer modeling and analytic calculation extended the test results to a flowing UF{sub 6} gas system. Neutron or gamma-ray measurements made at two downstream positions can be used to indicate both the {sup 235}U content and UF{sub 6} flow rate. Both the neutron and gamma-ray techniques have the benefits of simplicity and long-term reliability, combined with adequate sensitivity for low-intrusion monitoring of the blending process. Alternatively, measuring the neutron emission rate from (a, n) reactions in the UF{sub 6} provides an approximate measure of the {sup 235}U content without using a neutron source to induce fission.

  11. NSDann2BS, a neutron spectrum unfolding code based on neural networks technology and two bonner spheres

    NASA Astrophysics Data System (ADS)

    Ortiz-Rodríguez, J. M.; Reyes Alfaro, A.; Reyes Haro, A.; Solís Sánches, L. O.; Miranda, R. Castañeda; Cervantes Viramontes, J. M.; Vega-Carrillo, H. R.

    2013-07-01

    In this work a neutron spectrum unfolding code, based on artificial intelligence technology is presented. The code called "Neutron Spectrometry and Dosimetry with Artificial Neural Networks and two Bonner spheres", (NSDann2BS), was designed in a graphical user interface under the LabVIEW programming environment. The main features of this code are to use an embedded artificial neural network architecture optimized with the "Robust design of artificial neural networks methodology" and to use two Bonner spheres as the only piece of information. In order to build the code here presented, once the net topology was optimized and properly trained, knowledge stored at synaptic weights was extracted and using a graphical framework build on the LabVIEW programming environment, the NSDann2BS code was designed. This code is friendly, intuitive and easy to use for the end user. The code is freely available upon request to authors. To demonstrate the use of the neural net embedded in the NSDann2BS code, the rate counts of 252Cf, 241AmBe and 239PuBe neutron sources measured with a Bonner spheres system.

  12. A thermal neutron source imager using coded apertures

    SciTech Connect

    Vanier, P.E.; Forman, L.; Selcow, E.C.

    1995-08-01

    To facilitate the process of re-entry vehicle on-site inspections, it would be useful to have an imaging technique which would allow the counting of deployed multiple nuclear warheads without significant disassembly of a missile`s structure. Since neutrons cannot easily be shielded without massive amounts of materials, they offer a means of imaging the separate sources inside a sealed vehicle. Thermal neutrons carry no detailed spectral information, so their detection should not be as intrusive as gamma ray imaging. A prototype device for imaging at close range with thermal neutrons has been constructed using an array of {sup 3}He position-sensitive gas proportional counters combined with a uniformly redundant coded aperture array. A sealed {sup 252}Cf source surrounded by a polyethylene moderator is used as a test source. By means of slit and pinhole experiments, count rates of image-forming neutrons (those which cast a shadow of a Cd aperture on the detector) are compared with the count rates for background neutrons. The resulting ratio, which limits the available image contrast, is measured as a function of distance from the source. The envelope of performance of the instrument is defined by the contrast ratio, the angular resolution, and the total count rate as a function of distance from the source. These factors will determine whether such an instrument could be practical as a tool for treaty verification.

  13. CHICO2, a two-dimensional pixelated parallel-plate avalanche counter

    DOE PAGESBeta

    Wu, C. Y.; Cline, D.; Hayes, A.; Flight, R. S.; Melchionna, A. M.; Zhou, C.; Lee, I. Y.; Swan, D.; Fox, R.; Anderson, J. T.

    2016-01-27

    CHICO2 (Compact Heavy Ion COunter), is a large solid-angle, charged-particle detector array developed to provide both θ and Φ angle resolutions matching those of GRETINA (Gamma-Ray Energy Tracking In-beam Nuclear Array). CHICO2 was successfully tested at the Argonne National Laboratory where it was fielded as an auxiliary detector with GRETINA for γ-ray spectroscopic studies of nuclei using a 252Cf spontaneous fission source, stable beams, and radioactive beams from CARIBU. In field tests of the 72,76Ge beams on a 0.5 mg/cm2208Pb target at the sub-barrier energy, CHICO2 provided charged-particle angle resolutions (FWHM) of 1.55° in θ and 2.47° in Φ. Thismore » achieves the design goal for both coordinates assuming a beam-spot size (>3 mm) and the target thickness (>0.5 mg/cm 2). The combined angular resolution of GRETINA/CHICO2 resulted in a Doppler-shift corrected energy resolution of 0.60% for 1 MeV coincident de-excitation γ-rays. This is nearly a factor of two improvements in resolution and sensitivity compared to Gammasphere/CHICO. Kinematically-coincident detection of scattered ions by CHICO2 still maintains the mass resolution (ΔM/M) of ~5% that enhanced isolation of scattered weak beams of interest from scattered contaminant beams.« less

  14. Calibration Tools for Measurement of Highly Enriched Uranium in Oxide and Mixed Uranium-Plutonium Oxide with a Passive-Active Neutron Drum Shuffler

    SciTech Connect

    Mount, M; O'Connell, W; Cochran, C; Rinard, P

    2003-06-13

    Lawrence Livermore National Laboratory (LLNL) has completed an extensive effort to calibrate the LLNL passive-active neutron drum (PAN) shuffler (Canberra Model JCC-92) for accountability measurement of highly enriched uranium (HEU) oxide and HEU in mixed uranium-plutonium (U-Pu) oxide. Earlier papers described the PAN shuffler calibration over a range of item properties by standards measurements and an extensive series of detailed simulation calculations. With a single normalization factor, the simulations agree with the HEU oxide standards measurements to within {+-}1.2% at one standard deviation. Measurement errors on mixed U-Pu oxide samples are in the {+-}2% to {+-}10% range, or {+-}20 g for the smaller items. The purpose of this paper is to facilitate transfer of the LLNL procedure and calibration algorithms to external users who possess an identical, or equivalent, PAN shuffler. Steps include (1) measurement of HEU standards or working reference materials (WRMs); (2) MCNP simulation calculations for the standards or WRMs and a range of possible masses in the same containers; (3) a normalization of the calibration algorithms using the standard or WRM measurements to account for differences in the {sup 252}Cf source strength, the delayed-neutron nuclear data, effects of the irradiation protocol, and detector efficiency; and (4) a verification of the simulation series trends against like LLNL results. Tools include EXCEL/Visual Basic programs which pre- and post-process the simulations, control the normalization, and embody the calibration algorithms.

  15. DIVERSE ACTIVE WELL NEUTRON COINCIDENCE COUNTER UTILITY AT THE SAVANNAH RIVER NATIONAL LABORATORY

    SciTech Connect

    Dewberry, R; Saleem Salaymeh, S

    2007-01-08

    In this paper we describe use of the Aquila active well neutron coincidence counter for nuclear material assays of {sup 235}U in multiple analytical techniques at Savannah River Site (SRS), at the Savannah River National Laboratory (SRNL), and at Argonne West National Laboratory (AWNL). The uses include as a portable passive neutron counter for field measurements searching for evidence of {sup 252}Cf deposits and storage; as a portable active neutron counter using an external activation source for field measurements searching for trace {sup 235}U deposits and holdup; for verification measurements of U-Al reactor fuel elements; for verification measurements of uranium metal; and for verification measurements of process waste of impure uranium in a challenging cement matrix. The wide variety of uses described demonstrate utility of the technique for neutron coincidence verification measurements over the dynamic ranges of 100 g-5000 g for U metal, 200 g-1300 g for U-Al, and 8 g-35 g for process waste. In addition to demonstrating use of the instrument in both the passive and active modes, we also demonstrate its use in both the fast and thermal neutron modes.

  16. Research in radiobiology: Annual report of work in progress in the internal irradiation program

    SciTech Connect

    Miller, S.C.; Buster, D.S.

    1987-12-31

    In the early 1950's the Atomic Energy Commission established at the University of Utah a large, long-term study designed to investigate the toxicity of internally deposited radionuclides in beagles. The first animals were injected on December 1, 1952 and thus began an odyssey unusual in modern science both for its duration and continued scientific interest and relevance. The original dogs were injected with /sup 239/Pu and /sup 226/Ra. Later, studies were initiated with /sup 241/Am, /sup 249/Cf, /sup 252/Cf, /sup 253/Es, /sup 224/Ra, /sup 228/Ra, /sup 90/Sr, and /sup 228/Th. These studies were unique and have and will continue to contribute valuable scientific information on the behavior and effects of these substances in biological systems. We feel that the data collected from these studies will be useful for many decades to come as we ask more demanding questions relative to radionuclides and environmental, biological and health issues. While this publication will be the last of our series Research in Radiobiology, the lifespan carcinogenesis studies are continuing under a collaborative arrangement with the I.T.R.I. Beginning in 1988, the colony status tables of dogs in the Utah studies and reports of research by the Radiobiology faculty will be included in the annual I.T.R.I. report. Under our new collaborative arrangements with the I.T.R.I. for the conduct of the lifespan carcinogenesis studies, we expect a continued high level of scientific productivity from our faculty.

  17. Relative effectiveness of {sup 239}Pu and some other internal emitters for bone cancer induction in beagles

    SciTech Connect

    Lloyd, R.D.; Miller, S.C.; Taylor, G.N.; Bruenger, F.W.; Jee, W.S.S.; Angus, W.

    1994-10-01

    The toxicity ratio (relative effectiveness per gray of average skeletal dose) has been estimated for bone cancer induction in beagles injected as young adults with a number of bone-seeking internal emitters. These experiments yielded calculated toxicity ratios ({+-} SD) relative to {sup 226}Ra = 1.0 of {sup 239}Pu = 16 {+-} 5 (single exposure to monomeric Pu) and 32 {+-} 10 (continuous exposure from an extraskeletal deposit in the body), {sup 224}Ra = 16 {+-} 5 (chronic exposure) and approximately 6 {+-} 2 (single exposure), {sup 228}Th = 8.5 {+-} 2.3, {sup 241}Am = 6 {+-} 0.8, {sup 228}Ra = 2.0 {+-} 0.5, {sup 249}Cf = 6 {+-} 3, {sup 252}Cf = 4 {+-}2, {sup 90}Sr = 1.0 {+-} 0.5 (for high doses) and 0.05 {+-} 0.03 (for low doses) and 0.01 {+-} 0.01 (for extremely low doses). Because no skeletal malignancies were observed among beagles given only {sup 253}Es, the toxicity ratio is undefined. 43 refs., 2 tabs.

  18. Accumulation of /sup 254g/Es in the neutron irradiation of californium

    SciTech Connect

    Adaev, V.A.; Klinov, A.V.; Mamelin, A.V.; Toporov, Yu.G.

    1987-06-01

    Preliminary calculations have shown that the ratio of the rates of formation and burnup of /sup 254g/Es can be shifted toward the rate of formation, provided that the californium-containing targets are irradiated with neutrons having a very hard spectrum, (the hardness of the neutron spectrum is defined as the ratio of the flux density of ipithermal neutrons per unit mean logarithmic energy decrement to the flux density of the thermal neutrons). For the purpose of experimentally verifying this conclusion, we irradiated two test samples provided with metal cadmium shields and containing a mixture of californium isotopes as the initial material (approx. 70% of the total was /sup 252/Cf nuclei). After target irradiation, the targets were subjected to a radiochemical treatment and the concentration of the products accumulated was analyzed. It follows from a comparison of experimental and calculated data that the published data on the neutron cross section of the einsteinium isotopes render excessive /sup 254g/Es yields and too small /sup 253/Es yields. Therefore a series of calculations was made for the various values of the resonance integral of the /sup 253/Es absorption and of the partial resonances of the radiative capture integrals of /sup 253/Es in the reaction leading to the formation of /sup 254g/Es and /sup 254m/Es. The calculations have shown that the /sup 253/Es yield in the targets can be satisfactorily predicted with a resonance integral I/sub a/ = 3500 b of absorption

  19. Comparison of shuffler and differential die-away technique instruments for the assay of fissile materials in 55-gallon waste drums

    SciTech Connect

    Rinard, P.M.; Coop, K.L.; Nicholas, N.J.; Menlove, H.O. )

    1994-07-01

    The authors compare the features of a [sup 252]Cf shuffler and a differential die-away technique (DDT) instrument for the assay of 208-L (55-gal.) waste drums and the experimental results obtained using drums with 20 different simulated waste matrices. Active assays of uranium and plutonium were made, along with passive assays of plutonium. The major potential sources of inaccuracy for most wastes are self-shielding and nonuniform distribution of the fissile material throughout a drum's volume. They examined the distribution problem by placing small samples of plutonium and uranium at 15 representative locations within each test matrix. The combined responses from all these locations simulated the case of a uniform distribution. Inaccuracies can grow as the density of moderator or absorber in a matrix is increased, so a wide range of absorber and moderator densities was used in the test drums. Self-shielding and effects due to high-neutron backgrounds were also examined. The instruments' minimum detectable masses for uniform distributions of uranium and plutonium were calculated for the various matrices.

  20. USE OF PORTABLE GAMMA SPECTROMETERS FOR IDENTIFYING PERSONS EXPOSED IN A NUCLEAR CRITICALITY

    SciTech Connect

    Veinot, K. G.; Gose, B. T.; Bogard, James S

    2009-01-01

    At Y-12 triage-style assessments are used to identify persons potentially exposed to high doses from criticality accident radiations using portable instruments by assessing the presence of activated sodium atoms in a person's blood. Historically, simple hand-held Geiger-Mueller (G-M) probes were used for these purposes although it was recognized that, since these instruments contain no information on incident photon energy, it was impossible to differentiate between photons emitted by contamination on the potentially exposed worker from activation of sodium in the person s blood. This works examines the use of a portable gamma spectrometer for assessing blood sodium activation. Irradiations of a representative phantom were performed using two neutron source configurations (unmoderated and polyethylene-moderated 252Cf) and measurements were made using the spectrometer and a G-M detector following irradiation. Detection limits in terms of personnel neutron dose are given for two neutron fields representing metaland solution criticality spectra. Both Geiger-Mueller and spectrometer results indicate a low minimum detectable neutron dose indicating that both instrument are useful as an emergency response instrument. The spectrometer has the added benefit of discriminating between surface contamination and blood sodium activation.

  1. Oak Ridge Isotope Products and Services - Current and Expected Supply and Demand

    SciTech Connect

    Aaron, W.S.; Alexander, C.W.; Cline, R.L.; Collins, E.D.; Klein, J.A.; Knauer, J.B., Jr.; Mirzadeh, S.

    1999-08-29

    Oak Ridge National Laboratory (ORNL) has been a major center of isotope production research, development, and distribution for over 50 years. Currently, the major isotope production activities include (1) the production of transuranium element radioisotopes, including 252 Cf; (2) the production of medical and industrial radioisotopes; (3) maintenance and expansion of the capabilities for production of enriched stable isotopes; and, (4) preparation of a wide range of custom-order chemical and physical forms of isotope products, particularly in accelerator physics research. The recent supply of and demand for isotope products and services in these areas, research and development (R&D), and the capabilities for future supply are described in more detail below. The keys to continuing the supply of these important products and services are the maintenance, improvement, and potential expansion of specialized facilities, including (1) the High Flux Isotope Reactor (HFIR), (2) the Radiochemical Engineering Development Center (REDC) and Radiochemical Development Laboratory (RDL) hot cell facilities, (3) the electromagnetic calutron mass separators and the plasma separation process equipment for isotope enrichment, and (4) the Isotope Research Materials Laboratory (IRML) equipment for preparation of specialized chemical and physical forms of isotope products. The status and plans for these ORNL isotope production facilities are also described below.

  2. Recent advances in β-decay spectroscopy at CARIBU

    NASA Astrophysics Data System (ADS)

    Mitchell, A. J.; Copp, P.; Savard, G.; Lister, C. J.; Lane, G. J.; Carpenter, M. P.; Clark, J. A.; Zhu, S.; Ayangeakaa, A. D.; Bottoni, S.; Brown, T. B.; Chowdhury, P.; Chillery, T. W.; David, H. M.; Hartley, D. J.; Heckmaier, E.; Janssens, R. V. F.; Kolos, K.; Kondev, F. G.; Lauritsen, T.; McCutchan, E. A.; Norman, E. B.; Padgett, S.; Scielzo, N. D.; Seweryniak, D.; Smith, M. L.; Wilson, G. L.

    2016-09-01

    β-decay spectroscopy of nuclei far from stability can provide powerful insight into a broad variety of topics in nuclear science, ranging from exotic nuclear structure phenomena, stellar nucleosynthesis processes, and applied topics such as quantifying "decay heat" discrepancies for advanced nuclear fuel cycles. Neutronrich nuclei approaching the drip-line are difficult to access experimentally, leaving many key examples largely under studied. The CARIBU radioactive beam facility at Argonne National Laboratory exploits spontaneous fission of 252Cf in production of such beams. The X-Array and SATURN decay station have been commissioned to perform detailed decay spectroscopy of low-energy CARIBU beams. An extended science campaign was started during 2015; with projects investigating nuclear shape changes, collective octupole vibrations, β-delayed neutron emission, and decay-scheme properties which could explain the reactor antineutrino puzzle. In this article we review the current status of the setup, update on the first results and recent hardware upgrades, and look forward to future possibilities.

  3. A neutron multiplicity analysis method for uranium samples with liquid scintillators

    NASA Astrophysics Data System (ADS)

    Zhou, Hao; Lin, Hongtao; Liu, Guorong; Li, Jinghuai; Liang, Qinglei; Zhao, Yonggang

    2015-10-01

    A new neutron multiplicity analysis method for uranium samples with liquid scintillators is introduced. An active well-type fast neutron multiplicity counter has been built, which consists of four BC501A liquid scintillators, a n/γdiscrimination module MPD-4, a multi-stop time to digital convertor MCS6A, and two Am-Li sources. A mathematical model is built to symbolize the detection processes of fission neutrons. Based on this model, equations in the form of R=F*P*Q*T could be achieved, where F indicates the induced fission rate by interrogation sources, P indicates the transfer matrix determined by multiplication process, Q indicates the transfer matrix determined by detection efficiency, T indicates the transfer matrix determined by signal recording process and crosstalk in the counter. Unknown parameters about the item are determined by the solutions of the equations. A 252Cf source and some low enriched uranium items have been measured. The feasibility of the method is proven by its application to the data analysis of the experiments.

  4. A capture-gated neutron calorimeter using plastic scintillators and 3He drift tubes

    SciTech Connect

    Wang, Zhehui; Morris, Christopher L; Spaulding, Randy J; Bacon, Jeffrey D; Borozdin, Konstantin N; Chung, Kiwhan; Clark, Deborah J; Green, Jesse A; Greene, Steven J; Hogan, Gary E; Jason, Andrew; Lisowski, Paul W; Makela, Mark F; Mariam, Fessaha G; Miyadera, Haruo; Murray, Matthew M; Saunders, Alexander; Wysocki, Frederick J; Gray, Frederick E

    2010-01-01

    A segmented neutron calorimeter using nine 4-inch x 4-inch x 48-inch plastic scintillators and sixteen 2-inch-diameter 48-inch-long 200-mbar-{sup 3}He drift tubes is described. The correlated scintillator and neutron-capture events provide a means for n/{gamma} discrimination, critical to the neutron calorimetry when the {gamma} background is substantial and the {gamma} signals are comparable in amplitude to the neutron signals. A single-cell prototype was constructed and tested. It can distinguish between a {sup 17}N source and a {sup 252}Cf source when the {gamma} and the thermal neutron background are sufficiently small. The design and construction of the nine-cell segmented detector assembly follow the same principle. By recording the signals from individual scintillators, additional {gamma}-subtraction schemes, such as through the time-of-flight between two scintillators, may also be used. The variations of the light outputs from different parts of a scintillator bar are less than 10%.

  5. The Effects of Flux Spectrum Perturbation on Transmutation of Actinides: Optimizing the Production of Transcurium Isotopes

    SciTech Connect

    Hogle, Susan L; Maldonado, G Ivan; Alexander, Charles W

    2012-01-01

    This research presented herein involves the optimization of transcurium production in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Due to the dependence of isotope cross sections on incoming neutron energy, the efficiency with which an isotope is transmuted is highly dependent upon the flux spectrum. There are certain energy bands in which the rate of fission of transcurium production feedstock materials is minimized, relative to the rate of non-fission absorptions. It is proposed that by perturbing the flux spectrum, it is possible to increase the amount of key isotopes, such as 249Bk and 252Cf, that are produced during a transmutation cycle, relative to the consumption of feedstock material. This optimization process is carried out by developing an iterative objective framework involving problem definition, flux spectrum and cross section analysis, simulated transmutation, and analysis of final yields and transmutation parameters. It is shown that it is possible to perturb the local flux spectrum in the transcurium target by perturbing the composition of the target. It is further shown that these perturbations are able to alter the target yields in a non-negligible way. Future work is necessary to develop the optimization framework, and identify the necessary algorithms to update the problem definition based upon progress towards the optimization goals.

  6. NSDann2BS, a neutron spectrum unfolding code based on neural networks technology and two bonner spheres

    SciTech Connect

    Ortiz-Rodriguez, J. M.; Reyes Alfaro, A.; Reyes Haro, A.; Solis Sanches, L. O.; Miranda, R. Castaneda; Cervantes Viramontes, J. M.; Vega-Carrillo, H. R.

    2013-07-03

    In this work a neutron spectrum unfolding code, based on artificial intelligence technology is presented. The code called ''Neutron Spectrometry and Dosimetry with Artificial Neural Networks and two Bonner spheres'', (NSDann2BS), was designed in a graphical user interface under the LabVIEW programming environment. The main features of this code are to use an embedded artificial neural network architecture optimized with the ''Robust design of artificial neural networks methodology'' and to use two Bonner spheres as the only piece of information. In order to build the code here presented, once the net topology was optimized and properly trained, knowledge stored at synaptic weights was extracted and using a graphical framework build on the LabVIEW programming environment, the NSDann2BS code was designed. This code is friendly, intuitive and easy to use for the end user. The code is freely available upon request to authors. To demonstrate the use of the neural net embedded in the NSDann2BS code, the rate counts of {sup 252}Cf, {sup 241}AmBe and {sup 239}PuBe neutron sources measured with a Bonner spheres system.

  7. New Results on Helium and Tritium Gas Production From Ternary Fission

    NASA Astrophysics Data System (ADS)

    Serot, O.; Wagemans, C.; Heyse, J.

    2005-05-01

    Ternary fission constitutes an important source of helium and tritium gas production in nuclear reactors and in used fuel elements. Data related to this production are therefore requested by nuclear industry. In the present paper, we report results from measurements of the 4He and 3H emission probabilities (denoted LRA/B and t/B, respectively). These measurements concern both thermal neutron-induced fission reactions as well as spontaneous fission decays. For spontaneous fission, data are reported for nuclides ranging from 238Pu up to 252Cf. For thermal neutron-induced fission, results cover target nuclei between 229Th and 251Cf. Based on these and other results, semi-empirical relations are proposed. These correlations are only valid if spontaneous fission data and neutron-induced fission data are considered separately, which shows the impact of the fissioning nucleus-excitation energy on the ternary particle-emission process. In this way, t/B and LRA/B values could be evaluated for fissioning systems not investigated so far. These results could be used for the ternary fission-yield evaluation of the JEFF3.1 library.

  8. Apparatus and method for quantitative assay of generic transuranic wastes from nuclear reactors

    DOEpatents

    Caldwell, J.T.; Kunz, W.E.; Atencio, J.D.

    1982-03-31

    A combination of passive and active neutron measurements which yields quantitative information about the isotopic composition of transuranic wastes from nuclear power or weapons material manufacture reactors is described. From the measurement of prompt and delayed neutron emission and the incidence of two coincidentally emitted neutrons from induced fission of fissile material in the sample, one can quantify /sup 233/U, /sup 235/U and /sup 239/Pu isotopes in waste samples. Passive coincidence counting, including neutron multiplicity measurement and determination of the overall passive neutron flux additionally enables the separate quantitative evaluation of spontaneous fission isotopes such as /sup 240/Pu, /sup 244/Cm and /sup 252/Cf, and the spontaneous alpha particle emitter /sup 241/Am. These seven isotopes are the most important constituents of wastes from nuclear power reactors and once the mass of each isotope present is determined by the apparatus and method of the instant invention, the overall alpha particle activity can be determined to better than 1 nCi/g from known radioactivity data. Therefore, in addition to the quantitative analysis of the waste sample useful for later reclamation purposes, the alpha particle activity can be determined to decide whether permanent low-level burial is appropriate for the waste sample.

  9. Apparatus and method for quantitative assay of generic transuranic wastes from nuclear reactors

    DOEpatents

    Caldwell, John T.; Kunz, Walter E.; Atencio, James D.

    1984-01-01

    A combination of passive and active neutron measurements which yields quantitative information about the isotopic composition of transuranic wastes from nuclear power or weapons material manufacture reactors is described. From the measurement of prompt and delayed neutron emission and the incidence of two coincidentally emitted neutrons from induced fission of fissile material in the sample, one can quantify .sup.233 U, .sup.235 U and .sup.239 Pu isotopes in waste samples. Passive coincidence counting, including neutron multiplicity measurement and determination of the overall passive neutron flux additionally enables the separate quantitative evaluation of spontaneous fission isotopes such as .sup.240 Pu, .sup.244 Cm and .sup.252 Cf, and the spontaneous alpha particle emitter .sup.241 Am. These seven isotopes are the most important constituents of wastes from nuclear power reactors and once the mass of each isotope present is determined by the apparatus and method of the instant invention, the overall alpha particle activity can be determined to better than 1 nCi/g from known radioactivity data. Therefore, in addition to the quantitative analysis of the waste sample useful for later reclamation purposes, the alpha particle activity can be determined to decide whether "permanent" low-level burial is appropriate for the waste sample.

  10. Effect of irradiation of wheat grains with fast neutrons on the grain yield and other characteristics of the plants.

    PubMed

    Hanafy, Magda S; Mohamed, Hanan A

    2014-04-01

    The effects of fast neutrons from a (252)Cf source in the fluence range 10(5)-10(8)n/cm(2) on the Egyptian wheat cultivar (Sakha 92) were studied. The experiment was conducted for three successive seasons (2008/2009, 2009/2010, and 2010/2011) to study the effect of the irradiation on the plant growth, grain yield, and physiological changes of three generations of plants produced by irradiated moisturized grains. A low fast-neutron fluence 2 × 10(6)n/cm(2) increased the yield throughout the three mutagenic generations considerably. It also increased concentrations of the total chlorophyll, sugars, and crude protein. These changes improve the quantity and quality of the grain. Also, a study of the effect of salinity of the irrigation water on the characteristics of the third-generation grains produced by neutron-irradiated grains was performed. With increasing concentration of sodium chloride in the irrigation water in the range 0.5-1.5%, concentrations of osmoprotectants, namely, reducing sugars and proline amino acids, increased. The concentration of Na(+) in the grains increased in parallel with the salinity of the irrigation water regardless of irradiation, while the concentrations of Ca(2+) and K(+) decreased.

  11. Biological effectiveness of neutron irradiation on animals and man

    SciTech Connect

    Straume, T.

    1982-11-01

    Neutron experiments on a highly radiosensitive in vivo system - oocytes in mice - provide new insight into the nature of the radiosensitive targets of these important cells. With the radiobiological literature as background, neutron data from animals and humans are integrated, and the controversial question of radiation protection standards for neutrons is addressed. Oocyte killing in juvenile mice by 0.43-MeV, /sup 252/Cf-fission, and 15 MeV neutrons, compared with that by /sup 60/Co gamma rays, yields unusually low neutron RBEs (relative biological effectiveness). At 0.1 rad of 0.43-MeV neutrons the RBE is only 1.8, contrasting greatly with values of 100 or more reported at low-doses for other endpoints. In mice just prior to birth, however, when oocytes are less radiosensitive, the neutron RBE is much higher, similar to values for most other mammalian endpoints. This dramatic change in neutron RBE with mouse age (occurring within 2 to 3 days) can be explained as the result of a shift from a less radiosensitive target (presumably nuclear DNA) to a much more radiosensitive one (probably the oocyte plasma membrane). Using various approaches, a value for the neutron Quality Factor (Q, a radiation protection standard) is estimated as 17 (+-100%), much lower than 100 which has been suggested. With the large uncertainty, 17 is not markedly different from the value of 10 presently in general use.

  12. Organic scintillator detector response simulations with DRiFT

    NASA Astrophysics Data System (ADS)

    Andrews, M. T.; Bates, C. R.; McKigney, E. A.; Solomon, C. J.; Sood, A.

    2016-09-01

    This work presents the organic scintillation simulation capabilities of DRiFT, a post-processing Detector Response Function Toolkit for MCNP® output. DRiFT is used to create realistic scintillation detector response functions to incident neutron and gamma mixed-field radiation. As a post-processing tool, DRiFT leverages the extensively validated radiation transport capabilities of MCNP® 6 , which also provides the ability to simulate complex sources and geometries. DRiFT is designed to be flexible, it allows the user to specify scintillator material, PMT type, applied PMT voltage, and quenching data used in simulations. The toolkit's capabilities, which include the generation of pulse shape discrimination plots and full-energy detector spectra, are demonstrated in a comparison of measured and simulated neutron contributions from 252Cf and PuBe, and photon spectra from 22Na and 228Th sources. DRiFT reproduced energy resolution effects observed in EJ-301 measurements through the inclusion of scintillation yield variances, photon transport noise, and PMT photocathode and multiplication noise.

  13. Operational experience with the Argonne National Laboratory Californium Rare Ion Breeder Upgrade facility and electron cyclotron resonance charge breeder

    NASA Astrophysics Data System (ADS)

    Vondrasek, R.; Clark, J.; Levand, A.; Palchan, T.; Pardo, R.; Savard, G.; Scott, R.

    2014-02-01

    The Californium Rare Ion Breeder Upgrade (CARIBU) of the Argonne National Laboratory Argonne Tandem Linac Accelerator System (ATLAS) facility provides low-energy and accelerated neutron-rich radioactive beams to address key nuclear physics and astrophysics questions. A 350 mCi 252Cf source produces fission fragments which are thermalized and collected by a helium gas catcher into a low-energy particle beam with a charge of 1+ or 2+. An electron cyclotron resonance (ECR) ion source functions as a charge breeder in order to raise the ion charge sufficiently for acceleration in the ATLAS linac. The ECR charge breeder has achieved stable beam charge breeding efficiencies of 10.1% for 23Na7+, 17.9% for 39K10+, 15.6% for 84Kr17+, and 12.4% for 133Cs27+. For the radioactive beams, a charge breeding efficiency of 11.7% has been achieved for 143Cs27+ and 14.7% for 143Ba27+. The typical breeding times are 10 ms/charge state, but the source can be tuned such that this value increases to 100 ms/charge state with the best breeding efficiency corresponding to the longest breeding times—the variation of efficiencies with breeding time will be discussed. Efforts have been made to characterize and reduce the background contaminants present in the ion beam through judicious choice of q/m combinations. Methods of background reduction are being investigated based upon plasma chamber cleaning and vacuum practices.

  14. Reactor technology. Progress report, July-September 1980

    SciTech Connect

    Breslow, M.

    1980-12-01

    Progress in the Space Power Advanced Reactor (SPAR) Program includes indications that revision of the BeO reflector configuration can reduce system weight. Observed boiling limit restrictions on the performance of the annular-wick core heat pipe have accelerated transition to the development of the target-design arterial heat pipe. Successful bends of core heat pipes have been made with sodium as the mandrel material. With the phasing out of the GCFR Program, work on the Low Power Safety Experiments Program is now concentrated on completion of the third 37-rod Full Length Subgroup test. In the Reactor Safety/Structural Analysis area, effort on the Category I Structures Program is toward developing an experimental test plan focusing on a specific structural design. Buckling experiments on thin-walled cylindrical shells with circular cutouts are reported. Results of a three-dimensional analysis of thermal stresses in the Fort St. Vrain core support block are presented. Materials investigations and operation of a molybdenum-core SiC heat pipe are reported. Entrainment limits for gravity-assisted heat pipes and heat pipe configurations for application to energy conservation are being investigated. The new solution critical assembly, SHEBA, was completed. Godiva IV was temporarily relocated at TA-15. Influence of scattered radiations in the test vault on InRad measurements was determined from detector scans of the vault produced by /sup 252/Cf neutron and /sup 137/Cs gamma sources.

  15. Applied nuclear data research and development. Progress report, January 1-March 31, 1981

    SciTech Connect

    Baxman, C.I.; Young, P.G.

    1981-07-01

    Activities of the Los Alamos Nuclear Data Group for January 1 through March 31, 1981, are described. Topics include: (1) peripheral effects in R-matrix theory; (2) Coulomb corrections in light nuclei; (3) new R-matrix analysis of reactions in the /sup 7/Li system; (4) variance-covariance analysis of n + Li reactions; (5) calculated charged-particle emission in the mass-90 region; (6) determination of deformed optical model parameters for neutron reactions on /sup 235/U and /sup 239/Pu; (7) calculation of excited state cross sections for actinide nuclei; (8) calculation of the prompt neutron spectrum and ..nu../sub p/ for the spontaneous fission of /sup 252/Cf; (9) international nuclear model codes comparison study; (10) an improved calculation of heating and radiation damage from neutron capture; (11) LMFBR cross-section production with MAX; (12) TRANSX development; (13) THOR calculations; (14) covariance processing; (15) analysis of charges for use of central computing facility; (16) S/sub n/ calculations for D/sub 2/O sphere; (17) integral data testing of ENDF/B fission-product data; (18) decay power comparisons using ENDF/B-IV and -V data in CINDER-10; (19) ENDF/B-V data testing and summary data; (20) SPEC5: code to produce multigroup spectra; and (21) calculation of H. B. Robinson-2 fuel isotopics and comparison with measurements. (WHK)

  16. Effects of exposing rat embryos in utero to physical or chemical teratogens are expressed later as enhanced induction of heat-shock proteins when embryonic hearts are cultured in vitro

    SciTech Connect

    Higo, H.; Higo, K.; Lee, J.Y.; Hori, H.; Satow, Y.

    1988-01-01

    In order to get more insight into the effects of teratogens on developing embryos, we investigated the protein synthesis patterns of the target organs isolated from teratogen-treated embryos. Rat embryos were either irradiated in utero with either 252Cf fission neutrons or 60Co gamma rays on day 8 of gestation or treated in utero with a bis(dichloroacetyl)diamine (a chemical teratogen) on days 9 and 10. Hearts were removed from the embryos on day 12 and were incubated in vitro at 37 degrees C in the presence of (35S)methionine for up to 8 hr. The newly synthesized labeled proteins were then analyzed qualitatively by two-dimensional polyacrylamide gel electrophoresis. Enhanced and prolonged induction of a family of heat-shock (stress) proteins with a molecular weight of about 70,000 (SP70s) was observed as compared with those of controls. Among the teratogen-treated hearts, those with gross malformations already detectable at this early stage showed especially higher inductions of SP70s than did the others. The abnormal expression of SP70s observed in the present study appears to be a reflection of persisting cellular (tissue) damage inflicted by the teratogens, and the extent of the induction may be indicative of the degree and/or type of the damage. Such persisting defects in surviving cells, manifested by abnormal induction of SP70s in the present study, might be related to malformation of embryonic hearts.

  17. TRIGA-SPEC: A setup for mass spectrometry and laser spectroscopy at the research reactor TRIGA Mainz

    NASA Astrophysics Data System (ADS)

    Ketelaer, J.; Krämer, J.; Beck, D.; Blaum, K.; Block, M.; Eberhardt, K.; Eitel, G.; Ferrer, R.; Geppert, C.; George, S.; Herfurth, F.; Ketter, J.; Nagy, Sz.; Neidherr, D.; Neugart, R.; Nörtershäuser, W.; Repp, J.; Smorra, C.; Trautmann, N.; Weber, C.

    2008-09-01

    The research reactor TRIGA Mainz is an ideal facility to provide neutron-rich nuclides with production rates sufficiently large for mass spectrometric and laser spectroscopic studies. Within the TRIGA-SPEC project, a Penning trap as well as a beamline for collinear laser spectroscopy are being installed. Several new developments will ensure high sensitivity of the trap setup enabling mass measurements even on a single ion. Besides neutron-rich fission products produced in the reactor, also heavy nuclides such as 235U or 252Cf can be investigated for the first time with an off-line ion source. The data provided by the mass measurements will be of interest for astrophysical calculations on the rapid neutron-capture process as well as for tests of mass models in the heavy-mass region. The laser spectroscopic measurements will yield model-independent information on nuclear ground-state properties such as nuclear moments and charge radii of neutron-rich nuclei of refractory elements far from stability. TRIGA-SPEC also serves as a test facility for mass and laser spectroscopic experiments at SHIPTRAP and the low-energy branch of the future GSI facility FAIR. This publication describes the experimental setup as well as its present status.

  18. Applicability of the Ge(n,γ) Reaction for Estimating Thermal Neutron Flux

    NASA Astrophysics Data System (ADS)

    Nikolov, J.; Medić, Ž.; Jovančević, N.; Hansman, J.; Todorović, N.; Krmar, M.

    A simple experimental setup was used to measure gamma lines appearing in spectra after interactions of neutrons with Ge in the active volume of a high-purity germanium detector placed in a low-background shield. As source of neutrons a 252Cf spontaneous fission source and different thicknesses of PVC plates were used to slow down neutrons. A cadmiumenvelope was placed over the detector dipstick to identify the effect from slow and fast neutrons. Intensities of several characteristic γ-lines were measured, including intensity of the 139.9 keV γ-line from the reaction 74Ge(n,γ)75mGe, usually used for estimation of thermal neutron flux. Obtained results signify that only a part of the detected 139.9 keV γ-rays originate from thermal neutron capture. Some preliminary results indicate that in our detection setup thermal neutron capture contributes with 30% to 50% to the total intensity of the 139.9 keV γ-line, depending on the thickness of the PVC plates.

  19. INVESTIGATION OF THE EXTENDED RANGE REM-COUNTER SMARTREM-LINUS IN REFERENCE AND WORKPLACE FIELDS EXPECTED AROUND HIGH-ENERGY ACCELERATORS.

    PubMed

    Hohmann, Eike; Trovati, S; Strauch, U; Mayer, S

    2016-09-01

    Radiation survey instrumentation is adequate for the use around high-energy accelerators if capable to measure the dose arising from neutrons with energies ranging from thermal up to a few gigaelectronvolts. The SmartREM-LINUS is a commercial extended range rem-counter, consisting of a central (3)He-proportional counter surrounded by a spherical moderator made of borated polyethylene with an internal shield made of lead. The dose rate indicated by the SmartREM-LINUS was investigated for two different irradiation conditions. The linearity and the angular dependence of the indicated dose rate were investigated using reference neutron fields produced by (241)AmBe and (252)Cf. Additional measurements were performed in two different workplace fields with a component of neutrons with energies >20 MeV, namely the CERN-EU high-energy reference field and near the beam dump of the SwissFEL injector test facility. The measured dose rates were compared to a commercial rem-counter (WENDI2) and the results of Monte Carlo simulations. PMID:27315828

  20. The design of a high-efficiency neutron counter for waste drums to provide optimized sensitivity for plutonium assay

    SciTech Connect

    Menlove, H.O.; Beddingfield, D.H.; Pickrell, M.M.

    1997-11-01

    An advanced passive neutron counter has been designed to improve the accuracy and sensitivity for the nondestructive assay of plutonium in scrap and waste containers. The High-Efficiency Neutron Counter (HENC) was developed under a Cooperative Research Development Agreement between the Los Alamos National Laboratory and Canberra Industries. The primary goal of the development was to produce a passive assay system for 200-L drums that has detectability limits and multiplicity counting features that are superior to previous systems. A detectability limit figure of merit (FOM) was defined that included the detector efficiency, the neutron die-away time, and the detector`s active volume and density that determine the cosmic-ray background. Monte Carlo neutron calculations were performed to determine the parameters to provide an optimum FOM. The system includes the {sup 252}Cf {open_quotes}add-a-source{close_quotes} feature to improve the accuracy as well as statistical filters to reduce the cosmic-ray spallation neutron background. The final decision gave an efficiency of 32% for plutonium with a detector {sup 3}He tube volume that is significantly smaller than for previous high-efficiency systems for 200-L drums. Because of the high efficiency of the HENC, we have incorporated neutron multiplicity counting for matrix corrections for those cases where the plutonium is localized in nonuniform hydrogenous materials. The paper describes the design and performance testing of the advanced system. 5 refs., 8 figs., 3 tabs.

  1. The need for precise and well-documented experimental data on prompt fission neutron spectra from neutron-induced fission of 239Pu

    DOE PAGESBeta

    Neudecker, Denise; Taddeucci, Terry Nicholas; Haight, Robert Cameron; Lee, Hye Young; White, Morgan Curtis; Rising, Michael Evans

    2016-01-06

    The spectrum of neutrons emitted promptly after 239Pu(n,f)—a so-called prompt fission neutron spectrum (PFNS)—is a quantity of high interest, for instance, for reactor physics and global security. However, there are only few experimental data sets available that are suitable for evaluations. In addition, some of those data sets differ by more than their 1-σ uncertainty boundaries. We present the results of MCNP studies indicating that these differences are partly caused by underestimated multiple scattering contributions, over-corrected background, and inconsistent deconvolution methods. A detailed uncertainty quantification for suitable experimental data was undertaken including these effects, and test-evaluations were performed with themore » improved uncertainty information. The test-evaluations illustrate that the inadequately estimated effects and detailed uncertainty quantification have an impact on the evaluated PFNS and associated uncertainties as well as the neutron multiplicity of selected critical assemblies. A summary of data and documentation needs to improve the quality of the experimental database is provided based on the results of simulations and test-evaluations. Furthermore, given the possibly substantial distortion of the PFNS by multiple scattering and background effects, special care should be taken to reduce these effects in future measurements, e.g., by measuring the 239Pu PFNS as a ratio to either the 235U or 252Cf PFNS.« less

  2. High spin states in {sup 151,153}Pr, {sup 157}Sm, and {sup 93}Kr

    SciTech Connect

    Hwang, J. K.; Ramayya, A. V.; Hamilton, J. H.; Liu, S. H.; Brewer, N. T.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.; Donangelo, R.

    2010-09-15

    High spin states are observed for the first time in the neutron-rich nuclei {sup 151,153}Pr, {sup 157}Sm, and {sup 93}Kr from the spontaneous fission of {sup 252}Cf. Twenty new transitions in {sup 151}Pr, twelve in {sup 153}Pr, five in {sup 157}Sm, and four in {sup 93}Kr were identified by using x-ray(Pr/Sm)-{gamma}-{gamma} and {gamma}-{gamma}-{gamma} triple coincidences. From the measured total internal conversion coefficients {alpha}{sub T} of four low-energy transitions in {sup 151,153}Pr, we determine that two bands in each nucleus have opposite parity. The interlacing E1 transitions between the bands suggest a form of parity doubling in {sup 151,153}Pr. New bands in {sup 157}Sm and {sup 93}Kr are reported. The half-life of the 354.8 keV state in {sup 93}Kr is measured to be 10(2) ns.

  3. Development of a thin scintillation films fission-fragment detector and a novel neutron source

    DOE PAGESBeta

    Rusev, Gencho Yordanov; Jandel, Marian; Baramsai, Bayarbadrakh; Bond, Evelyn M.; Bredeweg, Todd Allen; Couture, Aaron Joseph; Daum, Jaimie Kay; Favalli, Andrea; Ianakiev, Kiril Dimitrov; Iliev, Metodi L.; et al

    2015-08-26

    Here, investigation of prompt fission and neutron-capture Υ rays from fissile actinide samples at the Detector for Advanced Neutron Capture Experiments (DANCE) requires use of a fission-fragment detector to provide a trigger or a veto signal. A fission-fragment detector based on thin scintillating films and silicon photomultipliers has been built to serve as a trigger/veto detector in neutron-induced fission measurements at DANCE. The fissile material is surrounded by scintillating films providing a 4π detection of the fission fragments. The scintillations were registered with silicon photomultipliers. A measurement of the 235U(n,f) reaction with this detector at DANCE revealed a correct time-of-flightmore » spectrum and provided an estimate for the efficiency of the prototype detector of 11.6(7)%. Design and test measurements with the detector are described. A neutron source with fast timing has been built to help with detector-response measurements. The source is based on the neutron emission from the spontaneous fission of 252Cf and the same type of scintillating films and silicon photomultipliers. Overall time resolution of the source is 0.3 ns. Design of the source and test measurements with it are described. An example application of the source for determining the neutron/gamma pulse-shape discrimination by a stilbene crystal is given.« less

  4. RAD/COMM ''Cricket'' Test Report

    SciTech Connect

    Chiaro, P.J.

    2002-05-20

    A series of tests were performed at Oak Ridge National Laboratory (ORNL) to evaluate and characterize the radiological response of a ''Cricket'' radiation detection system. The ''Cricket'' is manufactured by RAD/COMM Systems Corp., which is located in Ontario, Canada. The system is designed to detect radioactive material that may be contained in scrap metal. The Cricket's detection unit is mounted to the base of a grappler and monitors material, while the grappler's tines hold the material. It can also be used to scan material in an attempt to isolate radioactive material if an alarm occurs. Testing was performed at the Environmental Effects Laboratory located at ORNL and operated by the Engineering Science and Technology Division. Tests performed included the following: (1) Background stability, (2) Energy response using {sup 241}Am, {sup 137}Cs, and {sup 60}Co, (3) Surface uniformity, (4) Angular dependence, (5) Alarm actuation, (6) Alarm threshold vs. background, (7) Shielding, (8) Response to {sup 235}U, (9) Response to neutrons using unmoderated {sup 252}Cf, and (10) Response to transient radiation. This report presents a summary of the test results. Background measurements were obtained prior to the performance of each individual test.

  5. Determination of air/water ratio in pipes by fast neutrons: experiment and Monte Carlo simulation.

    PubMed

    AboAlfaraj, Tareq; Abdul-Majid, Samir

    2012-04-01

    Fast neutron dose attenuation from a (252)Cf neutron source is used for the determination of air to water ratio in pipes. Such measurement of the two-phase flow volume fraction is important for many industrial plants such as desalination plants and oil refineries. Fast neutrons penetrate liquid more than slow neutrons or gamma rays. Using diameters from 11.5 cm to 20.76 cm and with wall thicknesses from 0.45 to 1.02 cm, attenuation was independent of pipe wall thicknesses and diameters. Experimental data was in good agreement with values calculated using MCNP codes. The measured neutron flux values decreased with increasing water levels in pipes up to about 14 cm, indicating that our system can be used successfully in desalination plants in pipes of different sizes. The experimental sensitivity was found to be about 0.015 mSv/hcm and the system can be used to measure water level changes down to few millimeters. Use of such a system in fixed positions in the plant can provide information on plant's overall performance and can detect loss of flow immediately before any consequences. A portable system could be designed to measure the air to water ratio in different locations in the plant in a relatively short time.

  6. Development of position-sensitive time-of-flight spectrometer for fission fragment research

    SciTech Connect

    Arnold, C. W.; Tovesson, F.; Meierbachtol, K.; Bredeweg, T.; Jandel, M.; Jorgenson, H. J.; Laptev, A.; Rusev, G.; Shields, D. W.; White, M.; Blakeley, R. E.; Mader, D. M.; Hecht, A. A.

    2014-07-09

    A position-sensitive, high-resolution time-of-flight detector for fission fragments has been developed. The SPectrometer for Ion DEtermination in fission Research (SPIDER) is a 2E–2v spectrometer designed to measure the mass of light fission fragments to a single mass unit. The time pick-off detector pairs to be used in SPIDER have been tested with α-particles from 229Th and its decay chain and α-particles and spontaneous fission fragments from 252Cf. Each detector module is comprised of thin electron conversion foil, electrostatic mirror, microchannel plates, and delay-line anodes. Particle trajectories on the order of 700 mm are determined accurately to within 0.7 mm. Flight times were measured with 250 ps resolution FWHM. Computed particle velocities are accurate to within 0.06 mm/ns corresponding to a precision of 0.5%. As a result, an ionization chamber capable of 400 keV energy resolution coupled with the velocity measurements described here will pave the way for modestly efficient measurements of light fission fragments with unit mass resolution.

  7. Development of position-sensitive time-of-flight spectrometer for fission fragment research

    DOE PAGESBeta

    Arnold, C. W.; Tovesson, F.; Meierbachtol, K.; Bredeweg, T.; Jandel, M.; Jorgenson, H. J.; Laptev, A.; Rusev, G.; Shields, D. W.; White, M.; et al

    2014-07-09

    A position-sensitive, high-resolution time-of-flight detector for fission fragments has been developed. The SPectrometer for Ion DEtermination in fission Research (SPIDER) is a 2E–2v spectrometer designed to measure the mass of light fission fragments to a single mass unit. The time pick-off detector pairs to be used in SPIDER have been tested with α-particles from 229Th and its decay chain and α-particles and spontaneous fission fragments from 252Cf. Each detector module is comprised of thin electron conversion foil, electrostatic mirror, microchannel plates, and delay-line anodes. Particle trajectories on the order of 700 mm are determined accurately to within 0.7 mm. Flightmore » times were measured with 250 ps resolution FWHM. Computed particle velocities are accurate to within 0.06 mm/ns corresponding to a precision of 0.5%. As a result, an ionization chamber capable of 400 keV energy resolution coupled with the velocity measurements described here will pave the way for modestly efficient measurements of light fission fragments with unit mass resolution.« less

  8. Application of stochastic and artificial intelligence methods for nuclear material identification

    SciTech Connect

    Pozzi, S.; Segovia, F.J.

    1999-12-01

    Nuclear materials safeguard efforts necessitate the use of non-destructive methods to determine the attributes of fissile samples enclosed in special, non-accessible containers. To this end, a large variety of methods has been developed at the Oak Ridge National Laboratory (ORNL) and elsewhere. Usually, a given set of statistics of the stochastic neutron-photon coupled field, such as source-detector, detector-detector cross correlation functions, and multiplicities are measured over a range of known samples to develop calibration algorithms. In this manner, the attributes of unknown samples can be inferred by the use of the calibration results. The organization of this paper is as follows: Section 2 describes the Monte Carlo simulations of source-detector cross correlation functions for a set of uranium metallic samples interrogated by the neutrons and photons from a {sup 252}Cf source. From this database, a set of features is extracted in Section 3. The use of neural networks (NN) and genertic programming to provide sample mass and enrichment values from the input sets of features is illustrated in Sections 4 and 5, respectivelyl. Section 6 is a comparison of the results, while Section 7 is a brief summary of the work.

  9. Evaluation of the neutron dosimeter used by Martin Marietta Energy Systems, Inc., ability to meet the requirements of the American National Standard for Personnel Neutron Dosimeters (neutron energies less than 20 MeV) ANSI N319-1976

    SciTech Connect

    Gunter, R.J.

    1994-07-01

    An evaluation of the neutron dosimeter used by the Centralized External Dosimetry System of Martin Marietta Energy Systems, Inc., was performed, and the dosimeter was shown to meet the requirements of the American National Standard for Personnel Neutron Dosimeters, ANSI N319-1976. This report details the requirements of the Standard, describes the tests performed, and evaluates the results of testing. To demonstrate compliance with the Standard, dosimeters were irradiated with a {sup 252}Cf source while mounted on a standard phantom. Dose was measured using the routine methodology employed by the Centralized External Dosimetry System for neutron dosimetry. The ability to accurately measure neutron dose was compared to specific performance criteria from the Standard. This includes testing the lower limit of detection, upper limit of detection, precision of results, and the capability to detect neutrons in a high gamma dose environment. In addition to neutron exposure, the dosimeters were required to be exposed to environmental factors including temperature extremes, high humidity, exposure to room light, and a drop to a hard surface. Only after exposure to these conditions were the dosimeters read, with results compared to the requirements of the Standard. Normal use factors of routine neutron dosimetry influencing the accuracy, sensitivity, or precision of the dosimetry system were also evaluated to measure their impact on dosimeter response.

  10. Longevity Tests of High-Sensitivity BD-PND Bubble Dosimeters

    SciTech Connect

    Radev, R; Carlberg, E

    2002-07-09

    Medium- and very-high-sensitivity neutron bubble dosimeters (BD-PNDs) made by Bubble Technology Industries (BTI) were used to study the life span of such dosimeters in a standard setup with a {sup 252}Cf source. Although data on the longevity of bubble dosimeters with low and medium sensitivity exist, such data for dosimeters with high and very high sensitivity are not readily available. The manufacturer guarantees optimum dosimeter performance for 3 months after receipt. However, it is important to know the change in the dosimeters' characteristics with time, especially after the first 3 months. The long-term performance of four sets of very high sensitivity and one set of medium-sensitivity bubble dosimeters was examined for periods of up to 13 months. During that time, the detectors were exposed and reset more than 20 times. Although departures from initial detection sensitivity were observed in several cases, the detectors indicated a significantly longer life span than stated in the manufacturer's warranty. In addition, the change in the number of bubbles and in evaluated neutron dose as a function of the time from the end of exposure until the dosimeters were read was investigated.

  11. Impact of low-energy photons on the characteristics of prompt fission γ -ray spectra

    NASA Astrophysics Data System (ADS)

    Oberstedt, A.; Billnert, R.; Hambsch, F.-J.; Oberstedt, S.

    2015-07-01

    In this paper we report on a new study of prompt γ -rays from the spontaneous fission of 252Cf . Photons were measured in coincidence with fission fragments by employing four different lanthanide halide scintillation detectors. Together with results from a previous work of ours, we determined characteristic parameters with high precision, such as the average γ -ray multiplicity ν¯γ=(8.29 ±0.13 ), the average energy per photon ɛγ=(0.80 ±0.02 ) MeV, and the total γ -ray energy release per fission Eγ ,tot=(6.65 ±0.10 ) MeV. The excellent agreement between the individual results obtained in all six measurements proves the good repeatability of the applied experimental technique. The impact of low-energy photons, i.e., below 500 keV, on prompt fission γ -ray spectra characteristics has been investigated as well by comparing our results with those taken with the DANCE detector system, which appears to suffer from absorption effects in the low-energy region. Correction factors for this effect were estimated, giving results comparable to ours as well as to historical ones. From this we demonstrate that the different techniques of determining the average γ -ray multiplicity, either from a properly measured and normalized spectrum or a measured multiplicity distribution, give equivalent and consistent results.

  12. Coincident measurements of prompt fission γ rays and fission fragments at DANCE

    NASA Astrophysics Data System (ADS)

    Walker, C. L.; Baramsai, B.; Jandel, M.; Rusev, G.; Couture, A.; Mosby, S.; Ullmann, J.; Kawano, T.; Stetcu, I.; Talou, P.

    2015-10-01

    Modern statistical approaches to modeling fission involve the calculation of not only average quantities but also fully correlated distributions of all fission products. Applications such as those involving the detection of special nuclear materials also rely on fully correlated data of fission products. Experimental measurements of correlated data are thus critical to the validation of theory and the development of important applications. The goal of this experiment was to measure properties of prompt fission gamma-ray emission as a function of fission fragments' total kinetic energy in the spontaneous fission of 252Cf. The measurement was carried out at the Detector for Advanced Neutron Capture Experiments (DANCE), a 4 π γ-ray calorimeter. A prototype design consisting of two silicon detectors was installed in the center of DANCE, allowing simultaneous measurement of fission fragments and γ rays. Effort has been taken to simulate fragment kinetic energy losses as well as γ-ray attenuation in DANCE using such tools as GEANT4 and SRIM. Theoretical predictions generated by the code CGMF were also incorporated as input for these simulations. Results from the experiment and simulations will be presented, along with plans for future measurements.

  13. Ion desorption from frozen H 2O irradiated by MeV heavy ions

    NASA Astrophysics Data System (ADS)

    Collado, V. M.; Farenzena, L. S.; Ponciano, C. R.; Silveira, E. F. da; Wien, K.

    2004-10-01

    Nitrogen (0.13-0.85 MeV) and 252Cf fission fragments (˜65 MeV) beams are employed to sputter positive and negative secondary ions from frozen water. Desorption yields are measured for different ice temperatures and projectile energies. Target surface is continuously refreshed by condensed water while the target temperature varies and ice thickness changes. In both projectile energy ranges, the preferentially ejected ions are H +, H2+ and (H 2O) nH +-cluster ions. The yields of the corresponding negative ions H - and (H 2O) nO - or (H 2O) nOH - are 1-2 orders of magnitude lower. The (H 2O) nH + desorption yields decrease exponentially as the cluster size, n, increases. In the low energy range, the desorption of positive ion clusters may occur in a two-step process: first, desorption of preformed H 2O clusters and, then, ionization by H + or H 3O + capture. For 0.81 MeV N + projectile ions, the cluster ion emission contributes with 0.05% to the total H 2O desorbed yield. There are indications that emission of the (H 2O) nH + disappears for an electronic energy loss lower than 20 eV/Å. For the high energy range, desorption of small ion clusters is particularly enhanced, revealing that a fragmentation process also exists.

  14. Ultra-separation of nickel from copper metal for the measurement of 63Ni by AMS

    NASA Astrophysics Data System (ADS)

    Marchetti, A. A.; Hainsworth, L. J.; McAninch, J. E.; Leivers, M. R.; Jones, P. R.; Proctor, I. D.; Straume, T.

    1997-03-01

    Measurements of 63Ni (t{1}/{2} = 100 yr) produced by the reaction 63Cu(n,p)63Ni could be used in the assessment of fast-neutron fluence from the Hiroshima atomic bomb. Such measurements would add new information to help resolve the current discrepancy between measured thermal neutron activation values and those calculated with the DS86 dosimetry system. It has been estimated that the 63Ni production at 5 m from the hypocenter was (1.4 ± 0.1) × 107 atoms/g Cu. Because of its sensitivity, accelerator mass spectrometry (AMS) is ideal for measurements at this low level. However, 63Ni has to be separated from large amounts of stable atomic isobar 63Cu (69% of pure Cu). In this study, a procedure is presented for the electrochemical separation of ultra-low amounts of Ni from Cu. The method was developed using samples of electrical Cu wire that were irradiated with fission neutrons from a 252Cf source. The wire samples were electrochemically dissolved in a solution containing 1 mg of Ni carrier. The Cu was selectively deposited on a cathode at controlled potential. Measurements of total Ni after electroseparation indicate ˜ 100% carrier recovery. To prevent Cu contamination, AMS targets were prepared by nickel carbonyl generation. The AMS results show a successful quantitative separation of ˜ 107 atoms of 63Ni from 2-20 g samples of Cu.

  15. Composite polycrystalline semiconductor neutron detectors

    NASA Astrophysics Data System (ADS)

    Schieber, M.; Zuck, A.; Marom, G.; Khakhan, O.; Roth, M.; Alfassi, Z. B.

    2007-08-01

    Composite polycrystalline semiconductor detectors bound with different binders, both inorganic molten glasses, such as B 2O 3, PbO/B 2O 3, Bi 2O 3/PbO, and organic polymeric binders, such as isotactic polypropylene (iPP), polystyrene or nylon-6, and coated with different metal electrodes were tested at room temperature for α-particles and very weak thermal neutron sources. The detector materials tested were natural occurring hexagonal BN and cubic LiF, where both are not containing enriched isotopes of 10B or 6Li. The radiation sources were 5.5 MeV α's from 241Am, 5.3 MeV from 210Po and also 4.8 MeV from 226Ra. Some of these detectors were also tested with thermal neutrons from very weak 227Ac 9Be, 241Am- 10Be sources and also from a weak 238Pu+ 9Be and somewhat stronger 252Cf sources. The neutrons were thermalized with paraffin. Despite very low signal to noise ratio of only ˜2, the neutrons could be counted by subtracting the noise from the signal.

  16. A neutron Albedo system with time rejection for landmine and IED detection

    NASA Astrophysics Data System (ADS)

    Kovaltchouk, V. D.; Andrews, H. R.; Clifford, E. T. H.; Faust, A. A.; Ing, H.; McFee, J. E.

    2011-10-01

    A neutron Albedo system has been developed for imaging of buried landmines and improvised explosive devices (IEDs). It involves irradiating the ground with fast neutrons and subsequently detecting the thermalized neutrons that return. A scintillating 6Li loaded ZnS(Ag) screen with a sensitive area of 40 cm×40 cm is used as a thermal neutron detector. Scintillation light is captured by orthogonal arrays of wavelength-shifting fibers placed on either side of the scintillator surface and then transferred to X and Y multi-pixel PMTs. A timing circuit, used with pulsed neutron sources, records the time when a neutron detection takes place relative to an external synchronization pulse from the pulsed source. Experimental tests of the Albedo system performance have been done in a sand box with a 252Cf neutron source (no time gating) and with pulsed D-D (2.6 MeV) neutrons from the Defense R&D Ottawa Van de Graaff accelerator (with time gating). Information contained in the time evolution of the thermal neutron field provided improved detection capability and image reconstruction. The detector design is described and experimental results are discussed.

  17. Investigation of neutron converters for production of optically stimulated luminescence (OSL) neutron dosimeters using Al 2O 3:C

    NASA Astrophysics Data System (ADS)

    Mittani, J. C. R.; da Silva, A. A. R.; Vanhavere, F.; Akselrod, M. S.; Yukihara, E. G.

    2007-07-01

    This paper presents the optically stimulated luminescence (OSL) properties of neutron dosimeters in powder and in the form of pellets prepared with a mixture of Al 2O 3:C and neutron converters. The neutron converters investigated were high density polyethylene (HDPE), lithium fluoride (LiF), lithium fluoride 95% enriched with 6Li ( 6LiF), lithium carbonate 95% enriched with 6Li ( 6Li 2CO 3), boric acid enriched with 99% of 10B (H310BO) and gadolinium oxide (Gd 2O 3). The proportion of Al 2O 3:C and neutron converter in the mixture was varied to optimize the total OSL signal and neutron sensitivity. The neutron sensitivity and dose-response were determined for the OSL dosimeters using a bare 252Cf source and compared to the response of Harshaw TLD-600 and TLD-700 dosimeters ( 6LiF:Mg,Ti and 7LiF:Mg,Ti). The results demonstrate the possibility of developing an OSL dosimeter made of Al 2O 3:C powder and neutron converter with a neutron sensitivity (defined as the ratio between the 60Co equivalent gamma dose and the reference neutron absorbed dose) and neutron-gamma discrimination comparable to the TLD-600/TLD-700 combination. It was shown that the shape of the OSL decay curves varied with the type of the neutron converter, demonstrating the influence of the energy deposition mechanism and ionization density on the OSL process in Al 2O 3:C.

  18. Reliability of Monte Carlo simulations in modeling neutron yields from a shielded fission source

    NASA Astrophysics Data System (ADS)

    McArthur, Matthew S.; Rees, Lawrence B.; Czirr, J. Bart

    2016-08-01

    Using the combination of a neutron-sensitive 6Li glass scintillator detector with a neutron-insensitive 7Li glass scintillator detector, we are able to make an accurate measurement of the capture rate of fission neutrons on 6Li. We used this detector with a 252Cf neutron source to measure the effects of both non-borated polyethylene and 5% borated polyethylene shielding on detection rates over a range of shielding thicknesses. Both of these measurements were compared with MCNP calculations to determine how well the calculations reproduced the measurements. When the source is highly shielded, the number of interactions experienced by each neutron prior to arriving at the detector is large, so it is important to compare Monte Carlo modeling with actual experimental measurements. MCNP reproduces the data fairly well, but it does generally underestimate detector efficiency both with and without polyethylene shielding. For non-borated polyethylene it underestimates the measured value by an average of 8%. This increases to an average of 11% for borated polyethylene.

  19. New work on updating and extending the nuclear data standards

    SciTech Connect

    Carlson, A.D.; Pronyaev, V.G.; Capote, R.; Hambsch, F.J.; Kaeppeler, F.; Lederer, C.; Mannhart, W.; Mengoni, A.; Nelson, R. O.; Schillebeeckx, P.; Talou, P.; Tagesen, S.; Vonach, H.; Vorobyev, A.; Wallner, A.

    2011-07-01

    An International Atomic Energy Agency (IAEA) Data Development Project was initiated to provide a mechanism for allowing new experimental data and improvements in evaluation procedures to be incorporated into new evaluations of the standards. The work on this project is ongoing. In the past very long periods sometimes occurred between evaluations of the standards. Through the use of this Project, such long periods should not occur. Work on the cross section standards through this Project has included an update of the experimental data to be used in the cross section standards evaluations, a study of the uncertainties obtained in the international standards evaluation, and improvements in the smoothing procedure for capture cross sections. It was decided that this Project should have a broader range of activities than just the cross section standards and thus encompass standards related activities. The following are being investigated: improvements in the gold cross section at energies below where it is considered a standard and work on certain cross sections that are not as well known as the cross section standards but could be very useful as reference cross sections relative to which certain types of cross section measurements can be made. This work includes prompt gamma-ray production in fast neutron-induced reactions, and work on the {sup 252}Cf spontaneous fission neutron spectrum and the {sup 235}U thermal neutron fission spectrum. Most of the data investigated through this Project are used in dosimetry applications. (authors)

  20. Further investigations on CR-39 fast neutron personal dosemeter

    NASA Astrophysics Data System (ADS)

    Djeffal, S.; Lounis, Z.; Allab, M.; Izerrouken, M.

    1997-02-01

    A fast neutron personal dosemeter based on CR-39 nuclear track detectors has been developed in as simple a form as possible to be used in routine monitoring. It has been investigated during the last joint irradiation exposures to neutrons organised by EURADOS-CENDOS committee on the application of track detectors in neutron dosimetry. The energy response and the angle dependence of two types of CR-39 material, produced by Pershore Mouldings Ltd (as standard grade material) and American Acrylics (as dosimetry grade material), have been studied using neutron energies ranging from 144 keV up to 66 MeV and the 252Cf neutron spectrum at different angles of incidence, i.e. 0°, 30°, 60° and 85°. Irradiated detectors have been processed using a conventional chemical etching (CE) and a two-step electrochemical etching at low (200 Hz) and high (2 kHz) frequencies (ECE). Under the ECE etching conditions a 80 μSv minimum dose equivalent value is achieved. The response of these detectors to the ambient dose equivalent in the range 0.4-13 mSv has also been studied for monoenergetic neutron beams of 1.2, 5.3 and 15.1 MeV. The dosimetric characteristics of the proposed dosemeter have been much improved by using the ECE conditions. The variations and values of these characteristics approach the required ones in a better way than that given till now in previous works.

  1. CHICO2, a two-dimensional pixelated parallel-plate avalanche counter

    NASA Astrophysics Data System (ADS)

    Wu, C. Y.; Cline, D.; Hayes, A.; Flight, R. S.; Melchionna, A. M.; Zhou, C.; Lee, I. Y.; Swan, D.; Fox, R.; Anderson, J. T.

    2016-04-01

    CHICO2 (Compact Heavy Ion COunter), is a large solid-angle, charged-particle detector array developed to provide both θ and ϕ angle resolutions matching those of GRETINA (Gamma-Ray Energy Tracking In-beam Nuclear Array). CHICO2 was successfully tested at the Argonne National Laboratory where it was fielded as an auxiliary detector with GRETINA for γ-ray spectroscopic studies of nuclei using a 252Cf spontaneous fission source, stable beams, and radioactive beams from CARIBU. In field tests of the 72,76Ge beams on a 0.5 mg/cm2208Pb target at the sub-barrier energy, CHICO2 provided charged-particle angle resolutions (FWHM) of 1.55° in θ and 2.47° in ϕ. This achieves the design goal for both coordinates assuming a beam-spot size (>3 mm) and the target thickness (>0.5 mg/cm2). The combined angular resolution of GRETINA/CHICO2 resulted in a Doppler-shift corrected energy resolution of 0.60% for 1 MeV coincident de-excitation γ-rays. This is nearly a factor of two improvements in resolution and sensitivity compared to Gammasphere/CHICO. Kinematically-coincident detection of scattered ions by CHICO2 still maintains the mass resolution (ΔM/M) of ~5% that enhanced isolation of scattered weak beams of interest from scattered contaminant beams.

  2. Detection of Landmines by Neutron Backscattering: Effects of Soil Moisture on the Detection System

    SciTech Connect

    Baysoy, D. Y.; Subasi, M.

    2010-01-21

    Detection of buried land mines by using neutron backscattering technique (NBS) is a well established method. It depends on detecting a hydrogen anomaly in dry soil. Since a landmine and its plastic casing contain much more hydrogen atoms than the dry soil, this anomaly can be detected by observing a rise in the number of neutrons moderated to thermal or epithermal energy. But, the presence of moisture in the soil limits the effectiveness of the measurements. In this work, a landmine detection system using the NBS technique was designed. A series of Monte Carlo calculations was carried out to determine the limits of the system due to the moisture content of the soil. In the simulations, an isotropic fast neutron source ({sup 252}Cf, 100 mug) and a neutron detection system which consists of five {sup 3}He detectors were used in a practicable geometry. In order to see the effects of soil moisture on the efficiency of the detection system, soils with different water contents were tested.

  3. A militarily fielded thermal neutron activation sensor for landmine detection

    NASA Astrophysics Data System (ADS)

    Clifford, E. T. H.; McFee, J. E.; Ing, H.; Andrews, H. R.; Tennant, D.; Harper, E.; Faust, A. A.

    2007-08-01

    The Canadian Department of National Defence has developed a teleoperated, vehicle-mounted, multi-sensor system to detect anti-tank landmines on roads and tracks in peacekeeping operations. A key part of the system is a thermal neutron activation (TNA) sensor which is placed above a suspect location to within a 30 cm radius and confirms the presence of explosives via detection of the 10.835 MeV gamma ray associated with thermal neutron capture on 14N. The TNA uses a 100 μg252Cf neutron source surrounded by four 7.62 cm×7.62 cm NaI(Tl) detectors. The system, consisting of the TNA sensor head, including source, detectors and shielding, the high-rate, fast pulse processing electronics and the data processing methodology are described. Results of experiments to characterize detection performance are also described. The experiments have shown that anti-tank mines buried 10 cm or less can be detected in roughly a minute or less, but deeper mines and mines significantly displaced horizontally take considerably longer time. Mines as deep as 30 cm can be detected for long count times (1000 s). Four TNA detectors are now in service with the Canadian Forces as part of the four multi-sensor systems, making it the first militarily fielded TNA sensor and the first militarily fielded confirmation sensor for landmines. The ability to function well in adverse climatic conditions has been demonstrated, both in trials and operations.

  4. Dose coefficients and derived guidance and clinical decision levels for contaminated wounds

    SciTech Connect

    Bertelli, Luiz; Toohey, Richard E

    2009-01-01

    The NCRP Wound Model describing the retention of selected radionuclides at the site of a contaminated wound and their uptake into the transfer compartment has been combined with the ICRP element-specific systemic models for those radionuclides to derive dose coefficients for intakes via contaminated wounds. Those coefficients have been used to generate derived guidance levels (i.e., the activity in a wound that would result in an effective dose of 20 or 50 mSv, or in some cases, a committed organ equivalent dose of 500 mSv), and clinical decision levels (i.e., activity levels that would indicate the need for consideration of medical intervention to remove activity from the wound site or administration of decorporation therapy or both), typically set at 5 times the derived guidance levels. Data are provided for the radionuclides commonly encountered at nuclear power plants and nuclear weapons, fuel fabrication or recycling, waste disposal, medical and research facilities. These include: {sup 60}Co, {sup 90}Sr, {sup 99m}Tc, {sup 131}I, {sup 137}Cs, {sup 192}Ir, {sup 210}Po, {sup 226,228}Ra, {sup 228,232}Th, {sup 235,238}U, {sup 237}Np, {sup 238,239}Pu, {sup 241}Am, {sup 242,244}Cm, and {sup 252}Cf.

  5. Source storage and transfer cask: Users Guide

    SciTech Connect

    Eccleston, G.W.; Speir, L.G.; Garcia, D.C.

    1985-04-01

    The storage and shield cask for the dual californium source is designed to shield and transport up to 3.7 mg (2 Ci) of /sup 252/Cf. the cask meets Department of Transportation (DOT) license requirements for Type A materials (DOT-7A). The cask is designed to transfer sources to and from the Flourinel and Fuel Storage (FAST) facility delayed-neutron interrogator. Californium sources placed in the cask must be encapsulated in the SR-CF-100 package and attached to Teleflex cables. The cask contains two source locations. Each location contains a gear box that allows a Teleflex cable to be remotely moved by a hand crank into and out of the cask. This transfer procedure permits sources to be easily removed and inserted into the delayed-neutron interrogator and reduces personnel radiation exposure during transfer. The radiation dose rate with the maximum allowable quantity of californium (3.7 mg) in the cask is 30 mR/h at the surface and less than 2 mR/h 1 m from the cask surface. This manual contains information about the cask, californium sources, describes the method to ship the cask, and how to insert and remove sources from the cask. 28 figs.

  6. Neutron angular distribution in plutonium-240 spontaneous fission

    NASA Astrophysics Data System (ADS)

    Marcath, Matthew J.; Shin, Tony H.; Clarke, Shaun D.; Peerani, Paolo; Pozzi, Sara A.

    2016-09-01

    Nuclear safeguards applications require accurate fission models that exhibit prompt neutron anisotropy. In the laboratory reference frame, an anisotropic neutron angular distribution is observed because prompt fission neutrons carry momentum from fully accelerated fission fragments. A liquid organic scintillation detector array was used with pulse shape discrimination techniques to produce neutron-neutron cross-correlation time distributions and angular distributions from spontaneous fission in a 252Cf, a 0.84 g 240Pueff metal, and a 1.63 g 240Pueff metal sample. The effect of cross-talk, estimated with MCNPX-PoliMi simulations, is removed from neutron-neutron coincidences as a function of the angle between detector pairs. Fewer coincidences were observed at detector angles near 90°, relative to higher and lower detector angles. As light output threshold increases, the observed anisotropy increases due to spectral effects arising from fission fragment momentum transfer to emitted neutrons. Stronger anisotropy was observed in Cf-252 spontaneous fission prompt neutrons than in Pu-240 neutrons.

  7. Total prompt γ-ray emission in fission

    NASA Astrophysics Data System (ADS)

    Wu, C. Y.; Chyzh, A.; Kwan, E.; Henserson, R. A.; Bredeweg, T. A.; Haight, R. C.; Hayes-Sterbenz, A. C.; Lee, H. Y.; O'Donnell, J. M.; Ullmann, J. L.

    2016-06-01

    The total prompt γ-ray energy distributions for the neutron-induced fission of 235U, 239,241Pu at incident neutron energy of 0.025 eV ‒ 100 keV, and the spontaneous fission of 252Cf were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) array in coincidence with the detection of fission fragments by a parallel-plate avalanche counter. DANCE is a highly segmented, highly efficient 4π γ-ray calorimeter. Corrections were made to the measured distribution by unfolding the two-dimension spectrum of total γ-ray energy vs multiplicity using a simulated DANCE response matrix. The mean values of the total prompt γ-ray energy, determined from the unfolded distributions, are ~ 20% higher than those derived from measurements using single γ-ray detector for all the fissile nuclei studied. This raises serious concern on the validity of the mean total prompt γ-ray energy obtained from the product of mean values for both prompt γ-ray energy and multiplicity.

  8. New high-spin level schemes and excitation modes of 117,118,119,120,122 Cd

    SciTech Connect

    J. D. Cole

    2012-01-01

    High-spin level schemes of {sup 117,118,119,120,122}Cd are expanded by analyzing our high-statistics triple and higher-fold coincidence events of prompt fission {gamma} rays from {sup 252}Cf at Gammasphere. Spin/parity assignments were made based on new {gamma}-{gamma} angular correlation measurements and level systematics in the neighboring isotopes. Stretch-aligned band structures observed in low-lying levels in {sup 117,119,121}Cd are seen to weaken with increasing spins, with a quasi-rotational degree of freedom manifested at higher spins. The{sup 5-}levels in even-N{sup 118,120}Cd were tentatively interpreted as candidates of quadrupole-octupole (QOC) coupling. The model-independent spin versus {h_bar}{omega} curves for even-N and odd-N Cd isotopes imply quasirotational alignment of an h11/2 neutron pair in the even-N Cd isotopes. The relative energies of the lowest 11/{sup 2-}, 9/{sup 2-}, 7/{sup 2-}, and 15/{sup 2-} levels in {sup 117}Cd and {sup 119}Cd suggest triaxial shapes based on Meyer-Ter-Vehn theory for these odd-N Cd nuclei. For the even-N Cd isotopes evidence of triaxiality may also be provided by the Shell Correction version of the Tilted Axis Cranking model (SCTAC).

  9. The 3He long-counter TETRA at the ALTO ISOL facility

    NASA Astrophysics Data System (ADS)

    Testov, D.; Verney, D.; Roussière, B.; Bettane, J.; Didierjean, F.; Flanagan, K.; Franchoo, S.; Ibrahim, F.; Kuznetsova, E.; Li, R.; Marsh, B.; Matea, I.; Penionzhkevich, Yu.; Pai, H.; Smirnov, V.; Sokol, E.; Stefan, I.; Suzuki, D.; Wilson, J. N.

    2016-04-01

    A new β-decay station (BEDO) has been installed behind the PARRNe mass separator operated on-line at the electron-driven ALTO ISOL facility. The station is equipped with a movable tape collector allowing the creation of the radioactive sources of interest at the very center of a modular detection system. The mechanical structure was designed to host various assemblies of detectors in compact geometry. We report here the first on-line use of this system equipped with the 4π 3He neutron counter TETRA built at JINR Dubna associated with HPGe and plastic 4π β detectors. The single neutron detection efficiency achieved is 53(2)% measured using the 252Cf source. For β-delayed neutron measurements the neutron detection efficiency was derived from the comparison of gated γ-spectra. The on-line commissioning of the TETRA setup was performed with laser-ionized gallium beams. β and neutron events were recorded as a function of time. From these data we report P1n(82Ga)=22(2)% and T1/2(82Ga)=0.604(11) s in good agreement with values available in the literature. The new detection system will be used in other experiments aimed at investigations of β-decay properties of neutron-rich isotopes produced at ALTO.

  10. Collective Motions in A = 100-112 Nuclei

    SciTech Connect

    Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Goodin, C.; Zhu, S. J.; Luo, Y. X.; Rasmussen, J. O.; Frauendorf, S.; Ter-Akopian, G. M.

    2010-10-11

    With a very high statistics data set with 5.7x10{sup 11} triple and higher fold {gamma} coincidences from the spontaneous fission of {sup 252}Cf, a wealth of fascinating new collective motions in nuclei with A = 100-112 have been observed. Nothing was known previously about one- and two-phonon {gamma}-bands in odd-A nuclei. We discovered the first one-and two- phonon {gamma} vibrational bands in an odd N-even Z nucleus, {sup 105}Mo. The energies of the one- and two- phonon bands in {sup 104}Mo, {sup 105}Mo, {sup 106}Mo and {sup 108}Mo were recently studied and are remarkably similar in energies. The first chiral doublet bands in e-e nuclei were observed in triaxial {sup 106,108}Mo and {sup 110,112}Ru while such chiral band in {sup 108}Ru are perturbed by its {gamma}-soft shape. The experimental evidences, including our recent angular correlation studies are presented along with what these new bands are telling us about the evolving collective structures and deformation in this region.

  11. NIST Calibration of a Neutron Spectrometer ROSPEC.

    PubMed

    Heimbach, Craig

    2006-01-01

    A neutron spectrometer was acquired for use in the measurement of National Institute of Standards and Technology neutron fields. The spectrometer included options for the measurement of low and high energy neutrons, for a total measurement range from 0.01 eV up to 17 MeV. The spectrometer was evaluated in calibration fields and was used to determine the neutron spectrum of an Americium-Beryllium neutron source. The calibration fields used included bare and moderated (252)Cf, monoenergetic neutron fields of 2.5 MeV and 14 MeV, and a thermal-neutron beam. Using the calibration values determined in this exercise, the spectrometer gives a good approximation of the neutron spectrum, and excellent values for neutron fluence, for all NIST calibration fields. The spectrometer also measured an Americium-Beryllium neutron field in a NIST exposure facility and determined the field quite well. The spectrometer measured scattering effects in neutron spectra which previously could be determined only by calculation or integral measurements.

  12. Calibration of indium response functions in an Au-In-BSE system up to 800 MeV.

    PubMed

    Wang, Zhonglu; Howell, Rebecca M; Burgett, Eric A; Kry, Stephen F; Hertel, Nolan E; Salehpour, Mohammad

    2010-06-01

    Calibration of the response functions of a gold (Au)-indium (In) dual foil Bonner sphere extended (BSE) system was described. The response of the In and Au foil of the system was calculated using MCNPX code with different activation cross-sectional libraries: (ACTL and ENDF VI for gold and ACTL and 532DOS2 for In). To verify and correct the calculated response functions the Bonner sphere set (BSS) was irradiated using (252)Cf and (241)AmBe sources of known neutron strengths for neutrons ranging from thermal to 20 MeV, and was irradiated at the 800-MeV neutron beam of the Los Alamos Neutron Science Center. The neutron spectrum of the 800 MeV beam was determined using time-of-flight (TOF) technique. We observed that the uncertainty of activation cross section in the resonance region can result in great uncertainty in the MCNPX-calculated response functions of activation foil-based BSS. The MCNPX-calculated response functions must be corrected using neutron sources of known spectrum and strength.

  13. Study of a nTHGEM-based thermal neutron detector

    NASA Astrophysics Data System (ADS)

    Li, Ke; Zhou, Jian-Rong; Wang, Xiao-Dong; Xiong, Tao; Zhang, Ying; Xie, Yu-Guang; Zhou, Liang; Xu, Hong; Yang, Gui-An; Wang, Yan-Feng; Wang, Yan; Wu, Jin-Jie; Sun, Zhi-Jia; Hu, Bi-Tao

    2016-07-01

    With new generation neutron sources, traditional neutron detectors cannot satisfy the demands of the applications, especially under high flux. Furthermore, facing the global crisis in 3He gas supply, research on new types of neutron detector as an alternative to 3He is a research hotspot in the field of particle detection. GEM (Gaseous Electron Multiplier) neutron detectors have high counting rate, good spatial and time resolution, and could be one future direction of the development of neutron detectors. In this paper, the physical process of neutron detection is simulated with Geant4 code, studying the relations between thermal conversion efficiency, boron thickness and number of boron layers. Due to the special characteristics of neutron detection, we have developed a novel type of special ceramic nTHGEM (neutron THick GEM) for neutron detection. The performance of the nTHGEM working in different Ar/CO2 mixtures is presented, including measurements of the gain and the count rate plateau using a copper target X-ray source. A detector with a single nTHGEM has been tested for 2-D imaging using a 252Cf neutron source. The key parameters of the performance of the nTHGEM detector have been obtained, providing necessary experimental data as a reference for further research on this detector. Supported by National Natural Science Foundation of China (11127508, 11175199, 11205253, 11405191), Key Laboratory of Neutron Physics, CAEP (2013DB06, 2013BB04) and CAS (YZ201512)

  14. Addition of Tomographic Capabilities to NMIS

    SciTech Connect

    Mullens, J.A.

    2003-03-11

    This paper describes tomographic capabilities for the Nuclear Materials Identification System (NMIS). The tomographic capabilities add weapons component spatial and material properties information that result in a more detailed item signature (template) and provide more information for physical attributes analyses. The Nuclear Materials Identification System (NMIS) is used routinely to confirm the identity of HEU components in sealed containers. It does this through a radiation signature acquired by shining a {sup 252}Cf source through the container and measuring the radiation at four detectors stacked vertically on the other side. This measurement gives a gamma and neutron radiation transmission profile of the weapons component, mixed with the radiation production due to the induced fissions in the fissile materials. This information is sufficient to match an ''unknown'' weapons component signature to a template signature from a reference item when measuring under controlled conditions. Tomography measures the interior of an item by making transmission measurements from all angles around the item, whereas NMIS makes the measurements from a single angle. Figure 1 is a standard example of tomographic reconstruction, the Shepp-Logan human brain phantom. The measured quantity is attenuation so high values (white) are highly attenuating areas.

  15. Design and verification of the shielding around the new Neutron Standards Laboratory (LPN) at CIEMAT.

    PubMed

    Méndez-Villafañe, R; Guerrero, J E; Embid, M; Fernández, R; Grandio, R; Pérez-Cejuela, P; Márquez, J L; Alvarez, F; Ortego, P

    2014-10-01

    The construction of the new Neutron Standards Laboratory at CIEMAT (Laboratorio de Patrones Neutrónicos) has been finalised and is ready to provide service. The facility is an ∼8 m×8 m×8 m irradiation vault, following the International Organization for Standardization 8529 recommendations. It relies on several neutron sources: a 5-GBq (5.8× 10(8) s(-1)) (252)Cf source and two (241)Am-Be neutron sources (185 and 11.1 GBq). The irradiation point is located 4 m over the ground level and in the geometrical centre of the room. Each neutron source can be moved remotely from its storage position inside a water pool to the irradiation point. Prior to this, an important task to design the neutron shielding and to choose the most appropriate materials has been developed by the Radiological Security Unit and the Ionizing Radiations Metrology Laboratory. MCNPX was chosen to simulate the irradiation facility. With this information the walls were built with a thickness of 125 cm. Special attention was put on the weak points (main door, air conditioning system, etc.) so that the ambient dose outside the facility was below the regulatory limits. Finally, the Radiation Protection Unit carried out a set of measurements in specific points around the installation with an LB6411 neutron monitor and a Reuter-Stokes high-pressure ion chamber to verify experimentally the results of the simulation.

  16. Comparing standard Bonner spheres and high-sensitivity Bonner cylinders.

    PubMed

    Lee, Kuo-Wei; Yuan, Ming-Chen; Jiang, Shiang-Huei; Sheu, Rong-Jiun

    2014-10-01

    Standard Bonner spheres and proposed high-sensitivity Bonner cylinders were calibrated in a neutron calibration room, using a (252)Cf source. The Bonner sphere system consists of 11 polyethylene (PE) spheres of various diameters and 4 extended spheres that comprise embedded metal shells. Similar to the design of Bonner spheres, a set of Bonner cylinders was assembled using a large cylindrical (3)He tube as the central probe, which was wrapped using various thicknesses of PE. A layer of lead was employed inside one of the PE cylinders to increase the detection efficiency of high-energy neutrons. The central neutron probe used in the Bonner cylinders exhibited an efficiency of ∼17.9 times higher than that of the Bonner spheres. However, compared with the Bonner spheres, the Bonner cylinders are not fully symmetric in their geometry, exhibiting angular dependence in their responses to incoming neutrons. Using a series of calculations and measurements, this study presents a systematic comparison between Bonner spheres and cylinders in terms of their response functions, detection efficiencies, angular dependences and spectrum unfolding.

  17. Precision mass measurements of neutron-rich nuclei, and limitations on the r-process environment

    NASA Astrophysics Data System (ADS)

    Van Schelt, Jonathon A.

    2012-05-01

    The masses of 65 neutron-rich nuclides and 6 metastable states from Z = 49 to 64 were measured at a typical precision of δm/m= 10-7 using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. The measurements are on fission fragments from 252Cf spontaneous fission sources, including those measurements made at the new Californium Rare Isotope Breeder Upgrade facility (CARIBU) and an earlier source. The measured nuclides lie on or approach the predicted path of the astrophysical r process. Where overlap exists, this data set is largely consistent with previous measurements from Penning traps, storage rings, and reaction energetics, but large systematic deviations are apparent in β-endpoint measurements. Simulations of the r process were undertaken to determine how quickly material can pass through the studied elements for a variety of conditions, placing limits on what temperatures densities allow passage on a desired timescale. The new masses produce manifold differences in effective lifetime compared to simulations performed with some model masses.

  18. Organic scintillation detector response simulation using non-analog MCNPX-PoliMi

    SciTech Connect

    Prasad, S.; Clarke, S. D.; Pozzi, S. A.; Larsen, E. W.

    2012-07-01

    Organic liquid scintillation detectors are valuable for the detection of special nuclear material since they are capable of detecting both neutrons and gamma rays. Scintillators can also provide energy information which is helpful in identification and characterization of the source. In order to design scintillation based measurement systems appropriate simulation tools are needed. MCNPX-PoliMi is capable of simulating scintillation detector response; however, simulations have traditionally been run in analog mode which leads to long computation times. In this paper, non-analog MCNPX-PoliMi mode which uses variance reduction techniques is applied and tested. The non-analog MCNPX-PoliMi simulation test cases use source biasing, geometry splitting and a combination of both variance reduction techniques to efficiently simulate pulse height distribution and then time-of-flight for a heavily shielded case with a {sup 252}Cf source. An improvement factor (I), is calculated for distributions in each of the three cases above to analyze the effectiveness of the non-analog MCNPX-PoliMi simulations in reducing computation time. It is found that of the three cases, the last case which uses a combination of source biasing and geometry splitting shows the most improvement in simulation run time for the same desired variance. For pulse height distributions speedup ranging from a factor 5 to 25 is observed, while for time-of-flights the speedup factors range from 3 to 10. (authors)

  19. γ -soft 146Ba and the role of nonaxial shapes at N ≈90

    NASA Astrophysics Data System (ADS)

    Mitchell, A. J.; Lister, C. J.; McCutchan, E. A.; Albers, M.; Ayangeakaa, A. D.; Bertone, P. F.; Carpenter, M. P.; Chiara, C. J.; Chowdhury, P.; Clark, J. A.; Copp, P.; David, H. M.; Deo, A. Y.; DiGiovine, B.; D'Olympia, N.; Dungan, R.; Harding, R. D.; Harker, J.; Hota, S. S.; Janssens, R. V. F.; Kondev, F. G.; Liu, S. H.; Ramayya, A. V.; Rissanen, J.; Savard, G.; Seweryniak, D.; Shearman, R.; Sonzogni, A. A.; Tabor, S. L.; Walters, W. B.; Wang, E.; Zhu, S.

    2016-01-01

    Low-spin states in the neutron-rich, N =90 nuclide 146Ba were populated following β decay of 146Cs, with the goal of clarifying the development of deformation in barium isotopes through delineation of their nonyrast structures. Fission fragments of 146Cs were extracted from a 1.7-Ci 252Cf source and mass selected using the CAlifornium Rare Ion Breeder Upgrade (CARIBU) facility. Low-energy ions were deposited at the center of a box of thin β detectors, surrounded by a highly efficient high-purity Ge array. The new 146Ba decay scheme now contains 31 excited levels extending up to ˜2.5 MeV excitation energy, double what was previously known. These data are compared to predictions from the interacting boson approximation (IBA) model. It appears that the abrupt shape change found at N =90 in Sm and Gd is much more gradual in Ba and Ce, due to an enhanced role of the γ degree of freedom.

  20. Three-cluster model for the {alpha}-accompanied fission of californium nuclei

    SciTech Connect

    Manimaran, K.; Balasubramaniam, M.

    2009-02-15

    A three-cluster model is proposed to explain the particle-accompanied binary fission of radioactive nuclei. The model is developed as an extension of the preformed cluster model of Gupta and collaborators. The advantage of this model is that, for a fixed third fragment, we can calculate the fragmentation potential minimized in charge coordinate. For our study we chose the various neutron-deficient to neutron-rich californium nuclei, whose analysis reveals that the closed-shell effect of any one of the fragments in ternary fragmentation presents itself as the most favorable configuration to be observed. As one goes from a neutron-deficient to a neutron-rich californium isotope, the role of the neutron closed shell associated with any one of the preferred fragments changes to that of the proton closed shell, and for very neutron rich isotopes of californium the presence of a double closed shell nucleus enhances the decay probability. The quadrupole deformation of the light fragment (A{sub 2}) associated with the preferred configuration in the symmetric mass region also has a transition from positive to negative deformation as one goes from neutron-deficient to neutron-rich californium isotopes. The calculated relative yields of different fragmentation channels are compared with the available experimental yields for {sup 252}Cf.

  1. Spontaneous Partitioning of Californium from Curium: Curious Cases from the Crystallization of Curium Coordination Complexes.

    PubMed

    Cary, Samantha K; Silver, Mark A; Liu, Guokui; Wang, Jamie C; Bogart, Justin A; Stritzinger, Jared T; Arico, Alexandra A; Hanson, Kenneth; Schelter, Eric J; Albrecht-Schmitt, Thomas E

    2015-12-01

    The reaction of (248)CmCl3 with excess 2,6-pyridinedicarboxylic acid (DPA) under mild solvothermal conditions results in crystallization of the tris-chelate complex Cm(HDPA)3 · H2O. Approximately half of the curium remains in solution at the end of this process, and evaporation of the mother liquor results in crystallization of the bis-chelate complex [Cm(HDPA)(H2DPA)(H2O)2Cl]Cl·2H2O. (248)Cm is the daughter of the α decay of (252)Cf and is extracted in high purity from this parent. However, trace amounts of (249,250,251)Cf are still present in all samples of (248)Cm. During the crystallization of Cm(HDPA)3 · H2O and [Cm(HDPA)(H2DPA)(H2O)2Cl]Cl · 2H2O, californium(III) spontaneously separates itself from the curium complexes and is found doped within crystals of DPA in the form of Cf(HDPA)3. These results add to the growing body of evidence that the chemistry of californium is fundamentally different from that of earlier actinides.

  2. Operational experience with the Argonne National Laboratory Californium Rare Ion Breeder Upgrade facility and electron cyclotron resonance charge breeder.

    PubMed

    Vondrasek, R; Clark, J; Levand, A; Palchan, T; Pardo, R; Savard, G; Scott, R

    2014-02-01

    The Californium Rare Ion Breeder Upgrade (CARIBU) of the Argonne National Laboratory Argonne Tandem Linac Accelerator System (ATLAS) facility provides low-energy and accelerated neutron-rich radioactive beams to address key nuclear physics and astrophysics questions. A 350 mCi (252)Cf source produces fission fragments which are thermalized and collected by a helium gas catcher into a low-energy particle beam with a charge of 1+ or 2+. An electron cyclotron resonance (ECR) ion source functions as a charge breeder in order to raise the ion charge sufficiently for acceleration in the ATLAS linac. The ECR charge breeder has achieved stable beam charge breeding efficiencies of 10.1% for (23)Na(7+), 17.9% for (39)K(10+), 15.6% for (84)Kr(17+), and 12.4% for (133)Cs(27+). For the radioactive beams, a charge breeding efficiency of 11.7% has been achieved for (143)Cs(27+) and 14.7% for (143)Ba(27+). The typical breeding times are 10 ms/charge state, but the source can be tuned such that this value increases to 100 ms/charge state with the best breeding efficiency corresponding to the longest breeding times-the variation of efficiencies with breeding time will be discussed. Efforts have been made to characterize and reduce the background contaminants present in the ion beam through judicious choice of q/m combinations. Methods of background reduction are being investigated based upon plasma chamber cleaning and vacuum practices.

  3. NIST Calibration of a Neutron Spectrometer ROSPEC

    PubMed Central

    Heimbach, Craig

    2006-01-01

    A neutron spectrometer was acquired for use in the measurement of National Institute of Standards and Technology neutron fields. The spectrometer included options for the measurement of low and high energy neutrons, for a total measurement range from 0.01 eV up to 17 MeV. The spectrometer was evaluated in calibration fields and was used to determine the neutron spectrum of an Americium-Beryllium neutron source. The calibration fields used included bare and moderated 252Cf, monoenergetic neutron fields of 2.5 MeV and 14 MeV, and a thermal-neutron beam. Using the calibration values determined in this exercise, the spectrometer gives a good approximation of the neutron spectrum, and excellent values for neutron fluence, for all NIST calibration fields. The spectrometer also measured an Americium-Beryllium neutron field in a NIST exposure facility and determined the field quite well. The spectrometer measured scattering effects in neutron spectra which previously could be determined only by calculation or integral measurements. PMID:27274944

  4. Radioactive beams from Californium fission at the CARIBU facility

    NASA Astrophysics Data System (ADS)

    Savard, Guy; Pardo, Richard; Baker, Sam; Davids, Cary; Peterson, Don; Phillips, Don; Vondrasek, Rick; Zabransky, Bruce; Zinkann, Gary

    2009-10-01

    The Californium Rare Ion Breeder Upgrade (CARIBU) of the ATLAS superconducting linac facility aims at providing low energy and reaccelerated neutron-rich radioactive beams to address key nuclear physics and astrophysics questions. These beams are obtained from fission fragments of a 1 Ci ^252Cf source, thermalized and collected into a low-energy particle beam by a helium gas catcher, mass analyzed by an isobar separator, and charge breed to higher charge states for acceleration in ATLAS. The method described is fast and universal and short-lived isotope yield scale essentially with Californium fission yields. Expected intensities of reaccelerated beams are up to ˜5x10^5 (10^7 at low energy) far-from-stability ions per second on target. Initial commissioning is being performed with weaker 2.5 and 80 mCi sources. Commissioning results, together with the nuclear physics and astrophysics program that will be pursued with the neutron-rich beams made available, will be presented. Plans for installation of the 1 Ci source will be discussed.

  5. Precision Mass Measurements at CARIBU

    NASA Astrophysics Data System (ADS)

    Lascar, D.; van Schelt, J.; Savard, G.; Caldwell, S.; Chaudhuri, A.; Clark, J. A.; Levand, A. F.; Li, G.; Sternberg, M.; Sun, T.; Zabransky, B. J.; Segel, R.; Sharma, K.

    2010-02-01

    Neutron separation energies (Sn) are essential inputs to models of explosive r-process nucleosynthesis. However, for nuclei farther from stability, the precision of Sn decreases as production decreases and observation of those nuclei become more difficult. Many of the most critical inputs to the models are based on extrapolations from measurements of masses closer to stability than the predicted r-process path. Measuring masses that approach and lie on the predicted r-process path will further constrain the systematic uncertainties in these extrapolated values. The Canadian Penning Trap Mass Spectrometer (CPT) at Argonne National Laboratory (ANL) has measured the masses of more than 160 nuclei to high precision. A recent move to the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) at ANL has given the CPT unique access to weakly produced nuclei that cannot be easily reached via proton induced fission of ^238U. CARIBU will eventually use a 1 Ci source of ^252Cf to produce these nuclei. Installation of the CPT at CARIBU as well as the first CPT mass measurements of neutron rich nuclei at CARIBU will be discussed. )

  6. First results from CARIBU

    NASA Astrophysics Data System (ADS)

    Savard, Guy

    2011-10-01

    The Californium Rare Ion Breeder Upgrade (CARIBU) of the ATLAS superconducting linac facility aims at providing low energy and reaccelerated neutron-rich radioactive beams to address key nuclear physics, astrophysics and application issues. These beams are obtained from fission fragments of a 1 Ci 252Cf source, thermalized and collected into a low-energy particle beam by a helium gas catcher, mass analyzed by an isobar separator, and charge breed to higher charge states for acceleration in ATLAS. The method described is fast and universal and short-lived isotope yield scale essentially with Californium fission yields. The facility is now commissioned and operating with a 100 mCi source which has yielded extracted low-energy mass separated radioactive beams at intensities in excess of 100000 ions per second. Radioactive beams have been charge bred with an efficiency of up to 12% and reaccelerated to 6 MeV/u. Commissioning results, together with the results from first astrophysics experiments at CARIBU using the beams from the 100 mCi source will be presented. The final 1 Ci source is currently under fabrication and is expected to be installed by the end of the year. This work was supported by the US DOE, Office of Nuclear Physics, under contract DE-AC02-06CH11357.

  7. Development and commissioning of the CARIBU project

    NASA Astrophysics Data System (ADS)

    Sun, Tao; Savard, G.; Pardo, R. C.; Baker, S.; Davids, C. N.; Levand, A.; Peterson, D.; Phillips, D. R.; Vondrasek, R.; Zabransky, B.; Zinkann, G. P.

    2010-02-01

    The Californium Rare Ion Breeder Upgrade (CARIBU) will enhance the radioactive beam capability of the ATLAS accelerator by providing high quality neutron-rich beam from a ^252Cf fission. The whole apparatus consists of four main components: 1)A Helium filled gas catcher and RFQ ion cooler that thermalizes fission products and forms a low-energy ion beam; 2)An isobar separator that magnetically purifies ion cocktails to a mass resolution of approximately 1/20000; 3)A charge breeder ECR ion source where ions of low charge states are further ionized by electron bombardment in the plasma; 4)A low energy experimental area where ions are trapped and bunched to suit high precision experiments. Ion optical simulations for CARIBU ion cooling, bunching and transmission will be presented. Experimental results from commissioning will be compared with the corresponding calculations. Other technical details of the facility and insight gained in its commissioning will also be presented. Current status of CARIBU will be given. )

  8. Some more new etchants for CR-39 detector.

    PubMed

    Matiullah; Rehman, S; Rehman, S; Mati, N; Ahmad, S

    2005-10-01

    Recently, several new etchants have been reported for CR-39 detector (Molten Ba(OH)2. 8H2O as an etchant for CR-39 detector, Radiat. Meas. 37 (2003) 205; Discovery of new etchants for CR-39 detector, Radiat. Meas. (2004)). We have made further progress in this direction and have unveiled two more new etchants which are reported in this article. CR-39 detectors were irradiated with fission fragments and alpha particles from a thin 252Cf disc source. The irradiated detectors were then etched in our newly introduced etching solutions as well as in conventionally used 6 M NaOH aqueous solution at 70 degrees C. The newly prepared etching solutions included NaOH dissolved in methanol and NaOH dissolved in methanol + water. Optimum values of NaOH concentration in methanol as well as in methanol + water were determined. Optimum etching temperatures were also determined for both the above-mentioned etchants. From fission and alpha track diameters, bulk etching rate (VB), track etching rate (VT) and etching efficiency (eta) were determined and compared with that obtained for 6 M NaOH at 70 degrees C. Both the newly introduced etchants were found more efficient than the conventionally used 6 M aqueous NaOH (64%) at 70 degrees C and have relatively much smaller etching time.

  9. Commissioning and first radioactive beam experiments at the CARIBU facility

    NASA Astrophysics Data System (ADS)

    Savard, Guy; Baker, Sam; Caldwell, Shane; Clark, Jason; Davids, Cary; Lascar, Daniel; Levand, Anthony; Pardo, Richard; Peterson, Donald; Phillips, Don; Sternberg, Matthew; Sun, Tao; van Schelt, Jon; Vondrasek, Rick; Zabransky, Bruce

    2011-04-01

    The Californium Rare Ion Breeder Upgrade (CARIBU) of the ATLAS superconducting linac facility aims at providing low energy and reaccelerated neutron-rich radioactive beams to address key nuclear physics and astrophysics questions. These beams are obtained from fission fragments of a 1 Ci 252Cf source, thermalized and collected into a low-energy particle beam by a helium gas catcher, mass analyzed by an isobar separator, and charge breed to higher charge states for acceleration in ATLAS. The facility has ramped up with first operation with a weaker 2.5 mCi source and now a 100 mCi source. Low-energy mass separated radioactive beams have been extracted, charge bred with an efficiency of about 8%, and reaccelerated to 6 MeV/u. Commissioning results, together with the results from first astrophysics experiments at CARIBU using the beams from the 100 mCi source will be presented. The final 1 Ci source is expected to be available in the spring. This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract No. DE-AC02-06CH11357.

  10. High-spin structure and multiphonon {gamma} vibrations in very neutron-rich {sup 114}Ru

    SciTech Connect

    Yeoh, E. Y.; Wang, J. G.; Ding, H. B.; Gu, L.; Xu, Q.; Xiao, Z. G.; Zhu, S. J.; Hamilton, J. H.; Li, K.; Ramayya, A. V.; Hwang, J. K.; Liu, Y. X.; Liu, S. H.; Sheikh, J. A.; Bhat, G. H.; Luo, Y. X.; Rasmussen, J. O.; Lee, I. Y.; Ma, W. C.

    2011-05-15

    High-spin levels of the neutron-rich {sup 114}Ru have been investigated by measuring the prompt {gamma} rays in the spontaneous fission of {sup 252}Cf. The ground-state band and one-phonon {gamma}-vibrational band have been extended up to 14{sup +} and 9{sup +}, respectively. Two levels are proposed as the members of a two-phonon {gamma}-vibrational band. A back bending (band crossing) has been observed in the ground-state band at ({h_bar}/2{pi}){omega}{approx_equal} 0.40 MeV. Using the triaxial deformation parameters, the cranked shell model calculations indicate that this back bending in {sup 114}Ru should originate from the alignment of a pair of h{sub 11/2} neutrons. Triaxial projected shell model calculations for the {gamma}-vibrational band structures of {sup 114}Ru are in good agreement with the experimental data. However, when using the oblate deformation parameters, both of the above-calculated results are not in agreement with the experimental data.

  11. Investigation of phenomenological models for the Monte Carlo simulation of the prompt fission neutron and {gamma} emission

    SciTech Connect

    Litaize, O.; Serot, O.

    2010-11-15

    A Monte Carlo simulation of the fission fragment deexcitation process was developed in order to analyze and predict postfission-related nuclear data which are of crucial importance for basic and applied nuclear physics. The basic ideas of such a simulation were already developed in the past. In the present work, a refined model is proposed in order to make a reliable description of the distributions related to fission fragments as well as to prompt neutron and {gamma} energies and multiplicities. This refined model is mainly based on a mass-dependent temperature ratio law used for the initial excitation energy partition of the fission fragments and a spin-dependent excitation energy limit for neutron emission. These phenomenological improvements allow us to reproduce with a good agreement the {sup 252}Cf(sf) experimental data on prompt fission neutron multiplicity {nu}(A), {nu}(TKE), the neutron multiplicity distribution P({nu}), as well as their energy spectra N(E), and lastly the energy release in fission.

  12. Improved charge breeding efficiency of light ions with an electron cyclotron resonance ion source

    NASA Astrophysics Data System (ADS)

    Vondrasek, R.; Delahaye, P.; Kutsaev, Sergey; Maunoury, L.

    2012-11-01

    The Californium Rare Isotope Breeder Upgrade is a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS). The facility utilizes a 252Cf fission source coupled with an electron cyclotron resonance ion source to provide radioactive beam species for the ATLAS experimental program. The californium fission fragment distribution provides nuclei in the mid-mass range which are difficult to extract from production targets using the isotope separation on line technique and are not well populated by low-energy fission of uranium. To date the charge breeding program has focused on optimizing these mid-mass beams, achieving high charge breeding efficiencies of both gaseous and solid species including 14.7% for the radioactive species 143Ba27+. In an effort to better understand the charge breeding mechanism, we have recently focused on the low-mass species sodium and potassium which up to present have been difficult to charge breed efficiently. Unprecedented charge breeding efficiencies of 10.1% for 23Na7+ and 17.9% for 39K10+ were obtained injecting stable Na+ and K+ beams from a surface ionization source.

  13. Realization of highly efficient hexagonal boron nitride neutron detectors

    NASA Astrophysics Data System (ADS)

    Maity, A.; Doan, T. C.; Li, J.; Lin, J. Y.; Jiang, H. X.

    2016-08-01

    We report the achievement of highly efficient 10B enriched hexagonal boron nitride (h-10BN) direct conversion neutron detectors. These detectors were realized from freestanding 4-in. diameter h-10BN wafers 43 μm in thickness obtained from epitaxy growth and subsequent mechanical separation from sapphire substrates. Both sides of the film were subjected to ohmic contact deposition to form a simple vertical "photoconductor-type" detector. Transport measurements revealed excellent vertical transport properties including high electrical resistivity (>1013 Ω cm) and mobility-lifetime (μτ) products. A much larger μτ product for holes compared to that of electrons along the c-axis of h-BN was observed, implying that holes (electrons) behave like majority (minority) carriers in undoped h-BN. Exposure to thermal neutrons from a californium-252 (252Cf) source moderated by a high density polyethylene moderator reveals that 43 μm h-10BN detectors possess 51.4% detection efficiency at a bias voltage of 400 V, which is the highest reported efficiency for any semiconductor-based neutron detector. The results point to the possibility of obtaining highly efficient, compact solid-state neutron detectors with high gamma rejection and low manufacturing and maintenance costs.

  14. Development of neutron measurement in high gamma field using new nuclear emulsion

    SciTech Connect

    Kawarabayashi, J.; Ishihara, K.; Takagi, K.; Tomita, H.; Iguchi, T.; Naka, T.; Morishima, K.; Maeda, S.

    2011-07-01

    To precisely measure the neutron emissions from a spent fuel assembly of a fast breeder reactor, we formed nuclear emulsions based on a non-sensitized Oscillation Project with Emulsion tracking Apparatus (OPERA) film with AgBr grain sizes of 60, 90, and 160 nm. The efficiency for {sup 252}Cf neutron detection of the new emulsion was calculated to be 0.7 x 10{sup -4}, which corresponded to an energy range from 0.3 to 2 MeV and was consistent with a preliminary estimate based on experimental results. The sensitivity of the new emulsion was also experimentally estimated by irradiating with 565 keV and 14 MeV neutrons. The emulsion with an AgBr grain size of 60 nm had the lowest sensitivity among the above three emulsions but was still sensitive enough to detect protons. Furthermore, the experimental data suggested that there was a threshold linear energy transfer of 15 keV/{mu}m for the new emulsion, below which no silver clusters developed. Further development of nuclear emulsion with an AgBr grain size of a few tens of nanometers will be the next stage of the present study. (authors)

  15. Neutron-Rich Nuclei Beyond {sup 132}Sn: Spherical Shapes and Octupole Correlations

    SciTech Connect

    Liu Shaohua; Hamilton, Joseph H.; Ramayya, Akunuri V.; Goodin, Christopher T.; Hwang, Jae-Kwang; Luo Yixiao; Rasmussen, John O.; Covello, Aldo; Gargano, Angel; Stone, Nick J.; Daniel, Andrey V.; Ter-Akopian, Gurgen M.; Oganessian, Yuri Ts.; Zhu Shengjiang

    2010-04-30

    Nuclear properties of nuclei with a few valence nucleons outside the doubly-magic {sup 132}Sn core and located in the octupole correlation region have been investigated via gamma-gamma-gamma coincidence measurements of prompt gamma-ray emitted in the spontaneous fission of {sup 252}Cf with Gammasphere. The high spin level scheme of {sup 134}I has been identified for the first time. Shell model calculations reproduce the level scheme quite well. The level schemes of {sup 137}I and {sup 139}Cs have been reinvestigated and extended. Their nuclear structure is well described by realistic shell model calculations. The g-factors of the 4{sup +} state in {sup 134}Te, 15/2{sup +} state in {sup 135}I, and 15/2{sup -} state in {sup 137}Xe were determined using a newly developed program for angular correlation analysis. The measured g-factors compared favorably with shell model calculations. Octupole correlations are proposed in {sup 141}Cs and {sup 142}Cs. The variations of D{sub 0} in the Cs isotopes exhibit a pronounced drop of dipole moment with increasing neutron number.

  16. Fission fragment mass and energy distributions as a function of incident neutron energy measured in a lead slowing-down spectrometer

    SciTech Connect

    Romano, C.; Danon, Y.; Block, R.; Thompson, J.; Blain, E.; Bond, E.

    2010-01-15

    A new method of measuring fission fragment mass and energy distributions as a function of incident neutron energy in the range from below 0.1 eV to 1 keV has been developed. The method involves placing a double-sided Frisch-gridded fission chamber in Rensselaer Polytechnic Institute's lead slowing-down spectrometer (LSDS). The high neutron flux of the LSDS allows for the measurement of the energy-dependent, neutron-induced fission cross sections simultaneously with the mass and kinetic energy of the fission fragments of various small samples. The samples may be isotopes that are not available in large quantities (submicrograms) or with small fission cross sections (microbarns). The fission chamber consists of two anodes shielded by Frisch grids on either side of a single cathode. The sample is located in the center of the cathode and is made by depositing small amounts of actinides on very thin films. The chamber was successfully tested and calibrated using 0.41+-0.04 ng of {sup 252}Cf and the resulting mass distributions were compared to those of previous work. As a proof of concept, the chamber was placed in the LSDS to measure the neutron-induced fission cross section and fragment mass and energy distributions of 25.3+-0.5 mug of {sup 235}U. Changes in the mass distributions as a function of incident neutron energy are evident and are examined using the multimodal fission mode model.

  17. [The CT-stereotaxic neutron brachytherapy of brain tumors with californium sources on the ANET-B apparatus].

    PubMed

    Melikian, A G; Liass, F M; Shkol'nik, F G; Chekhonadskiĭ, V N; Elisiutin, G P; Golanov, A V; Kachkov, I A; Borodkin, S M; Lobanov, S A; Spasokukotskaia, O N

    1992-01-01

    A method for stereotaxic intratissue radiotherapy of brain tumors based on the findings of computed tomography is described. Radiosurgical implantation of sources with increased 252Cf content emitting mixed neutron + gamma-radiation was accomplished by means of an ANET-B apparatus by the afterloading method. Neutron irradiation is particularly effective in patients with malignant tumors possessing a large fraction of cells in a state of deep anoxia. Dosimetric planning was conducted by means of an original computer system. Devices and radiation-technical equipment for adaptation of the ANET-B apparatus for irradiation of neurosurgical patients are described. The indications for the use of this method and its place among the complex of measures for the treatment of patients with new growths of the brain are discussed. The first experience in using CT-stereotaxic neutron brachytherapy with californium sources on the ANET-B apparatus for the treatment of 6 patients with malignant glial tumors of the brain is dwelt on.

  18. Mass spectrometric peptide mapping analysis and structural characterization of dihydrodiol dehydrogenase isoenzymes.

    PubMed Central

    Gauss, C; Klein, J; Post, K; Suckau, D; Schneider, K; Thomas, H; Oesch, F; Przybylski, M

    1990-01-01

    The direct molecular weight determination and structural analysis of polypeptides and peptide mixtures have become amenable by the recent development of fast atom bombardment (FABMS) and 252Cf-plasma desorption (PDMS) mass spectrometry. FABMS and PDMS peptide mapping, i.e., the direct analysis of peptide mixtures resulting from proteolytic digestion, have been developed as powerful methods for the structural characterization of epoxide-metabolizing isoenzymes. The major advantage of this approach is provided by the selectivity of the endoproteolytic cleavage, combined with the specific and accurate molecular weight determination of complex digest mixtures containing peptides up to several thousands daltons in size. Furthermore, the mass spectrometric peptide mapping analysis can be combined with a range of protein-chemical modification reactions and with sequential degradation such as by carboxypeptidases. Both FABMS and PDMS peptide mapping have already been successfully applied to the structural differentiation of glutathione transferase and epoxide hydrolase isoenzymes in cases where references sequence data for at least one isoenzyme form was available. In the application described here, for a series of dihydrodiol dehydrogenase (DDH) isoenzymes with hitherto undetermined primary structures, a direct correlation between the structural differentiation from peptide mapping data and differences in their substrate specificities could be demonstrated. The mass spectrometric peptide mapping analysis of isoenzymes proved to be an efficient basis for the elucidation of the structure of one major DDH isoenzyme form; partial sequence data for this protein are reported. PMID:2272334

  19. High-Resistivity Semi-insulating AlSb on GaAs Substrates Grown by Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Vaughan, E. I.; Addamane, S.; Shima, D. M.; Balakrishnan, G.; Hecht, A. A.

    2016-04-01

    Thin-film structures containing AlSb were grown using solid-source molecular beam epitaxy and characterized for material quality, carrier transport optimization, and room-temperature radiation detection response. Few surface defects were observed, including screw dislocations resulting from shear strain between lattice-mismatched layers. Strain was also indicated by broadening of the AlSb peak in x-ray diffraction measurements. Threading dislocations and interfacial misfit dislocations were seen with transmission electron microscopy imaging. Doping of the AlSb layer was introduced during growth using GaTe and Be to determine the effect on Hall transport properties. Hall mobility and resistivity were largest for undoped AlSb samples, at 3000 cm2/V s and 106 Ω cm, respectively, and increased doping levels progressively degraded these values. To test for radiation response, p-type/intrinsic/ n-type (PIN) diode structures were grown using undoped AlSb on n-GaAs substrates, with p-GaSb cap layers to protect the AlSb from oxidation. Alpha-particle radiation detection was achieved and spectra were produced for 241Am, 252Cf, and 239Pu sources. Reducing the detector surface area increased the pulse height observed, as expected based on voltage-capacitance relationships for diodes.

  20. Properties of true quaternary fission of nuclei with allowance for its multistep and sequential character

    NASA Astrophysics Data System (ADS)

    Kadmensky, S. G.; Titova, L. V.; Bulychev, A. O.

    2015-07-01

    An analysis of basicmechanisms of binary and ternary fission of nuclei led to the conclusion that true ternary and quaternary fission of nuclei has a sequential two-step (three-step) character, where, at the first step, a fissile nucleus emits a third light particle (third and fourth light particles) under shakeup effects associated with a nonadiabatic character of its collective deformation motion, whereupon the residual nucleus undergoes fission to two fission fragments. Owing to this, the formulas derived earlier for the widths with respect to sequential two- and three-step decays of nuclei in constructing the theory of two-step twoproton decays and multistep decays in chains of genetically related nuclei could be used to describe the relative yields and angular and energy distributions of third and fourth light particles emitted in ( α, α), ( t, t), and ( α, t) pairs upon the true quaternary spontaneous fission of 252Cf and thermal-neutron-induced fission of 235U and 233U target nuclei. Mechanisms that explain a sharp decrease in the yield of particles appearing second in time and entering into the composition of light-particle pairs that originate from true quaternary fission of nuclei in relation to the yields of analogous particles in true ternary fission of nuclei are proposed.

  1. Spontaneous fission of the heaviest elements

    SciTech Connect

    Hoffman, D.C.

    1989-04-01

    Although spontaneous fission was discovered in /sup 238/U in 1940, detailed studies of the process were first made possible in the 1960's with the availability of milligram quantities of /sup 252/Cf. The advent of solid-state detectors made it possible to perform measurements of coincident fission fragments from even very short-lived spontaneous fission activities or those available in only very small quantities. Until 1971 it was believed that the main features of the mass and kinetic-energy distributions were essentially the same as those for thermal neutron-induced fission and that all low-energy fission proceeded via asymmetric mass division with total kinetic energies which could be derived by linear extrapolation from those of lighter elements. In 1971, measurements of /sup 257/Fm showed an increase in symmetric mass division with anomalously high TKE's. Subsequent experiments showed that in /sup 258/Fm and /sup 259/Fm, the most probable mass split was symmetric with very high total kinetic energy. Measurements for the heavier elements have shown symmetric mass distributions with both high and low total kinetic energies. Recent results for spontaneous fission properties of the heaviest elements are reviewed and compared with theory. 31 refs., 8 figs., 1 tab.

  2. Improved charge breeding efficiency of light ions with an electron cyclotron resonance ion source

    SciTech Connect

    Vondrasek, R.; Kutsaev, Sergey; Delahaye, P.; Maunoury, L.

    2012-11-15

    The Californium Rare Isotope Breeder Upgrade is a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS). The facility utilizes a {sup 252}Cf fission source coupled with an electron cyclotron resonance ion source to provide radioactive beam species for the ATLAS experimental program. The californium fission fragment distribution provides nuclei in the mid-mass range which are difficult to extract from production targets using the isotope separation on line technique and are not well populated by low-energy fission of uranium. To date the charge breeding program has focused on optimizing these mid-mass beams, achieving high charge breeding efficiencies of both gaseous and solid species including 14.7% for the radioactive species {sup 143}Ba{sup 27+}. In an effort to better understand the charge breeding mechanism, we have recently focused on the low-mass species sodium and potassium which up to present have been difficult to charge breed efficiently. Unprecedented charge breeding efficiencies of 10.1% for {sup 23}Na{sup 7+} and 17.9% for {sup 39}K{sup 10+} were obtained injecting stable Na{sup +} and K{sup +} beams from a surface ionization source.

  3. High-level dosimetry at the demagnetization experiments of permanent magnets.

    PubMed

    Lee, H S; Qiu, R; Hong, S; Chung, C W; Bizen, T; Li, J

    2007-01-01

    The measurements of high-energy and high dose mixed radiation from high-energy electron accelerator are carried out using a radiation damage monitor. It consists of two Radiation-Sensing Field-Effect Transistors (RADFETs) for total absorbed dose from mainly gamma ray and other charged particles and a Si PIN diode for neutron fluence. This is a part of the demagnetization study of rare earth permanent magnet irradiated by 2.5-GeV electron beam. The sensitivities of damage detectors are measured using 65-MeV quasi-monoenergic neutron, 14-MeV D-T neutron, (252)Cf neutron for Si PIN diode and (60)Co and (137)Cs gamma ray for RADFETs. Measured sensitivities are in acceptable range in the comparison of producer's proposed values. The dose and fluence measurements are carried out for the same target condition, Cu and Ta, as that for the demagnetization study. The 5 x 5 cm(2) cross-sectional and 5.5-cm-thick Pb target is also used for the general comparison with photoneutron yields. All measured dose and fluence are compared with the calculated results using the FLUKA code and agree well each other. The application of this kind of radiation damage monitor to high-level dosimetry at high-energy electron accelerator has been discussed. PMID:17575293

  4. Registration of alpha particles in Makrofol-E nuclear track detectors

    NASA Astrophysics Data System (ADS)

    Rammah, Y. S.; Abdalla, Ayman M.; Ashraf, O.; Ashry, A. H.

    2016-06-01

    Fast detection of alpha particles in the range from 1 to 5 MeV in Makrofol-E polycarbonate nuclear track detectors (PCTDs) using a new chemical etchant was investigated. 252Cf and 241Am-thin open sources were used for irradiating Makrofol-E detectors with fission fragments and alpha particles in air at normal pressure and temperature (NPT). A chain of experimental work has been carried out using new etchants to register alpha particle in short time in Makrofol-E polycarbonate detectors. The etching efficiency were exhibited a clear dependence on the amount of methanol in the etching solution and etching time. The optimized chemical condition obtained at this stage of development for 200 μm Makrofol-E detectors are (8 ml of 10 N NaOH + 2 ml CH3OH) etching solutions at 60 °C for 3 h. In this study; it is possible to observe energy detection windows for Makrofol-E detectors according to applied etching duration. Makrofol-E introduced the characteristic Bragg peak, which indicates the advantages of this detector as alpha spectrometer. Consequently, the suggested new etchant can be developed for heavy ions detection and monitoring radon levels and its daughters.

  5. Study of the Interactions Between Transition Metal Ions and Peptides by CALIFORNIUM-252 Plasma Desorption Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Hu, Zhaohong

    This dissertation focuses on the study of interactions between transition metal ions (Cu(II), Zn(II), Pd(II), Pt(II)) and peptides (bradykinins and angiotensins). Chapter I provides an overview on the fundamental issues related to and techniques used for studying transition metal ion -peptide/protein complexes. It also reviews different mass spectroscopic techniques used for metal ion-peptide studies. Chapter II delineates the principle of ^{252 }Cf-PDMS instrumentation and the sample preparation methods utilized for this dissertation research. In order to study metal ion-peptide complexes with PDMS, it is essential to define the relationship between complex structures identified from PD mass spectra and complexes formed in solution phase. Chapter III includes the studies of the effects of solution conditions on the detection of metal ion-peptide complexes in PDMS. Solution pH is the most important factor for determining the formation of a complex. Reaction time, reactant concentration, and reaction temperature all display distinct influences on PDMS results. It demonstrates that the PDMS results are closely correlated with the complexes pre-formed in aqueous solution. Chapter IV provides ample spectroscopic data on peptides and their metal ion complexes. The metal ion -containing molecular ions observed provide information on numbers of metal ion-binding sites in a peptide and metal ion-affinity of the peptide. By analyzing fragmentation patterns, amino acid residues and functional groups involved in metal ion binding in a peptide can be identified.

  6. Development of a neutron measurement system in unified non-destructive assay for the PRIDE facility

    NASA Astrophysics Data System (ADS)

    Seo, Hee; Park, Se-Hwan; Won, Byung-Hee; Ahn, Seong-Kyu; Shin, Hee-Sung; Na, Sang-Ho; Song, Dae-Yong; Kim, Ho-Dong; Lee, Seung Kyu

    2013-12-01

    The Korea Atomic Energy Research Institute (KAERI) has made an effort to develop pyroprocessing technology to resolve an on-going problem in Korea, i.e., the management of spent nuclear fuels. To this end, a test-bed facility for pyroprocessing, called PRIDE (PyRoprocessing Integrated inactive DEmonstration facility), is being constructed at KAERI. The main objective of PRIDE is to evaluate the performance of the unit processes, remote operation, maintenance, and proliferation resistance. In addition, integrating all unit processes into a one-step process is also one of the main goals. PRIDE can also provide a good opportunity to test safeguards instrumentations for a pyroprocessing facility such as nuclear material accounting devices, surveillance systems, radiation monitoring systems, and process monitoring systems. In the present study, a non-destructive assay (NDA) system for the testing of nuclear material accountancy of PRIDE was designed by integrating three different NDA techniques, i.e., neutron, gamma-ray, and mass measurements. The developed neutron detection module consists of 56 3He tubes and 16 AMPTEK A111 signal processing circuits. The amplifiers were matched in terms of the gain and showed good uniformity after a gain-matching procedure (%RSD=0.37%). The axial and the radial efficiency distributions within the cavity were then measured using a 252Cf neutron source and were compared with the MCNPX calculation results. The measured efficiency distributions showed excellent agreement with the calculations, which confirmed the accuracy of the MCNPX model of the system.

  7. Chemical and nuclear properties of Rutherfordium (Element 104)

    SciTech Connect

    Kacher, C.D.

    1995-10-30

    The chemical-properties of rutherfordium (Rf) and its group 4 homologs were studied by sorption on glass support surfaces coated with cobalt(II)ferrocyanide and by solvent extraction with tributylphosphate (TBP) and triisooctylamine (TIOA). The surface studies showed that the hydrolysis trend in the group 4 elements and the pseudogroup 4 element, lb, decreases in the order Rf>Zr{approx}Hf>Th. This trend was attributed to relativistic effects which predicted that Rf would be more prone to having a coordination number of 6 than 8 in most aqueous solutions due to a destabilization of the 6d{sub 5/2} shell and a stabilization of the 7p{sub l/2} shell. This hydrolysis trend was confirmed in the TBP/HBr solvent extraction studies which showed that the extraction trend decreased in the order Zr>Hf>Rf?Ti for HBr, showing that Rf and Ti did not extract as well because they hydrolyzed more easily than Zr and Hf. The TIOA/HF solvent extraction studies showed that the extraction trend for the group 4 elements decreased in the order Ti>Zr{approx}Hf>Rf, in inverse order from the trend of ionic radii Rf>Zr{approx}Hf>Ti. An attempt was made to produce {sup 263}Rf (a) via the {sup 248}Cm({sup 22}Ne, {alpha}3n) reaction employing thenoyltrifluoroacetone (TTA) solvent extraction chemistry and (b) via the {sup 249}Bk({sup 18}O,4n) reaction employing the Automated Rapid Chemistry Apparatus (ARCA). In the TTA studies, 16 fissions were observed but were all attributed to {sup 256}Fm. No alpha events were observed in the Rf chemical fraction. A 0.2 nb upper limit production cross section for the {sup 248}Cm({sup 22}Ne, {alpha}3n){sup 263}Rf reaction was calculated assuming the 500-sec half-life reported previously by Czerwinski et al. [CZE92A].

  8. Applications of Skyrme energy-density functional to fusion reactions for synthesis of superheavy nuclei

    SciTech Connect

    Wang Ning; Scheid, Werner; Wu Xizhen; Liu Min; Li Zhuxia

    2006-10-15

    The Skyrme energy-density functional approach has been extended to study massive heavy-ion fusion reactions. Based on the potential barrier obtained and the parametrized barrier distribution the fusion (capture) excitation functions of a lot of heavy-ion fusion reactions are studied systematically. The average deviations of fusion cross sections at energies near and above the barriers from experimental data are less than 0.05 for 92% of 76 fusion reactions with Z{sub 1}Z{sub 2}<1200. For the massive fusion reactions, for example, the {sup 238}U-induced reactions and {sup 48}Ca+{sup 208}Pb, the capture excitation functions have been reproduced remarkably well. The influence of structure effects in the reaction partners on the capture cross sections is studied with our parametrized barrier distribution. By comparing the reactions induced by double-magic nucleus {sup 48}Ca and by {sup 32}S and {sup 35}Cl, the ''threshold-like'' behavior in the capture excitation function for {sup 48}Ca-induced reactions is explored and an optimal balance between the capture cross section and the excitation energy of the compound nucleus is studied. Finally, the fusion reactions with {sup 36}S, {sup 37}Cl, {sup 48}Ca, and {sup 50}Ti bombarding {sup 248}Cm, {sup 247,249}Bk, {sup 250,252,254}Cf, and {sup 252,254}Es, as well as the reactions leading to the same compound nucleus with Z=120 and N=182, are studied further. The calculation results for these reactions are useful for searching for the optimal fusion configuration and suitable incident energy in the synthesis of superheavy nuclei.

  9. On the scintillation efficiency of carborane-loaded liquid scintillators for thermal neutron detection

    NASA Astrophysics Data System (ADS)

    Chang, Zheng; Okoye, Nkemakonam C.; Urffer, Matthew J.; Green, Alexander D.; Childs, Kyle E.; Miller, Laurence F.

    2015-01-01

    The scintillation efficiency in response to thermal neutrons was studied by loading different concentrations of carborane (0-8.5 wt%) and naphthalene (0 and 100 g/L) in five liquid organic scintillators. The sample was characterized in Pb and Cd shields under the irradiation of the thermal neutrons from a 252Cf source. A method was developed to extract the net neutron response from the pulse-height spectra. It was found that the order of scintillation efficiencies for both γ-rays and thermal neutrons is as follows: diisopropylnaphthalene>toluene (concentrated solutes)>toluene~pseudocumene~m-xylene. The quench constants, obtained by fitting the Stern-Volmer model to the plots of light output versus carborane concentration, are in the range of 0.35-1.4 M-1 for all the scintillators. The Birks factors, estimated using the specific energy loss profiles of the incident particles, are in the range of 9.3-14 mg cm-2 MeV-1 for all the samples. The light outputs are in the range of 63-86 keV electron equivalents (keVee) in response to thermal neutrons. Loading naphthalene generally promotes the scintillation efficiency of the scintillator with a benzene derivative solvent. Among all the scintillators tested, the diisopropylnaphthalene-based scintillator shows the highest scintillation efficiency, lowest Birks factor, and smallest quench constants. These properties are primarily attributed to the double fused benzene-ring structure of the solvent, which is more efficient to populate to the excited singlet state under ionizing radiation and to transfer the excitation energy to the fluorescent solutes.

  10. Systematic evaluation of neutron shielding effects for materials

    SciTech Connect

    Ueki, K.; Ohashi, A.; Nariyama, N.; Nagayama, S.; Fujita, T.; Hattori, K.; Anayama, Y.

    1996-11-01

    Three types of experiments with a {sup 252}Cf neutron source are proposed to evaluate systematically the neutron shielding effects of a material. The type 1 experiment deals with each shielding material alone, the type 2 experiment combines a shielding material and a structural material, and the type 3 experiment constructs the optimization with the materials used in the type 2 experiment. In the stainless steel (SS) + polyethylene shielding system, because of the location of the SS slabs at the source side, the tenth layer of the polyethylene becomes approximately one-half the value as when the polyethylene is employed alone. This is the enhancement effect of the SS. In the type 3 experiment, the total thickness of the SS + polyethylene shielding system is 40 cm, and the total thicknesses of the SS and the polyethylene slabs are fixed at 25 and 15 cm thick, respectively. The minimum total dose-equivalent rate (neutron + secondary gamma rays) is observed when the polyethylene slabs are located at a 20-cm depth from the source side, with an arrangement of 20-cm-thick SS + 15-cm-thick polyethylene + 5-cm-thick and SS, and with a ratio of the maximum to the minimum dose-equivalent rate of 2.5. The shielding optimization can be constructed by combining the materials having different shielding characteristics. The experimental results of the three types of experiments are reproduced fairly well by using the continuous-energy Monte Carlo code MCNP 4A with a next-event surface crossing estimator.

  11. A capture-gated fast neutron detection method

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Yang, Yi-Gang; Tai, Yang; Zhang, Zhi

    2016-07-01

    To address the problem of the shortage of neutron detectors used in radiation portal monitors (RPMs), caused by the 3He supply crisis, research on a cadmium-based capture-gated fast neutron detector is presented in this paper. The detector is composed of many 1 cm × 1 cm × 20 cm plastic scintillator cuboids covered by 0.1 mm thick film of cadmium. The detector uses cadmium to absorb thermal neutrons and produce capture γ-rays to indicate the detection of neutrons, and uses plastic scintillator to moderate neutrons and register γ-rays. This design removes the volume competing relationship in traditional 3He counter-based fast neutron detectors, which hinders enhancement of the neutron detection efficiency. Detection efficiency of 21.66% ± 1.22% has been achieved with a 40.4 cm × 40.4 cm × 20 cm overall detector volume. This detector can measure both neutrons and γ-rays simultaneously. A small detector (20.2 cm × 20.2 cm × 20 cm) demonstrated a 3.3 % false alarm rate for a 252Cf source with a neutron yield of 1841 n/s from 50 cm away within 15 s measurement time. It also demonstrated a very low (<0.06%) false alarm rate for a 3.21×105 Bq 137Cs source. This detector offers a potential single-detector replacement for both neutron and the γ-ray detectors in RPM systems. Supported by National Natural Science Foundation of China (11175098, 11375095)

  12. Digital fast neutron radiography of steel reinforcing bar in concrete

    NASA Astrophysics Data System (ADS)

    Mitton, K.; Jones, A.; Joyce, M. J.

    2014-12-01

    Neutron imaging has previously been used in order to test for cracks, degradation and water content in concrete. However, these techniques often fall short of alternative non-destructive testing methods, such as γ-ray and X-ray imaging, particularly in terms of resolution. Further, thermal neutron techniques can be compromised by the significant expense associated with thermal neutron sources of sufficient intensity to yield satisfactory results that can often precipitate the need for a reactor. Such embodiments are clearly not portable in the context of the needs of field applications. This paper summarises the results of a study to investigate the potential for transmission radiography based on fast neutrons. The objective of this study was to determine whether the presence of heterogeneities in concrete, such as reinforcement structures, could be identified on the basis of variation in transmitted fast-neutron flux. Monte-Carlo simulations have been performed and the results from these are compared to those arising from practical tests using a 252Cf source. The experimental data have been acquired using a digital pulse-shape discrimination system that enables fast neutron transmission to be studied across an array of liquid scintillators placed in close proximity to samples under test, and read out in real time. Whilst this study does not yield sufficient spatial resolution, a comparison of overall flux ratios does provide a basis for the discrimination between samples with contrasting rebar content. This approach offers the potential for non-destructive testing that gives less dose, better transportability and better accessibility than competing approaches. It is also suitable for thick samples where γ-ray and X-ray methods can be limited.

  13. Quantitative NDA of isotopic neutron sources.

    PubMed

    Lakosi, L; Nguyen, C T; Bagi, J

    2005-01-01

    A non-destructive method for assaying transuranic neutron sources was developed, using a combination of gamma-spectrometry and neutron correlation technique. Source strength or actinide content of a number of PuBe, AmBe, AmLi, (244)Cm, and (252)Cf sources was assessed, both as a safety issue and with respect to combating illicit trafficking. A passive neutron coincidence collar was designed with (3)He counters embedded in a polyethylene moderator (lined with Cd) surrounding the sources to be measured. The electronics consist of independent channels of pulse amplifiers and discriminators as well as a shift register for coincidence counting. The neutron output of the sources was determined by gross neutron counting, and the actinide content was found out by adopting specific spontaneous fission and (alpha,n) reaction yields of individual isotopes from the literature. Identification of an unknown source type and constituents can be made by gamma-spectrometry. The coincidences are due to spontaneous fission in the case of Cm and Cf sources, while they are mostly due to neutron-induced fission of the Pu isotopes (i.e. self-multiplication) and the (9)Be(n,2n)(8)Be reaction in Be-containing sources. Recording coincidence rate offers a potential for calibration, exploiting a correlation between the Pu amount and the coincidence-to-total ratio. The method and the equipment were tested in an in-field demonstration exercise, with participation of national public authorities and foreign observers. Seizure of the illicit transport of a PuBe source was simulated in the exercise, and the Pu content of the source was determined. It is expected that the method could be used for identification and assay of illicit, found, or not documented neutron sources.

  14. Neutron multiplicities in spontaneous fission and nuclear structure studies

    SciTech Connect

    Hamilton, J.H.; Kormicki, J.; Lu, Q.

    1993-12-31

    New insights into the fission process can be gained by better quantitative knowledge of how the energy released in fission is distributed between the kinetic energy of the two fragments, the excitation energy of the two fragments and the number of neutrons emitted. Studies of prompt gamma-rays emitted in spontaneous fission (SF) with large arrays of Compton suppressed Ge detector arrays are providing new quantitative answers to longstanding questions concerning fission as well as new insights into the structure of neutron-rich nuclei. For the first time the triple gamma coincidence technique was employed in spontaneous fission studies. Studies of SF of {sup 252}Cf and {sup 242}Pu have been carried out. These {gamma}-{gamma}-{gamma} data provide powerful ways to identify uniquely gamma rays from a particular nucleus in the very complex gamma-ray spectra given off by the over 100 different nuclei produced. The emphasis of this paper is on the first quantitative measurements of the multiplicities of the neutrons emitted in SF and the energy levels populated in the fragments. Indeed, in the break up into Mo-Ba pairs, we have identified for the first time fragments associated with from zero up to ten neutrons emitted and observed the excited energy states populated in these nuclei. The zero neutron emission pairs like {sup 104}Mo- {sup 148}Ba, {sup 106}Mo- {sup 146}Ba and {sup 104}Zr- {sup 148}Ce observed in this work are particularly interesting because they represent a type of cold fission or a new mode of cluster radioactivity as proposed by Greiner, Sandulescu and co-workers. These data provide new insights into the processes of cluster radioactivity and cold fission.

  15. High spin states in {sup 112,114,116}Pd

    SciTech Connect

    Zhu, S.J.; Hamilton, J.H.; Ramayya, A.V.

    1995-10-01

    High spin sates have been established using {gamma}{gamma}, x - x, x - {gamma}, and {gamma} {gamma} {gamma} coincidence techniques following the spontaneous fission of {sup 252}Cf. Data from a series of three different experiments conducted viz., with the early implementation of gammasphere at LBL, with the Compton-suppressed Ge-array at ORNL and x-{gamma} setup of INEL, was used to establish the high spin structures. In {sup 112}Pd yrast levels with energies of 349, 883, 1550, 2318, 3050, 3598 and 4205 keV connected by E2 transitions have been identified. In {sup 114}Pd yrast levels with energies of 333, 852, 1500, 2216, 2860, 3443, 4147 and 5011 and in {sup 116}Pd levels with energies of 341, 878, 1560, 2344, 3092, 3684, 4395 and 5244 decaying through a cascade of E2 transitions have been established. Also {gamma}-bands with energies of 737, 1096, 1362, 1759, 2002, 2483 and 2691 keV in {sup 114}Pd; 695, 1012, 1320, 1631, 1984, 2290, 2655, 2906, 3338 and 3504 keV in {sup 114}Pd; and 7838, 1067, 1374, 1719, 2101, 2493, 2931, 3256, and 3807 keV have been identified. In addition two negative parity bands with enerigies of 2183(5{sup -}), 2599(7{sup -}), 3105(9{sup -}), 3738(11{sup -}), 4473(13{sup -}) and 5256(15{sup -}) keV in {sup 114}Pd and 1984(5{sup -}), 2437(7{sup -}), 2972(9{sup -}), 3632(11{sup -}), and 4417(13{sup -}) keV have been established. The systematics of the yrast bands in these nuclei will be discussed.

  16. Simultaneous measurement of (n, γ) and (n, fission) cross sections with the DANCE 4π BaF 2 array

    NASA Astrophysics Data System (ADS)

    Bredeweg, T. A.; Fowler, M. M.; Becker, J. A.; Bond, E. M.; Chadwick, M. B.; Clement, R. R. C.; Esch, E.-I.; Ethvignot, T.; Granier, T.; Jandel, M.; Macri, R. A.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Wu, C. Y.

    2007-08-01

    We have recently begun a program of high precision measurements of the key production and destruction reactions of important radiochemical diagnostic isotopes, including several isotopes of uranium, plutonium and americium. The detector for advanced neutron capture experiments (DANCE), a 4π BaF2 array located at the Los Alamos Neutron Science Center, will be used to measure the neutron capture cross sections for most of the isotopes of interest. However, neutron capture measurements on many of the actinides are complicated by the presence of prompt γ-rays arising from low energy neutron-induced fission, which competes with neutron capture to varying degrees. Previous measurements of 235U using the DANCE array have shown that we can partially resolve capture from fission events based on total γ-ray calorimetry (i.e. total γ-ray energy versus γ-ray multiplicity). The addition of a dedicated fission-tagging detector to the DANCE array has greatly improved our ability to separate these two competing processes. In addition to higher quality neutron capture data, the addition of a fission-tagging detector offers a means to determine the capture-to-fission ratio (σγ/σf) in a single measurement, which should reduce the effect of systematic uncertainties. We are currently using a dual parallel-plate avalanche counter (PPAC) with the target material electro-deposited directly on the center cathode foil. This design provides a high efficiency for detecting fission fragments and allows loading of pre-assembled target/detector assemblies into the neutron beam line at DANCE. Results from tests of the fission-tag detector, as well as preliminary results from measurements on 235U and 252Cf that utilized the fission-tag detector will be presented.

  17. VALIDATION OF HANFORD PERSONNEL AND EXTREMITY DOSIMETERS IN PLUTONIUM ENVIRONMENTS

    SciTech Connect

    Scherpelz, Robert I.; Fix, John J.; Rathbone, Bruce A.

    2000-02-10

    A study was performed in the Plutonium Finishing Plant to assess the performance of Hanford personnel neutron dosimetry. The study was assessed whole body dosimetry and extremity dosimetry performance. For both parts of the study, the TEPC was used as the principle instrument for characterizing workplace neutron fields. In the whole body study, 12.7-cm-diameter TEPCs were used in ten different locations in the facility. TLD and TED personnel dosimeters were exposed on a water-filled phantom to enable a comparison of TEPC and dosimeter response. In the extremity study, 1.27-cm-diameter TEPCs were exposed inside the fingers of a gloveboxe glove. Extremity dosimeters were wrapped around the TEPCs. The glove was then exposed to six different cans of plutonium, simulating the exposure that a worker's fingers would receive in a glovebox. The comparison of TEPC-measured neutron dose equivalent to TLD-measured gamma dose equivalent provided neutron-to-gamma ratios that can be used to estimate the neutron dose equivalent received by a worker's finger based on the gamma readings of an extremity dosimeter. The study also utilized a Snoopy and detectors based on bubble technology for assessing neutron exposures, providing a comparison of the effectiveness of these instruments for workplace monitoring. The study concludes that the TLD component of the HCND performs adequately overall, with a positive bias of 30%, but exhibits excessive variability in individual results due to instabilities in the algorithm. The TED response was less variable but only 20% of the TEPC reference dose on average because of the low neutron energies involved. The neutron response of the HSD was more variable than the TLD component of the HCND and biased high by a factor of 8 overall due to its calibration to unmoderated 252Cf. The study recommends further work to correct instabilities in the HCND algorithm and to explore the potential shown by the bubble-based dosimeters.

  18. Development of a Characterized Radiation Field for Evaluating Sensor Performance

    SciTech Connect

    Rogers, D.M.; Coggins, T.L.; Marsh, J.; Mann, St.D.; Waggoner, Ch.A.

    2008-07-01

    Numerous efforts are funded by US agencies (DOE, DoD, DHS) for development of novel radiation sensing and measurement systems. An effort has been undertaken to develop a flexible shielding system compatible with a variety of sources (beta, X-ray, gamma, and neutron) that can be highly characterized using conventional radiation detection and measurement systems. Sources available for use in this system include americium-beryllium (AmBe), plutonium-beryllium (PuBe), strontium-90 (Sr-90), californium-252 (Cf-252), krypton-85 (Kr-85), americium-241 (Am-241), and depleted uranium (DU). Shielding can be varied by utilization of materials that include lexan, water, oil, lead, and polyethylene. Arrangements and geometries of source(s) and shielding can produce symmetrical or asymmetrical radiation fields. The system has been developed to facilitate accurately repeatable configurations. Measurement positions are similarly capable of being accurately re-created. Stand-off measurement positions can be accurately re-established using differential global positioning system (GPS) navigation. Instruments used to characterize individual measurement locations include a variety of sodium iodide (NaI(Tl)) (3 x 3 inch, 4 x 4 x 16 inch, Fidler) and lithium iodide (LiI(Eu)) detectors (for use with multichannel analyzer software) and detectors for use with traditional hand held survey meters such as boron trifluoride (BF{sub 3}), helium-3 ({sup 3}He), and Geiger-Mueller (GM) tubes. Also available are Global Dosimetry thermoluminescent dosimeters (TLDs), CR39 neutron chips, and film badges. Data will be presented comparing measurement techniques with shielding/source configurations. The system is demonstrated to provide a highly functional process for comparison/characterization of various detector types relative to controllable radiation types and levels. Particular attention has been paid to use of neutron sources and measurements. (authors)

  19. Phase 1 environmental report for the Advanced Neutron Source at Oak Ridge National Laboratory

    SciTech Connect

    Blasing, T.J.; Brown, R.A.; Cada, G.F.; Easterly, C.; Feldman, D.L.; Hagan, C.W.; Harrington, R.M.; Johnson, R.O.; Ketelle, R.H.; Kroodsma, R.L.; McCold, L.N.; Reich, W.J.; Scofield, P.A.; Socolof, M.L.; Taleyarkhan, R.P.; Van Dyke, J.W.

    1992-02-01

    The US Department of Energy (DOE) has proposed the construction and operation of the Advanced Neutron Source (ANS), a 330-MW(f) reactor, at Oak Ridge National Laboratory (ORNL) to support neutron scattering and nuclear physics experiments. ANS would provide a steady-state source of neutrons that are thermalized to produce sources of hot, cold, and very coal neutrons. The use of these neutrons in ANS experiment facilities would be an essential component of national research efforts in basic materials science. Additionally, ANS capabilities would include production of transplutonium isotopes, irradiation of potential fusion and fission reactor materials, activation analysis, and production of medical and industrial isotopes such as {sup 252}Cf. Although ANS would not require licensing by the US Nuclear Regulatory Commission (NRC), DOE regards the design, construction, and operation of ANS as activities that would produce a licensable facility; that is, DOE is following the regulatory guidelines that NRC would apply if NRC were licensing the facility. Those guidelines include instructions for the preparation of an environmental report (ER), a compilation of available data and preliminary analyses regarding the environmental impacts of nuclear facility construction and operation. The ER, described and outlined in NRC Regulatory Guide 4.2, serves as a background document to facilitate the preparation of environmental impact statements (EISs). Using Regulatory Guide 4.2 as a model, this ANS ER provides analyses and information specific to the ANS site and area that can be adopted (and modified, if necessary) for the ANS EIS. The ER is being prepared in two phases. Phase 1 ER includes many of the data and analyses needed to prepare the EIS but does not include data or analyses of alternate sites or alternate technologies. Phase 2 ER will include the additional data and analyses stipulated by Regulatory Guide 4.2.

  20. The optimum choice of gate width for neutron coincidence counting

    NASA Astrophysics Data System (ADS)

    Croft, S.; Henzlova, D.; Favalli, A.; Hauck, D. K.; Santi, P. A.

    2014-11-01

    In the measurement field of international nuclear safeguards, passive neutron coincidence counting is used to quantify the spontaneous fission rate of certain special nuclear materials. The shift register autocorrelation analysis method is the most commonly used approach. However, the Feynman-Y technique, which is more commonly applied in reactor noise analysis, provides an alternative means to extract the correlation information from a pulse train. In this work we consider how to select the optimum gate width for each of these two time-correlation analysis techniques. The optimum is considered to be that which gives the lowest fractional precision on the net doublets rate. Our theoretical approach is approximate but is instructional in terms of revealing the key functional dependence. We show that in both cases the same performance figure of merit applies so that common design criteria apply to the neutron detector head. Our prediction is that near optimal results, suitable for most practical applications, can be obtained from both techniques using a common gate width setting. The estimated precision is also comparable in the two cases. The theoretical expressions are tested experimentally using 252Cf spontaneous fission sources measured in two thermal well counters representative of the type in common use by international inspectorates. Fast accidental sampling was the favored method of acquiring the Feynman-Y data. Our experimental study confirmed the basic functional dependences predicted although experimental results when available are preferred. With an appropriate gate setting Feynman-Y analysis provides an alternative to shift register analysis for safeguards applications which is opening up new avenues of data collection and data reduction to explore.

  1. Total Absorption Gamma-ray Spectrometer (TAGS) Intensity Distributions from INL's Gamma-Ray Spectrometry Center

    DOE Data Explorer

    Greenwood, R. E.

    A 252Cf fission-product source and the INL on-line isotope separator were used to supply isotope-separated fission-product nuclides to a total absorption -ray spectrometer. This spectrometer consisted of a large (25.4-cm diameter x 30.5-cm long) NaI(Tl) detector with a 20.3-cm deep axial well in which is placed a 300-mm2 x 1.0-mm Si detector. The spectra from the NaI(Tl) detector are collected both in the singles mode and in coincidence with the B-events detected in the Si detector. Ideally, this detector would sum all the energy of the B- rays in each cascade following the population of daughter level by B- decay, so that the event could be directly associated with a particular daughter level. However, there are losses of energy from attenuation of the rays before they reach the detector, transmission of rays through the detector, escape of secondary photons from Compton scattering, escape of rays through the detector well, internal conversion, etc., and the measured spectra are thus more complicated than the ideal case and the analysis is more complex. Analysis methods have been developed to simulate all of these processes and thus provide a direct measure of the B- intensity distribution as a function of the excitation energy in the daughter nucleus. These data yield more accurate information on the B- distribution than conventional decay-scheme studies for complex decay schemes with large decay energies, because in the latter there are generally many unobserved and observed but unplaced rays. The TAGS data have been analyzed and published [R. E. Greenwood et al., Nucl Instr. and metho. A390(1997)] for 40 fission product-nuclides to determine the B- intensity distributions. [Copied from the TAGS page at http://www.inl.gov/gammaray/spectrometry/tags.shtml]. Those values are listed on this page for quick reference.

  2. New insights into the nuclear structure in neutron-rich 112,114,115,116,117,118Pd

    SciTech Connect

    Y. X. Luo; J. O. Rasmussen; J. H. Hamilton; A. V. Ramayya; S. Frauendorf; J. K. Hwang; N. J. Stone; S. J. Zhu; N. T. Brewer; E. Wang; I. Y. Lee; S. H. Liu; G. M. TerAkopian; A. V. Daniel; Yu.Ts. Oganessian; M. A. Stoyer; R. Donangelo; W.C. Ma; J. Cole; Yue Shi; F. R. Xu

    2013-12-01

    New level schemes of 112,114,115,116,117,118Pd are established by means of ?–?–??–?–?, ?–?–?–??–?–?–? and ?–?(0)?–?(0) measurements of prompt fission y rays from 252Cf using the Gammasphere multi-detector array. Spins/parities were assigned to levels based on ?–??–? angular correlation measurements, level systematics and decay patterns. In the even-N isotopes 112,114,116Pd, two sets of odd-parity bands were identified and extended with spins measured in each band. The odd-parity bands with large level staggerings were interpreted as disturbed chirality with less pronounced triaxial deformations in the Pd isotopes than observed in the chiral symmetry breaking 110,112Ru with maximum triaxiality. Onset of wobbling motion was identified from the sign of the signature splitting in the ? band of even–even 114Pd, and probably also in 116Pd, as first seen in the N=68N=68 isotone 112Ru. Maximal triaxiality in Ru and Pd isotopes is found to be reached for N=68N=68, 112Ru and 114Pd, 4 neutrons more than predicted in the theoretical calculations. The new data and TRS calculations allowed a systematic study of the band crossings in the even-N112,114,116Pd and odd-N115,117Pd isotopes. Now we find a new overall, more complex shape evolution than previously proposed from triaxial prolate in 110Pd via triaxial oblate in 112Pd to nearly oblate in 114,116Pd with a large change of the triaxial deformation parameter y toward nearly oblate in the (pi g 9/2)2 alignment in 114,115,116,117,118Pd, and triaxial-prolate–triaxial-oblate shape coexisting bands in 115Pd.

  3. Optimizing moderation of He-3 neutron detectors for shielded fission sources

    DOE PAGESBeta

    Rees, Lawrence B.; Czirr, J. Bart

    2012-07-10

    Abstract: The response of 3-He neutron detectors is highly dependent on the amount of moderator incorporated into the detector system. If there is too little moderation, neutrons will not react with the 3-He. If there is too much moderation, neutrons will not reach the 3-He. In applications for portal or border monitors where 3He detectors are used to interdict illicit Importation of plutonium, the fission source is always shielded to some extent. Since the energy distribution of neutrons emitted from the source depends on the amount and type of shielding present, the optimum placement of moderating material around 3-He tubesmore » is a function of shielding. In this paper, we use Monte Carlo techniques to model the response of 3-He tubes placed in polyethylene boxes for moderation. To model the shielded fission neutron source, we use a 252-Cf source placed in the center of spheres of water of varying radius. Detector efficiency as a function of box geometry and shielding are explored. We find that increasing the amount of moderator behind and to the sides of the detector generally improves the detector response, but that benefits are limited if the thickness of the polyethylene moderator is greater than about 5-7 cm. The thickness of the moderator in front of the 3He tubes, however, is very important. For bare sources, about 5-6 cm of moderator is optimum, but as the shielding increases, the optimum thickness of this moderator decreases to 0-1 cm. A two-tube box with a moderator thickness of 5 cm in front of the first tube and a thickness of 1 cm in front of the second tube is proposed to improve the detector's sensitivity to lower-energy neutrons.« less

  4. New insights into the nuclear structure in neutron-rich 112,114,115,116,117,118Pd

    NASA Astrophysics Data System (ADS)

    Luo, Y. X.; Rasmussen, J. O.; Hamilton, J. H.; Ramayya, A. V.; Frauendorf, S.; Hwang, J. K.; Stone, N. J.; Zhu, S. J.; Brewer, N. T.; Wang, E.; Lee, I. Y.; Liu, S. H.; TerAkopian, G. M.; Daniel, A. V.; Oganessian, Yu. Ts.; Stoyer, M. A.; Donangelo, R.; Ma, W. C.; Cole, J. D.; Shi, Yue; Xu, F. R.

    2013-12-01

    New level schemes of 112,114,115,116,117,118Pd are established by means of γ-γ-γ, γ-γ-γ-γ and γ-γ(θ) measurements of prompt fission γ rays from 252Cf using the Gammasphere multi-detector array. Spins/parities were assigned to levels based on γ-γ angular correlation measurements, level systematics and decay patterns. In the even-N isotopes 112,114,116Pd, two sets of odd-parity bands were identified and extended with spins measured in each band. The odd-parity bands with large level staggerings were interpreted as disturbed chirality with less pronounced triaxial deformations in the Pd isotopes than observed in the chiral symmetry breaking 110,112Ru with maximum triaxiality. Onset of wobbling motion was identified from the sign of the signature splitting in the γ band of even-even 114Pd, and probably also in 116Pd, as first seen in the N=68 isotone 112Ru. Maximal triaxiality in Ru and Pd isotopes is found to be reached for N=68, 112Ru and 114Pd, 4 neutrons more than predicted in the theoretical calculations. The new data and TRS calculations allowed a systematic study of the band crossings in the even-N112,114,116Pd and odd-N115,117Pd isotopes. Now we find a new overall, more complex shape evolution than previously proposed from triaxial prolate in 110Pd via triaxial oblate in 112Pd to nearly oblate in 114,116Pd with a large change of the triaxial deformation parameter γ toward nearly oblate in the ( alignment in 114,115,116,117,118Pd, and triaxial-prolate-triaxial-oblate shape coexisting bands in 115Pd.

  5. The Neutron Energy Response of the Panasonic Model 809 Personnel Dosimeter

    SciTech Connect

    Frederick Cummings

    2010-04-01

    In 2010, the U.S. Department of Energy will adopt a new set of radiation weighting factors and quality factors to be consistent with values recommended by the International Commission on Radiological Protection. The change will affect the magnitude of occupational exposure assigned to radiation workers exposed to neutron radiation. Understanding the energy response of the dosimeter and the effect of the new quantities is critical to accurately ensuring that occupational exposure remains below the established regulatory limits. Therefore, the factors used to interpret dosimeter readings must be re-evaluated for each irradiation field over the range of neutron energies in which the dosimeter is used. This paper describes one method of determining the neutron response of the dosimeter. A Monte Carlo approach was used to model the energy response of the Panasonic Model 809 dosimeter over the range of energies from 1.0 x 10^-8 to 20 MeV. The response, normalized to the response at 2.1 MeV, ranged from approximately 0.5 at 20 MeV to approximately 26 at 1 eV. The response was then divided at each energy by the appropriate dose conversion coefficient to determine the dose response of the dosimeter. The dose responses, normalized to the response at 2.1 MeV, ranged from approximately 0.4 at 20 MeV to 765 at 1 eV. Dose conversion factors were determined for various reference neutron spectra and plotted on the dose response curve. Good agreement was observed except for the case of D2Omoderated 252Cf.

  6. Advancements in the development of a directional-position sensing fast neutron detector using acoustically tensioned metastable fluids

    NASA Astrophysics Data System (ADS)

    Archambault, Brian C.; Webster, Jeffrey A.; Grimes, Thomas F.; Fischer, Kevin F.; Hagen, Alex R.; Taleyakhan, Rusi P.

    2015-06-01

    Advancements in the development of a direction and position sensing fast neutron detector which utilizes the directional acoustic tensioned metastable fluid detector (D-ATMFD) are described. The resulting D-ATMFD sensor is capable of determining the direction of neutron radiation with a single compact detector versus use of arrays of detectors in conventional directional systems. Directional neutron detection and source positioning offer enhanced detection speeds in comparison to traditional proximity searching; including enabling determination of the neutron source shape, size, and strength in near real time. This paper discusses advancements that provide the accuracy and precision of ascertaining directionality and source localization information utilizing enhanced signal processing-cum-signal analysis, refined computational algorithms, and on-demand enlargement capability of the detector sensitive volume. These advancements were accomplished utilizing experimentation and theoretical modeling. Benchmarking and qualifications studies were successfully conducted with random and fission based special nuclear material (SNM) neutron sources (239Pu-Be and 252Cf). These results of assessments have indicated that the D-ATMFD compares well in technical performance with banks of competing directional fast neutron detector technologies under development worldwide, but it does so with a single detector unit, an unlimited field of view, and at a significant reduction in both cost and size while remaining completely blind to common background (e.g., beta-gamma) radiation. Rapid and direct SNM neutron source imaging with two D-ATMFD sensors was experimentally demonstrated, and furthermore, validated via multidimensional nuclear particle transport simulations utilizing MCNP-PoliMi. Characterization of a scaled D-ATMFD based radiation portal monitor (RPM) as a cost-effective and efficient 3He sensor replacement was performed utilizing MCNP-PoliMi simulations, the results of which

  7. Nuclear shape and structure in neutron-rich {sup 110,111}Tc

    SciTech Connect

    Luo, Y. X.; Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Gore, P. M.; Jones, E. F.; Fong, D.; Rasmussen, J. O.; Lee, I. Y.; Stefanescu, I.; Che, X. L.; Zhu, S. J.; Wu, S. C.; Ginter, T. N.; Ma, W. C.; Ter-Akopian, G. M.; Daniel, A. V.; Stoyer, M. A.; Donangelo, R.; Gelberg, A.

    2006-08-15

    The high-spin nuclear structure of Tc isotopes is extended to more neutron-rich regions based on the measurements of prompt {gamma} rays from the spontaneous fission of {sup 252}Cf at the Gammasphere. The high-spin level scheme of N=67 neutron-rich {sup 110}Tc (Z=43) is established for the first time, and that of {sup 111}Tc is extended and expanded. The ground band of {sup 111}Tc reaches the band-crossing region, and the new observation of the weakly populated {alpha}=-1/2 member of the band provides important information on signature splitting. The systematics of band crossings in the isotopic and isotonic chains and a CSM calculation suggest that the band crossing of the ground band of {sup 111}Tc is due to alignment of a pair of h{sub 11/2} neutrons. The best fit to signature splitting, branching ratios, and excitations of the ground band of {sup 111}Tc by the rigid triaxial rotor plus particle model calculations result in a shape of {epsilon}{sub 2}=0.32 and {gamma}=-26 deg. for this nucleus. Its triaxiality is larger than that of {sup 107,109}Tc, which indicates increasing triaxiality in Tc isotopes with increasing neutron number. The identification of the weakly populated K+2 satellite band provides strong evidence for the large triaxiality of {sup 111}Tc. In {sup 110}Tc, the four lowest-lying levels observed are very similar to those in {sup 108}Tc. At an excitation of 478.9 keV above the lowest state observed, ten states of a {delta}I=1 band are observed. This band of {sup 110}Tc is very analogous to the {delta}I=1 bands in {sup 106,108}Tc, but it has greater and reversal signature splitting at higher spins.

  8. Radioisotope Production for Medical and Physics Applications

    NASA Astrophysics Data System (ADS)

    Mausner, Leonard

    2012-10-01

    Radioisotopes are critical to the science and technology base of the US. Discoveries and applications made as a result of the availability of radioisotopes span widely from medicine, biology, physics, chemistry and homeland security. The clinical use of radioisotopes for medical diagnosis is the largest sector of use, with about 16 million procedures a year in the US. The use of ^99Mo/^99mTc generator and ^18F make up the majority, but ^201Tl, ^123I, ^111In, and ^67Ga are also used routinely to perform imaging of organ function. Application of radioisotopes for therapy is dominated by use of ^131I for thyroid malignancies, ^90Y for some solid tumors, and ^89Sr for bone cancer, but production of several more exotic species such as ^225Ac and ^211At are of significant current research interest. In physics ^225Ra is of interest for CP violation studies, and the actinides ^242Am, ^249Bk, and ^254Es are needed as targets for experiments to create superheavy elements. Large amounts of ^252Cf are needed as a fission source for the CARIBU experiment at ANL. The process of radioisotope production is multidisciplinary. Nuclear physics input based on nuclear reaction excitation function data is needed to choose an optimum target/projectile in order to maximize desired isotope production and minimize unwanted byproducts. Mechanical engineering is needed to address issues of target heating, induced mechanical stress and material compatibility of target and claddings. Radiochemists are involved as well since chemical separation to purify the desired final radioisotope product from the bulk target and impurities is also usually necessary. Most neutron rich species are produced at a few government and university reactors. Other radioisotopes are produced in cyclotrons in the commercial sector, university/hospital based facilities, and larger devices at the DOE labs. The landscape of US facilities, the techniques involved, and current supply challenges will be reviewed.

  9. Secondary Ion Mass Spectrometry by Time-Of

    NASA Astrophysics Data System (ADS)

    Ens, Erich Werner

    The operation and performance of the Manitoba time-of-flight mass spectrometer is described. The recent implementation of a commercial time-to-digital converter is described and compared to the conventional timing method (time-to-amplitude conversion) used earlier. Mass spectra obtained here with keV alkali ions and in Rockefeller University with (TURN)100 MeV fission fragments from ('252)Cf were found to be similar. Yields of secondary ions from alanine were measured for primary alkali ions (Cs('+), K('+), Na('+), and Li('+)) at energies 1 keV to 16 keV. Yields increase greatly with increasing energy and with the mass of the bombarding particle, suggesting that in this energy region the nuclear stopping is mainly responsible for the secondary ion production. This is in contrast to the case for fission fragments where electronic stopping must be responsible. Thus, it appears that the mass spectra are fairly insensitive to the form of the incident energy loss. Secondary ions {(CsI)(,n)Cs}('+), with n up to (TURN)40, were produced by 8 keV Cs('+) bombardment of CsI. The yield of clusters decreased smoothly with n when observed in a time-of-flight mass spectrometer at effective times (TURN)0.2 (mu)s after emission. Clusters with n > 7 were found to be metastable, with lifetimes << 100 (mu)s. A large anomaly in the population of the disintegration products was measured at (TURN)70 (mu)s after emission, n = 13 clusters being favored and n = 14 and 15 being suppressed. A marked increase in the yield of cations, anions and all cluster ions was observed after irradiating alkali halides with >(, )10('14) alkali ions/cm('2). In addition, the irradiation was found to produce emission of cluster ions delayed by (TURN)200 ns after the primary ion impact.

  10. A potential alternative/complement to the traditional thermal neutron based counting in Nuclear Safeguards and Security

    NASA Astrophysics Data System (ADS)

    Chernikova, Dina; Naeem, Syed F.; Axell, Kåre; Trnjanin, Nermin; Nordlund, Anders

    2016-02-01

    A new concept for thermal neutron based correlation and multiplicity measurements is proposed in this paper. The main idea of the concept consists of using 2.223 MeV gammas (or 1.201 MeV, DE) originating in the 1 H (n , γ) 2 D-reaction instead of using traditional thermal neutron counting. Results of investigations presented in this paper indicate that gammas from thermal neutron capture reactions preserve the information about the correlation characteristics of thermal (fast) neutrons in the same time scale. Therefore, instead of thermal neutron detectors (or as a complement) one may use traditional and inexpensive gamma detectors, such as NaI, BGO, CdZnTe or any other gamma detector. In this work we used D8×8 cm2 NaI scintillator to test the concept. Thus, the new approach helps to address the problem of replacement of 3He-counters and problems related to the specific measurements of spent nuclear fuel directly in the spent fuel pool. It has a particular importance for Nuclear Safeguards and Security. Overall, this work represents the proof of concept study and reports on the experimental and numerical evidence that thermal neutron capture gammas may be used in the context of correlation and multiplicity measurements. Investigations were performed using a 252Cf-correlated neutron source and an 241Am-Be-random neutron source. The related idea of the Gamma Differential Die-Away approach is investigated numerically in this paper as well, and will be tested experimentally in future work.

  11. On the Development of a Miniature Neutron Generator for the Brachytherapy Treatment of Cancer

    NASA Astrophysics Data System (ADS)

    Forman, L.

    2009-03-01

    Brachytherapy refers to application of an irradiation source within a tumor. 252Cf needles used in brachytherapy have been successfully applied to treatment of some of the most virulent cancers but it is doubtful that it will be widely used because of difficulty in dealing with unwanted dose (source cannot be turned off) and in adhering to stringent NRC regulations that have been exacerbated in our post 911 environment. We have been working on the development of a miniature neutron generator with the reaction target placed at the end of a needle (tube) for brachytherapy applications. Orifice geometries are most amenable, e.g. rectum and cervix, but interstitial use is possible with microsurgery. This paper dicusses the results of a 30 watt DD neutron generator SBU project that demonstrates that sufficient hydrogen isotope current can be delivered down a small diameter needle required for a DT neutron treatment device, and, will summarize the progress of building a commercial device pursued by the All Russian Institute for Automatics (VNIIA) supported by the DOE's Industrial Proliferation Prevention Program (IPP). It is known that most of the fast neutron (FN) beam cancer treatment facilities have been closed down. It appears that the major limitation in the use of FN beams has been damage to healthy tissue, which is relatively insensitive to photons, but this problem is alleviated by brachytherapy. Moreover, recent clinical results indicate that fast neutrons in the boost mode are most highly effective in treating large, hypoxic, and rapidly repopulating diseases. It appears that early boost application of FN may halt angiogenesis (development and repair of tumor vascular system) and shrink the tumor resulting in lower hypoxia. The boost brachytherapy application of a small, low cost neutron generator holds promise of significant contribution to the treatment of cancer.

  12. Secondary ion emission from CO2-H2O ice irradiated by energetic heavy ions: Part II: Analysis-search for organic ions

    NASA Astrophysics Data System (ADS)

    Ponciano, C. R.; Farenzena, L. S.; Collado, V. M.; da Silveira, E. F.; Wien, K.

    2005-06-01

    Secondary ion mass spectrometry is used to investigate ion emission from a frozen-gas mixture of CO2 and H2O (T = 80-90 K) bombarded by MeV nitrogen ions and by 252Cf fission fragments. The aim of the experiment is to detect organic molecules, produced in the highly excited material around the nuclear track, which appear as ions in the flux of sputtered particles. Part I of the present work [L.S. Farenzena, V.M. Collado, C.R Ponciano, E.F. da Silveira, K. Wien. Int. J. Mass Spectrom. 243 (2005) 85-93] described the method and presented the time-of-flight mass spectra; a list of the CO2 specific and H2O specific reaction products was provided. In Part II, the peaks of the TOF mass spectra are analyzed. Projectile-ice direct coulomb interaction leads to the production in the track of the H+, C+, O+, O2+, CO+ and CO2+ primarily ions, which react in the highly energized nuclear track plasma mainly with CO2 and H2O or H2CO3. The positive molecular hybrid ions formed are identified as organic species like COH+, COOH+, CHn = 1-3+, Hn = 1,2COOH+ and cluster ions. Similarly, the negative primarily ions O- and OH- formed by electron capture produce negative hybrid ions such as (CO2)nOH-, the four ions (CO4Hm = 0-3)- and the corresponding cluster ions. By far, most of the molecular ions have been formed by one-step reactions; exceptions are eventually the CO4Hm- ions created by a reaction between CO3- and water molecules. An intense mass line corresponding to HCO3+ has been observed, but not the one due to formaldehyde ion. Weak signals of ionic ketene, hydrogen peroxide and carbonic acid were seen.

  13. Secondary ion emission from CO2-H2O ice irradiated by energetic heavy ions: Part I. Measurement of the mass spectra

    NASA Astrophysics Data System (ADS)

    Farenzena, L. S.; Collado, V. M.; Ponciano, C. R.; da Silveira, E. F.; Wien, K.

    2005-05-01

    Secondary ion mass spectrometry is used to investigate ion emission from a frozen-gas mixture (T = 80-90 K) of CO2 and H2O bombarded by MeV nitrogen ions and by 252Cf fission fragments (FF). The aim of the experiments is to produce organic molecules in the highly excited material around the nuclear track and to detect them in the flux of sputtered particles. Such sputter processes are known to occur at the icy surfaces of planetary or interstellar objects. Time-of-flight (TOF) mass spectrometry is employed to identify the desorbed ions. Mass spectra of positive and negative ions were taken for several molecular H2O/CO2 ratios. In special, positive ions induced by MeV nitrogen beam were analyzed for 9 and 18% H2O concentrations of the CO2-H2O ice and negative ions for ~5% H2O. The ion peaks are separated to generate exclusive the spectra of CO2 specific ions, H2O specific ions and hybrid molecular ions, the latter ones corresponding to ions that contain mostly H and C atoms. In the mass range from 10 to 320 u, the latter exhibits 35 positive and 58 negative ions. The total yield of the positive ions is 0.35 and 0.57 ions/impact, respectively, and of negative ions 0.066 ions/impact. Unexpected effects of secondary ion sputtering yields on H2O/CO2 ratio are attributed to the influence of water molecules concentration on the ionization process.

  14. Gas-phase chemistry of ruthenium and rhodium carbonyl complexes.

    PubMed

    Cao, Shiwei; Wang, Yang; Qin, Zhi; Fan, Fangli; Haba, Hiromitsu; Komori, Yukiko; Wu, Xiaolei; Tan, Cunmin; Zhang, Xin

    2016-01-01

    Short-lived ruthenium and rhodium isotopes were produced from a (252)Cf spontaneous fission (SF) source. Their volatile carbonyl complexes were formed in gas-phase reactions in situ with the carbon-monoxide containing gas. A gas-jet system was employed to transport the volatile carbonyls from the recoil chamber to the chemical separation apparatus. The gas-phase chemical behaviors of these carbonyl complexes were studied using an online low temperature isothermal chromatography (IC) technique. Long IC columns made up of FEP Teflon were used to obtain the chemical information of the high-volatile Ru and Rh carbonyls. By excluding the influence of precursor effects, short-lived isotopes of (109-110)Ru and (111-112)Rh were used to represent the chemical behaviours of Ru and Rh carbonyls. Relative chemical yields of about 75% and 20% were measured for Ru(CO)5 and Rh(CO)4, respectively, relative to the yields of KCl aerosols transported in Ar gas. The adsorption enthalpies of ruthenium and rhodium carbonyl complexes on a Teflon surface were determined to be around ΔHads = -33(+1)(-2) kJ mol(-1) and -36(+2)(-1) kJ mol(-1), respectively, by fitting the breakthrough curves of the corresponding carbonyl complexes with a Monte Carlo simulation program. Different from Mo and Tc carbonyls, a small amount of oxygen gas was found to be not effective for the chemical yields of ruthenium and rhodium carbonyl complexes. The general chemical behaviors of short-lived carbonyl complexes of group VI-IX elements were discussed, which can be used in the future study on the gas-phase chemistry of superheavy elements - Bh, Hs, and Mt carbonyls. PMID:26573993

  15. Nuclear shape and structure in neutron-rich 110,111Tc

    SciTech Connect

    Luo, Y.X.; Hamilton, J.H.; Rasmussen, J.O.; Ramayya, A.V.; Stefanescu, I.; Hwang, J.K.; Zhu, S.J.; Gore, P.M.; Jones, E.F.; Fong,D.; Wu, S.C.; Lee, I.Y.; Ginter, T.N.; Ter-Akopian, G.M.; Daniel, A.V.; Stoyer, M.A.; Donangelo, R.; Gelberg, A.

    2006-02-02

    The structure of Tc nuclei is extended to the moreneutron-rich regions based on measurements of prompt gamma rays from thespontaneous fission of 252Cf at Gammasphere. The level scheme of N=67neutron-rich (Z=43) 110Tc is established for the first time and that of111Tc is expanded. The ground-state band of 111Tc reaches theband-crossing region and the new observation of the weakly populatedalpha = -1/2 member of the band provides important information ofsignature splitting. The systematics of band crossings in the isotopicand isotonic chains and a CSM calculation suggest that the band crossingof the gs band of 111Tc is due to alignment of a pair of h11/2 neutrons.The best fit to signature splitting, branching ratios, and excitations ofthe ground-state band of 111Tc by RTRP model calculations result in ashape of epsilon2 = 0.32 and gamma = -26 deg. for this nucleus. Itstriaxiality is larger than that of 107Tc, to indicate increasingtriaxiality with increasing neutron number. The identification of theweakly-populated "K+2 satellite" band provides strong evidence for thelarge triaxiality of 111Tc. In 110Tc the four lowest-lying levelsobserved are very similar to those in 108Tc. At an excitation of 478.9keV above the lowest state observed, ten states of a delta I = 1 band areobserved. This band is very analogous to the delta I = 1 bands in106,108Tc, but it has greater signature splitting at higherspins.

  16. Octupole excitations in 141,144Cs and the pronounced decrease of dipole moments with neutron number in odd- Z neutron-rich 141,143,144Cs

    NASA Astrophysics Data System (ADS)

    Luo, Y. X.; Rasmussen, J. O.; Hamilton, J. H.; Ramayya, A. V.; Liu, S. H.; Jones, E. F.; Gore, P. M.; Goodin, C.; Stone, N. J.; Zhu, S. J.; Hwang, J. K.; Li, Ke; Crowell, H. L.; Lee, I. Y.; Ter-Akopian, G. M.; Daniel, A. V.; Stoyer, M. A.; Donangelo, R.; Ma, W. C.; Cole, J. D.

    2010-07-01

    The level scheme of odd- Z neutron-rich 141Cs ( Z=55, N=86) was extended and expanded and that of 144Cs ( N=89) was identified for the first time by means of γ-γ-γ coincidence measurements of prompt γ rays in the spontaneous fission of 252Cf with Gammasphere. Spin/parity was assigned to the levels based on angular correlations and level systematics in 141,143Cs. Parity doublets characteristic of both simplex quantum number s=+i and s=-i were proposed in 141Cs. The tests by using rotational frequency ratio ω(I)/ω(I) imply octupole vibrations in 141Cs and 143Cs. B(E1)/B(E2) values and electric dipole moments D were calculated for 141Cs, and re-determined for 143Cs. It was found that B(E1)/B(E2) values of 141Cs are simplex-dependent and the average value is one order of magnitude larger than that of 143Cs, and the deduced dipole moment D of 141Cs is considerably larger than that of 143Cs, and comparable to the N=86 isotone 142Ba. For 144Cs the yrast sequence looks like a well-deformed rotational band, but no octupole band structure was identified in this nucleus. The overall variations of D in 141,143,144Cs exhibit a pronounced drop of dipole moment with increasing neutron number in this odd- Z isotopic chain, which may be analogous in nature to the quenching of D observed in even-even 146Ba ( Z=56, N=90) and 224Ra ( Z=88, N=136), and to the drop of D in the odd- Z neutron-rich 147La ( Z=57, N=90) reported by our collaboration.

  17. Spatial response characterization of liquid scintillator detectors using collimated gamma-ray and neutron beams

    NASA Astrophysics Data System (ADS)

    Naeem, S. F.; Clarke, S. D.; Pozzi, S. A.

    2013-10-01

    Liquid scintillators are suitable for many applications because they can detect and characterize fast neutrons as well as gamma-rays. This paper presents the response of a 15-cm-in-length×15-cm-in-height×8.2-cm-in-width EJ-309 liquid scintillator with respect to the position of neutron and gamma-ray interactions. Liquid scintillator cells are typically filled with 97% of the scintillating cocktail to address thermal expansion of the liquid in varying temperature conditions. Measurements were taken with collimated 137Cs and 252Cf sources for gamma-ray and neutron mapping of the detector, respectively. MCNPX-PoliMi (ver. 2.0) simulations were also performed to demonstrate the spatial response of the detector. Results show that the detector response is greatest at the center and decreases when the collimated neutron and gamma-ray beam is moved toward the edge of the detector. The measured response in the voxels surrounding the detector center decreased by approximately 6% and 12% for gamma-ray and neutron scans, respectively, when compared to the center voxel. The measured decrease in the detector response was most pronounced at the corners of detector assembly. For the corner voxels located in the bottom row of the detector, the measured response decreased by approximately 39% for both gamma-ray and neutron scans. For the corner voxels located in the top row of the detector, the measured response decreased by approximately 66% and 48% for gamma-ray and neutron scans, respectively. Both measurements and simulations show the inefficient production of secondary charged particles in the voxels located in the top portion of the detector due to the presence of expansion volume. Furthermore, the presence of the expansion volume potentially affects the transport of the scintillation light through the coupling window between the liquid scintillator and the photocathode in the photomultiplier tube.

  18. Development of prototype induced-fission-based Pu accountancy instrument for safeguards applications.

    PubMed

    Seo, Hee; Lee, Seung Kyu; An, Su Jung; Park, Se-Hwan; Ku, Jeong-Hoe; Menlove, Howard O; Rael, Carlos D; LaFleur, Adrienne M; Browne, Michael C

    2016-09-01

    Prototype safeguards instrument for nuclear material accountancy (NMA) of uranium/transuranic (U/TRU) products that could be produced in a future advanced PWR fuel processing facility has been developed and characterized. This is a new, hybrid neutron measurement system based on fast neutron energy multiplication (FNEM) and passive neutron albedo reactivity (PNAR) methods. The FNEM method is sensitive to the induced fission rate by fast neutrons, while the PNAR method is sensitive to the induced fission rate by thermal neutrons in the sample to be measured. The induced fission rate is proportional to the total amount of fissile material, especially plutonium (Pu), in the U/TRU product; hence, the Pu amount can be calibrated as a function of the induced fission rate, which can be measured using either the FNEM or PNAR method. In the present study, the prototype system was built using six (3)He tubes, and its performance was evaluated for various detector parameters including high-voltage (HV) plateau, efficiency profiles, dead time, and stability. The system's capability to measure the difference in the average neutron energy for the FNEM signature also was evaluated, using AmLi, PuBe, (252)Cf, as well as four Pu-oxide sources each with a different impurity (Al, F, Mg, and B) and producing (α,n) neutrons with different average energies. Future work will measure the hybrid signature (i.e., FNEM×PNAR) for a Pu source with an external interrogating neutron source after enlarging the cavity size of the prototype system to accommodate a large-size Pu source (~600g Pu).

  19. Organic liquid scintillation detectors for on-the-fly neutron/gamma alarming and radionuclide identification in a pedestrian radiation portal monitor

    NASA Astrophysics Data System (ADS)

    Paff, Marc Gerrit; Ruch, Marc L.; Poitrasson-Riviere, Alexis; Sagadevan, Athena; Clarke, Shaun D.; Pozzi, Sara

    2015-07-01

    We present new experimental results from a radiation portal monitor based on the use of organic liquid scintillators. The system was tested as part of a 3He-free radiation portal monitor testing campaign at the European Commission's Joint Research Centre in Ispra, Italy, in February 2014. The radiation portal monitor was subjected to a wide range of test conditions described in ANSI N42.35, including a variety of gamma-ray sources and a 20,000 n/s 252Cf source. A false alarm test tested whether radiation portal monitors ever alarmed in the presence of only natural background. The University of Michigan Detection for Nuclear Nonproliferation Group's system triggered zero false alarms in 2739 trials. It consistently alarmed on a variety of gamma-ray sources travelling at 1.2 m/s at a 70 cm source to detector distance. The neutron source was detected at speeds up to 3 m/s and in configurations with up to 8 cm of high density polyethylene shielding. The success of on-the-fly radionuclide identification varied with the gamma-ray source measured as well as with which of two radionuclide identification methods was used. Both methods used a least squares comparison between the measured pulse height distributions to library spectra to pick the best match. The methods varied in how the pulse height distributions were modified prior to the least squares comparison. Correct identification rates were as high as 100% for highly enriched uranium, but as low as 50% for 241Am. Both radionuclide identification algorithms produced mixed results, but the concept of using liquid scintillation detectors for gamma-ray and neutron alarming in radiation portal monitor was validated.

  20. Development of prototype induced-fission-based Pu accountancy instrument for safeguards applications.

    PubMed

    Seo, Hee; Lee, Seung Kyu; An, Su Jung; Park, Se-Hwan; Ku, Jeong-Hoe; Menlove, Howard O; Rael, Carlos D; LaFleur, Adrienne M; Browne, Michael C

    2016-09-01

    Prototype safeguards instrument for nuclear material accountancy (NMA) of uranium/transuranic (U/TRU) products that could be produced in a future advanced PWR fuel processing facility has been developed and characterized. This is a new, hybrid neutron measurement system based on fast neutron energy multiplication (FNEM) and passive neutron albedo reactivity (PNAR) methods. The FNEM method is sensitive to the induced fission rate by fast neutrons, while the PNAR method is sensitive to the induced fission rate by thermal neutrons in the sample to be measured. The induced fission rate is proportional to the total amount of fissile material, especially plutonium (Pu), in the U/TRU product; hence, the Pu amount can be calibrated as a function of the induced fission rate, which can be measured using either the FNEM or PNAR method. In the present study, the prototype system was built using six (3)He tubes, and its performance was evaluated for various detector parameters including high-voltage (HV) plateau, efficiency profiles, dead time, and stability. The system's capability to measure the difference in the average neutron energy for the FNEM signature also was evaluated, using AmLi, PuBe, (252)Cf, as well as four Pu-oxide sources each with a different impurity (Al, F, Mg, and B) and producing (α,n) neutrons with different average energies. Future work will measure the hybrid signature (i.e., FNEM×PNAR) for a Pu source with an external interrogating neutron source after enlarging the cavity size of the prototype system to accommodate a large-size Pu source (~600g Pu). PMID:27337652

  1. Neutron experiments at Portsmouth for measuring flow and {sup 235}U content in UF{sub 6} gas

    SciTech Connect

    Stromswold, D C; Reeder, P L; Peurrung, A J

    1997-04-01

    The Portsmouth Gaseous Diffusion Plant produces enriched uranium for use in commercial power reactors. The plant also aids disposal of excess high-enrichment uranium (HEU) by blending it with lower-enrichment material. Experiments were conducted to test two neutron-based methods for monitoring the down-blending of HEU. Results of the initial experiments showed that gas (on-off) could be detected, but that additional tests and data are needed to quantify the flow velocity and {sup 235}U content. The experiments used a {sup 252}Cf neutron source to induce fission in a small fraction of the {sup 235}U contained in the UF{sub 6} gas. The first method measured the attenuation of neutrons passing through the low-pressure UF{sub 6} gas in a 7.6-cm diameter pipe. The concept was based on the fact that some of the thermal neutrons are absorbed by {sup 235}U, thus changing the observed count rate. The second method, tested on a 20-cm diameter pipe where gas pressure was higher, used a modulated neutron flux to induce fission in the {sup 235}U. Modulation was achieved by moving a neutron source. During both experiments, plant monitoring equipment showed that light gases (freon, oxygen, and nitrogen) were present in widely varying amounts, along with the UF{sub 6} gas. These gases may have affected the experimental results, at least to the extent that they replaced UF{sub 6}. This report also contains results of computer simulations and tests performed on the electronics after the experiments were completed at Portsmouth. Recommendations are made for follow-on work to measure the flow velocity and {sup 235}U content.

  2. New isomers and medium-spin structure of the {sup 95}Y nucleus

    SciTech Connect

    Urban, W.; Sieja, K.; Simpson, G. S.; Rzaca-Urban, T.; Zlomaniec, A.; Lukasiewicz, M.; Smith, A. G.; Durell, J. L.; Smith, J. F.; Varley, B. J.; Nowacki, F.; Ahmad, I.

    2009-04-15

    Excited states in {sup 95}Y, populated following the spontaneous fission of {sup 248}Cm and {sup 252}Cf and following fission of {sup 235}U induced by thermal neutrons, were studied by means of {gamma} spectroscopy using the EUROGAM2 and GAMMASPHERE multidetector Ge arrays and the LOHENGRIN fission-fragment separator, respectively. We have found a new (17/2{sup -}) isomer in {sup 95}Y at 3142.2 keV with a half-life of T{sub 1/2}=14.9(5) ns. Another isomer was identified in {sup 95}Y at 5022.1 keV and it was assigned a spin-parity (27/2{sup -}). For this isomer a half-life of T{sub 1/2}=65(4) ns was determined and four decay branches were found, including an E3 decay. A new E3 decay branch was also found for the known, 1087.5-keV isomer in {sup 95}Y, for which we measured a half-life of 51.2(9) {mu}s. The B(E3) and B(E1) transition rates, of 2.0 and 3.8x10{sup -7} W.u., respectively, observed in {sup 95}Y are significantly lower than in the neighboring {sup 96}Zr core, suggesting that octupole correlations in this region are mainly due to the coupling of proton {delta}j=3 orbitals. Shell-model calculations indicate that the (27/2{sup -}) isomer in {sup 95}Y corresponds to the {pi}g{sub 9/2}{nu}(g{sub 7/2}h{sub 11/2}) maximally aligned configuration and that all three isomers in {sup 95}Y decay, primarily, by M2 transitions between proton g{sub 9/2} and f{sub 5/2} orbitals.

  3. [Early-onset radiation complications and tissue damage in the treatment of head and neck tumors].

    PubMed

    Isaev, P A; Medvedev, V S; Pasov, V V; Semin, D Iu; Derbugov, D N; Pol'kin, V V; Terekhov, O V

    2010-01-01

    The report discusses the results of an evaluation of the effectiveness of combined radiotherapy in 1,192 cases of head and neck tumors divided into 4 groups: distant radiotherapy in standard fractions of 1.8-2.3 Gy, 5 times a week, TTD of 60 Gy (group 1 - 486 40.8%); radiotherapy + local UHF hyperthermia + regional intraarterial chemotherapy + hyper glycemia + administrations of regional intraarterial chemotherapy + hyperglycemia + local UHF hyperthermia (group 2 - 244 20.5%); accelerated superfractition radiotherapy with variable STD of 1 and 1.5/2 Gy, TTD of 60 Gy, plus neoadjuvant polychemotherapy with cisplatin 100 mg/lm2 + 5-fluorouracil, continuous intravenous infusion of 3,000 mg for 72 h (group 3 - 204 17%1); combined photon-neutron therapy (group 4 - 258 21.6%): neutron beam therapy - 36 (3%); interstitial neutron brachytherapy with 252 Cf sources in combination with external beam gamma-therapy and chemotherapy. Overall radiation injury incidence was 1,087 (91.2%); oral mucositis grade I (WHO) - 110 (9.2%), grade II - 166(13.9%), grade III - 811 (68%), radiation dermatitis - 279 (23.4%), grade I/II - 196 (16.4%), grade III/IV - 83 (7%). Grade III/IV side effects developed in 26.7% after gamma therapy and in 72.2% - in the photon-neutron group (p < or = 0.0001). Skin damage was rare, as expected, in the photon-brachytherapy group (1.8%) (p < or = 0.0001). Hence, Cf252 neutron brachytherapy and radiotherapy with concomitant chemotherapy appeared to produce the most sparing effects. PMID:21137234

  4. Expansion of the radioactive ion beam program at Argonne

    NASA Astrophysics Data System (ADS)

    Clark, J. A.

    2011-01-01

    The Argonne Tandem Linear Accelerator System (ATLAS) at Argonne National Laboratory (ANL) provides a wide range of stable ion beams and radioactive beams which have contributed to our understanding of nuclear structure and reactions. Until now, most radioactive ion beams at ATLAS were produced in flight using light-ion reactions such as (p, n), (d, n), (d, p), (d,3He), and (3He,n). Within the next few months, the radioactive ion beam program at ATLAS will acquire much extended, new capabilities with the commissioning of a new facility: the CAlifornium Rare Isotope Breeder Upgrade (CARIBU). CARIBU will supply ion beams of 252Cf fission fragments, which are thermalized in a gas catcher. The singly- and doubly-charged ions extracted from the gas catcher will be mass-separated and either delivered to a low-energy experimental area, or charge bred with a modified ECR source and subsequently reaccelerated by the ATLAS facility. Properties of hundreds of these neutron-rich nuclides will be investigated using ion traps, decay stations, the newly commissioned HELical Orbit Spectrometer (HELIOS), and other available experimental equipment such as Gammasphere and the FMA. HELIOS was constructed to take advantage of rare ion beams, such as those provided by CARIBU, through light-ion transfer reactions in inverse kinematics, and represents a new approach to the study of direct reactions in inverse kinematics which avoids kinematic broadening. Experiments are currently being conducted with HELIOS, and first results with the d(28Si,p) and d(12B,p) reactions have shown excellent energy resolution.

  5. Current Issues in Nuclear Data Evaluation Methodology: {sup 235}U Prompt Fission Neutron Spectra and Multiplicity for Thermal Neutrons

    SciTech Connect

    Trkov, A.; Capote, R.; Pronyaev, V.G.

    2015-01-15

    Issues in evaluation methodology of the prompt fission neutron spectra (PFNS) and neutron multiplicity for the thermal-neutron-induced fission of the {sup 235}U are discussed. The inconsistency between the experimental differential and integral data is addressed. By using differential data as ”shape data” good consistency was achieved between available sets of differential data. Integral dosimetry data have been used to define the PFNS slope at high outgoing neutron energies, where the quality of the differential data is poor. The inclusion into the fit of measured integral (spectrum-averaged) cross sections had a very small impact in the region where differential PFNS data are abundant and accurate, but removed the discrepancy with integral data at higher neutron emission energies. All experimental data are consistently fitted giving a PFNS average energy of 2.008 MeV. The impact on criticality prediction of the newly evaluated PFNS was tested. The highly enriched {sup 235}U solution assemblies with high leakage HEU-SOL-THERM-001 and HEU-SOL-THERM-009 benchmarks are the most sensitive to the PFNS. Criticality calculations for those solutions show a significant increase in reactivity if the average neutron energy of the fission neutrons is reduced from the ENDF/B-VI.5 value of 2.03 MeV. The proposed reduction of the PFNS average energy by 1.1% can be compensated by reducing the average number of neutrons per fission ν{sup ¯} at the thermal energy to the Gwin et al. measured value. The simple least-squares PFNS fit was confirmed by a more sophisticated combined fit of differential PFNS data for {sup 233,235}U, {sup 239}Pu and {sup 252}Cf nuclides with the generalised least-squares method using the GMA and GANDR codes.

  6. EBIS charge breeder for radioactive ion beams at ATLAS.

    SciTech Connect

    Ostroumov, P.; Kondrashev, S.; Pardo, R.; Savard, G.; Vondrasek, R.; Alessi, J.; Beebe, E.; Pikin, A.

    2010-07-01

    The construction of the Californium Rare Isotope Breeder Upgrade (CARIBU) for the Argonne National Laboratory ATLAS facility is completed and its commissioning is being performed. In its full capacity, the CARIBU facility will use fission fragments from a 1 Curie (Ci) {sup 252}Cf source. The ions will be thermalized and collected into a low-energy ion beam by a helium gas catcher, mass analyzed by an isobar separator, and charge bred to higher charge states for acceleration in ATLAS. To reach energies E/A 10 MeV/u, one should inject ions with charge-to-mass ratio (q/A) {ge} 1/7 into the ATLAS linac. In the first stage, the existing Electron Cyclotron Resonance (ECR) ion source will be used as a charge breeder. The maximum intensity of radioactive ion beams at the output of the gas catcher will not exceed 10{sup 7} ions per second. A charge breeder based on an Electron Beam Ion Source (EBIS) has significant advantages over the ECR option for ion beam intensities up to about 10{sup 9} ions per second, providing 3-4 times higher efficiency and significantly better purity of highly charged radioactive ion beams for further acceleration. The proposed EBIS project for CARIBU will heavily utilize state-of-the-art EBIS technology recently developed at Brookhaven National Laboratory. This will allow us to reduce both the project cost and timescale, simultaneously insuring reliable technical realization of the cutting-edge technology. Several parameters of the CARIBU EBIS charge breeder (EBIS-CB) will be relaxed with respect to the BNL EBIS in favor of higher reliability and lower cost. Technical performance of the CARIBU charge breeder will not suffer from such a relaxation and will provide high efficiency for a whole range of radioactive ion beams. The goal of this paper is to present the initial design of the EBIS charge breeder for radioactive ion beams at ATLAS.

  7. EBIS charge breeder for radioactive ion beams at ATLAS

    NASA Astrophysics Data System (ADS)

    Ostroumov, P.; Kondrashev, S.; Pardo, R.; Savard, G.; Vondrasek, R.; Alessi, J.; Beebe, E.; Pikin, A.

    2010-07-01

    The construction of the Californium Rare Isotope Breeder Upgrade (CARIBU) for the Argonne National Laboratory ATLAS facility is completed and its commissioning is being performed. In its full capacity, the CARIBU facility will use fission fragments from a 1 Curie (Ci) 252Cf source. The ions will be thermalized and collected into a low-energy ion beam by a helium gas catcher, mass analyzed by an isobar separator, and charge bred to higher charge states for acceleration in ATLAS. To reach energies E/A 10 MeV/u, one should inject ions with charge-to-mass ratio (q/A) >= 1/7 into the ATLAS linac. In the first stage, the existing Electron Cyclotron Resonance (ECR) ion source will be used as a charge breeder. The maximum intensity of radioactive ion beams at the output of the gas catcher will not exceed 107 ions per second. A charge breeder based on an Electron Beam Ion Source (EBIS) has significant advantages over the ECR option for ion beam intensities up to about 109 ions per second, providing 3-4 times higher efficiency and significantly better purity of highly charged radioactive ion beams for further acceleration. The proposed EBIS project for CARIBU will heavily utilize state-of-the-art EBIS technology recently developed at Brookhaven National Laboratory. This will allow us to reduce both the project cost and timescale, simultaneously insuring reliable technical realization of the cutting-edge technology. Several parameters of the CARIBU EBIS charge breeder (EBIS-CB) will be relaxed with respect to the BNL EBIS in favor of higher reliability and lower cost. Technical performance of the CARIBU charge breeder will not suffer from such a relaxation and will provide high efficiency for a whole range of radioactive ion beams. The goal of this paper is to present the initial design of the EBIS charge breeder for radioactive ion beams at ATLAS.

  8. Radiation Transport Analysis in Chalcogenide-Based Devices and a Neutron Howitzer Using MCNP

    NASA Astrophysics Data System (ADS)

    Bowler, Herbert

    As photons, electrons, and neutrons traverse a medium, they impart their energy in ways that are analytically difficult to describe. Monte Carlo methods provide valuable insight into understanding this behavior, especially when the radiation source or environment is too complex to simplify. This research investigates simulating various radiation sources using the Monte Carlo N-Particle (MCNP) transport code, characterizing their impact on various materials, and comparing the simulation results to general theory and measurements. A total of five sources were of interest: two photon sources of different incident particle energies (3.83 eV and 1.25 MeV), two electron sources also of different energies (30 keV and 100 keV), and a californium-252 (Cf-252) spontaneous fission neutron source. Lateral and vertical programmable metallization cells (PMCs) were developed by other researchers for exposure to these photon and electron sources, so simplified PMC models were implemented in MCNP to estimate the doses and fluences. Dose rates measured around the neutron source and the predicted maximum activity of activation foils exposed to the neutrons were determined using MCNP and compared to experimental results obtained from gamma-ray spectroscopy. The analytical fluence calculations for the photon and electron cases agreed with MCNP results, and differences are due to MCNP considering particle movements that hand calculations do not. Doses for the photon cases agreed between the analytical and simulated results, while the electron cases differed by a factor of up to 4.8. Physical dose rate measurements taken from the neutron source agreed with MCNP within the 10% tolerance of the measurement device. The activity results had a percent error of up to 50%, which suggests a need to further evaluate the spectroscopy setup.

  9. EBIS charge breeder for radioactive ion beams at ATLAS

    SciTech Connect

    Ostroumov, P.; Alessi, J.; Kondrashev, S.; Pardo, R.; Savard, G.; Vondrasek, R.; Beebe, E.; Pikin, A.

    2010-07-20

    The construction of the Californium Rare Isotope Breeder Upgrade (CARIBU) for the Argonne National Laboratory ATLAS facility is completed and its commissioning is being performed. In its full capacity, the CARIBU facility will use fission fragments from a 1 Curie (Ci) {sup 252}Cf source. The ions will be thermalized and collected into a low-energy ion beam by a helium gas catcher, mass analyzed by an isobar separator, and charge bred to higher charge states for acceleration in ATLAS. To reach energies E/A 10 MeV/u, one should inject ions with charge-to-mass ratio (q/A) {ge} 1/7 into the ATLAS linac. In the first stage, the existing Electron Cyclotron Resonance (ECR) ion source will be used as a charge breeder. The maximum intensity of radioactive ion beams at the output of the gas catcher will not exceed 10{sup 7} ions per second. A charge breeder based on an Electron Beam Ion Source (EBIS) has significant advantages over the ECR option for ion beam intensities up to about 10{sup 9} ions per second, providing 3-4 times higher efficiency and significantly better purity of highly charged radioactive ion beams for further acceleration. The proposed EBIS project for CARIBU will heavily utilize state-of-the-art EBIS technology recently developed at Brookhaven National Laboratory. This will allow us to reduce both the project cost and timescale, simultaneously insuring reliable technical realization of the cutting-edge technology. Several parameters of the CARIBU EBIS charge breeder (EBIS-CB) will be relaxed with respect to the BNL EBIS in favor of higher reliability and lower cost. Technical performance of the CARIBU charge breeder will not suffer from such a relaxation and will provide high efficiency for a whole range of radioactive ion beams. The goal of this paper is to present the initial design of the EBIS charge breeder for radioactive ion beams at ATLAS.

  10. From ground state to fission fragments: A complex, multi-dimensional multi-path problem

    SciTech Connect

    Moeller, P.; Nix, J.R.; Swiatecki, W.J.

    1992-03-01

    Experimental results on the fission properties of nuclei close to {sup 264}Fm show sudden and large changes with a change of only one or two neutrons or protons. The nucleus {sup 258}Fm, for instance, undergoes symmetric fission with a half-life of about 0.4 ms and a kinetic-energy distribution peaked at about 235 MeV whereas {sup 256}Fm undergoes asymmetric fission with a half-life of about 3 h and a kinetic-energy distribution peaked at about 200 MeV. Qualitatively, these sudden changes have been postulated to be due to the emergence of fragment shells in symmetric-fission products close to {sup 132}Sn. Here we present a quantitative calculation that shows where high-kinetic-energy symmetric fusion occurs and why it is associated with a sudden and large decrease in fission half-lives. We base our study on calculations of potential-energy surfaces in the macroscopic-microscopic model and a semi-empirical model for the nuclear inertia. We use the three-quadratic-surface parameterization to generate the shapes for which the potential-energy surfaces are calculated. The use of this parameterization and the use of the finite-range macroscopic model allows for the study of two touching spheres and similar shapes. Since these shapes are thought to correspond to the scission shapes for the high-kinetic-energy events it is of crucial importance that a continuous sequence of shapes leading from the nuclear ground state to these configurations can be studied within the framework of the model. We present the results of the calculations in terms of potential-energy surfaces and fission half-lives for heavy even nuclei. The surfaces are displayed in the form of contour diagrams as functions of two moments of the shape. They clearly show the appearance of a second fission valley, which leads to scission configurations close to tow touching spheres, for fissioning systems in the vicinity of {sup 264}Fm.

  11. From ground state to fission fragments: A complex, multi-dimensional multi-path problem

    SciTech Connect

    Moeller, P. ); Nix, J.R. ); Swiatecki, W.J. )

    1992-01-01

    Experimental results on the fission properties of nuclei close to {sup 264}Fm show sudden and large changes with a change of only one or two neutrons or protons. The nucleus {sup 258}Fm, for instance, undergoes symmetric fission with a half-life of about 0.4 ms and a kinetic-energy distribution peaked at about 235 MeV whereas {sup 256}Fm undergoes asymmetric fission with a half-life of about 3 h and a kinetic-energy distribution peaked at about 200 MeV. Qualitatively, these sudden changes have been postulated to be due to the emergence of fragment shells in symmetric-fission products close to {sup 132}Sn. Here we present a quantitative calculation that shows where high-kinetic-energy symmetric fusion occurs and why it is associated with a sudden and large decrease in fission half-lives. We base our study on calculations of potential-energy surfaces in the macroscopic-microscopic model and a semi-empirical model for the nuclear inertia. We use the three-quadratic-surface parameterization to generate the shapes for which the potential-energy surfaces are calculated. The use of this parameterization and the use of the finite-range macroscopic model allows for the study of two touching spheres and similar shapes. Since these shapes are thought to correspond to the scission shapes for the high-kinetic-energy events it is of crucial importance that a continuous sequence of shapes leading from the nuclear ground state to these configurations can be studied within the framework of the model. We present the results of the calculations in terms of potential-energy surfaces and fission half-lives for heavy even nuclei. The surfaces are displayed in the form of contour diagrams as functions of two moments of the shape. They clearly show the appearance of a second fission valley, which leads to scission configurations close to tow touching spheres, for fissioning systems in the vicinity of {sup 264}Fm.

  12. Determination the total neutron yields of several semiconductor compounds using various alpha emitters

    NASA Astrophysics Data System (ADS)

    Abdullah, Ramadhan Hayder; Sabr, Barzan Nehmat

    2016-03-01

    In the present work, the cross-sections of (α,n) reactions available in the literature as a function of α-particle energies for light and medium elements have been rearranged for α-particle energies from near threshold up to 10 MeV in steps of (0.050MeV) using the (Excel and Matlab) computer programs. The obtained data were used to calculate the neutron yields (n/106α) using the quick basic-computer program (Simpson Rules). The stopping powers of alpha particle energies from near threshold to 10 MeV for light and medium elements such as (nat.Be,10B,11B,13C,14N,nat.O,nat.F,nat.Mg,nat.Al,29Si,30Si, nat.P and 46.48Ti) have been calculated using the Zeigler formula. The kinetic energies (Tα) and the branching ratios of each α-emitters such as (211Bi, 210Po, 211Po, 215Po, 217At, 218Rn, 219Rn, 222Rn, 224Ra, 226Ra, 215Th, 228Th, 232U, 234U, 236U, 238U, 238Pu, 239Pu, 241Am, 245Es, 252Fm, 254Fm, 256Fm, 257Fm and 257Md) are taken into consideration to calculate the mean kinetic energy . The polynomial expressions were used to fitting the calculated weighted average of neutron yields (n/106α) for natural light and medium elements such as (Be, B, C, N, O, F, Mg, Al, Si, P and Ti) to determine the adopted neutron yields from the best fitting equation with minimum (CHISQ) at mean kinetic energies of various α-emitters. The total neutron yields (n/s/gx/ppmi) of the mentioned natural light and medium elements have been calculated using the adopted neutron yields (n/106α) from the fitting equations at mean kinetic energies of various α-emitters. The total neutron yields (n/s/gα-emitters/gcompounds) of semiconductor compounds such as (AlN, AlP, BN, BP, SiC, TiO2, BeSiN2, MgCN2, MgSiN2 and MgSiP2) have been calculated by mixing (1gram) of compounds with (1gram) of pure α-emitters using the quick basic computer program. The aim of the present work is to constructed and fabricate the neutron sources theoretically

  13. Real-Time Active Cosmic Neutron Background Reduction Methods

    SciTech Connect

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald; Mitchell, Stephen; Guss, Paul

    2013-09-01

    from man-made sources like 252Cf or Am-Be was removed.

  14. Assessment of present and future radwaste generation in Saudi Arabia for the design of treatment and storage facilities

    SciTech Connect

    Abdul-Majid, S.; Kutbi, I.I.; Al-Marshad, A.I.

    1996-12-31

    Radwastes are produced in medical, industrial and educational institutions in Saudi Arabia. In medical centers many of the unsealed sources were low beta/gamma emitters of low radio-toxicity and less than about 4 months half-life. Significant radionuclides in this category were: {sup 99m}Tc, {sup 131}I, {sup 125}I, {sup 123}I, {sup 111}In, {sup 201}Tl, {sup 67}Ga and some of others. Longer lived sources such as {sup 57}Co, {sup 3}H, and {sup 14}C were also found in appreciable quantity. Delay and decay procedure followed by release to the sewerage or municipal landfill has been practiced for short-lived radwaste. Pretreatment and temporary storage were encouraged at large centers. Industrial sealed sources used primarily in radiography and well logging were mainly: {sup 60}Co, {sup 137}Cs, {sup 192}Ir, {sup 241}Am, {sup 241}Am-Be and {sup 252}Cf. It was agreed that radwastes whose half lives are above 138.4 days, the half life of {sup 210}Po, should be subject to conditioning treatment and permanent storage. It was anticipated that two main parameters affect the increase in radwaste in the future. The first is the increase of radionuclides use in hospitals in diagnosis and therapy in the country. The second is the increase in population which should be associated with increase in medical services in general. The annual long lived waste that need treatment, conditioning and storage as a function of time is expected to follow the relation: V= 10+0.48t{sup 2}, where V is the waste volume in m{sup 3} and t is the time in years after 1995. The expected long lived cumulative treated, conditioned, and liquid wastes in that year if not subject to volume reduction in m{sup 3} are expected to be: 500, 75, and 100 respectively. Comparisons were made with IAEA waste volume expectations for countries of similar conditions: the cumulative radwastes in m{sup 3} in 2020 are expected to be: 800, 125 and 175 respectively.

  15. Blend Down Monitoring System Fissile Mass Flow Monitor and its Implementation at the Siberian Chemical Enterprise, Seversk, Russia

    SciTech Connect

    Uckan, T

    2005-07-28

    In this paper the implementation plans and preparations for installation of the Fissile Mass Flow Monitor (FMFM) equipment at the Siberian Chemical Enterprise (SChE), Seversk, Russia, are presented. The FMFM, developed by Oak Ridge National Laboratory, is part of the Blend Down Monitoring System (BDMS) for the U.S. Department of Energy Highly Enriched Uranium (HEU) Transparency Implementation Program. The BDMS provides confidence to the United States that the Russian nuclear facilities supplying the lower assay ({approx}4%) product low enriched uranium (PLEU) to the United States from down-blended weapon-grade HEU are meeting the nonproliferation goals of the government-to-government HEU purchase agreement signed between the Russian Federation and the United States in 1993. The first BDMS has been operational at Ural Electrochemical Integrated Plant, Novouralsk, since February 1999. The second BDMS has been operational at Electro Chemical Plant, Zelenogorsk, since March 2003. These systems are successfully providing HEU transparency data to the United States. The third BDMS was successfully installed on the HEU down-blending tee in the SChE Enrichment Plant in October 2004. The FMFM makes use of a set of thermalized {sup 252}Cf spontaneous neutron sources for modulated fission activation of the UF{sub 6} gas stream for measuring the {sup 235}U fissile mass flow rate. To do this, the FMFM measures the transport time of the fission fragments created from the fission activation process under the modulated source to the downstream detectors by detecting the delayed gamma rays from the fission fragments retained in the flow. The FMFM provides unattended nonintrusive measurements of the {sup 235}U mass flow of the UF{sub 6} gas in the blending tee legs of HEU, the LEU blend stock, and the resulting P-LEU. The FMFM also confirms that highly enriched UF{sub 6} gas identified in the HEU leg flows through the blending tee into the P-LEU leg. This report contains details of

  16. INL Neutron Interrogation R&D: FY2010 MPACT End of Year Report

    SciTech Connect

    D. L. Chichester; E. H. Seabury; J. Wharton; S. M. Watson

    2010-08-01

    Experiments have been carried out to investigate the feasibility and utility of using neutron interrogation and small-scale, portable prompt gamma-ray neutron activation analysis (PGNAA) instruments for assaying uranium for safeguards applications. Prior work has shown the potential of the PGNAA technique for assaying uranium using reactor-based neutron sources and high-yield electronic neutron generators (ENGs). In this project we adapted Idaho National Laboratory's portable isotopic neutron spectroscopy (PINS) PGNAA system for measuring natural-enrichment uranium yellowcake and metallic depleted uranium and highly enriched uranium. This work used 252Cf as well as deuterium-deuterium (DD) and deuterium-tritium (DT) ENGs. For PGNAA measurements a limiting factor when assaying large objects is the detector dead time due to fast-neutron scattering off of the uranium; this limits the maximum useable neutron source strength to O(107) neutrons per second. Under these conditions the low PGNAA reaction cross sections for uranium prohibited the collection of useful uranium PGNAA signatures from either the yellowcake or metallic uranium samples. Measurement of the decay product activation in these materials following irradiation in the PGNAA geometry similarly did not produce useful uranium activation product – fission product signatures. A customized irradiation geometry tailored to optimally thermalize the interrogation neutron source, intended only for generating long-lived activation products – fission products and not intended for PGNAA measurements, might be possible using small scale ENGs but an application need and a modeling and simulation exercise would be recommended before advancing to experiments. Neutron interrogation PGNAA using a DT-ENG was found to be a quick and useful qualitative method for detecting the presence of oxygen in natural-enrichment uranium yellowcake. With a low effort of development work it would be reasonable to expect this measurement

  17. Determination of Plutonium Content in Spent Fuel with Nondestructive Assay

    SciTech Connect

    Tobin, S. J.; Sandoval, N. P.; Fensin, M. L.; Lee, S. Y.; Ludewigt, Bernhard A.; Menlovea, H. O.; Quiter, B. J.; Rajasingume, A.; Schearf, M. A.; Smith, L. E.; Swinhoe, M. T.; Thompson, S. J.

    2009-06-30

    Neutrons, Differential Die-Away, Differential Die-Away Self-Interrogation, Lead Slowing Down Spectrometer, Neutron Multiplicity, Nuclear Resonance Fluorescence, Passive Prompt Gamma, Passive Neutron Albedo Reactivity, Self-integration Neutron Resonance Densitometry, Total Neutron (Gross Neutron), X-Ray Fluorescence, 252Cf Interrogation with Prompt Neutron Detection.

  18. Assay for uranium and determination of disequilibrium by means of in situ high resolution gamma-ray spectrometry

    USGS Publications Warehouse

    Tanner, Allan B.; Moxham, Robert M.; Senftle, F.E.

    1977-01-01

    Two sealed sondes, using germanium gamma-ray detectors cooled by melting propane, have been field tested to depths of 79 m in water-filled boreholes at the Pawnee Uranium Mine in Bee Co., Texas. When, used as total-count devices, the sondes are comparable in logging speed and counting rate with conventional scintillation detectors for locating zones of high radioactivity. When used with a multichannel analyzer, the sondes are detectors with such high resolution that individual lines from the complex spectra of the uranium and thorium series can be distinguished. Gamma rays from each group of the uranium series can be measured in ore zones permitting determination of the state of equilibrium at each measurement point. Series of 10-minute spectra taken at 0.3- to 0.5-m intervals in several holes showed zones where maxima from the uranium group and from the 222Rn group were displaced relative to each other. Apparent excesses of 230Th at some locations suggest that uranium-group concentrations at those locations were severalfold greater some tens of kiloyears, ago. At the current state of development a 10-minute count yields a sensitivity of about 80 ppm U308. Data reduction could in practice be accomplished in about 5 minutes. The result is practically unaffected by disequilibrium or radon contamination. In comparison with core assay, high-resolution spectrometry samples a larger volume; avoids problems due to incomplete core recovery, loss of friable material to drilling fluids, and errors in depth and marking; and permits use of less expensive drilling methods. Because gamma rays from the radionuclides are accumulated simultaneously, it also avoids the problems inherent in trying to correlate logs made in separate runs with different equipment. Continuous-motion delayed-gamma activation by a 163-?g 252Cf neutron source attached to the sonde yielded poor sensitivity. A better neutron-activation method, in which the sonde is moved in steps so as to place the detector

  19. Student Progress Report: Summer 2012

    SciTech Connect

    Tucker, Lucas P

    2012-08-06

    The Los Alamos SOURCES 4C code has been benchmarked for alpha particle beam problems and common neutron source materials (e.g. those containing plutonium or beryllium), but little benchmarking has been performed for more exotic isotopic neutron sources or uranium mixtures. This work extends SOURCES 4C benchmarking effort. Experimental data was found in the literature for several isotopic neutron sources, namely Am/Be, Am/F, Am/B, Cm/Be, {sup 238}Pu/{sup 13}C, {sup 252}Cf, and Am/Li. SOURCES 4C simulations were run for each of these materials and the output was used to develop a source term for use in MCNP, which allowed other physical effects such as down scattering and multiplication to be accounted for. Neutron emission rate and energy spectra results were compared for these sources, generally yielding order-of-magnitude agreement for the neutron emission rate and qualitative agreement for the shape of the neutron energy spectra. An exception was the neutron energy spectrum calculated for {sup 238}Pu/{sup 13}C whose primary peak was calculated to be 1 MeV higher than was measured. The accuracy of SOURCES is highly dependent on an accurate material definition. This discrepancy is likely due to inhomogeneity of the source materials, which cannot be simulated by SOURCES or MCNP, and chemical impurities not reported by the experimentalist. The results of the Am/Li calculation demonstrate that even small impurities are capable of dramatically changing the results. The neutron emission rates of numerous uranium compounds were also calculated with SOURCES and benchmarked with experimentally determined values found in the literature. The calculated results were similar to the experimental results with less than 10% error for the following compounds: uranyl fluoride, uranyl nitrate, UO{sub 3}, UO{sub 2}F{sub 2}, UF{sub 4}, UF{sub 6}, and U-metal of less than 90% enrichment. This work demonstrates the robustness of SOURCES as a tool for calculating neutron emission rates

  20. Measurement of {sup 63}Ni and {sup 59}Ni by accelerator mass spectrometry using characteristic projectile x-rays

    SciTech Connect

    McAninch, J.E.; Hainsworth, L.J.; Marchetti, A.A.

    1996-05-01

    The long-lived isotopes of nickel ({sup 59}Ni, {sup 63}Ni) have current and potential use in a number of applications including cosmic radiation studies, biomedical tracing, characterization of low-level radioactive wastes, and neutron dosimetry. Methods are being developed at LLNL for the routine detection of these isotopes by AMS. One intended application is in Hiroshima dosimetry. The reaction {sup 63}Cu(n,p){sup 63}Ni has been identified as one of a small number of reactions which might be used for the direct determination of the fast neutron fluence emitted by the Hiroshima bomb. AMS measurement of {sup 63}Ni(t{sub 1/2} = 100 y) requires the chemical removal of {sup 63}Cu, which is a stable isobar of {sup 63}Ni. Following the electrochemical separation of Ni from gram-sized copper samples, the Cu concentration is further lowered to < 2 x 10{sup -8} (Cu/Ni) using the reaction of Ni with carbon monoxide to form the gas Ni(CO){sub 4}. The Ni(CO){sub 4} is thermally decomposed directly in sample holders for measurement by AMS. After analysis in the AMS spectrometer, the ions are identified using characteristic projectile x-rays, allowing further rejection of remaining {sup 63}Cu. In a demonstration experiment, {sup 63}Ni was measured in Cu wires (2-20 g) which had been exposed to neutrons from a {sup 252}Cf source. We successfully measured {sup 63}Ni at levels necessary for the measurement of Cu samples exposed near the Hiroshima hypocenter. For the demonstration samples, the Cu content was chemically reduced by a factor of 10{sup 12} with quantitative retention of {sup 63}Ni. Detection sensitivity (3{sigma}) was {approximately}20 fg {sup 63}Ni in 1 mg Ni carrier ({sup 63}Ni/Ni {approx} 2 x 10{sup -11}). Significant improvements in sensitivity are expected with planned incremental changes in the methods. Preliminary results indicate that a similar sensitivity is achievable for {sup 59}Ni (t{sub 1/2} = 10{sup 5} y).