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Sample records for albedo neutron decay

  1. Nuclear cascades in Saturn's rings - Cosmic ray albedo neutron decay and origins of trapped protons in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Cooper, J. F.

    1983-05-01

    The nearly equatorial trajectory of the Pioneer 11 spacecraft through Saturn's high energy proton radiation belts and under the main A-B-C rings provided a unique opportunity to study the radial dependence of the greater than 30 MeV proton intensities in the belts in terms of models for secondary nucleon production by cosmic ray interactions in the rings, in situ proton injection in the radiation belts by neutron beta decay, magnetospheric diffusion, and absorption by planetary rings and satellites. Maximum trapped proton intensities measured by Pioneer 11 in the radiation belts are compared with calculated intensities and found consistent with trapping times of roughly 40 years and a radial diffusion coefficient of about 10 to the -15th L to the 9th Rs squared/s. Differential energy spectra proportional to E to the -2 estimated from integral measurements of trapped photons with E greater than 100 MeV are consistent with the beta decay model, but an inferred turndown of the spectra toward lower energies and reported integral proton anisotropies of a specified form both indicate the need for more realistic calculations of the neutron source from the rings and the radiation belt loss processes.

  2. Radiation Dose from Lunar Neutron Albedo

    NASA Technical Reports Server (NTRS)

    Adams, J. H., Jr.; Bhattacharya, M.; Lin, Zi-Wei; Pendleton, G.

    2006-01-01

    The lunar neutron albedo from thermal energies to 8 MeV was measured on the Lunar Prospector Mission in 1998-1999. Using GEANT4 we have calculated the neutron albedo due to cosmic ray bombardment of the moon and found a good-agreement with the measured fast neutron spectra. We then calculated the total effective dose from neutron albedo of all energies, and made comparisons with the effective dose contributions from both galactic cosmic rays and solar particle events to be expected on the lunar surface.

  3. Calculation of albedos for neutrons and photons

    NASA Astrophysics Data System (ADS)

    Brockhoff, Ronald Carl

    2003-07-01

    The albedo concept is used to describe radiation that appears to be reflected from a surface, although in reality this reflected radiation is comprised of radiation that has entered the medium, and is subsequently scattered back through the surface. The albedo often offers a computationally simple alternative to estimate doses from radiation reflected from surfaces surrounding a streaming region. However, albedo data available prior to this study, are limited to relatively few source energies and reflecting media, and are based on obsolete and incomplete cross sections and response functions. The Monte Carlo code MCNP is applied in this study to calculate the differential photon and neutron dose albedos, along with the differential secondary-photon dose albedo, based on modern response functions and cross section data. Differential photon dose albedo data were calculated for source energies ranging from 0.1 to 10 MeV incident on slabs of concrete, iron, lead, and water. Differential neutron dose albedo data, and the associated differential secondary-photon dose albedo data, were calculated for source energy bands ranging from 0.1 to 10 MeV, and for thermal, Californium, and 14 MeV source spectra, incident on the same four reflecting media. The results indicate that (1) the approximation of the differential photon dose albedo proposed by Chilton and Huddleston usually deviates from the raw albedo data by less than 10% for source energies between 0.1 and 10.0 MeV, (2) the new 24-parameter approximation of the differential neutron dose albedo deviates from the raw albedo data by less than 10% for source energy bands between 0.1 and 10 MeV, and (3) the five-parameter approximation of the secondary-photon dose albedo deviates from the raw albedo data by less than 25% for source energies between 0.1 and 10 MeV. The differential dose albedo approximations obtained in this study are used to solve several example radiation transport problems, where the dose from reflected

  4. Calibration system for albedo neutron dosimeters

    SciTech Connect

    Rothermich, N.E.

    1981-01-01

    Albedo neutron dosimeters have proven to be effective as a method of measuring the dose from neutron exposures that other types of neutron detectors cannot measure. Results of research conducted to calibrate an albedo neutron dosemeter are presented. The calibration procedure consisted of exposing the TLD chips to a 46 curie /sup 238/PuBe source at known distances, dose rates and exposure periods. The response of the TLD's is related to the dose rate measured with a dose rate meter to obtain the calibration factor. This calibration factor is then related to the ratio of the counting rates determined by 9-inch and 3-inch Bonner spheres (also called remmeters) and a calibration curve was determined. 17 references, 10 figures, 3 tables.

  5. Use of wrist albedo neutron dosimeters

    SciTech Connect

    Hankins, D.E.

    1983-01-01

    We are developing a wrist dosimeter that can be used to measure the exposure at the wrist to x-rays, gamma rays, beta-particles, thermal neutrons and fast neutrons. It consists of a modified Hankins Type albedo neutron dosimeter and also contains three pieces of CR-39 plastic. ABS plastic in the form of an elongated hemisphere provides the beta and low energy x-ray shielding necessary to meet the requirement of depth dose measurements at 1 cm. The dosimeter has a beta window located in the side of the hemisphere oriented towards an object being held in the hands. A TLD 600 is positioned under the 1 cm thick ABS plastic and is used to measure the thermal neutron dose. At present we are using Velcro straps to hold the dosimeter on the inside of the wrist. 9 figures.

  6. Variable control of neutron albedo in toroidal fusion devices

    DOEpatents

    Jassby, Daniel L.; Micklich, Bradley J.

    1986-01-01

    An arrangement is provided for controlling neutron albedo in toroidal fusion devices having inboard and outboard vacuum vessel walls for containment of the neutrons of a fusion plasma. Neutron albedo material is disposed immediately adjacent the inboard wall, and is movable, preferably in vertical directions, so as to be brought into and out of neutron modifying communication with the fusion neutrons. Neutron albedo material preferably comprises a liquid form, but may also take pebble, stringer and curtain-like forms. A neutron flux valve, rotatable about a vertical axis is also disclosed.

  7. The albedo effect on neutron transmission probability.

    PubMed

    Khanouchi, A; Sabir, A; Boulkheir, M; Ichaoui, R; Ghassoun, J; Jehouani, A

    1997-01-01

    The aim of this study is to evaluate the albedo effect on the neutron transmission probability through slab shields. For this reason we have considered an infinite homogeneous slab having a fixed thickness equal to 20 lambda (lambda is the mean free path of the neutron in the slab). This slab is characterized by the factor Ps (scattering probability) and contains a vacuum channel which is formed by two horizontal parts and an inclined one (David, M. C. (1962) Duc and Voids in shields. In Reactor Handbook, Vol. III, Part B, p. 166). The thickness of the vacuum channel is taken equal to 2 lambda. An infinite plane source of neutrons is placed on the first of the slab (left face) and detectors, having windows equal to 2 lambda, are placed on the second face of the slab (right face). Neutron histories are sampled by the Monte Carlo method (Booth, T. E. and Hendricks, J. S. (1994) Nuclear Technology 5) using exponential biasing in order to increase the Monte Carlo calculation efficiency (Levitt, L. B. (1968) Nuclear Science and Engineering 31, 500-504; Jehouani, A., Ghassoun, J. and Abouker, A. (1994) In Proceedings of the 6th International Symposium on Radiation Physics, Rabat, Morocco) and we have applied the statistical weight method which supposes that the neutron is born at the source with a unit statistical weight and after each collision this weight is corrected. For different values of the scattering probability and for different slopes of the inclined part of the channel we have calculated the neutron transmission probability for different positions of the detectors versus the albedo at the vacuum channel-medium interface. Some analytical representations are also presented for these transmission probabilities. PMID:9463883

  8. Earth albedo neutrons from 10 to 100 MeV.

    NASA Technical Reports Server (NTRS)

    Preszler, A. M.; Simnett, G. M.; White, R. S.

    1972-01-01

    We report the measurement of the energy and angular distributions of earth albedo neutrons from 10 to 100 MeV at 40 deg N geomagnetic latitude from a balloon at 120,000 ft, below 4.65 g/sq cm. The albedo-neutron omnidirectional energy distribution is flat to 50 MeV, then decreases with energy. The absolute neutron energy distribution is of the correct strength and shape for the albedo neutrons to be the source of the protons trapped in earth's inner radiation belt.

  9. Charred Forests Increase Snow Albedo Decay: Watershed-Scale Implications of the Postfire Snow Albedo Effect

    NASA Astrophysics Data System (ADS)

    Gleason, K. E.; Nolin, A. W.

    2014-12-01

    Recent work shows that after a high severity forest fire, approximately 60% more solar radiation reaches the snow surface due to the reduction in canopy density. Also, significant amounts of black carbon (BC) particles and larger burned woody debris (BWD) are shed from standing charred trees, which concentrate on the snowpack, darken its surface, and reduce snow albedo by 50% during ablation. The postfire forest environment drives a substantial increase in net shortwave radiation at the snowpack surface, driving earlier and more rapid melt, however hydrologic models do not explicitly incorporate forest fire disturbance effects to snowpack dynamics. In this study we characterized, parameterized, and validated the postfire snow albedo effect: how the deposition and concentration of charred forest debris decreases snow albedo, increases snow albedo decay rates, and drives an earlier date of snow disappearance. For three study sites in the Oregon High Cascade Mountains, a 2-yr old burned forest, a 10-yr burned forest, and a nearby unburned forest, we used a suite of empirical data to characterize the magnitude and duration of the postfire effect to snow albedo decay. For WY 2012, WY2013, and WY2014 we conducted spectral albedo measurements, snow surface sampling, in-situ snow and meteorological monitoring, and snow energy balance modeling. From these data we developed a new parameterization which represents the postfire effect to snow albedo decay as a function of days-since-snowfall. We validated our parameterization using a physically-based, spatially-distributed snow accumulation and melt model, in-situ snow monitoring, net snowpack radiation, and remote sensing data. We modeled snow dynamics across the extent of all burned area in the headwaters of the McKenzie River Basin and validated the watershed-scale implications of the postfire snow albedo effect using in-situ micrometeorological and remote sensing data. This research quantified the watershed scale postfire

  10. Variable control of neutron albedo in toroidal fusion devices

    DOEpatents

    Jassby, D.L.; Micklich, B.J.

    1983-06-01

    This invention pertains to methods of controlling in the steady state, neutron albedo in toroidal fusion devices, and in particular, to methods of controlling the flux and energy distribution of collided neutrons which are incident on an outboard wall of a toroidal fusion device.

  11. Analytical modeling of thermoluminescent albedo detectors for neutron dosimetry.

    PubMed

    Glickstein, S S

    1983-02-01

    In order to gain an in-depth understanding of the neutron physics of a 6LiF TLD when used as an albedo neutron dosimeter, an analytical model was developed to simulate the response of a 6LiF chip. The analytical model was used to examine the sensitivity of the albedo TLD response to incident monoenergetic neutrons and to evaluate a multiple chip TLD neutron dosimeter. Contrary to initial experimental studies, which were hampered by statistical uncertainties, the analytical evaluation revealed that a three-energy-group detector could not reliably measure the dose equivalent to personnel exposed to multiple neutron spectra. The analysis clearly illustrates that there may be order of magnitude errors in the measured neutron dose if the dosimeter has not been calibrated for the same flux spectrum to which it is exposed. As a result of this analysis, it was concluded that, for personnel neutron monitoring, a present TLD badge must be calibrated for the neutron spectrum into which the badge is to be introduced. The analytical model used in this study can readily be adopted for evaluating other possible detectors and shield material that might be proposed in the future as suitable for use in neutron dosimetry applications. PMID:6826377

  12. New technique to improve the accuracy of albedo neutron dosimeter evaluations

    NASA Astrophysics Data System (ADS)

    Hankins, D. E.

    The calibration factor for albedo neutron dosimeters varies greatly depending upon the energy of the neutrons in the exposure. Calibration results obtained over an eight-year period at each Lawrence Livermore National Laboratory facility where neutron exposure may occur were reviewed. A stronger relationship than expected was found between the ratio of the readings of the 9-in. to 3-in. spheres and the percent thermal. Readings from personnel and albedo badges were reviewed. The readings were consistent with the use of a calibration factor for the albedo dosimeter which varies with changes in the ratio of the personnel and albedo dosimeter TLD readings.

  13. New technique to improve the accuracy of albedo neutron dosimeter evaluations

    SciTech Connect

    Hankins, D.E.

    1984-01-01

    The calibration factor for albedo neutron dosimeters varies greatly depending upon the energy of the neutrons in the exposure. Calibration results obtained over an eight-year period at each Lawrence Livermore National Laboratory facility where neutron exposure may occur were reviewed. A stronger relationship than expected was found between the ratio of the readings of the 9-in. to 3-in. spheres and the percent thermal. Readings from personnel and albedo badges were reviewed. The readings were consistent with the use of a calibration factor for the albedo dosimeter which varies with changes in the ratio of the personnel and albedo dosimeter TLD readings. 2 references, 6 figures. (ACR)

  14. Precision Neutron Polarimetry for Neutron Beta Decay

    PubMed Central

    Penttila, S. I.; Bowman, J. D.

    2005-01-01

    The abBA collaboration is developing a new type of field-expansion spectrometer for a measurement of the three correlation coefficients a, A, and B and the shape parameter b. The measurement of A and B requires precision neutron polarimetry. We will polarize a pulsed cold neutron beam from the SNS using a 3He neutron spin filter. The well-known polarizing cross section for n-3He has a 1/v dependence, where v is the neutron velocity, which is used to determine the absolute beam polarization through a time-of-flight (TOF) measurement. We show that by measuring the TOF dependence of A and B, the coefficients and the neutron polarization can be determined with a small loss of the statistical precision and with negligible systematic error. We conclude that it is possible to determine the neutron polarization averaged over a long run in the neutron beta decay experiment with a statistical error less than 10−4. We discuss various sources of systematic uncertainty in the measurement of A and B and conclude that the fractional systematic errors are less than 2 × 10−4. PMID:27308142

  15. Precision neutron polarimetry for neutron beta decay

    SciTech Connect

    Penttila, S. I.; Bowman, J. D.

    2004-01-01

    The abBA collaboration is developing a new type of field-expansion spectrometer for measurement of the three correlation coefficients a, A, and B and shape parameter b. The measurement of A and B requires precision neutron polarimetry. We will polarize a pulsed cold neutron beam from SNS using a {sup 3}He neutron spin filter. The well-known polarizing cross section for n-{sup 3}He has 1/v dependence, which is used to determine the absolute beam polarization through a time-of-flight (TOF) measurement. We show that measuring the TOF dependence of A and B, the coefficients and the neutron polarization can be determined with small loss of statistical precision and negligible systematic error. We conclude that it is possible to determine the neutron polarization averaged over a run in the neutron beta decay experiment to better than 10{sup -3}. We discuss various sources of systematic uncertainties in the measurement of A and B and conclude that they are less than 10{sup -4}.

  16. Testing Supersymmetry with Neutron Decay

    NASA Astrophysics Data System (ADS)

    Wilburn, W. S.; Cirigliano, V.; Klein, A.; McGaughey, P. L.; Makela, M. F.; Morris, C. L.; Ramsey, J.; Salas-Bacci, A.; Saunders, A.; Broussard, L. J.; Young, A. R.

    2009-10-01

    It has been recently realized that the neutrino correlation parameter B in neutron decay is sensitive to Minimal Supersymmetric Models for the case of maximal mixing. B is currently known to a precision of 3x10-3, but a precision of better than 1x10-3 is required to test these models. Improvements in experimental techniques developed for the ongoing UCNA experiment and the planned abBA experiment may allow an improved measurement of B with a precision approaching 1x10-4. An emerging concept for combining these techniques into an experiment to measure B using ultracold neutrons and large-area silicon detectors will be discussed.

  17. Neutron Beta Decay Studies with Nab

    SciTech Connect

    Baessler, S.; Alarcon, R.; Alonzi, L. P.; Balascuta, S.; Barron-Palos, L.; Bowman, James David; Bychkov, M. A.; Byrne, J.; Calarco, J; Chupp, T.; Cianciolo, T. V.; Crawford, C.; Frlez, E.; Gericke, M. T.; Glück, F.; Greene, G. L.; Grzywacz, R. K.; Gudkov, V.; Harrison, D.; Hersman, F. W.; Ito, T.; Makela, M.; Martin, J.; McGaughey, P. L.; McGovern, S.; Page, S.; Penttila, Seppo I; Pocanic, Dinko; Salas-Bacci, A.; Tompkins, Z.; Wagner, D.; Wilburn, W. S.; Young, A. R.

    2013-01-01

    Precision measurements in neutron beta decay serve to determine the coupling constants of beta decay and allow for several stringent tests of the standard model. This paper discusses the design and the expected performance of the Nab spectrometer.

  18. Application of the TLD albedo technique for monitoring and interpretation of neutron stray radiation fields

    NASA Astrophysics Data System (ADS)

    Piesch, E.; Burgkhardt, B.

    1980-09-01

    A single sphere albedo technique with TLD 600/TLD 700 detectors has been applied in neutron monitoring to calibrate albedo dosimeters and to interpret neutron stray radiation fields in terms of neutron dose equivalent separated for the energy groups below 0.4 eV, 0.4-10 keV and 10 keV-10 MeV, and Eeff for fast neutrons. The paper describes the technique for field and personnel monitoring under the aspect of an on-line computer program for data recording and processing.

  19. Simulation and test of a new albedo personal dosimeter for neutrons

    NASA Astrophysics Data System (ADS)

    Manfredotti, C.; Zanini, A.; Rollet, S.; Arman, G.

    1989-12-01

    A new personal dosimeter for neutrons, using three TLD 600s and one TLD 700 in a cadmium housing and detecting both incoming and albedo neutrons, has been designed, developed, tested and simulated by the code MORSE. Its response in the energy region between 10 -8 and 10 MeV is more similar to ICRP fluence-dose equivalent calibration factor behaviour with respect to previous albedo dosimeters, and particularly fast neutron tissue dose equivalents are less underestimated. Present data confirm that both accuracy and precision fulfil the International Commissions requests (NCR, NCRP, ANSI). Theory, simulation and experimental results obtained with a laboratory prototype are presented and discussed.

  20. Neutron Decay with PERC: a Progress Report

    NASA Astrophysics Data System (ADS)

    Konrad, G.; Abele, H.; Beck, M.; Drescher, C.; Dubbers, D.; Erhart, J.; Fillunger, H.; Gösselsberger, C.; Heil, W.; Horvath, M.; Jericha, E.; Klauser, C.; Klenke, J.; Märkisch, B.; Maix, R. K.; Mest, H.; Nowak, S.; Rebrova, N.; Roick, C.; Sauerzopf, C.; Schmidt, U.; Soldner, T.; Wang, X.; Zimmer, O.; Perc Collaboration

    2012-02-01

    The PERC collaboration will perform high-precision measurements of angular correlations in neutron beta decay at the beam facility MEPHISTO of the Forschungs-Neutronenquelle Heinz Maier-Leibnitz in Munich, Germany. The new beam station PERC, a clean, bright, and versatile source of neutron decay products, is designed to improve the sensitivity of neutron decay studies by one order of magnitude. The charged decay products are collected by a strong longitudinal magnetic field directly from inside a neutron guide. This combination provides the highest phase space density of decay products. A magnetic mirror serves to perform precise cuts in phase space, reducing related systematic errors. The new instrument PERC is under development by an international collaboration. The physics motivation, sensitivity, and applications of PERC as well as the status of the design and preliminary results on uncertainties in proton spectroscopy are presented in this paper.

  1. Neutron Decay Array for beta-delayed neutron Decay Studies

    NASA Astrophysics Data System (ADS)

    Lorusso, Giuseppe; Pereira, J.; Hosmer, P.; Kern, L.; Kratz, K.; Montes, F.; Reeder, P.; Santi, P.; Schatz, H.; Schertz, F.; Wör, A.

    The Neutron Emission Ratio Observer (NERO), has been constructed for use at the National Superconducting Cyclotron Laboratory to work in conjunction with the NSCL Beta Counting System BCS [1] in order to detect β-delayed neutrons. The design of the detector provides high and flat efficiency for a wide range of neutron energies, as well as a low neutron background.

  2. The Dynamic Albedo of Neutrons (DAN) experiment for NASA's 2009 Mars Science Laboratory.

    PubMed

    Litvak, M L; Mitrofanov, I G; Barmakov, Yu N; Behar, A; Bitulev, A; Bobrovnitsky, Yu; Bogolubov, E P; Boynton, W V; Bragin, S I; Churin, S; Grebennikov, A S; Konovalov, A; Kozyrev, A S; Kurdumov, I G; Krylov, A; Kuznetsov, Yu P; Malakhov, A V; Mokrousov, M I; Ryzhkov, V I; Sanin, A B; Shvetsov, V N; Smirnov, G A; Sholeninov, S; Timoshenko, G N; Tomilina, T M; Tuvakin, D V; Tretyakov, V I; Troshin, V S; Uvarov, V N; Varenikov, A; Vostrukhin, A

    2008-06-01

    We present a summary of the physical principles and design of the Dynamic Albedo of Neutrons (DAN) instrument onboard NASA's 2009 Mars Science Laboratory (MSL) mission. The DAN instrument will use the method of neutron-neutron activation analysis in a space application to study the abundance and depth distribution of water in the martian subsurface along the path of the MSL rover. PMID:18598140

  3. 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.

  4. Magnetic field decay in isolated neutron stars

    NASA Technical Reports Server (NTRS)

    Goldreich, Peter; Reisenegger, Andreas

    1992-01-01

    Three mechanisms that promote the loss of magnetic flux from an isolated neutron star - Ohmic decay, ambipolar diffusion, and Hall drift - are investigated. Equations of motions are solved for charged particles in the presence of a magnetic field and a fixed background of neutrons, while allowing for the creation and destruction of particles by weak interactions. Although these equations apply to normal neutrons and protons, the present interpretations of their solutions are extended to cover cases of neutron superfluidity and proton superconductivity. The equations are manipulated to prove that, in the presence of a magnetic force, the charged particles cannot be simultaneously in magnetostatic equilibrium and chemical equilibrium with the neutrons. The application of the results to real neutron stars is discussed.

  5. Radiation damage in silicon due to albedo neutrons emitted from hadronic beam dumps (Fe and U)

    SciTech Connect

    Gabriel, T.A.; Bishop, B.L.

    1987-01-01

    Calculations have been carried out to determine the level of radiation damage that can be expected from albedo neutrons when 1- and 5-GeV negative pions are incident on iron and uranium beam dumps. The calculated damage data are presented in several ways including neutron fluence above 0.111 MeV, 1 MeV equivalent neutron fluence, damage energy deposition, and DPA or displacements per atom. Details are presented as to the method of calculation. 14 refs., 1 fig., 1 tab.

  6. Time reversal invariance in polarized neutron decay

    SciTech Connect

    Wasserman, E.G.

    1994-03-01

    An experiment to measure the time reversal invariance violating (T-violating) triple correlation (D) in the decay of free polarized neutrons has been developed. The detector design incorporates a detector geometry that provides a significant improvement in the sensitivity over that used in the most sensitive of previous experiments. A prototype detector was tested in measurements with a cold neutron beam. Data resulting from the tests are presented. A detailed calculation of systematic effects has been performed and new diagnostic techniques that allow these effects to be measured have been developed. As the result of this work, a new experiment is under way that will improve the sensitivity to D to 3 {times} 10{sup {minus}4} or better. With higher neutron flux a statistical sensitivity of the order 3 {times} 10{sup {minus}5} is ultimately expected. The decay of free polarized neutrons (n {yields} p + e + {bar v}{sub e}) is used to search for T-violation by measuring the triple correlation of the neutron spin polarization, and the electron and proton momenta ({sigma}{sub n} {center_dot} p{sub p} {times} p{sub e}). This correlation changes sign under reversal of the motion. Since final state effects in neutron decay are small, a nonzero coefficient, D, of this correlation indicates the violation of time reversal invariance. D is measured by comparing the numbers of coincidences in electron and proton detectors arranged symmetrically about a longitudinally polarized neutron beam. Particular care must be taken to eliminate residual asymmetries in the detectors or beam as these can lead to significant false effects. The Standard Model predicts negligible T-violating effects in neutron decay. Extensions to the Standard Model include new interactions some of which include CP-violating components. Some of these make first order contributions to D.

  7. Decay of neutron pulses in graphite assemblies

    SciTech Connect

    Malik, U.; Kothari, L.S.

    1982-09-01

    A new neutron scattering kernel for graphite has been developed with the frequency distribution function generated by the authors using the unfolding technique. This has been used to study the decay of neutron pulses in different graphite assemblies. This kernel (with theta /SUB D/ = 2000 K) can give a slightly better explanation of the experimental results than those based on the Krumhansl and Brooks model or the Young and Koppel model of lattice vibrations.

  8. Observation of lunar neutron albedo along the 24th Solar cycle

    NASA Astrophysics Data System (ADS)

    Sanin, Anton; Mitrofanov, Igor; Litvak, Maxim; Bodnarik, Julia; Boynton, William; Chin, Gordon; Evans, Larry; Golovin, Dmitry; Harshman, Karl; Livengood, Timothy; Malakhov, Alexey; Mokrousov, Maxim; McClanahan, Timothy; Sagdeev, Roald; Starr, Richard; Vostrukhin, Andrey

    2015-04-01

    It is well known that the Sun is not a steady source of radiation and demonstrates quasi-periodic variations of its activity with an average period of 11 years. The variation in solar activity yields a number of important physical effects that impact the entire heliosphere. Some of these effects are important for human life, since variations of the solar wind and the interplanetary magnetic field in the Solar System may produce variations of geomagnetic field and Van Allen radiation belts. Moreover, after strong Solar Coronal Mass Ejection events global geomagnetic storms are possible. Solar variability generates a strong modulation of the Galactic Cosmic Ray (GCR) flux inside the heliosphere and results in a modulation of the neutron albedo of the Moon and other celestial bodies that lack a strong global magnetic field. Observations of the lunar neutron albedo and its variability are quite important for future human missions on the Moon since they provide an understanding of that radiation environment on the surface and in the subsurface. We have used the data of collimated and omnidirectional epithermal neutron detectors of the Lunar Exploration Neutron Detector (LEND) gathered from September 2009 up to present. This period covers the first half of the 24th Solar cycle from period of minimum solar activity with maximum lunar neutron albedo up to high solar activity and less neutron albedo. It was found that for the observed time period, the amplitude of neutron flux drops down by a factor of ~1.7 after a maximal values observed at December 2009. We have compared LEND measurements with ongoing observations of GCR variability by neutron detectors on-board other spacecraft orbiting around Earth (BTN/ISS) and Mars (HEND/Odyssey). All neutron instruments show similar global trends and local variations. It was found that HEND on Martian orbit has detected highest amplitude of neutron flux variations (~1.8 times) and the peak of neutron flux occurred by a couple of

  9. - and -delayed neutron- decay of neutron-rich copper isotopes

    SciTech Connect

    Korgul, A.; Rykaczewski, Krzysztof Piotr; Winger, J. A.; Ilyushkin, S.; Gross, Carl J; Batchelder, J. C.; Bingham, C. R.; Borzov, Ivan N; Goodin, C.; Grzywacz, Robert Kazimierz; Hamilton, Joseph H; Krolas, W.; Liddick, S. N.; Mazzocchi, C.; Nelson, C.; Nowacki, F.; Padgett, Stephen; Piechaczek, A.; Rajabali, M. M.; Shapira, Dan; Sieja, K.; Zganjar, E. F.

    2012-01-01

    The {beta}-decay properties of neutron-rich Cu isotopes produced in proton-induced fission of {sup 238}U were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The data were collected using high-resolution online mass separation, reacceleration, and digital {beta}-{gamma} spectroscopy methods. An improved decay scheme of N = 49 {sup 78}Cu and the first observation of N = 50 {sup 79}Cu {beta}-delayed neutron decay followed by a gamma transition are reported. Spin and parity (5{sup -}) are deduced for {sup 78gs}Cu. The {beta}-delayed neutron branching ratios (P{sub {beta}n}) for the {sup 77}Cu and {sup 79}Cu precursors are analyzed with the help of nuclear structure models.

  10. An investigation into the sensitivity of various albedo neutron dosimeters aimed at correcting the readings

    NASA Astrophysics Data System (ADS)

    Alekseev, A. G.; Mokrov, Yu. V.; Morozova, S. V.

    2012-03-01

    The results of an experimental determination of the sensitivity of three types of individual neutron albedo dosimeters in neutron reference fields on the basis of radionuclide sources and at the top concrete shielding of the U-70 accelerator are presented. The results show that the ratios between the responses of the albedo dosimeters designed earlier at the Joint Institute for Nuclear Research (the albedo dosimeter (AD) and the multicomponent dosimeter (MD)) and the currently used DVGN-01 dosimeter are constant within 25% in a wide range of neutron energy. This fact makes it possible to use the results of measuring the AD and MD responses obtained earlier in neutron fields of nuclear-physical installations at the Joint Institute for Nuclear Research (JINR) for the correction of DVGN-01 dosimeter measurement results to apply it to personal radiation monitoring (PRM) at these installations. The correction factors for DVGN-01 measurement results are found and recommended to be used in PRM for most JINR installations.

  11. Dynamic Albedo of Neutrons (DAN) Experiment Onboard NASA's Mars Science Laboratory

    NASA Astrophysics Data System (ADS)

    Mitrofanov, I. G.; Litvak, M. L.; Varenikov, A. B.; Barmakov, Y. N.; Behar, A.; Bobrovnitsky, Y. I.; Bogolubov, E. P.; Boynton, W. V.; Harshman, K.; Kan, E.; Kozyrev, A. S.; Kuzmin, R. O.; Malakhov, A. V.; Mokrousov, M. I.; Ponomareva, S. N.; Ryzhkov, V. I.; Sanin, A. B.; Smirnov, G. A.; Shvetsov, V. N.; Timoshenko, G. N.; Tomilina, T. M.; Tret'yakov, V. I.; Vostrukhin, A. A.

    2012-09-01

    The description of Dynamic Albedo of Neutrons (DAN) experiment is presented, as a part of the NASA's Mars Science Laboratory mission onboard the mars rover Curiosity. The instrument DAN includes Pulsing Neutron Generator (PNG) producing pulses of 14.1 MeV neutrons for irradiation of subsurface material below the rover, and Detectors and Electronics (DE) unit, which operates the instrument itself and measures the die-away time profiles of epithermal and thermal neutrons following each neutron pulse. It is shown that the DAN investigation will measure a content of hydrogen along the path of the MSL rover, and it will also provide information about a depth distribution of hydrogen at 10-20 regions selected for the detailed studies and sampling analysis.

  12. N-SAP and G-SAP neutron and gamma ray albedo model scatter shield analysis program

    NASA Technical Reports Server (NTRS)

    Sapovchak, B. J.; Stephenson, L. D.

    1967-01-01

    Computer program calculates neutron or gamma ray first order scattering from a plane or cylindrical surface to a detector point. The SAP Codes, G-SAP and N-SAP, constitute a multiple scatter albedo model shield analysis.

  13. Constraining decaying dark matter with neutron stars

    NASA Astrophysics Data System (ADS)

    Pérez-García, M. Ángeles; Silk, Joseph

    2015-05-01

    The amount of decaying dark matter, accumulated in the central regions in neutron stars together with the energy deposition rate from decays, may set a limit on the neutron star survival rate against transitions to more compact objects provided nuclear matter is not the ultimate stable state of matter and that dark matter indeed is unstable. More generally, this limit sets constraints on the dark matter particle decay time, τχ. We find that in the range of uncertainties intrinsic to such a scenario, masses (mχ /TeV) ≳ 9 ×10-4 or (mχ /TeV) ≳ 5 ×10-2 and lifetimes τχ ≲1055 s and τχ ≲1053 s can be excluded in the bosonic or fermionic decay cases, respectively, in an optimistic estimate, while more conservatively, it decreases τχ by a factor ≳1020. We discuss the validity under which these results may improve with other current constraints.

  14. Radiative Corrections for Neutron Decay and Search for New Physics

    PubMed Central

    Gudkov, V.; Kubodera, K.; Myhrer, F.

    2005-01-01

    The expected increased accuracy of neutron β-decay experiments at the new Spallation Neutron Source could result in more stringent tests of the Standard Model. For an unambiguous search for new physics in neutron decay experiments and for a precise determination of fundamental constants, it is necessarily to understand and evaluate all corrections for neutron decay with higher accuracy than the expected experimental precision. We discuss the possibility to estimate the accuracy of radiative corrections. New results based on the applications of effective field theory for neutron decay is presented. PMID:27308143

  15. Neutron decay of the Giant Pairing Vibration in 15C

    NASA Astrophysics Data System (ADS)

    Cavallaro, M.; Agodi, C.; Assié, M.; Azaiez, F.; Cappuzzello, F.; Carbone, D.; de Séréville, N.; Foti, A.; Pandola, L.; Scarpaci, J. A.; Sgouros, O.; Soukeras, V.

    2016-06-01

    The neutron decay of the resonant states of light neutron-rich nuclei is an important and poorly explored property, useful to extract valuable nuclear structure information. The neutron decay of the 15C resonances populated via the two-neutron transfer reaction 13C(18O,16O n) at 84 MeV incident energy is studied using an innovative technique which couples the MAGNEX magnetic spectrometer and the EDEN neutron detector array. The data show that the recently observed 15C Giant Pairing Vibration at 13.7 MeV mainly decays via two-neutron emission.

  16. New precision measurements of free neutron beta decay with cold neutrons

    SciTech Connect

    Baeßler, Stefan; Bowman, James David; Penttilä, Seppo I.; Počanić, Dinko

    2014-10-14

    Precision measurements in free neutron beta decay serve to determine the coupling constants of beta decay, and offer several stringent tests of the standard model. This study describes the free neutron beta decay program planned for the Fundamental Physics Beamline at the Spallation Neutron Source at Oak Ridge National Laboratory, and finally puts it into the context of other recent and planned measurements of neutron beta decay observables.

  17. Solar neutron decay proton observations in cycle 21

    NASA Technical Reports Server (NTRS)

    Evenson, Paul; Kroeger, Richard; Meyer, Peter; Reames, Donald

    1990-01-01

    Measurement of the flux and energy spectrum of the protons resulting from the decay of solar flare neutrons gives unique information on the spectrum of neutrons from 5 to 200 MeV. Neutrons from three flares have been observed in this manner during solar cycle 21. The use of the decay protons to determine neutron energy spectra is reviewed, and new and definitive energy spectra are presented for the two large flares on June 3, 1982 and April 25, 1984.

  18. Effects of geochemical composition on neutron die-away measurements: Implications for Mars Science Laboratory's Dynamic Albedo of Neutrons experiment

    NASA Astrophysics Data System (ADS)

    Hardgrove, C.; Moersch, J.; Drake, D.

    2011-12-01

    The Dynamic Albedo of Neutrons (DAN) experiment, part of the scientific payload of the Mars Science Laboratory (MSL) rover mission, will have the ability to assess both the abundance and the burial depth of subsurface hydrogen as the rover traverses the Martian surface. DAN will employ a method of measuring neutron fluxes called “neutron die-away” that has not been used in previous planetary exploration missions. This method requires the use of a pulsed neutron generator that supplements neutrons produced via spallation in the subsurface by the cosmic ray background. It is well established in neutron remote sensing that low-energy (thermal) neutrons are sensitive not only to hydrogen content, but also to the macroscopic absorption cross-section of near-surface materials. To better understand the results that will be forthcoming from DAN, we model the effects of varying abundances of high absorption cross-section elements that are likely to be found on the Martian surface (Cl, Fe) on neutron die-away measurements made from a rover platform. Previously, the Mars Exploration Rovers (MER) Spirit and Opportunity found that elevated abundances of these two elements are commonly associated with locales that have experienced some form of aqueous activity in the past, even though hydrogen-rich materials are not necessarily still present. By modeling a suite of H and Cl compositions, we demonstrate that (for abundance ranges reasonable for Mars) both the elements will significantly affect DAN thermal neutron count rates. Additionally, we show that the timing of thermal neutron arrivals at the detector can be used together with the thermal neutron count rates to independently determine the abundances of hydrogen and high neutron absorption cross-section elements (the most important being Cl). Epithermal neutron die-away curves may also be used to separate these two components. We model neutron scattering in actual Martian compositions that were determined by the MER Alpha

  19. Modes of decay in neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Kumar, B.; Biswal, S. K.; Singh, S. K.; Lahiri, C.; Patra, S. K.

    2016-03-01

    We calculate the ground, first intrinsic excited states and density distribution for neutron-rich thorium and uranium isotopes, within the framework of relativistic mean field (RMF) approach using axially deformed basis. The total nucleon densities are calculated, from which the cluster-structures inside the parent nuclei are determined. The possible modes of decay, like α-decay and β-decay are analyzed. We find the neutron-rich isotopes are stable against α-decay, however they are very much unstable against β-decay. The life time of these nuclei predicted to be tens of second against β-decay.

  20. Neutron beta decay measurements planned for the SNS

    NASA Astrophysics Data System (ADS)

    Pocanic, Dinko

    2009-10-01

    A cold neutron beam line, dedicated to fundamental neutron physics (FnPB), is presently being completed at the Oak Ridge, TN, Spallation Neutron Source. Among other experiments, the beamline will host a comprehensive set of precise studies of the neutron beta decay. Neutron beta decay is characterised by the decay rate (or its inverse, the neutron lifetime), and a set of decay parameters describing the kinematical and spin correlations among the participating particles. Within the standard model (SM), the neutron lifetime and three decay parameters (a, A, and B) are fixed by two parameters: the Vud element of the Cabibbo-Kobayashi-Maskawa mixing matrix, and λ=GA/GV, the ratio of axial vector and vector nucleon form factors. This overdetermined system provides a unique opportunity to explore possible departures from the simple SM, as well as the nature of such departures, e.g., left-right supersymmetric extensions, leptoquarks, non-(V-A) admixtures, etc., with broad implications in subatomic physics. The FnPB neutron beta decay program will include measurements of the neutron lifetime, continuing the present NIST experiment, a measurement of a, the electron-neutrino correlation, and b, the Fierz interference term, (the ``Nab'' experiment), along with measurements of A and B, the correlations between neutron spin and electron and neutrino momenta, respectively, (the ``abBA'' experiment). Current plans for these experiments will be discussed in detail.

  1. Non-destructive assay of spent nuclear fuel using passive neutron Albedo reactivity

    SciTech Connect

    Evans, L G; Schear, M A; Croft, S; Tobin, S J; Swinhoe, M T; Menlove, H O

    2010-01-01

    Passive Neutron Albedo Reactivity (PNAR) is one of fourteen techniques that has been researched and evaluated to form part of a comprehensive and integrated detection system for the non-destructive assay (NDA) of spent nuclear fuel. PNAR implemented with {sup 3}He tubes for neutron detection (PNAR-{sup 3}He) is the measurement of time correlated neutrons from a spent fuel assembly with and without a Cadmium (Cd) layer surrounding the assembly. PNAR utilizes the self-interrogation of the fuel via reflection of neutrons born in the fuel assembly back in to the fuel assembly. The neutrons originate primarily from spontaneous fission events within the fuel itself (Curium-244) but are amplified by multiplication. The presence and removal of the Cd provides two measurement conditions with different neutron energy spectra and therefore different interrogating neutron characteristics. Cd has a high cross-section of absorption for slow neutrons and therefore greatly reduces the low energy (thermal) neutron fluence rate returning. The ratios of the Singles, Doubles and Triples count rates obtained in each case are known as the Cd ratios, which are related to fissile content. A potential safeguards application for which PNAR-{sup 3}He is particularly suited is 'fingerprinting'. Fingerprinting could function as an alternative to plutonium (Pu) mass determination; providing confidence that material was not diverted during transport between sites. PNAR-{sup 3}He has six primary NDA signatures: Singles, Doubles and Triples count rates measured with two energy spectra at both shipping and receiving sites. This is to uniquely identify the fuel assembly, and confirm no changes have taken place during transport. Changes may indicate all attempt to divert material for example. Here, the physics of the PNAR-{sup 3}He concept will be explained, alongside a discussion on the development of a prototypical PNAR-{sup 3}He instrument using simulation. The capabilities and performance of the

  2. Ground Albedo Neutron Sensing (GANS) method for measurements of soil moisture in cropped fields

    NASA Astrophysics Data System (ADS)

    Andres Rivera Villarreyes, Carlos; Baroni, Gabriele; Oswald, Sascha E.

    2013-04-01

    Measurement of soil moisture at the plot or hill-slope scale is an important link between local vadose zone hydrology and catchment hydrology. However, so far only few methods are on the way to close this gap between point measurements and remote sensing. This study evaluates the applicability of the Ground Albedo Neutron Sensing (GANS) for integral quantification of seasonal soil moisture in the root zone at the scale of a field or small watershed, making use of the crucial role of hydrogen as neutron moderator relative to other landscape materials. GANS measurements were performed at two locations in Germany under different vegetative situations and seasonal conditions. Ground albedo neutrons were measured at (i) a lowland Bornim farmland (Brandenburg) cropped with sunflower in 2011 and winter rye in 2012, and (ii) a mountainous farmland catchment (Schaefertal, Harz Mountains) since middle 2011. At both sites depth profiles of soil moisture were measured at several locations in parallel by frequency domain reflectometry (FDR) for comparison and calibration. Initially, calibration parameters derived from a previous study with corn cover were tested under sunflower and winter rye periods at the same farmland. GANS soil moisture based on these parameters showed a large discrepancy compared to classical soil moisture measurements. Therefore, two new calibration approaches and four different ways of integration the soil moisture profile to an integral value for GANS were evaluated in this study. This included different sets of calibration parameters based on different growing periods of sunflower. New calibration parameters showed a good agreement with FDR network during sunflower period (RMSE = 0.023 m3 m-3), but they underestimated soil moisture in the winter rye period. The GANS approach resulted to be highly affected by temporal changes of biomass and crop types which suggest the need of neutron corrections for long-term observations with crop rotation. Finally

  3. Does mass accretion lead to field decay in neutron stars

    NASA Technical Reports Server (NTRS)

    Shibazaki, N.; Murakami, T.; Shaham, Jacob; Nomoto, K.

    1989-01-01

    The recent discovery of cyclotron lines from gamma-ray bursts indicates that the strong magnetic fields of isolated neutron stars might not decay. The possible inverse correlation between the strength of the magnetic field and the mass accreted by the neutron star suggests that mass accretion itself may lead to the decay of the magnetic field. The spin and magnetic field evolution of the neutron star was calculated under the hypothesis of the accretion-induced field decay. It is shown that the calculated results are consistent with the observations of binary and millisecond radio pulsars.

  4. MoNA and Two-Neutron Decay Analysis

    NASA Astrophysics Data System (ADS)

    Grovom, Amanda; Aulie, Alegra; Rogers, Warren F.

    2010-11-01

    The Modular Neutron Array (MoNA) is a large, high-efficiency position-sensitive neutron detector array housed at the National Superconducting Cyclotron Laboratory at Michigan State University, consisting of 144 2-meter long scintillator bars with a PMT positioned at each end, designed to detect the energy and trajectory of fast neutrons emitted in the breakup of exotic neutron-rich nuclei. Because a single neutron can scatter multiple times within MoNA, (including a large presence of dark-scattering from Carbon), the experimental challenge to distinguish between single and multiple neutron decay events is significant. We've developed special data-sorting routines that selectively filter on a combination of factors such as neutron velocity and scattering angle, hit-pattern distribution, neutron-fragment opening angle, and decay energy in order to reduce the Carbon scattering background and enhance correlations between pairs of neutrons. We've applied this analysis to the 2-neutron decays of ^24O and ^13Li from data sets from previous MoNA experiments. Results will be presented.

  5. New limit on T violation in neutron decay

    NASA Astrophysics Data System (ADS)

    Soldner, T.; Beck, L.; Plonka, C.; Schreckenbach, K.; Zimmer, O.

    2004-02-01

    We have measured the triple correlation D of the neutron polarisation and the momenta of electron and antineutrino, dW∝1+DP(pe×pν¯), in neutron beta decay. Our result is D=[-2.8±6.4(stat)±3.0(syst)]×10-4. The corresponding phase between gA and gV in V-A-theory follows as φAV=180.04°±0.09°. This result improves the limit on a possible T violation in neutron beta decay.

  6. Integral Quantification of Soil Water Content at the Intermediate Catchment Scale by Ground Albedo Neutron Sensing (GANS)

    NASA Astrophysics Data System (ADS)

    Rivera Villarreyes, C. A.; Baroni, G.; Oswald, S. E.

    2012-04-01

    Soil water content at the plot or hill-slope scale is an important link between local vadose zone hydrology and catchment hydrology. However, so far only few methods are on the way to close this gap between point measurements and remote sensing. One new measurement methodology for integral quantifications of mean areal soil water content at the intermediate catchment scale is the aboveground sensing of cosmic-ray neutrons, more precisely ground albedo neutron sensing (GANS). Ground albedo natural neutrons, are generated by collisions of secondary cosmic rays with land surface materials (soil, water, biomass, snow, etc). Neutrons measured at the air/ground interface correlate with soil moisture contained in a footprint of ca. 600 m diameter and a depth ranging down to a few decimeters. This correlation is based on the crucial role of hydrogen as neutron moderator compared to others landscape materials. The present study performed ground albedo neutron sensing in different locations in Germany under different vegetative situations (cropped and bare field) and different seasonal conditions (summer, autumn and winter). Ground albedo neutrons were measured at (i) a farmland close to Potsdam (Brandenburg, Germany) cropped with corn in 2010 and sunflowers in 2011, and (ii) a mountainous farmland catchment (Schaefertal, Harz Mountains, Germany) in 2011. In order to test this method, classical soil moisture devices and meteorological data were used for comparison. Moreover, calibration approach, and transferability of calibration parameters to different times and locations are also evaluated. Our observations suggest that GANS can overcome the lack of data for hydrological processes at the intermediate scale. Soil water content from GANS compared quantitatively with mean water content values derived from a network of classical devices (RMSE = 0.02 m3/m3 and r2 = 0.98) in three calibration periods with cropped-field conditions. Then, same calibration parameters corresponded

  7. Observational Evidence of a Hemispheric-wide Ice-ocean Albedo Feedback Effect on Antarctic Sea-ice Decay

    NASA Technical Reports Server (NTRS)

    Nihashi, Sohey; Cavalieri, Donald J.

    2007-01-01

    The effect of ice-ocean albedo feedback (a kind of ice-albedo feedback) on sea-ice decay is demonstrated over the Antarctic sea-ice zone from an analysis of satellite-derived hemispheric sea ice concentration and European Centre for Medium-Range Weather Forecasts (ERA-40) atmospheric data for the period 1979-2001. Sea ice concentration in December (time of most active melt) correlates better with the meridional component of the wind-forced ice drift (MID) in November (beginning of the melt season) than the MID in December. This 1 month lagged correlation is observed in most of the Antarctic sea-ice covered ocean. Daily time series of ice , concentration show that the ice concentration anomaly increases toward the time of maximum sea-ice melt. These findings can be explained by the following positive feedback effect: once ice concentration decreases (increases) at the beginning of the melt season, solar heating of the upper ocean through the increased (decreased) open water fraction is enhanced (reduced), leading to (suppressing) a further decrease in ice concentration by the oceanic heat. Results obtained fi-om a simple ice-ocean coupled model also support our interpretation of the observational results. This positive feedback mechanism explains in part the large interannual variability of the sea-ice cover in summer.

  8. β- decay of the neutron-rich isotope 215Pb

    NASA Astrophysics Data System (ADS)

    De Witte, H.; Eeckhaudt, S.; Andreyev, A. N.; Borzov, I. N.; Cederkäll, J.; De Smet, A.; Fedorov, D. V.; Fedoseyev, V. N.; Franchoo, S.; Górska, M.; Grawe, H.; Huber, G.; Huyse, M.; Janas, Z.; Köster, U.; Kurcewicz, W.; Kurpeta, J.; Płochocki, A.; Van de Vel, K.; Van Duppen, P.; Weissman, L.

    2013-06-01

    This Brief Report reports on the first observation of the β--delayed γ decay of 215Pb, feeding states in 215Bi. The 215Pb beam was produced using resonant laser ionization and mass separated at the ISOLDE-CERN on-line mass separator. This ensured clean identification of the γ rays as belonging to the decay of 215Pb or its β-decay daughters. A half-life of 147(12) s was measured for the 215Pb β decay and a level scheme for the daughter nucleus 215Bi is proposed, resulting in an extended systematics of the excited states of the neutron-rich Bi isotopes.

  9. Gamma-ray bursts and neutron star field decay

    NASA Technical Reports Server (NTRS)

    Hartmann, Dieter; Blumenthal, George; Chuang, Kuan-Wen; Hurley, Kevin; Kargatis, Vincent; Liang, Edison; Linder, Eric

    1992-01-01

    Assuming a Galactic origin of gamma-ray bursts, we use pulsar data to calculate the spatial distribution of neutron stars and determine the sampling depths of current detectors. Based on these distance limits, we calculate the corresponding age distribution of Galactic neutron stars and apply an exponential field decay model to test whether the observed high incidence rate of cyclotron lines is consistent with suggested field decay time scales of order 10 exp 7 years. We find that the properties of the observed population of gamma-ray bursts are inconsistent with the idea that bursts originate at arbitrary times on neutron stars whose fields decay on time scales shorter than about 10 exp 9 years. Possible interpretations of this inconsistency are discussed.

  10. Decay-Assisted Laser Spectroscopy of Neutron-Deficient Francium

    NASA Astrophysics Data System (ADS)

    Lynch, K. M.; Billowes, J.; Bissell, M. L.; Budinčević, I.; Cocolios, T. E.; De Groote, R. P.; De Schepper, S.; Fedosseev, V. N.; Flanagan, K. T.; Franchoo, S.; Garcia Ruiz, R. F.; Heylen, H.; Marsh, B. A.; Neyens, G.; Procter, T. J.; Rossel, R. E.; Rothe, S.; Strashnov, I.; Stroke, H. H.; Wendt, K. D. A.

    2014-01-01

    This paper reports on the hyperfine-structure and radioactive-decay studies of the neutron-deficient francium isotopes Fr202-206 performed with the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at the ISOLDE facility, CERN. The high resolution innate to collinear laser spectroscopy is combined with the high efficiency of ion detection to provide a highly sensitive technique to probe the hyperfine structure of exotic isotopes. The technique of decay-assisted laser spectroscopy is presented, whereby the isomeric ion beam is deflected to a decay-spectroscopy station for alpha-decay tagging of the hyperfine components. Here, we present the first hyperfine-structure measurements of the neutron-deficient francium isotopes Fr202-206, in addition to the identification of the low-lying states of Fr202,204 performed at the CRIS experiment.

  11. Calculation of neutron-decay-proton trapping in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Thomas, J. R.; Doherty, W. R.

    1972-01-01

    Investigations on the possible proton fluxes resulting from cosmic ray albedo neutron decay (CRAND) are summarized. It is recalled that experimental data on the earth's belts are reasonably consistent with a CRAND source for most of the protons with energies 50 MeV in the heart of the inner belt. It is assumed that the CRAND and cosmic ray flux and spectrum for Jupiter are the same as for the Earth, with the significant difference that considerably higher energy particles are needed to reach the Jupiter atmosphere at the same magnetic latitude. The ratio of the CRAND source averaged over an L shell on Jupiter to that on Earth at L = 1.3 is derived from a geometrical calculation. The ratio of average loss rate on Jupiter to that for the Earth is also discussed. The flux around Jupiter is obtained by scaling according to the ratio of source to loss from the flux observed in the Earth's inner belt.

  12. Neutronics performance and decay heat calculation of a solid target for a spallation neutron source

    NASA Astrophysics Data System (ADS)

    Nio, D.; Ooi, M.; Takenaka, N.; Furusaka, M.; Kawai, M.; Mishima, K.; Kiyanagi, Y.

    2005-08-01

    A solid target is expected to give higher neutron intensity than a liquid target of mercury at a spallation neutron source with a power of around 1 MW. We have studied the neutronic performance of a target-moderator-reflector assembly with a tungsten solid target. It is found that the neutron intensities from moderators were higher in the solid target system than in the mercury liquid target. However, the tungsten target required cladding to prevent tungsten from the corrosion of cooling water. A tungsten target with tantalum cladding has been already developed although tantalum has high decay heat. Therefore, we estimated the decay heat of the target and found that the decay heat of 0.5 mm thick tantalum was still high. We need a thinner tantalum or new cladding materials. It was revealed that adoption of a thinner tantalum or new cladding material such as chrome nitride reduced the decay heat effectively.

  13. Protons from the decay of solar flare neutrons

    NASA Technical Reports Server (NTRS)

    Evenson, P.; Meyer, P.; Pyle, K. R.

    1983-01-01

    Fluxes of energetic protons in interplanetary space are observed which are interpreted as the decay products of neutrons generated in a solar flare on 1982 June 3 at 11:42 UT. Because of the particular geometry of this event the spectrum of neutrons escaping from the sun can be constructed with great accuracy in the kinetic energy range 10-100 MeV. The resulting spectrum places stringent constraints on the free parameters used in previously published calculations of neutron production in solar flares. An estimate is made of the diffusion mean free path of charged particles in the interplanetary medium in a new way.

  14. Detecting the Radiative Decay Mode of the Neutron

    PubMed Central

    Fisher, B. M.; Wietfeldt, F. E.; Dewey, M. S.; Gentile, T. R.; Nico, J. S.; Thompson, A. K.; Coakley, K. J.; Beise, E. J.; Kiriluk, K. G.; Byrne, J.

    2005-01-01

    Beta decay of the neutron into a proton, electron, and electron antineutrino is occasionally accompanied by the emission of a photon. Despite decades of detailed experimental studies of neutron beta-decay, this rare branch of a fundamental weak decay has never been observed. An experiment to study the radiative beta-decay of the neutron is currently being developed for the NG-6 fundamental physics endstation at the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR). The experiment will make use of the existing apparatus for the NIST proton-trap lifetime experiment, which can provide substantial background reduction by providing an electron-proton coincidence trigger. Tests and design of a detector for gamma-rays in the 10 keV to 200 keV range are under development. The need for a large solid-angle gamma-ray detector that can operate in a strong magnetic field and at low temperature has led us to consider scintillating crystals in conjunction with avalanche photodiodes. The motivation and experimental technique will be discussed. PMID:27308161

  15. Limits on tensor coupling from neutron β decay

    NASA Astrophysics Data System (ADS)

    Pattie, R. W., Jr.; Hickerson, K. P.; Young, A. R.

    2013-10-01

    Limits on the tensor couplings generating a Fierz interference term b in mixed Gamow-Teller Fermi decays can be derived by combining data from measurements of angular correlation parameters in neutron decay, the neutron lifetime, and GV=GFVud as extracted from measurements of the Ft values from the 0+→0+ superallowed decay data set. These limits are derived by comparing the neutron β-decay rate as predicted in the standard model with the measured decay rate while allowing for the existence of beyond the standard model (BSM) couplings. We analyze limits derived from the electron-neutrino asymmetry a, or the beta asymmetry A, finding that the most stringent limits for CT/CA under the assumption of no right-handed neutrinos is -0.0026

  16. Characterization of segmented Silicon detectors for neutron beta decay experiments

    NASA Astrophysics Data System (ADS)

    Salas, Americo; McGaughey, Patrick

    2012-03-01

    The ``Nab'', and ``UCNB'' collaborations will measure the correlation parameters ``a'', ``b'', and ``B'' that are found in the triple differential rate equation from neutron β-decay ( n ->p + e + νe). These parameters that offer an atractive platform for searches of signals of new physics beyond standard model will be measured using unpolarized cold neutrons (Nab) at SNS, ORNL,and polarized ultracold neutrons (UCNB) at LANL. Following a neutron β-decay the electron and proton, will be accelerated in a 4π-field spectrometer, and detected by a novel detector design consisting of two opposite large area and thick silicon detectors segmented in 127 pixels per detector, and operated at ˜ 100 Kelvin. We have successfully completed the first phase of detector characterization, operating 0.5, 1.0, and 1.5 mm thick Silicon detectors of 11 cm in diameter for neutron β-decay experiments at Los Alamos National Laboratory, and detected ˜ 300 Hz protons from 15 to 35 keV at NCSU with a FWHM resolution of ˜ 3.2 keV with a potential of another factor of two improvement. Custom amplifiers based on FETs mounted directly on the detector reduced the noise and made possible the proton detection.

  17. Nab: precise experimental study of unpolarized neutron beta decay

    NASA Astrophysics Data System (ADS)

    Pocanic, Dinko; Nab Collaboration

    2014-09-01

    Nab, a program of experimental study of unpolarized neutron decays at the Spallation Neutron Source, Oak Ridge, TN, aims to determine a, the electron-neutrino correlation with precision of δa / a =10-3 , and b, the Fierz interference term, with uncertainty δb ~= 3 ×10-3 . Neutron beta decay's simple theoretical description in the Standard Model (SM) is overconstrained by the set of available observables, providing opportunities to search for evidence of SM extensions. Planned Nab results will lead to a new precise determination of the ratio λ =GA /GV , and to significant reductions in the allowed limits for both right- and left-handed scalar and tensor currents. Alternatively, the experiment may detect a discrepancy from SM predictions consistent with certain realizations of supersymmetry. An optimized, asymmetric spectrometer has been designed to achieve the narrow proton momentum response function required to meet the physics goals of the experiment. The apparatus is to be used in a follow-up measurement (ABba) of asymmetry observables A and B in polarized neutron decay. Nab is funded, now in the construction stage, with planned beam readiness in 2016. We discuss the experiment's motivation, expected reach, design and method. Nab, a program of experimental study of unpolarized neutron decays at the Spallation Neutron Source, Oak Ridge, TN, aims to determine a, the electron-neutrino correlation with precision of δa / a =10-3 , and b, the Fierz interference term, with uncertainty δb ~= 3 ×10-3 . Neutron beta decay's simple theoretical description in the Standard Model (SM) is overconstrained by the set of available observables, providing opportunities to search for evidence of SM extensions. Planned Nab results will lead to a new precise determination of the ratio λ =GA /GV , and to significant reductions in the allowed limits for both right- and left-handed scalar and tensor currents. Alternatively, the experiment may detect a discrepancy from SM

  18. Ground Albedo Neutron Sensing (GANS) for Measurement of Integral Soil Water Content at the Small Catchment Scale

    NASA Astrophysics Data System (ADS)

    Rivera Villarreyes, C.; Baroni, G.; Oswald, S. E.

    2012-12-01

    Soil water content at the plot or hill-slope scale is an important link between local vadose zone hydrology and catchment hydrology. One largest initiative to cover the measuring gap of soil moisture between point scale and remote sensing observations is the COSMOS network (Zreda et al., 2012). Here, cosmic-ray neutron sensing, which may be more precisely named ground albedo neutron sensing (GANS), is applied. The measuring principle is based on the crucial role of hydrogen as neutron moderator compared to others landscape materials. Soil water content contained in a footprint of ca. 600 m diameter and a depth ranging down to a few decimeters is inversely correlated to the neutron flux at the air-ground interface. This approach is now implemented, e.g. in USA (Zreda et al., 2012) and Germany (Rivera Villarreyes et al., 2011), based on its simple installation and integral measurement of soil moisture at the small catchment scale. The present study performed Ground Albedo Neutron Sensing on farmland at two locations in Germany under different vegetative situations (cropped and bare field) and different seasonal conditions (summer, autumn and winter). Ground albedo neutrons were measured at (i) a farmland close to Potsdam and Berlin cropped with corn in 2010, sunflower in 2011 and winter rye in 2012, and (ii) a mountainous farmland catchment (Schaefertal, Harz Mountains) since middle 2011. In order to test this methodology, classical soil moisture devices and meteorological data were used for comparison. Moreover, several calibration approaches, role of vegetation cover and transferability of calibration parameters to different times and locations were also evaluated. Observations suggest that GANS can overcome the lack of data for hydrological processes at the intermediate scale. Soil moisture from GANS compared quantitatively with mean values derived from a network of classical devices under vegetated and non- vegetated conditions. The GANS approach responded well

  19. Nab: a precise study of unpolarized neutron beta decay

    NASA Astrophysics Data System (ADS)

    Pocanic, Dinko; Nab Collaboration

    2015-10-01

    Nab is a program of measurements of unpolarized neutron decays at the Spallation Neutron Source, Oak Ridge, TN. Nab aims to determine a, the e- ν correlation with precision of δa / a =10-3 , and b, the Fierz interference term, with uncertainty δb ~= 3 ×10-3 . The set of available observables overconstrains neutron beta decay in the Standard Model (SM), opening the door to searches for evidence of possible SM extensions. Projected Nab results will lead to a new precise determination of the ratio λ =GA /GV , and to significant reductions in the allowed limits for both right- and left-handed scalar and tensor currents. Alternatively, Nab may detect a discrepancy from SM predictions consistent with certain realizations of supersymmetry. A long asymmetric spectrometer, optimized to achieve the required narrow proton momentum response function, is currently under construction. The apparatus is to be used in follow-up measurements (ABba experiment) of asymmetry observables A and B in polarized neutron decay. Nab is planned for beam readiness in 2016. We discuss the experiment's motivation, expected reach, design and method, and update its status. Work supported by NSF Grants PHY-1126683, 1205833, 1307328, 1506320, and others.

  20. Nab: toward a precise experimental characterization of neutron beta decay

    NASA Astrophysics Data System (ADS)

    Pocanic, Dinko; Nab Collaboration

    2013-10-01

    Nab, a new program of measurements at the Spallation Neutron Source, Oak Ridge, TN, will study unpolarized neutron beta decays, with the goal to determine a, the electron-neutrino correlation with precision of δa / a =10-3 , and b, the Fierz interference term, with uncertainty δb ~= 3 ×10-3 . Neutron beta decay offers a means to study the weak interaction with great precision; its relatively simple theoretical description in the Standard Model (SM) is overconstrained by the set of available observables. Projected Nab results will lead to a new precise determination of the ratio λ =GA /GV , and to significant reductions in the allowed limits for both right- and left-handed scalar and tensor currents. Alternatively, the experiment may detect a discrepancy from SM predictions consistent with certain realizations of supersymmetry. An optimized, asymmetric spectrometer has been designed to achieve the narrow proton momentum response function required to meet the physics goals of the experiment. The apparatus is to be used in a follow-up measurement (abBA) of observables A and B in polarized neutron decay. Nab is fully funded, and is in the construction stage. We discuss the experiment's motivation, expected reach, and method. Work supported by NSF grants PHY-0970013, 1126683, and others.

  1. Precision Neutron Decay Studies with the Nab and UCNB Experiments

    NASA Astrophysics Data System (ADS)

    Sprow, Aaron; Nab Collaboration; UCNB Collaboration

    2016-03-01

    Precision neutron decay correlation experiments are a sensitive means to study the standard model and probe for beyond the standard model physics. Nab and UCNB are two such experiments that will measure the neutrino-electron correlation term, a, and the neutrino asymmetry, B, respectively. Thick, highly-segmented silicon detectors will be used to directly measure the proton and electron from each decay event in coincidence, leading to the extraction of these angular correlations. Preliminary work to understand the systematic uncertainties associated with these experiments, as well as the early analysis of data taken from the 2015-2016 beam time at Los Alamos National Laboratory will be presented.

  2. Radiative Neutron β-Decay in Effective Field Theory

    PubMed Central

    Gardner, Susan; Bernard, Véronique; Meißner, Ulf-G.; Zhang, Chi

    2005-01-01

    We consider radiative β-decay of the neutron in heavy baryon chiral perturbation theory. Nucleon-structure effects not encoded in the weak coupling constants gA and gV are determined at next-to-leading order in the chiral expansion, and enter at the O(0.5%)-level, making a sensitive test of the Dirac structure of the weak currents possible. PMID:27308159

  3. A Precision Measurement of Neutron Beta Decay Angular Correlations with Polarized Pulsed Cold Neutrons

    NASA Astrophysics Data System (ADS)

    Seo, Pil-Neyo

    2004-05-01

    The abBA collaboration is developing an experiment to measure the neutron beta decay angular correlations, a, b, B, A, to 0.1the very high pulsed cold neutron intensities in a new nuclear physics beam line that is under construction at SNS. The design of the experiment is based on three important technical advances: the pulsed cold neutron beam, a polarized ^3He neutron spin filter, and large-area thin-dead layer silicon detectors. Both electrons and protons resulting from the decay will be guided in the spectrometer by electric and magnetic fields and then detected in coincidence with two 2π large-segmented silicon detectors. Measuring the correlations in the same apparatus provides a redundant measurement of λ=G_A/G_V. I will describe the experiment and report the status of the development.

  4. Measurement of the neutrino-spin correlation parameter B neutron decay using ultracold neutrons

    SciTech Connect

    Wilburn, Wesley S

    2009-01-01

    We present a new approach to measuring the neutrino-spin correlation parameter B in neutron decay. The approach combines the technology of large-area ion-implanted silicon detectors being developed for the abBA experiment, with an ultracold neutron source to provide more precise neutron polarimetry. The technique detects both proton and electron from the neutron decay in coincidence. B is determined from an electron-energy-dependent measurement of the proton spin asymmetry. This approach will provide a statistical precision of 1 x 10-4 . The systematic precision is still being evaluated, but is expected to be below 1 x 10-3 , and could approach 1 x 10-4 . A measurement of B with this precision would place constraints on supersymmetric extensions to the Standard Model.

  5. Neutron decay widths of excited states of {sup 11}Be

    SciTech Connect

    Haigh, P. J.; Freer, M.; Ashwood, N. I.; Bloxham, T.; Curtis, N.; McEwan, P.; Bohlen, H. G.; Dorsch, T.; Kokalova, Tz.; Schulz, Ch.; Wheldon, C.

    2009-01-15

    The two-neutron transfer reaction {sup 9}Be({sup 16}O, {sup 14}O){sup 11}Be[{sup 10}Be +n] has been used to measure the branching ratios for the neutron decay of excited states of {sup 11}Be. The {sup 14}O ejectile was detected by a Q3D spectrometer at forward angles. The energies and angles of the {sup 10}Be fragments of the decaying {sup 11}Be* recoil were measured in coincidence with the {sup 14}O ejectile using a double-sided silicon strip detector array at backward angles. This enabled a kinematic reconstruction of the reaction to be performed. Theoretical decay branch ratios were calculated using barrier penetrability factors and were compared to the measured ratios to provide information on the relative reduced widths of the states. The decay widths have been used to link states in {sup 11}Be with a common structure and structurally to states in the daughter nucleus {sup 10}Be. The 3/2{sup -} 8.82-MeV state was identified as a candidate for a molecular band head.

  6. Time reversal invariance - a test in free neutron decay

    SciTech Connect

    Lising, Laura J.

    1999-05-18

    Time reversal invariance violation plays only a small role in the Standard Model, and the existence of a T-violating effect above the predicted level would be an indication of new physics. A sensitive probe of this symmetry in the weak interaction is the measurement of the T-violating ''D''-correlation in the decay of free neutrons. The triple-correlation D{sigma}{sub n}{center_dot}p{sub e} x p{sub v} involves three kinematic variables, the neutron spin, electron momentu, and neutrino (or proton) momentum, and changes sign under time reversal. This experiment detects the decay products of a polarized cold neutron beam with an octagonal array of scintillation and solid-state detectors. Data from first run at NIST's Cold Neutron Research Facility give a D-coefficient of -0.1 {+-} 1.3(stat.) {+-} 0.7(syst) x 10{sup -3}. This measurement has the greatest bearing on extensions to the Standard model that incorporate leptoquarks, although exotic fermion and lift-right symmetric models also allow a D as large as the present limit.

  7. Predicting fissile content of spent nuclear fuel assemblies with the passive neutron Albedo reactivity technique and Monte Carlo code emulation

    SciTech Connect

    Conlin, Jeremy Lloyd; Tobin, Stephen J

    2010-10-13

    There is a great need in the safeguards community to be able to nondestructively quantify the mass of plutonium of a spent nuclear fuel assembly. As part of the Next Generation of Safeguards Initiative, we are investigating several techniques, or detector systems, which, when integrated, will be capable of quantifying the plutonium mass of a spent fuel assembly without dismantling the assembly. This paper reports on the simulation of one of these techniques, the Passive Neutron Albedo Reactivity with Fission Chambers (PNAR-FC) system. The response of this system over a wide range of spent fuel assemblies with different burnup, initial enrichment, and cooling time characteristics is shown. A Monte Carlo method of using these modeled results to estimate the fissile content of a spent fuel assembly has been developed. A few numerical simulations of using this method are shown. Finally, additional developments still needed and being worked on are discussed.

  8. Beta-decay measurements of neutron-deficient cesium isotopes

    SciTech Connect

    Parry, R.F.

    1983-03-01

    Beta decay endpoint energy measurements of the neutron deficient cesium isotopes were done using an energy spectrum shape fitting technique. This was a departure from the typical method of endpoint energy analysis, the Fermi-Kurie plot. A discussion of the shape fitting procedure and its improved features are discussed. These beta endpoint measurements have led to total decay energies (Q/sub EC/) of the neutron deficient /sup 119/ /sup 123/Cs isotopes. The total decay energies of /sup 122m/Cs (Q/sub EC/ = 6.95 +- 0.25 MeV) and /sup 119/Cs (Q/sub EC/ = 6.26 +- 0.29 MeV) were new measurements. The total decay energies of /sup 123/Cs (Q/sub EC/ = 4.05 +- 0.18 MeV), /sup 122g/Cs (Q/sub EC/ = 7.05 +- 0.18 MeV), /sup 121/Cs (Q/sub EC/ = 5.21 +- 0.22 MeV), and /sup 120/Cs (Q/sub EC/ = 7.38 +- 0.23 MeV) were measurements with significantly improved uncertainties as compared to the literature. Further, a combination of the energy levels derived from previous literature gamma-gamma coincident measurements and the experimental beta-coincident gamma decay energies has supported an improved level scheme for /sup 121/Xe and the proposal of three new energy levels in /sup 119/Xe. Comparison of the experimental cesium mass excesses (determined with our Q/sub EC/ values and known xenon mass excesses) with both the literature and theoretical predicted values showed general agreement except for /sup 120/Cs. Possible explanations for this deviation are discussed.

  9. Nondestructive determination of plutonium mass in spent fuel: prelliminary modeling results using the passive neutron Albedo reactivity technique

    SciTech Connect

    Evans, Louise G; Tobin, Stephen J; Schear, Melissa A; Menlove, Howard O; Lee, Sang Y; Swinhoe, Martyn T

    2009-01-01

    There are a variety of motivations for quantifying plutonium (Pu) in spent fuel assemblies by means of nondestructive assay (NDA) including the following: strengthening the capability of the International Atomic Energy Agency (LAEA) to safeguard nuclear facilities, quantifying shipper/receiver difference, determining the input accountability value at pyrochemical processing facilities, providing quantitative input to burnup credit and final safeguards measurements at a long-term repository. In order to determine Pu mass in spent fuel assemblies, thirteen NDA techniques were identified that provide information about the composition of an assembly. A key motivation of the present research is the realization that none of these techniques, in isolation, is capable of both (1) quantifying the Pu mass of an assembly and (2) detecting the diversion of a significant number of rods. It is therefore anticipated that a combination of techniques will be required. A 5 year effort funded by the Next Generation Safeguards Initiative (NGSI) of the U.S. DOE was recently started in pursuit of these goals. The first two years involves researching all thirteen techniques using Monte Carlo modeling while the final three years involves fabricating hardware and measuring spent fuel. Here, we present the work in two main parts: (1) an overview of this NGSI effort describing the motivations and approach being taken; (2) The preliminary results for one of the NDA techniques - Passive Neutron Albedo Reactivity (PNAR). The PNAR technique functions by using the intrinsic neutron emission of the fuel (primarily from the spontaneous fission of curium) to self-interrogate any fissile material present. Two separate measurements of the spent fuel are made, both with and without cadmium (Cd) present. The ratios of the Singles, Doubles and Triples count rates obtained in each case are analyzed; known as the Cd ratio. The primary differences between the two measurements are the neutron energy spectrum

  10. Decay studies of the highly neutron-deficient indium isotopes

    SciTech Connect

    Wouters, J.M.

    1982-02-01

    An extension of the experimentally known nuclidic mass surface to nuclei far from the region of beta-stability is of fundamental interest in providing a better determination of the input parameters for the various nuclear mass formulae, allowing a more accurate prediction of the ultimate limits of nuclear stability. In addition, a study of the shape of the mass surface in the vicinity of the doubly-closed nuclide /sup 100/Sn provides initial information on the behavior of the shell closure to be expected when Z = N = 50. Experiments measuring the decay energies of /sup 103/ /sup 105/In by ..beta..-endpoint measurements are described with special attention focused on the development of a plastic scintillator ..beta..-telescope coupled to the on-line mass separator RAMA (Recoil Atom Mass Analyzer). An attempt to measure the ..beta..-endpoint energy of /sup 102/In is also briefly described. The experimentally determined decay energies and derived masses for /sup 103/ /sup 105/In are compared with the predictions of different mass models to identify which models are more successful in this region. Furthermore, the inclusion in these comparisons of the available data on the neutron-rich indium nuclei permits a systematic study of their ground state mass behavior as a function of the neutron number between the shell closures at N = 50 and N = 82. These analyses indicate that the binding energy of /sup 103/In is 1 MeV larger than predicted by the majority of the mass models. An examination of the Q/sub EC/ surface and the single- and two-neutron separation energies in the vicinity of /sup 103/ /sup 105/In is also performed to investigate further the deviation and other possible systematic variations in the mass surface in a model-independent way.

  11. Beta Decay Study of Neutron-rich Magnesium

    NASA Astrophysics Data System (ADS)

    Ash, John; Rajabali, Mustafa; Griffin Collaboration

    2015-10-01

    Within the ``island of inversion'' around the N = 20 shell gap, isotopes of magnesium, and aluminum deviate from the expected closed-shell structure. Particles promoted across the N = 20 shell gap result in a lower energy deformed ground state configuration rather than the expected spherical configuration. An experiment was conducted at TRIUMF laboratory in the summer of 2015 to study the decay of ``island of inversion'' isotopes 33 , 34 , 35Mg and the structure of the respective daughter nuclei. The isotopes of interest were produced by a proton beam from TRIUMF's 500 MeV cyclotron impacting on a UCx target. The magnesium decays populated states along the decay chain in Al, Si, P, and S isotopes. The new GRIFFIN spectrometer in the ISAC-I facility was used to detect the gamma rays. Two sets of scintillators, one for detecting the beta particles (SCEPTAR) and the other for detecting beta-delayed neutrons (DESCANT), were also used in conjunction with GRIFFIN. The GRIFFIN data were energy calibrated and partially analyzed for this project. New algorithms were developed for the analysis. Preliminary results for new transitions detected in 34Mg as well as the half lives obtained will be presented in their current form. This research was supported by the Tennessee Tech research office.

  12. Cadmium Subtraction Method for the Active Albedo Neutron Interrogation of Uranium

    SciTech Connect

    Worrall, Louise G.; Croft, Stephen

    2015-02-01

    This report describes work performed under the Next Generation Safeguards Initiative (NGSI) Cadmium Subtraction Project. The project objective was to explore the difference between the traditional cadmium (Cd) ratio signature and a proposed alternative Cd subtraction (or Cd difference) approach. The thinking behind the project was that a Cd subtraction method would provide a more direct measure of multiplication than the existing Cd ratio method. At the same time, it would be relatively insensitive to changes in neutron detection efficiency when properly calibrated. This is the first published experimental comparison and evaluation of the Cd ratio and Cd subtraction methods.

  13. Simulated Performance of the Integrated Passive Neutron Albedo Reactivity and Self-Interrogation Neutron Resonance Densitometry Detector Designed for Spent Fuel Measurement at the Fugen Reactor in Japan

    SciTech Connect

    Ulrich, Timothy J. II; Lafleur, Adrienne M.; Menlove, Howard O.; Swinhoe, Martyn T.; Tobin, Stephen J.; Seya, Michio; Bolind, Alan M.

    2012-07-16

    An integrated nondestructive assay instrument, which combined the Passive Neutron Albedo Reactivity (PNAR) and the Self-Interrogation Neutron Resonance Densitometry (SINRD) techniques, is the research focus for a collaborative effort between Los Alamos National Laboratory (LANL) and the Japanese Atomic Energy Agency as part of the Next Generation Safeguard Initiative. We will quantify the anticipated performance of this experimental system in two physical environments: (1) At LANL we will measure fresh Low Enriched Uranium (LEU) assemblies for which the average enrichment can be varied from 0.2% to 3.2% and for which Gd laced rods will be included. (2) At Fugen we will measure spent Mixed Oxide (MOX-B) and LEU spent fuel assemblies from the heavy water moderated Fugen reactor. The MOX-B assemblies will vary in burnup from {approx}3 GWd/tHM to {approx}20 GWd/tHM while the LEU assemblies ({approx}1.9% initial enrichment) will vary from {approx}2 GWd/tHM to {approx}7 GWd/tHM. The estimated count rates will be calculated using MCNPX. These preliminary results will help the finalization of the hardware design and also serve a guide for the experiment. The hardware of the detector is expected to be fabricated in 2012 with measurements expected to take place in 2012 and 2013. This work is supported by the Next Generation Safeguards Initiative, Office of Nuclear Safeguards and Security, National Nuclear Security Administration.

  14. Search for Radiative β-Decay of the Free Neutron

    PubMed Central

    Byrne, J.; Khafizov, R. U.; Mostovoi, Yu A.; Rozhnov, O.; Solovei, V. A.; Beck, M.; Kozlov, V. U.; Severijns, N.

    2005-01-01

    Results of the first experiment to search for the radiative decay mode of the free neutron are reported. The γ-spectrum was studied in the energy region from 35 keV to 100 keV in six Cs(Tl) scintillators, each set at an angle of 35° to, and shielded from, a central plastic scintillator electron detector. Triple coincidences were recorded with recoil protons detected in a micro-channel plate. A limit for the branching ratio BR < 6.9 × 10−3 (90 % confidence level) was obtained, which is greater that the theoretical prediction by not more than a few tenths of a percent. PMID:27308160

  15. Beta decay rates of neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Marketin, Tomislav; Huther, Lutz; Petković, Jelena; Paar, Nils; Martínez-Pinedo, Gabriel

    2016-06-01

    Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei. Aside from the astrophysical applications, the results of this calculation can also be employed in the modeling of the electron and antineutrino spectra from nuclear reactors.

  16. Beta decay rates of neutron-rich nuclei

    SciTech Connect

    Marketin, Tomislav; Huther, Lutz; Martínez-Pinedo, Gabriel

    2015-10-15

    Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. Currently, a single large-scale calculation is available based on a QRPA calculation with a schematic interaction on top of the Finite Range Droplet Model. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei.

  17. Neutron interactions in the CUORE neutrinoless double beta decay experiment

    NASA Astrophysics Data System (ADS)

    Dolinski, Michelle Jean

    Neutrinoless double beta decay (0nuDBD) is a lepton-number violating process that can occur only for a massive Majorana neutrino. The search for 0nuDBD is currently the only practical experimental way to determine whether neutrinos are identical to their own antiparticles (Majorana neutrinos) or have distinct particle and anti-particle states (Dirac neutrinos). In addition, the observation of 0nuDBD can provide information about the absolute mass scale of the neutrino. The Cuoricino experiment was a sensitive search for 0nuDBD, as well as a proof of principle for the next generation experiment, CUORE. CUORE will search for 0nuDBD of 130Te with a ton-scale array of unenriched TeO2 bolometers. By increasing mass and decreasing the background for 0nuDBD, the half-life sensitivity of CUORE will be a factor of twenty better than that of Cuoricino. The site for both of these experiments is the Laboratori Nazionali del Gran Sasso, an underground laboratory with 3300 meters water equivalent rock overburden and a cosmic ray muon attenuation factor of 10-6. Because of the extreme low background requirements for CUORE, it is important that all potential sources of background in the 0nuDBD peak region at 2530 keV are well understood. One potential source of background for CUORE comes from neutrons, winch can be produced underground both by (alpha,n) reactions and by fast cosmic ray muon interactions. Preliminary simulations by the CUORE collaboration indicate that these backgrounds will be negligible for CUORE. However, in order to accurately simulate the expected neutron background, it is important to understand the cross sections for neutron interactions with detector materials. In order to help refine these simulations, I have measured the gamma-ray production cross sections for interactions of neutrons on the abundant stable isotopes of Te using the GEANIE detector array at the Los Alamos Neutron Science Center. In addition, I have used the GEANIE data to set an upper

  18. Neutron Interactions in the CUORE Neutrinoless Double Beta Decay Experiment

    SciTech Connect

    Dolinski, Michelle Jean

    2008-10-01

    Neutrinoless double beta decay (0vDBD) is a lepton-number violating process that can occur only for a massive Majorana neutrino. The search for 0vDBD is currently the only practical experimental way to determine whether neutrinos are identical to their own antiparticles (Majorana neutrinos) or have distinct particle and anti-particle states (Dirac neutrinos). In addition, the observation of 0vDBD can provide information about the absolute mass scale of the neutrino. The Cuoricino experiment was a sensitive search for 0vDBD, as well as a proof of principle for the next generation experiment, CUORE. CUORE will search for 0vDBD of 130Te with a ton-scale array of unenriched TeO2 bolometers. By increasing mass and decreasing the background for 0vDBD, the half-life sensitivity of CUORE will be a factor of twenty better than that of Cuoricino. The site for both of these experiments is the Laboratori Nazionali del Gran Sasso, an underground laboratory with 3300 meters water equivalent rock overburden and a cosmic ray muon attenuation factor of 10-6. Because of the extreme low background requirements for CUORE, it is important that all potential sources of background in the 0vDBD peak region at 2530 keV are well understood. One potential source of background for CUORE comes from neutrons, which can be produced underground both by (α,n) reactions and by fast cosmic ray muon interactions. Preliminary simulations by the CUORE collaboration indicate that these backgrounds will be negligible for CUORE. However, in order to accurately simulate the expected neutron background, it is important to understand the cross sections for neutron interactions with detector materials. In order to help refine these simulations, I have measured the gamma-ray production cross sections for interactions of neutrons on the abundant stable isotopes of Te using the GEANIE detector array at the Los Alamos Neutron Science Center. In addition, I have used the GEANIE

  19. Radiative decay of neutron-unbound intruder states in 19O

    NASA Astrophysics Data System (ADS)

    Dungan, R.; Tabor, S. L.; Tripathi, Vandana; Volya, A.; Kravvaris, K.; Abromeit, B.; Caussyn, D. D.; Morrow, S.; Parker, J. J.; Tai, P.-L.; VonMoss, J. M.

    2016-02-01

    The 9Be(14C, α γ ) reaction at EL a b=30 and 35 MeV was used to study excited states of 19O. The Florida State University (FSU) γ detector array was used to detect γ radiation in coincidence with charged particles detected and identified with a silicon Δ E -E particle telescope. γ decays have been observed for the first time from six states ranging from 368 to 2147 keV above the neutron separation energy (Sn=3962 keV) in 19O. The γ -decaying states are interspersed among states previously observed to decay by neutron emission. The ability of electromagnetic decay to compete successfully with neutron decay is explained in terms of neutron angular momentum barriers and small spectroscopic factors implying higher spin and complex structure for these intruder states. These results illustrate the need for complementary experimental approaches to best illuminate the complete nuclear structure.

  20. Neutron decay of 15C resonances by measurements of neutron time-of-flight

    NASA Astrophysics Data System (ADS)

    Cavallaro, M.; Agodi, C.; Assié, M.; Azaiez, F.; Cappuzzello, F.; Carbone, D.; de Séréville, N.; Foti, A.; Pandola, L.; Scarpaci, J. A.; Sgouros, O.; Soukeras, V.; Tropea, S.

    2016-06-01

    The neutron decay of the resonant states of light neutron-rich nuclei is an important and poorly explored property, useful to extract valuable nuclear structure information. In the present paper the neutron decay of the 15C resonances populated via the two-neutron transfer reaction 13C(18O,16On ) at 84-MeV incident energy is reported for the first time using an innovative technique which couples the MAGNEX magnetic spectrometer and the EDEN neutron detector array. Experimental data show that the resonances below the one-neutron emission threshold decay to the 14C ground state via one-neutron emission with an almost 100 % total branching ratio, whereas the recently observed 15C giant pairing vibration at 13.7 MeV mainly decays via two-neutron emission.

  1. Determining fissile content in PWR spent fuel assemblies using a passive neutron Albedo reactivity with fission chambers technique

    SciTech Connect

    Conlin, Jeremy Lloyd; Tobin, Stephen J

    2010-01-01

    State regulatory bodies and organizations such as the IAEA that are concerned with preventing the proliferation of nuclear weapons are interested in a means of quantifying the amount of plutonium in a given spent fuel assembly. The complexity of spent nuclear fuel makes the measurement of plutonium content challenging. There are a variety of techniques that can measure various properties of spent nuclear fuel including burnup, and mass of fissile content. No single technique can provide all desired information, necessitating an approach using multiple detector systems and types. This paper presents our analysis of the Passive Neutron Albedo Reactivity Fission Chamber (PNAR-FC) detector system. PNAR-FC is a simplified version of the PNAR technique originally developed in 1997. This earlier research was performed with a high efficiency, {sup 3}He-based system (PNAR-3He) with which multiplicty analysis was performed. With the PNAR technique a portion of the spent fuel assembly is wrapped in a 1 mm thick cadmium liner. Neutron count rates are measured both with and without the cadmium liner present. The ratio of the count rate with the cadmium liner to the count rate without the cadmium liner is calculated and called the cadmium ratio. In the PNAR-3He technique, multiplicity measurements were made and the cadmium ratio was shown to scale with the fissile content of the material being measured. PNAR-FC simplifies the PNAR technique by using only a few fission chambers instead of many {sup 3}He tubes. Using a simplified PNAR-FC technique provides for a cheaper, lighter, and thus more portable detector system than was possible with the PNAR-3He system. The challenge with the PNAR-FC system are two-fold: (1) the change in the cadmium ratio is weaker as a afunction of the changing fissile content relative to multiplicity count rates, and (2) the efficiency for the fission chamber based system are poorer than for the {sup 3}He based detectors. In this paper, we present our

  2. UCNtau: A Precision Measurement of the Neutron Beta-Decay Lifetime

    NASA Astrophysics Data System (ADS)

    Liu, Chen-Yu

    2015-10-01

    Eighty years after Chadwick discovered the neutron, physicists today still debate over how long the neutron lives. Measurements of the neutron lifetime have achieved the 0.1% level of precision (~1 s), however, experiments using the bottle technique yield lifetime results systematically lower than those using the beam technique. Measuring the neutron lifetime is difficult due to several limitations: the low energy of the decay products, the inability to track slow neutrons, and the fact that the neutron lifetime is long (880 . 3 +/- 1 . 1 s, PDG2014). In particular, slow neutrons are susceptible to many loss mechanisms other than beta-decay, such as upscattering and absorption on material surfaces; they act on time scales comparable to the neutron beta-decay and thus make the extraction of the beta-decay lifetime very challenging. In the UCN τ experiment, we trap ultracold neutrons (UCN) in a magnetic-gravitational trap. The apparatus, installed at the Los Alamos UCN source, has been used to develop new techniques-using field confinements with attentions to the phase space evolution of trapped neutrons-with an aim to reduce the uncertainty to 1 s (and better). I will report first competitive results and discuss plans to quantify systematic effects. The work was supported by the NSF (Grant-1306942 to IU) and the LANL LDRD program.

  3. Search for Time Reversal Violating Effects: R-Correlation Measurement in Neutron Decay

    PubMed Central

    Bodek, K.; Ban, G.; Beck, M.; Bialek, A.; Bryś, T.; Czarnecki, A.; Fetscher, W.; Gorel, P.; Kirch, K.; Kistryn, St.; Kozela, A.; Kuźniak, M.; Lindroth, A.; Naviliat-Cuncic, O.; Pulut, J.; Serebrov, A.; Severijns, N.; Stephan, E.; Zejma, J.

    2005-01-01

    An experiment aiming at the simultaneous determination of both transversal polarization components of electrons emitted in the decay of free neutrons begins data taking using the polarized cold neutron beam (FUNSPIN) from the Swiss Neutron Spallation Source (SINQ) at the Paul-Scherrer Institute, Villigen. A non-zero value of R due to the e− polarization component, which is perpendicular to the plane spanned by the spin of the decaying neutron and the electron momentum, would signal a violation of time reversal symmetry and thus physics beyond the Standard Model. Present status of the project and the results from analysis of the first data sample will be discussed. PMID:27308168

  4. Neutron induced radio-isotopes and background for Ge double beta decay experiments

    NASA Astrophysics Data System (ADS)

    Chu, Pinghan; Majorana Collaboration

    2015-10-01

    Environmental neutrons, mostly produced by muons in the cosmic rays, might contribute backgrounds to the search for neutrinoless double beta decays. These neutrons can interact with materials and generate radio-isotopes, which can decay and produce radioactive backgrounds. Some of these neutron-induced isotopes have a signature of a time-delayed coincidence, allowing us to study these infrequent events. For example, such isotopes can decay by beta decay to metastable states and then decay by gamma decay to the ground state. Considering the time-delayed coincidence of these two processes, we can determine candidates for these neutron-induced isotopes in the data and estimate the flux of neutrons in the deep underground environment. In this report, we will list possible neutron-induced isotopes and the methodology to detect them, especially those that can affect the search for neutrinoless double beta decays in 76Ge. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics Program of the National Science Foundation, and the Sanford Underground Research Facility. We acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program.

  5. Testing JEFF-3.1.1 and ENDF/B-VII.1 Decay and Fission Yield Nuclear Data Libraries with Fission Pulse Neutron Emission and Decay Heat Experiments

    NASA Astrophysics Data System (ADS)

    Cabellos, O.; de Fusco, V.; Diez de la Obra, C. J.; Martinez, J. S.; Gonzalez, E.; Cano-Ott, D.; Alvarez-Velarde, F.

    2014-04-01

    The aim of this work is to test the present status of Evaluated Nuclear Decay and Fission Yield Data Libraries to predict decay heat and delayed neutron emission rate, average neutron energy and neutron delayed spectra after a neutron fission pulse. Calculations are performed with JEFF-3.1.1 and ENDF/B-VII.1, and these are compared with experimental values. An uncertainty propagation assessment of the current nuclear data uncertainties is performed.

  6. Standard Model Treatment of the Radiative Corrections to Neutron β-Decay

    PubMed Central

    Bunatian, G. G.

    2005-01-01

    Starting with the Standard Model electroweak Lagrangian, the radiative corrections to neutron β-decay are obtained. Nucleon compositeness is considered by appropriate parameterization of the nucleon weak transition current and electromagnetic form factors. PMID:27308144

  7. Albedo Boundary

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-510, 11 October 2003

    The sharp, nearly straight line that runs diagonally across the center of this April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is an albedo boundary. Albedois a term that refers to reflectance of sunlight. A surface with a low albedo is one that appears dark because it reflects less light than a high albedo (bright) surface. On Mars, albedo boundaries occur between two materials of differing texture, particle size, or composition, or some combination of these three factors. The boundary shown here is remarkable because it is so sharp and straight. This is caused by wind. Most likely, the entire surface was once covered with the lower-albedo (darker) material that is now seen in the upper half of the image. At some later time, wind stripped away this darker material from the surfaces in the lower half of the image. The difference in albedo here might be related to composition, and possibly particle size. This picture is located near the southwest rim of Schiaparelli Basin at 5.5oS, 345.9oW. The picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the left.

  8. Study of {beta}-Decay in the Proton-Neutron Interacting Boson-Fermion Model

    SciTech Connect

    Zuffi, L.; Brant, S.; Yoshida, N.

    2006-04-26

    We study {beta}-decay in odd-A nuclei together with the energy levels and other properties in the proton-neutron interacting-boson-fermion model. We also report on the preliminary results in the odd-odd nuclei in the proton-neutron interacting boson-fermion-fermion model.

  9. Continuum-state and bound-state β--decay rates of the neutron

    NASA Astrophysics Data System (ADS)

    Faber, M.; Ivanov, A. N.; Ivanova, V. A.; Marton, J.; Pitschmann, M.; Serebrov, A. P.; Troitskaya, N. I.; Wellenzohn, M.

    2009-09-01

    For the β--decay of the neutron we analyze the continuum-state and bound-state decay modes. We calculate the decay rates, the electron energy spectrum for the continuum-state decay mode, and angular distributions of the decay probabilities for the continuum-state and bound-state decay modes. The theoretical results are obtained for the new value for the axial coupling constant gA=1.2750(9), obtained recently by H. Abele [Prog. Part. Nucl. Phys. 60, 1 (2008)] from the fit of the experimental data on the coefficient of the correlation of the neutron spin and the electron momentum of the electron energy spectrum of the continuum-state decay mode. We take into account the contribution of radiative corrections and the scalar and tensor weak couplings. The calculated angular distributions of the probabilities of the bound-state decay modes of the polarized neutron can be used for the experimental measurements of the bound-state β--decays into the hyperfine states with total angular momentum F=1 and scalar and tensor weak coupling constants.

  10. Prompt neutron decay for an unreflected and unmoderated uranium (HEU) metal sphere

    SciTech Connect

    Mihalczo, J.T.

    1996-08-01

    Prompt neutron decay constants were measured for a delayed critical, unmoderated and unreflected U metal sphere at the Oak Ridge Critical Experiments Facility. Prompt neutron decay constant was 1.1095{+-}0.0013 {mu}s{sup -1}. This can be used to verify calculational methods, both deterministic and Monte Carlo neutron transport methods. This value is in agreement with the value from GODIVA I data corrected for effects of support structure (1.10{+-}0.01 {mu}s{sup -1}) but has a much smaller error as a result of the large number (167) of the measurements here and the high degree of sphericity of the sphere.

  11. Beta-decay properties of neutron-rich medium-mass nuclei

    NASA Astrophysics Data System (ADS)

    Sarriguren, Pedro

    2016-06-01

    β-decay properties of even-even and odd-A neutron-rich Ge, Se, Kr, Sr, Zr, Mo, Ru, and Pd isotopes involved in the astrophysical rapid neutron capture process are studied within a microscopic proton-neutron quasiparticle random-phase approximation. The underlying mean field is based on a self-consistent Skyrme Hartree-Fock + BCS calculation that includes deformation as a key ingredient. The isotopic evolution of the various nuclear equilibrium shapes and the corresponding charge radii are investigated in all the isotopic chains. The energy distributions of the Gamow-Teller strength, as well as the β-decay half-lives are discussed and compared with the available experimental information. It is shown that nuclear deformation plays a significant role in the description of the decay properties in this mass region. Reliable predictions of the strength distributions are essential to evaluate decay rates in astrophysical scenarios.

  12. Methods and apparatus for measuring thermal neutron decay characteristics of earth formations

    SciTech Connect

    Steinman, D.K.; Jacobson, L.A.

    1986-07-15

    A method is described for determining a thermal neutron decay characteristic of an earth formation, comprising the steps of: (a) irradiating an earth formation with a discrete burst of fast neutrons; (b) detecting indications of the thermal neutron concentration in the formation during a sequence of discrete time gates, the sequence of time gates beginning following a discrete time delay after the end of the neutron burst; (c) determining the zeroth order moment of the indications during the sequence of discrete time gates; (d) determining the first order moment of the indications during the sequence of discrete time gates; and (e) forming a ratio of the first order moment of step (d) to the zeroth order moment of step (c) to obtain the thermal neutron decay time constant of the earth formation.

  13. Measurement of Neutron Decay Parameters—The abBA Experiment

    PubMed Central

    Wilburn, W. S.; Bowman, J. D.; Mitchell, G. S.; O’Donnell, J. M.; Penttila, S. I.; Seo, P.-N.; Calarco, J. R.; Hersmann, F. W.; Chupp, T. E.; Cianciolo, T. V.; Rykaczewski, K. P.; Young, G. R.; De Souza, R. T.; Snow, W. M.; Desai, D.; Greene, G. L.; Grzywacz, R. K.; Frlez, E.; Pocanic, D.; Gentile, T. R.; Gudkov, V.; Jones, G. L.

    2005-01-01

    We are developing an experiment to measure the correlations a, A, and B, and the Fierz interference term b in neutron decay, with a precision of approximately 10−4. The experiment uses an electromagnetic spectrometer in combination with two large-area segmented silicon detectors to detect the proton and electron from the decay in coincidence, with 4π acceptance for both particles. For the neutron-polarization-dependent observables A and B, precision neutron polarimetry is achieved through the combination of a pulsed neutron beam, under construction at the SNS, and a polarized 3He neutron polarizer. Measuring a and A in the same apparatus provides a redundant determination of λ = gA/gV. Uncertainty in λ dominates the uncertainty of CKM unitarity tests. PMID:27308155

  14. Analysis of neutron and photon response of a TLD-ALBEDO personal dosemeter on an ISO slab phantom using TRIPOLI-4.3 Monte Carlo code.

    PubMed

    Lee, Y K

    2005-01-01

    TRIPOLI-4.3 Monte Carlo transport code has been used to evaluate the QUADOS (Quality Assurance of Computational Tools for Dosimetry) problem P4, neutron and photon response of an albedo-type thermoluminescence personal dosemeter (TLD) located on an ISO slab phantom. Two enriched 6LiF and two 7LiF TLD chips were used and they were protected, in front or behind, with a boron-loaded dosemeter-holder. Neutron response of the four chips was determined by counting 6Li(n,t)4He events using ENDF/B-VI.4 library and photon response by estimating absorbed dose (MeV g(-1)). Ten neutron energies from thermal to 20 MeV and six photon energies from 33 keV to 1.25 MeV were used to study the energy dependence. The fraction of the neutron and photon response owing to phantom backscatter has also been investigated. Detailed TRIPOLI-4.3 solutions are presented and compared with MCNP-4C calculations. PMID:16381740

  15. Conditions for jet formation in accreting neutron stars: the magnetic field decay

    NASA Astrophysics Data System (ADS)

    García, Federico; Aguilera, Deborah N.; Romero, Gustavo E.

    2011-02-01

    Accreting neutron stars can produce jets only if they are weakly magnetized (B ~ 108 G). On the other hand, neutron stars are compact objects born with strong surface magnetic fields (B ~ 1012 G). In this work we study the conditions for jet formation in a binary system formed by a neutron star and a massive donor star once the magnetic field has decayed due to accretion. We solve the induction equation for the magnetic field diffusion in a realistic neutron star crust and discuss the possibility of jet launching in systems like the recently detected Supergiant Fast X-ray Transients.

  16. Comparative sensitivity study and reading correction of various albedo dosimeters in neutron fields on the U-400M accelerator

    NASA Astrophysics Data System (ADS)

    Mokrov, Yu. V.; Morozov, S. V.; Shchegolev, V. Yu.

    2013-03-01

    The sensitivities of three types of albedo dosimeters are experimentally studied in U-400M accelerator radiation fields in the experimental hall (one point) and behind its shielding (three points). It is shown that the ratios of the sensitivity of the albedo dosimeter (AD) and the combined personal dosimeter (CPD) used earlier at the Joint Institute for Nuclear Research (JINR) to the sensitivity of the DVGN-01 dosimeter are constant within 25%. This allows the AD and CPD sensitivities obtained earlier at the JINR facilities to be used for correcting readings of the DVGN-01 now used at JINR for personal radiation monitoring. Correction coefficients are found for DVGN-01 readings behind the U-400M shielding. This has allowed a more reliable correction coefficient to be established for the Flerov Laboratory of Nuclear Reactions (FLNR).

  17. aCORN: A Measurement of the Beta-Antineutrino Correlation in Neutron Decay

    NASA Astrophysics Data System (ADS)

    Jones, Gordon

    2015-10-01

    The aCORN experiment has measured the electron-antineutrino angular correlation coefficient (the ``a'' coefficient) in free neutron decay. aCORN uses the dependence of the recoil proton momentum on the opening angle between the electron and the neutrino to form an asymmetry. The apparatus accepts decays where the antineutrino is restricted to two momentum groups having equal solid angle. In this geometry, proton time of flight distinguishes between decays with a large or small opening angle between the electron and the antineutrino. The correlation coefficient is determined from the asymmetry between two branches of the time of flight spectrum. The asymmetry was measured on the NG-6 neutron beam at the NIST Center for Neutron Research (NCNR), and a subsequent measurement has been started on the higher flux NG-C beam. An overview of the method and systematic effects will be presented, including results from the NG-6 dataset. National Science Foundation.

  18. Large β-delayed one and two neutron emission rates in the decay of 86Ga.

    PubMed

    Miernik, K; Rykaczewski, K P; Gross, C J; Grzywacz, R; Madurga, M; Miller, D; Batchelder, J C; Borzov, I N; Brewer, N T; Jost, C; Korgul, A; Mazzocchi, C; Mendez, A J; Liu, Y; Paulauskas, S V; Stracener, D W; Winger, J A; Wolińska-Cichocka, M; Zganjar, E F

    2013-09-27

    Beta decay of 86Ga was studied by means of β-neutron-γ spectroscopy. An isotopically pure ^{86}Ga beam was produced at the Holifield Radioactive Ion Beam Facility using a resonance ionization laser ion source and high-resolution electromagnetic separation. The decay of 86Ga revealed a half-life of 43(-15)(+21) ms and large β-delayed one-neutron and two-neutron branching ratios of P1n=60(10)% and P2n=20(10)%. The βγ decay of 86Ga populated a 527 keV transition that is interpreted as the deexcitation of the first 2+ state in the N=54 isotone 86Ge and suggests a quick onset of deformation in Ge isotopes beyond N=50. PMID:24116772

  19. Global Albedo

    Atmospheric Science Data Center

    2013-04-19

    ... to one in the visible region of the solar spectrum whereas deep clean ocean water has an albedo that is close to zero. Five years of ... Atmospheric Science Data Center's  MISR Level 3 Imagery  web site. The Multi-angle Imaging SpectroRadiometer observes the daylit ...

  20. β-decay properties of neutron-rich Zr and Mo isotopes

    NASA Astrophysics Data System (ADS)

    Sarriguren, P.; Pereira, J.

    2010-06-01

    Gamow-Teller strength distributions, β-decay half-lives, and β-delayed neutron emission are investigated in neutron-rich Zr and Mo isotopes within a deformed quasiparticle random-phase approximation. The approach is based on a self-consistent Skyrme Hartree-Fock mean field with pairing correlations and residual separable particle-hole and particle-particle forces. Comparison with recent measurements of half-lives stresses the important role that nuclear deformation plays in the description of β-decay properties in this mass region.

  1. Be11(βp), a quasi-free neutron decay?

    NASA Astrophysics Data System (ADS)

    Riisager, K.; Forstner, O.; Borge, M. J. G.; Briz, J. A.; Carmona-Gallardo, M.; Fraile, L. M.; Fynbo, H. O. U.; Giles, T.; Gottberg, A.; Heinz, A.; Johansen, J. G.; Jonson, B.; Kurcewicz, J.; Lund, M. V.; Nilsson, T.; Nyman, G.; Rapisarda, E.; Steier, P.; Tengblad, O.; Thies, R.; Winkler, S. R.

    2014-05-01

    We have observed β--delayed proton emission from the neutron-rich nucleus 11Be by analyzing a sample collected at the ISOLDE facility at CERN with accelerator mass spectrometry (AMS). With a branching ratio of (8.3±0.9)ṡ10-6 the strength of this decay mode, as measured by the BGT-value, is unexpectedly high. The result is discussed within a simple single-particle model and could be interpreted as a quasi-free decay of the 11Be halo neutron into a single-proton state.

  2. Fission Product Decay Heat Calculations for Neutron Fission of 232Th

    NASA Astrophysics Data System (ADS)

    Son, P. N.; Hai, N. X.

    2016-06-01

    Precise information on the decay heat from fission products following times after a fission reaction is necessary for safety designs and operations of nuclear-power reactors, fuel storage, transport flasks, and for spent fuel management and processing. In this study, the timing distributions of fission products' concentrations and their integrated decay heat as function of time following a fast neutron fission reaction of 232Th were exactly calculated by the numerical method with using the DHP code.

  3. Slowly decaying waves on spherically symmetric spacetimes and ultracompact neutron stars

    NASA Astrophysics Data System (ADS)

    Keir, Joe

    2016-07-01

    We prove that, in a class of spherically symmetric spacetimes exhibiting stable trapping of null geodesics, linear waves cannot (uniformly) decay faster than logarithmically. When these linear waves are treated as a model for nonlinear perturbations, this slow decay is highly suggestive of nonlinear instability. We also prove that, in a large class of asymptotically flat, spherically symmetric spacetimes, logarithmic decay actually holds as a uniform upper bound. In the presence of stable trapping, this result is therefore the best one can obtain. In addition, we provide an application of these results to ultracompact neutron stars, suggesting that all stars with r\\lt 3M might be unstable.

  4. A Precision Measurement of Neutron {beta}-Decay Angular Correlations with Pulsed Cold Neutrons -- The abBA Experiment

    SciTech Connect

    Seo, P.-N.; Bowman, J.D.; O'Donnell, J.M.; Mitchell, G.S.; Penttilae, S.I.; Wilburn, W.S.; Calarco, J.R.; Hersman, F.W.; Chupp, T.E.; Cianciolo, T.V.; Rykaczewski, K.P.; Young, G.R.; Desai, D.; Grzywacz, R.K.; Souza, R.T. de; Snow, W.M.; Frlez, E.; Pocanic, D.; Gentile, T.; Greene, G.L.

    2005-05-24

    The abBA collaboration is developing a new type of field-expansion spectrometer to measure neutron beta decay angular parameters, a, b, B, and A, to the 0.1% precision level. This precision will be achieved by combining three new technical approaches; a pulsed cold neutron beam, a 3He neutron spin filter, and segmented large-area thin-dead layer silicon detectors. Both the electron and proton resulting from the decay will be guided by electric and magnetic fields and detected in coincidence by two 2{pi} solid-angle silicon detectors. For the neutron polarization-dependent observables A and B, a novel precision neutron polarimetry technique has been developed. The parameters a and b will be obtained from the proton time-of-flight and the measured electron energy spectrum. Measurement of the four parameters in the same apparatus provides a redundant determination of parameter {lambda}=gA/gV, providing a test of the standard electroweak interaction.

  5. A Precision Measurement of Neutron β-Decay Angular Correlations with Pulsed Cold Neutrons — The abBA Experiment

    NASA Astrophysics Data System (ADS)

    Seo, P.-N.; Bowman, J. D.; Calarco, J. R.; Chupp, T. E.; Cianciolo, T. V.; Desai, D.; De Souza, R. T.; O'Donnell, J. M.; Frlež, E.; Gentile, T.; Greene, G. L.; Grzywacz, R. K.; Gudkov, V.; Hersman, F. W.; Jones, G. L.; Mitchell, G. S.; Penttilä, S. I.; Počanić, D.; Rykaczewski, K. P.; Snow, W. M.; Wilburn, W. S.; Young, G. R.

    2005-05-01

    The abBA collaboration is developing a new type of field-expansion spectrometer to measure neutron beta decay angular parameters, a, b, B, and A, to the 0.1% precision level. This precision will be achieved by combining three new technical approaches; a pulsed cold neutron beam, a 3He neutron spin filter, and segmented large-area thin-dead layer silicon detectors. Both the electron and proton resulting from the decay will be guided by electric and magnetic fields and detected in coincidence by two 2π solid-angle silicon detectors. For the neutron polarization-dependent observables A and B, a novel precision neutron polarimetry technique has been developed. The parameters a and b will be obtained from the proton time-of-flight and the measured electron energy spectrum. Measurement of the four parameters in the same apparatus provides a redundant determination of parameter λ=gA/gV, providing a test of the standard electroweak interaction.

  6. α decay of the very neutron-deficient isotopes 197-199Fr

    NASA Astrophysics Data System (ADS)

    Kalaninová, Z.; Andreyev, A. N.; Antalic, S.; Heßberger, F. P.; Ackermann, D.; Andel, B.; Drummond, M. C.; Hofmann, S.; Huyse, M.; Kindler, B.; Lane, J. F. W.; Liberati, V.; Lommel, B.; Page, R. D.; Rapisarda, E.; Sandhu, K.; Šáro, Š.; Thornthwaite, A.; Van Duppen, P.

    2013-04-01

    Decay properties of the very neutron-deficient isotopes 197-199Fr were studied at the velocity filter Separator for Heavy Ion reaction Products (SHIP) at GSI in Darmstadt. The isotopes were produced in the 2n-4n evaporation channels of the fusion-evaporation reaction 60Ni+141Pr → 201Fr*. Improved α-decay properties of 199Fr were determined and the possible existence of two α-decaying states in this nucleus is discussed. For the isotope 198Fr a broad α-decay energy distribution was detected in the range of (7470-7930) keV and two α-decaying states were observed with half-lives of 1.1(7) and 15(3) ms. The new isotope 197Fr was identified based on the observation of one α-decay chain yielding Eα=7728(15) keV and T1/2=0.6-0.3+3.0 ms. The systematics of reduced α-decay widths are presented for neutron-deficient francium, radon, and astatine isotopes.

  7. Enhanced γ -Ray Emission from Neutron Unbound States Populated in β Decay

    NASA Astrophysics Data System (ADS)

    Tain, J. L.; Valencia, E.; Algora, A.; Agramunt, J.; Rubio, B.; Rice, S.; Gelletly, W.; Regan, P.; Zakari-Issoufou, A.-A.; Fallot, M.; Porta, A.; Rissanen, J.; Eronen, T.; ńystö, J.; Batist, L.; Bowry, M.; Bui, V. M.; Caballero-Folch, R.; Cano-Ott, D.; Elomaa, V.-V.; Estevez, E.; Farrelly, G. F.; Garcia, A. R.; Gomez-Hornillos, B.; Gorlychev, V.; Hakala, J.; Jordan, M. D.; Jokinen, A.; Kolhinen, V. S.; Kondev, F. G.; Martínez, T.; Mendoza, E.; Moore, I.; Penttilä, H.; Podolyák, Zs.; Reponen, M.; Sonnenschein, V.; Sonzogni, A. A.

    2015-08-01

    Total absorption spectroscopy is used to investigate the β -decay intensity to states above the neutron separation energy followed by γ -ray emission in Br,8887 and 94Rb. Accurate results are obtained thanks to a careful control of systematic errors. An unexpectedly large γ intensity is observed in all three cases extending well beyond the excitation energy region where neutron penetration is hindered by low neutron energy. The γ branching as a function of excitation energy is compared to Hauser-Feshbach model calculations. For 87Br and 88Br the γ branching reaches 57% and 20%, respectively, and could be explained as a nuclear structure effect. Some of the states populated in the daughter can only decay through the emission of a large orbital angular momentum neutron with a strongly reduced barrier penetrability. In the case of neutron-rich 94Rb the observed 4.5% branching is much larger than the calculations performed with standard nuclear statistical model parameters, even after proper correction for fluctuation effects on individual transition widths. The difference can be reconciled by introducing an enhancement of 1 order of magnitude in the photon strength to neutron strength ratio. An increase in the photon strength function of such magnitude for very neutron-rich nuclei, if it proves to be correct, leads to a similar increase in the (n ,γ ) cross section that would have an impact on r process abundance calculations.

  8. Enhanced γ -Ray Emission from Neutron Unbound States Populated in β Decay

    DOE PAGESBeta

    Tain, J. L.; Valencia, E.; Algora, A.; Agramunt, J.; Rubio, B.; Rice, S.; Gelletly, W.; Regan, P.; Zakari-Issoufou, A. -A.; Fallot, M.; et al

    2015-08-01

    Total absorption spectroscopy was used to investigate the β -decay intensity to states above the neutron separation energy followed by γ -ray emission in 87,88Br and 94Rb. Accurate results were obtained thanks to the careful control of systematic errors. An unexpectedly large γ intensity was observed in all three cases extending well beyond the excitation energy region where neutron penetration is hindered by low neutron energy. The γ branching as a function of excitation energy was compared to Hauser-Feshbach model calculations. For 87Br and 88Br the branching reaches 57% and 20% respectively, and could be explained as a nuclear structuremore » effect. Some of the states populated in the daughter can only decay through the emission of a large orbital angular momentum neutron with a strongly reduced barrier penetrability. In the case of neutron-rich 94Rb the observed 4.5% branching is much larger than the calculations performed with standard nuclear statistical model parameters, even after proper correction for fluctuation effects on individual transition widths. The difference can be reconciled introducing an enhancement of one order-of-magnitude in the photon strength to neutron strength ratio. An increase in the photon strength function of such magnitude for very neutron-rich nuclei, if it proved to be correct, leads to a similar increase in the (n, γ) cross section that would have an impact on r process abundance calculations.« less

  9. Global Albedo

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A new sensor aboard NASA?s Terra satellite is now collecting the most detailed and accurate measurements ever made of how much sunlight the Earth?s surface reflects back up into the atmosphere. By quantifying precisely our planet?s reflectivity, or albedo, the Moderate Resolution Imaging Spectroradiometer (MODIS) is helping scientists better understand and predict how various surface features influence both short-term weather patterns as well as longer-term climate trends. (Click to read the press release.) The colors in this image emphasize the albedo over the Earth?s land surfaces, ranging from 0.0 to 0.4. Areas colored red show the brightest, most reflective regions; yellows and greens are intermediate values; and blues and violets show relatively dark surfaces. White indicates where no data were available, and no albedo data are provided over the oceans. This image was produced using data composited over a 16-day period, from April 7-22, 2002. Image courtesy Crystal Schaaf, Boston University, based upon data processed by the MODIS Land Science Team

  10. Decay Studies of Very Neutron Rich Nuclei near 78Ni

    SciTech Connect

    Winger, J. A.; Ilyushkin, S.; Korgul, A.; Gross, Carl J; Rykaczewski, Krzysztof Piotr; Batchelder, J. C.; Goodin, C.; Grzywacz, R.; Hamilton, J. H.; Krolas, W.; Liddick, Sean; Mazzocchi, C.; Nelson, C.; Padgett, Stephen; Piechaczek, A.; Rajabali, M. M.; Shapira, Dan; Zganjar, E. F.

    2008-01-01

    The properties of beta-gamma and beta-delayed neutron emission from 76-79Cu and 83-85Ga were measured at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory. Selected results on the decay properties of copper isotopes are briefly presented and discussed.

  11. The Physics of Ultracold Neutrons and Fierz Interference in Beta Decay

    NASA Astrophysics Data System (ADS)

    Hickerson, Kevin Peter

    In the first component of this thesis, we investigate the physics of ultacold neutrons (UCN). UCN are neutrons so cold they can be stored inside of material, magnetic and gravitational bottles. Using this property we use UCN nonimaging optics to design a type of reflector that directs UCN upward in to vertical paths. Next we examine UCN passing through thin, multilayered foils. In the remaining sections we investigate the so-called Fierz interference term of free neutron beta decay, denoted bn. It is theorized that contributions to scalar and tensor interactions from physics beyond the Standard Model could be detectable in the spectrum of neutron beta decay, manifest as a nonzero value for bn. We investigate three techniques for measuring bn. The first is to use the primordial helium abundance fraction and compare that to predictive Big Bang nucleosynthesis calculations. Second we extract bn from the spectral shape generated by the 2010 data set of the UCNA experiment. Third, we discuss progress toward constructing the UCNb experimental prototype. We present the design of this new experiment that uses the UCN source at LANSCE for measuring bn, in which UCN are guided into a shielded 4π calorimeter where they are stored and decay. From Big Bang nucleosynthesis we can place the limit 0.021 < bn < 0.277 (90% C.L.) on the neutron Fierz term and from the UCNA 2010 data we set -0.044 < bn < 0.218 (90% C.L.).

  12. β-decay properties of neutron-deficient Pt, Hg, and Pb isotopes

    SciTech Connect

    Sarriguren, P.; Boillos, J. M.; Moreno, O.; Moya de Guerra, E.

    2015-10-15

    Neutron-deficient isotopes in the lead region are well established examples of the shape coexistence phenomenon in nuclei. In this work, bulk and decay properties, including deformation energy curves, charge mean square radii, Gamow-Teller (GT) strength distributions, and β-decay half-lives, are studied in neutron-deficient Pt, Hg, and Pb isotopes. The nuclear structure involved is described microscopically from deformed quasiparticle random-phase approximation calculations with residual interactions in both particle-hole and particle-particle channels, performed on top of a self-consistent deformed quasiparticle Skyrme Hartree-Fock basis. The sensitivity to deformation of the GT strength distributions in those isotopes is proposed as an additional complementary signature of the nuclear shape. The β-decay half-lives resulting from the GT strength distributions are compared to experiment to demonstrate the ability of the method.

  13. Decay studies of neutron deficient rare earth isotopes with OASIS

    SciTech Connect

    Gilat, J.; Nitschke, J.M.; Wilmarth, P.A.; Vierinen, K.; Firestone, R.B.

    1987-09-01

    We report results on the decay of /sup 124/Pr, /sup 124,125/Ce, /sup 124,125/La, /sup 134-136/Eu, /sup 134-136/Sm, /sup 134-136/Pm, /sup 144/Ho, /sup 141,142,144/Dy, /sup 140,141,142,144/Tb, /sup 140-142/Gd, and /sup 140-142/Eu, produced by /sup 92/Mo(H.I.,xpyn) reactions at the Berkeley SuperHILAC, and studied with the OASIS on-line mass separator facility. Half-lives, delayed proton branching ratios, ..gamma..-ray energies and intensities, partial decay schemes and several J/sup ..pi../ assignments are presented. Level systematics of the even mass Nd and Sm isotopes and of the nu h/sub 11/2/ - nu s/sub 1/2/ isomers for N = 77 are discussed.

  14. Asymptotic Analysis of Time-Dependent Neutron Transport Coupled with Isotopic Depletion and Radioactive Decay

    SciTech Connect

    Brantley, P S

    2006-09-27

    We describe an asymptotic analysis of the coupled nonlinear system of equations describing time-dependent three-dimensional monoenergetic neutron transport and isotopic depletion and radioactive decay. The classic asymptotic diffusion scaling of Larsen and Keller [1], along with a consistent small scaling of the terms describing the radioactive decay of isotopes, is applied to this coupled nonlinear system of equations in a medium of specified initial isotopic composition. The analysis demonstrates that to leading order the neutron transport equation limits to the standard time-dependent neutron diffusion equation with macroscopic cross sections whose number densities are determined by the standard system of ordinary differential equations, the so-called Bateman equations, describing the temporal evolution of the nuclide number densities.

  15. A Novel Approach to β-delayed Neutron Spectroscopy Using the Beta-decay Paul Trap

    SciTech Connect

    Scielzo, N.D.; Yee, R.M.; Bertone, P.F.; Buchinger, F.; Caldwell, S.A.; Clark, J.A.; Czeszumska, A.; Deibel, C.M.; Greene, J.P.; Gulick, S.; Lascar, D.; Levand, A.F.; and others

    2014-06-15

    A new approach to β-delayed neutron spectroscopy has been demonstrated that circumvents the many limitations associated with neutron detection by instead inferring the decay branching ratios and energy spectra of the emitted neutrons by studying the nuclear recoil. Using the Beta-decay Paul Trap, fission-product ions were trapped and confined to within a 1-mm{sup 3} volume under vacuum using only electric fields. Results from recent measurements of {sup 137}I{sup +} and plans for development of a dedicated ion trap for future experiments using the intense fission fragment beams from the Californium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory are summarized. The improved nuclear data that can be collected is needed in many fields of basic and applied science such as nuclear energy, nuclear astrophysics, and stockpile stewardship.

  16. Beta Decay Spectroscopy of Neutron-Rich Nuclei at RIBF

    NASA Astrophysics Data System (ADS)

    Lorusso, G.; Nishimura, S.; Baba, H.; Doornenbal, P.; Isobe, T.; Söderström, P.-A.; Browne, F.; Daido, R.; Yifan, F.; Nishibata, H.; Yagi, A.; Gey, G.; Li, Z.; Wu, J.; Lubos, D.; Moschner, K.; Patel, Z.; Rice, S.; Sinclair, L.; Sumikama, T.; Taprogge, J.; Vajta, Zs.; Watanabe, H.; Xu, Z. Y.; Yoshinaga, K.

    2015-11-01

    The development of a high intensity 238U beam at the Radioactive Isotope Beam Factory (RIBF) has opened a new opportunity to explore exotic regions of the nuclear chart that were not accessible before. Along with beam development, the installation of the high efficiency γ-detector EURICA has made β-decay spectroscopy measurements of these regions possible, and a large international effort named the EURICA project has been launched to take advantage of this new opportunity.

  17. Failure of the gross theory of beta decay in neutron deficient nuclei

    SciTech Connect

    Firestone, R. B.; Schwengner, R.; Zuber, K.

    2015-05-28

    The neutron deficient isotopes 117-121Xe, 117-124Cs, and 122-124Ba were produced by a beam of 28Si from the LBNL SuperHILAC on a target of natMo. The isotopes were mass separated and their beta decay schemes were measured with a Total Absorption Spectrometer (TAS). The beta strengths derived from these data decreased dramatically to levels above ≈1 MeV for the even-even decays; 3–4 MeV for even-Z, odd-N decays; 4–5 MeV for the odd-Z, even-N decays; and 7–8 MeV for the odd-Z, odd-N decays. The decreasing strength to higher excitation energies in the daughters contradicts the predictions of the Gross Theory of Beta Decay. The integrated beta strengths are instead found to be consistent with shell model predictions where the single-particle beta strengths are divided amoung many low-lying levels. The experimental beta strengths determined here have been used calculate the half-lives of 143 neutron deficient nuclei with Z=51–64 to a precision of 20% with respect to the measured values.

  18. Failure of the gross theory of beta decay in neutron deficient nuclei

    DOE PAGESBeta

    Firestone, R. B.; Schwengner, R.; Zuber, K.

    2015-05-28

    The neutron deficient isotopes 117-121Xe, 117-124Cs, and 122-124Ba were produced by a beam of 28Si from the LBNL SuperHILAC on a target of natMo. The isotopes were mass separated and their beta decay schemes were measured with a Total Absorption Spectrometer (TAS). The beta strengths derived from these data decreased dramatically to levels above ≈1 MeV for the even-even decays; 3–4 MeV for even-Z, odd-N decays; 4–5 MeV for the odd-Z, even-N decays; and 7–8 MeV for the odd-Z, odd-N decays. The decreasing strength to higher excitation energies in the daughters contradicts the predictions of the Gross Theory of Betamore » Decay. The integrated beta strengths are instead found to be consistent with shell model predictions where the single-particle beta strengths are divided amoung many low-lying levels. The experimental beta strengths determined here have been used calculate the half-lives of 143 neutron deficient nuclei with Z=51–64 to a precision of 20% with respect to the measured values.« less

  19. Mars Albedo

    NASA Technical Reports Server (NTRS)

    2001-01-01

    These two views of Mars are derived from the MGS Thermal Emission Spectrometer (TES) measurements of global broadband (0.3 - 3.0 microns) visible and near-infrared reflectance, also known as albedo. The range of colors are in dimensionless units. The values are the ratio of the amount of electromagnetic energy reflected by the surface to the amount of energy incident upon it from the sun (larger values are brighter surfaces).

    The TES instrument was built by Santa Barbara Remote Sensing and is operated by Philip R. Christensen, of Arizona State University, Tempe, AZ.

  20. Neutron-Induced Reactions on Copper and Zero-Neutrino Double-Beta Decay Searches

    NASA Astrophysics Data System (ADS)

    Gooden, Matthew; Kelley, John; Fallin, Brent; Finch, Sean; Howell, Calvin; Rusev, Gencho; Tonchev, Anton; Tornow, Werner

    2012-10-01

    Cross-section measurements of (n,xγ) reactions on ^natCu were carried out at TUNL using monoenergetic neutrons at six energies of En = 6, 8, 10, 12, 14, 16 MeV. These studies were performed to provide accurate cross-section data on materials abundant in experimental setups involving HPGe detectors used to search for rare events, like the neutrino-less double-beta decay of ^76Ge. Spallation and (α,n) neutrons are expected to cause the largest source of external background in the energy region of interest. At TUNL pulsed neutron beams were produced via the ^2H(d,n)^3He reaction and the deexcitation γ rays from the reaction ^natCu(n,xγ) were detected with clover HPGe detectors. Our cross-section data will be compared to theoretical calculations and to data recently obtained at LANL with a white neutron beam.

  1. Evidence for Gamow-Teller Decay of ^{78}Ni Core from Beta-Delayed Neutron Emission Studies.

    PubMed

    Madurga, M; Paulauskas, S V; Grzywacz, R; Miller, D; Bardayan, D W; Batchelder, J C; Brewer, N T; Cizewski, J A; Fijałkowska, A; Gross, C J; Howard, M E; Ilyushkin, S V; Manning, B; Matoš, M; Mendez, A J; Miernik, K; Padgett, S W; Peters, W A; Rasco, B C; Ratkiewicz, A; Rykaczewski, K P; Stracener, D W; Wang, E H; Wolińska-Cichocka, M; Zganjar, E F

    2016-08-26

    The β-delayed neutron emission of ^{83,84}Ga isotopes was studied using the neutron time-of-flight technique. The measured neutron energy spectra showed emission from states at excitation energies high above the neutron separation energy and previously not observed in the β decay of midmass nuclei. The large decay strength deduced from the observed intense neutron emission is a signature of Gamow-Teller transformation. This observation was interpreted as evidence for allowed β decay to ^{78}Ni core-excited states in ^{83,84}Ge favored by shell effects. We developed shell model calculations in the proton fpg_{9/2} and neutron extended fpg_{9/2}+d_{5/2} valence space using realistic interactions that were used to understand measured β-decay lifetimes. We conclude that enhanced, concentrated β-decay strength for neutron-unbound states may be common for very neutron-rich nuclei. This leads to intense β-delayed high-energy neutron and strong multineutron emission probabilities that in turn affect astrophysical nucleosynthesis models. PMID:27610848

  2. {alpha} decay studies of very neutron-deficient francium and radium isotopes

    SciTech Connect

    Uusitalo, J.; Leino, M.; Enqvist, T.; Grahn, T.; Greenlees, P.T.; Jones, P.; Julin, R.; Juutinen, S.; Keenan, A.; Kettunen, H.; Koivisto, H.; Kuusiniemi, P.; Leppaenen, A.-P.; Nieminen, P.; Pakarinen, J.; Rahkila, P.; Scholey, C.; Eskola, K.

    2005-02-01

    Very neutron-deficient francium and radium isotopes have been produced in fusion evaporation reactions using {sup 63}Cu and {sup 65}Cu ions on {sup 141}Pr targets and {sup 36}Ar ions on {sup 170}Yb targets. The gas-filled recoil separator RITU was employed to collect the fusion products and to separate them from the scattered beam. The activities were implanted into a position-sensitive silicon detector after passing through a gas-counter system. The isotopes were identified using spatial and time correlations between the implants and decays. Two new {alpha} decaying radium isotopes, {sup 201}Ra and {sup 202}Ra, were identified. The {alpha} decay energy and half-life of {sup 203}Ra were measured with improved precision. The {alpha} decay properties measured for the francium isotopes {sup 201}Fr,{sup 202}Fr,{sup 203}Fr, and {sup 204}Fr were confirmed, in many cases with improved precision. For the first time, a ({pi}s{sub 1/2}{sup -1})1/2{sup +} proton intruder state was identified in francium isotopes, namely in {sup 201}Fr and tentatively in {sup 203}Fr. The measured decay properties for the neutron-deficient odd-mass Fr isotopes suggest an onset of substantial deformation at N=112.

  3. Decay heat measurement of fusion related materials in an ITER-like neutron field

    NASA Astrophysics Data System (ADS)

    Morimoto, Y.; Ochiai, K.; Maekawa, F.; Wada, M.; Nishitani, T.; Takeuchi, H.

    2002-12-01

    Decay heat is one of the most important factors for the safety aspect of ITER. Especially, the prediction of decay heat with an uncertainty less than 15% for the three most important materials, i.e., copper, type-316 stainless steel (SS316) and tungsten, is strongly requested by designers of ITER. To provide experimental decay heat data needed for validation of decay heat calculations for SS316 and copper, an experiment was conducted as the ITER/EDA task T-426. An ITER-like neutron field was constructed, and decay heat source distributions in thick copper and SS316 plates were measured with the whole energy absorption spectrometer. The measured decay heat distributions in the thick sample plates were compared with the predicted values by MCNP calculations. It was found that the use of an effective activation cross-section calculated by MCNP was needed to consider the self-shielding effects and, for both cases, MCNP calculations could predict the decay heat adequately.

  4. Decay of the neutron-rich isotope 171Ho and the identification of 169Dy

    NASA Astrophysics Data System (ADS)

    Chasteler, R. M.; Nitschke, J. M.; Firestone, R. B.; Vierinen, K. S.; Wilmarth, P. A.

    1990-10-01

    Neutron-rich rare-earth isotopes were produced in multinucleon transfer reactions between 170Er ions and natW targets. On-line mass separation was used together with β- and γ-ray spectroscopy in these studies. At mass A=169, the heaviest known dysprosium isotope, 39(8) s,169Dy, was identified. It was observed to β- decay to the ground state of 169Ho or through a level at 1578 keV. In the A=171 mass chain, a partial decay scheme for 55(3)-s 171Ho was determined.

  5. β Decay in the Region of Neutron-deficient {sup 69,70,71}Kr

    SciTech Connect

    Rogers, A.M.; Giovinazzo, J.; Blank, B.; Canchel, G.; France, G. de; Grévy, S.; Oliveira Santos, F. de; Stefan, I.; Thomas, J.-C.

    2014-06-15

    Decay spectroscopy was performed for neutron-deficient nuclei ranging from zinc to krypton with isospin −3/2 ≤T{sub z}≤0. Measurements of correlated β-delayed protons allowed us to determine the isobaric analog states fed from the decay of {sup 65}Se and {sup 69}Kr, constraining the spin of the {sup 69}Kr ground state. Preliminary results regarding the half lives for the T{sub z}=−1 systems, relevant to the rapid proton capture (rp) process, are discussed.

  6. β-decay studies of neutron-rich Tl, Pb, and Bi isotopes

    NASA Astrophysics Data System (ADS)

    Morales, A. I.; Benzoni, G.; Gottardo, A.; Valiente-Dobón, J. J.; Blasi, N.; Bracco, A.; Camera, F.; Crespi, F. C. L.; Corsi, A.; Leoni, S.; Million, B.; Nicolini, R.; Wieland, O.; Gadea, A.; Lunardi, S.; Górska, M.; Regan, P. H.; Podolyák, Zs.; Pfützner, M.; Pietri, S.; Boutachkov, P.; Weick, H.; Grebosz, J.; Bruce, A. M.; Núñez, J. Alcántara; Algora, A.; Al-Dahan, N.; Ayyad, Y.; Alkhomashi, N.; Allegro, P. R. P.; Bazzacco, D.; Benlliure, J.; Bowry, M.; Bunce, M.; Casarejos, E.; Cortes, M. L.; Bacelar, A. M. Denis; Deo, A. Y.; de Angelis, G.; Domingo-Pardo, C.; Doncel, M.; Dombradi, Zs.; Engert, T.; Eppinger, K.; Farrelly, G. F.; Farinon, F.; Farnea, E.; Geissel, H.; Gerl, J.; Goel, N.; Gregor, E.; Habermann, T.; Hoischen, R.; Janik, R.; Klupp, S.; Kojouharov, I.; Kurz, N.; Mandal, S.; Menegazzo, R.; Mengoni, D.; Napoli, D. R.; Naqvi, F.; Nociforo, C.; Prochazka, A.; Prokopowicz, W.; Recchia, F.; Ribas, R. V.; Reed, M. W.; Rudolph, D.; Sahin, E.; Schaffner, H.; Sharma, A.; Sitar, B.; Siwal, D.; Steiger, K.; Strmen, P.; Swan, T. P. D.; Szarka, I.; Ur, C. A.; Walker, P. M.; Wollersheim, H.-J.

    2014-01-01

    The fragmentation of relativistic uranium projectiles has been exploited at the Gesellschaft für Schwerionenforschung laboratory to investigate the β decay of neutron-rich nuclei just beyond 208Pb. This paper reports on β-delayed γ decays of 211-213Tl, 215Pb, and 215-219Bi de-exciting states in the daughters 211-213Pb, 215Bi, and 215-219Po. The resulting partial level schemes, proposed with the help of systematics and shell-model calculations, are presented. The role of allowed Gamow-Teller and first-forbidden β transitions in this mass region is discussed.

  7. Decay spectroscopy of neutron-rich rare-earth isotopes and collectivity around double midshell

    SciTech Connect

    Watanabe, Hiroshi

    2015-10-15

    Neutron-rich rare-earth isotopes with A ≈ 170, which locate near the middle of the major shells for both proton and neutron between the doubly magic nuclei {sup 132}Sn and {sup 208}Pb, have been investigated by means of decay spectroscopy techniques at the RIBF facility at RIKEN. The nuclei of interest were produced by in-flight fission of a high-intensity {sup 238}U beam at 345 MeV/u. In this contribution, scientific motivations, the details of experimental procedures, and some prospects of the data analysis are reported.

  8. Beta-decay studies of nickel-78 and other neutron-rich nuclei in the astrophysical r-process

    NASA Astrophysics Data System (ADS)

    Hosmer, Paul Thomas

    The β-decay properties of several neutron-rich nuclei including the doubly-magic 78Ni were studied. A low-energy neutron detector NERO was designed and calibrated for use in these measurements. β-decay measurements, especially those that combine both half-life and neutron-emission probability measurements, can offer first tests of nuclear theories of neutron-rich nuclei. In addition, 78Ni is an important waiting-point in the astrophysical r-process. The results of the measurements are compared to several nuclear models, and the astrophysical implications are explored.

  9. Beta-decay rate and beta-delayed neutron emission probability of improved gross theory

    NASA Astrophysics Data System (ADS)

    Koura, Hiroyuki

    2014-09-01

    A theoretical study has been carried out on beta-decay rate and beta-delayed neutron emission probability. The gross theory of the beta decay is based on an idea of the sum rule of the beta-decay strength function, and has succeeded in describing beta-decay half-lives of nuclei overall nuclear mass region. The gross theory includes not only the allowed transition as the Fermi and the Gamow-Teller, but also the first-forbidden transition. In this work, some improvements are introduced as the nuclear shell correction on nuclear level densities and the nuclear deformation for nuclear strength functions, those effects were not included in the original gross theory. The shell energy and the nuclear deformation for unmeasured nuclei are adopted from the KTUY nuclear mass formula, which is based on the spherical-basis method. Considering the properties of the integrated Fermi function, we can roughly categorized energy region of excited-state of a daughter nucleus into three regions: a highly-excited energy region, which fully affect a delayed neutron probability, a middle energy region, which is estimated to contribute the decay heat, and a region neighboring the ground-state, which determines the beta-decay rate. Some results will be given in the presentation. A theoretical study has been carried out on beta-decay rate and beta-delayed neutron emission probability. The gross theory of the beta decay is based on an idea of the sum rule of the beta-decay strength function, and has succeeded in describing beta-decay half-lives of nuclei overall nuclear mass region. The gross theory includes not only the allowed transition as the Fermi and the Gamow-Teller, but also the first-forbidden transition. In this work, some improvements are introduced as the nuclear shell correction on nuclear level densities and the nuclear deformation for nuclear strength functions, those effects were not included in the original gross theory. The shell energy and the nuclear deformation for

  10. Water equivalent hydrogen estimates from the first 200 sols of Curiosity's traverse (Bradbury Landing to Yellowknife Bay): Results from the Dynamic Albedo of Neutrons (DAN) passive mode experiment

    NASA Astrophysics Data System (ADS)

    Tate, C. G.; Moersch, J.; Jun, I.; Ming, D. W.; Mitrofanov, I.; Litvak, M.; Behar, A.; Boynton, W. V.; Deflores, L.; Drake, D.; Ehresmann, B.; Fedosov, F.; Golovin, D.; Hardgrove, C.; Harshman, K.; Hassler, D. M.; Kozyrev, A. S.; Kuzmin, R.; Lisov, D.; Malakhov, A.; Milliken, R.; Mischna, M.; Mokrousov, M.; Nikiforov, S.; Sanin, A. B.; Starr, R.; Varenikov, A.; Vostrukhin, A.; Zeitlin, C.

    2015-12-01

    The Dynamic Albedo of Neutrons (DAN) experiment on the Mars Science Laboratory (MSL) rover Curiosity is designed to detect neutrons to determine hydrogen abundance within the subsurface of Mars (Mitrofanov, I.G. et al. [2012]. Space Sci. Rev. 170, 559-582. http://dx.doi.org/10.1007/s11214-012-9924-y; Litvak, M.L. et al. [2008]. Astrobiology 8, 605-613. http://dx.doi.org/10.1089/ast.2007.0157). While DAN has a pulsed neutron generator for active measurements, in passive mode it only measures the leakage spectrum of neutrons produced by the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and Galactic Cosmic Rays (GCR). DAN passive measurements provide better spatial coverage than the active measurements because they can be acquired while the rover is moving. Here we compare DAN passive-mode data to models of the instrument's response to compositional differences in a homogeneous regolith in order to estimate the water equivalent hydrogen (WEH) content along the first 200 sols of Curiosity's traverse in Gale Crater, Mars. WEH content is shown to vary greatly along the traverse. These estimates range from 0.5 ± 0.1 wt.% to 3.9 ± 0.2 wt.% for fixed locations (usually overnight stops) investigated by the rover and 0.6 ± 0.2 wt.% to 7.6 ± 1.3 wt.% for areas that the rover has traversed while continuously acquiring DAN passive data between fixed locations. Estimates of WEH abundances at fixed locations based on passive mode data are in broad agreement with those estimated at the same locations using active mode data. Localized (meter-scale) anomalies in estimated WEH values from traverse measurements have no particular surface expression observable in co-located images. However at a much larger scale, the hummocky plains and bedded fractured units are shown to be distinct compositional units based on the hydrogen content derived from DAN passive measurements. DAN passive WEH estimates are also shown to be consistent with geologic models inferred from other

  11. β and β -n decay of the neutron-rich

    NASA Astrophysics Data System (ADS)

    Korgul, A.; Rykaczewski, K. P.; Grzywacz, R. K.; Bingham, C. R.; Brewer, N. T.; Gross, C. J.; Ciemny, A. A.; Jost, C.; Karny, M.; Madurga, M.; Mazzocchi, C.; Mendez, A. J.; Miernik, K.; Miller, D.; Padgett, S.; Paulauskas, S. V.; Piersa, M.; Stracener, D. W.; Stryjczyk, M.; Wolińska-Cichocka, M.; Zganjar, E. F.

    2016-06-01

    The β -decay properties of the very neutron-rich decay scheme and the order of the two lowest-lying levels in the daughter neutron emission was observed. The shell-model calculations and apparent β transition intensities were used to guide the spin assignment to the

  12. Proposed Measurement of the Beta-Neutrino Correlation in Neutron Decay

    PubMed Central

    Collett, B.; Anderman, R.; Balashov, S.; Bateman, F. B.; Byrne, J.; Dewey, M. S.; Fisher, B. M.; Goldin, L.; Jones, G.; Komives, A.; Konopka, T.; Leuschner, M.; Mostovoy, Yu.; Nico, J. S.; Thompson, A. K.; Trull, C.; Wietfeldt, F. E.; Wilson, R.; Yerozolimsky, B. G.

    2005-01-01

    Currently, the beta-neutrino asymmetry has the largest uncertainty (4 %) of the neutron decay angular correlations. Without requiring polarimetry this decay parameter can be used to measure λ (ga/gv), test Cabibbo-Kobayashi-Maskawa (CKM) unitarity limit scalar and tensor currents, and search for Charged Vector Current (CVC) violation. We propose to measure the beta-neutrino asymmetry coeffcient, a, using time-of-flight for the recoil protons. We hope to achieve a systematic uncertainty of σa / a ≈ 1.0 %. After tests at Indiana University’s Low Energy Neutron Source (LENS), the apparatus will be moved to the National Institute of Standards and Technology (NIST) where the measurement can achieve a statistical uncertainty of 1 % to 2 % in about 200 beam days. PMID:27308157

  13. Beta-decay study of neutron rich isotopes of Bromine and Krypton

    SciTech Connect

    Miernik, Krzysztof A; Gross, Carl J; Grzywacz, Robert Kazimierz; Madurga, M; Mendez, II, Anthony J; Miller, D.; Padgett, S; Paulauskas, Stanley V; Rykaczewski, Krzysztof Piotr; Stracener, Daniel W; Wolinska-Cichocka, Marzena; Zganjar, E. F.; Batchelder, J. C.; Brewer, N.T.; Cartegni, L.; Fijalkowska, Aleksandra G; Hamilton, J. H.; Hwang, J. K.; Ilyushkin, S.; Jost, Carola U; Karny, M.; Korgul, A.; Krolas, W.; Liu, S.H.; Ramayya, A. V.; Surman, Rebecca; Winger, J. A.; Wolinska-Cichocka, M

    2013-01-01

    Short lived neutron rich nuclei including 93 Br, 93 Kr and 94 Kr were produced in proton induced fission of 238 U at the HRIBF in Oak Ridge. Their beta decay was studied by means of a high resolution on line mass separator and beta gamma spectroscopy methods. The half life of 93Br T1/2 = 152(8) ms and delayed branching ratio of Pn = 53-8+11 may be compared to the previously reported values of T1/2 = 102(10) ms and Pn = 68(7)%. At the same time the half life of 94Kr T1/2 = 227(14) ms and B delayed branching ratio of Pn = 1.9+0.6 0.2 % of 93Kr are in very good agreement with literature values. The decay properties of 93Br include four new gamma transitions following beta delayed neutron emission.

  14. {beta}-decay in neutron-deficient Hg, Pb, and Po isotopes

    SciTech Connect

    Moreno, O.; Sarriguren, P.; Alvarez-Rodriguez, R.; Guerra, E. Moya de

    2006-05-15

    The effect of nuclear deformation on the energy distributions of the Gamow-Teller strength is studied in neutron-deficient Hg, Pb, and Po even isotopes. The theoretical framework is based on a self-consistent deformed Skyrme Hartree-Fock mean field with pairing correlations between like nucleons in BCS approximation and residual spin-isospin interactions treated in the proton-neutron quasiparticle random-phase approximation. After a systematic study of the Gamow-Teller strength distributions in the low-excitation-energy region, relevant for {beta}{sup +} decay, we have identified the best candidates to look for deformation signatures in their {beta}{sup +}-decay patterns. {beta}{sup +} half-lives and total Gamow-Teller strengths B(GT{sup {+-}}) are analyzed as well.

  15. The Beta-, Neutrino- and Proton-Asymmetry in Neutron β-Decay

    PubMed Central

    Abele, H.; Baeßler, S.; Deissenroth, M.; Glück, F.; Krempel, J.; Kreuz, M.; Märkisch, B.; Mund, D.; Schumann, M.; Soldner, T.

    2005-01-01

    This article describes measurements of angular-correlation coefficients in the decay of free neutrons with the superconducting spectrometer PERKEO II. A method for measuring the β-asymmetry coefficient A is presented, as well as a new method for determining the neutrino-asymmetry coefficient B, which allows a value for the proton-asymmetry coefficient C to be obtained for the first time. An ongoing experiment is trying to improve the accuracy of these quantities. PMID:27308153

  16. α -decay half-lives of odd-mass nuclei with differences between neutron and proton distributions

    NASA Astrophysics Data System (ADS)

    Ni, Dongdong; Ren, Zhongzhou

    2016-05-01

    Effects of differences between neutron and proton distributions on α decay are investigated for odd-mass nuclei within the generalized density-dependent cluster model. The neutron skin thickness is employed to gauge the differences and it is considered in numerically computing the double-folding α -nucleus potentials. In terms of the characteristic of odd-mass α emitters, special attention is paid to the α decays from ground or isomeric states which end in the ground states of daughter nuclei and furthermore belong to favored α decays. The calculations with the neutron skin thickness yield shorter half-lives, suggesting a smaller preformation factor. This is quite consistent with the conclusions for even-even α emitters. Moreover, α -decay calculations are extended for odd-mass isomers and superheavy nuclei. The calculated α -decay half-lives are found to be in good agreement with the experimental data.

  17. Realistic fission models, new beta-decay half-lives and the r-process in neutron star mergers

    SciTech Connect

    Shibagaki, S.; Kajino, T.; Chiba, S.; Lorusso, G.; Nishimura, S.; Mathews, G. J.

    2014-05-02

    Almost half of heavy nuclei beyond iron are considered to be produced by rapid neutron capture process (r-process). This process occurs in the neutron-rich environment such as core-collapse supernovae or neutron star mergers, but the main production site is still unknown. In the r-process of neutron star mergers, nuclear fission reactions play an important role. Also beta-decay half-lives of magic nuclei are crucial for the r-process. We have carried out r-process nucleosynthesis calculations based upon new theoretical estimates of fission fragment distributions and new beta-decay half-lives for N=82 nuclei measured at RIBF-RIKEN. We investigate the effect of nuclear fission on abundance patterns in the matter ejected from neutron star mergers with two different fission fragment mass distributions. We also discuss how the new experimental beta-decay half-lives affect the r-process.

  18. Search for the invisible decay of neutrons with KamLAND.

    PubMed

    Araki, T; Enomoto, S; Furuno, K; Gando, Y; Ichimura, K; Ikeda, H; Inoue, K; Kishimoto, Y; Koga, M; Koseki, Y; Maeda, T; Mitsui, T; Motoki, M; Nakajima, K; Nakamura, K; Ogawa, H; Ogawa, M; Owada, K; Ricol, J-S; Shimizu, I; Shirai, J; Suekane, F; Suzuki, A; Tada, K; Takeuchi, S; Tamae, K; Tsuda, Y; Watanabe, H; Busenitz, J; Classen, T; Djurcic, Z; Keefer, G; Leonard, D S; Piepke, A; Yakushev, E; Berger, B E; Chan, Y D; Decowski, M P; Dwyer, D A; Freedman, S J; Fujikawa, B K; Goldman, J; Gray, F; Heeger, K M; Hsu, L; Lesko, K T; Luk, K-B; Murayama, H; O'Donnell, T; Poon, A W P; Steiner, H M; Winslow, L A; Jillings, C; Mauger, C; McKeown, R D; Vogel, P; Zhang, C; Lane, C E; Miletic, T; Guillian, G; Learned, J G; Maricic, J; Matsuno, S; Pakvasa, S; Horton-Smith, G A; Dazeley, S; Hatakeyama, S; Rojas, A; Svoboda, R; Dieterle, B D; Detwiler, J; Gratta, G; Ishii, K; Tolich, N; Uchida, Y; Batygov, M; Bugg, W; Efremenko, Y; Kamyshkov, Y; Kozlov, A; Nakamura, Y; Karwowski, H J; Markoff, D M; Rohm, R M; Tornow, W; Wendell, R; Chen, M-J; Wang, Y-F; Piquemal, F

    2006-03-17

    The Kamioka Liquid scintillator Anti-Neutrino Detector is used in a search for single neutron or two-neutron intranuclear disappearance that would produce holes in the -shell energy level of (12)C nuclei. Such holes could be created as a result of nucleon decay into invisible modes (inv), e.g., n--> 3v or nn--> 2v. The deexcitation of the corresponding daughter nucleus results in a sequence of space and time-correlated events observable in the liquid scintillator detector. We report on new limits for one- and two-neutron disappearance: tau(n--> inv) > 5.8 x 10(29) years and tau (nn--> inv) > 1.4 x 10(30) years at 90% C.L. These results represent an improvement of factors of approximately 3 and >10(4) and over previous experiments. PMID:16605724

  19. An investigation into the accuracy of the albedo dosimeter DVGN-01 in measuring personnel irradiation doses in the fields of neutron radiation at nuclear power installations of the joint institute for nuclear research

    NASA Astrophysics Data System (ADS)

    Beskrovnaya, L. G.; Goroshkova, E. A.; Mokrov, Yu. V.

    2010-05-01

    The calculated results of research into the accuracy of an individual albedo dosimeter DVGN-01 as it corresponds to the personal equivalent dose for neutrons H p (10) and to the effective dose for neutrons E eff in the neutron fields at Joint Institute for Nuclear Research Nuclear Power Installations (JNPI) upon different geometries of irradiations are presented. It has been shown that correction coefficients are required for the specific estimation of doses by the dosimeter. These coefficients were calculated using the energy sensitivity curve of the dosimeter and the known neutron spectra at JNPI. By using the correction factors, the uncertainties of both doses will not exceed the limits given to the personnel according to the standards.

  20. Strong neutrino cooling by cycles of electron capture and β- decay in neutron star crusts.

    PubMed

    Schatz, H; Gupta, S; Möller, P; Beard, M; Brown, E F; Deibel, A T; Gasques, L R; Hix, W R; Keek, L; Lau, R; Steiner, A W; Wiescher, M

    2014-01-01

    The temperature in the crust of an accreting neutron star, which comprises its outermost kilometre, is set by heating from nuclear reactions at large densities, neutrino cooling and heat transport from the interior. The heated crust has been thought to affect observable phenomena at shallower depths, such as thermonuclear bursts in the accreted envelope. Here we report that cycles of electron capture and its inverse, β(-) decay, involving neutron-rich nuclei at a typical depth of about 150 metres, cool the outer neutron star crust by emitting neutrinos while also thermally decoupling the surface layers from the deeper crust. This 'Urca' mechanism has been studied in the context of white dwarfs and type Ia supernovae, but hitherto was not considered in neutron stars, because previous models computed the crust reactions using a zero-temperature approximation and assumed that only a single nuclear species was present at any given depth. The thermal decoupling means that X-ray bursts and other surface phenomena are largely independent of the strength of deep crustal heating. The unexpectedly short recurrence times, of the order of years, observed for very energetic thermonuclear superbursts are therefore not an indicator of a hot crust, but may point instead to an unknown local heating mechanism near the neutron star surface. PMID:24291788

  1. Strong neutrino cooling by cycles of electron capture and decay in neutron star crusts

    SciTech Connect

    Schatz, Hendrik; Gupta, Sanjib; Moeller, Peter; Beard, Mary; Brown, Edward; Deibel, A. T.; Gasques, Leandro; Hix, William Raphael; Keek, Laurens; Lau, Rita; Steiner, Andrew M; Wiescher, Michael

    2013-01-01

    The temperature in the crust of an accreting neutron star, which comprises its outermost kilometre, is set by heating from nuclear reactions at large densities, neutrino cooling and heat transport from the interior. The heated crust has been thought to affect observable phenomena at shallower depths, such as thermonuclear bursts in the accreted envelope. Here we report that cycles of electron capture and its inverse, decay, involving neutron-rich nuclei at a typical depth of about 150 metres, cool the outer neutron star crust by emitting neutrinos while also thermally decoupling the surface layers from the deeper crust. This Urca mechanism has been studied in the context of white dwarfs13 and type Ia supernovae, but hitherto was not considered in neutron stars, because previous models1, 2 computed the crust reactions using a zero-temperature approximation and assumed that only a single nuclear species was present at any given depth. The thermal decoupling means that X-ray bursts and other surface phenomena are largely independent of the strength of deep crustal heating. The unexpectedly short recurrence times, of the order of years, observed for very energetic thermonuclear superbursts are therefore not an indicator of a hot crust, but may point instead to an unknown local heating mechanism near the neutron star surface.

  2. Neutron Background Measurements by the the MSL Dynamic Albedo of Neutrons (DAN) Instrument during the First 360 sols of the Surface Operation at Mars

    NASA Astrophysics Data System (ADS)

    Jun, I.; Mitrofanov, I. G.; litvak, M. L.; Sanin, A.; Behar, A.; Boynton, W. V.; DeFlores, L.; Golovin, D.; Hardgrove, C. J.; Harshman, K.; Kozyrev, A.; Kuzmin, R.; Malakhov, A.; Mischna, M. A.; Moersch, J.; Mokrousov, M.; Nikiforov, S.; Shvetsov, V.; Tate, C.; Vostrukhin, A.; Team, M.

    2013-12-01

    Since first commissioned on sol 3 after landing in August 2012, DAN has been operating successfully and provided a wealth of surface measurement data both in Active mode and in Passive mode operations. Active mode measurements provide a means to determine the characteristics of subsurface in terms of layering structure, content of water equivalent hydrogen (WEH), and/or content of chlorine. Passive mode measurements provide a general background level of low energy (< ~1 keV) neutrons induced by Galactic Cosmic Ray (GCR) interactions with the Martian atmosphere and the surface material and from Multi Mission Radioisotope Thermonuclear Generator (MMRTG). Passive mode measurements have been done on almost every sols with durations ranging from 1 hour to ~9 hour, covering different times of a day. Extensive numerical simulations have been carried out to aid in interpreting the DAN passive data. Both surface operation and numerical simulations show that the passive data correlate very well with the active data. It was also found that the passive data alone could provide a general trend of WEH content variation along the rover traverse. A methodology to estimate the respective contribution from each source (i.e., MMRTG neutrons and GCR-induced neutrons) for the passive data has been developed and was used to understand the neutron background environment at the Rocknest site, where the rover stayed over an extended period of time (from sol 59 to sol 100). The result shows that the MMRTG contribution to the DAN passive counts was about 60% of the total, and the GCR-induced counts were estimated to be about 40%. Details of all these observations, modeling effort, and analysis and interpretation processes will be presented in the final paper by using the passive data collected through sol 360.

  3. First-forbidden β-decay rates, energy rates of β-delayed neutrons and probability of β-delayed neutron emissions for neutron-rich nickel isotopes

    NASA Astrophysics Data System (ADS)

    Nabi, Jameel-Un; Çakmak, Necla; Iftikhar, Zafar

    2016-01-01

    First-forbidden (FF) transitions can play an important role in decreasing the calculated half-lives specially in environments where allowed Gamow-Teller (GT) transitions are unfavored. Of special mention is the case of neutron-rich nuclei where, due to phase-space amplification, FF transitions are much favored. We calculate the allowed GT transitions in various pn-QRPA models for even-even neutron-rich isotopes of nickel. Here we also study the effect of deformation on the calculated GT strengths. The FF transitions for even-even neutron-rich isotopes of nickel are calculated assuming the nuclei to be spherical. Later we take into account deformation of nuclei and calculate GT + unique FF transitions, stellar β-decay rates, energy rate of β-delayed neutrons and probability of β-delayed neutron emissions. The calculated half-lives are in excellent agreement with measured ones and might contribute in speeding-up of the r-matter flow.

  4. β-decay study of neutron-rich ^102Rb at TRIUMF-ISAC

    NASA Astrophysics Data System (ADS)

    Wang, Zhimin

    2012-10-01

    Experimental investigations of the β-decay properties of nuclei which lie along the astrophysical r-process are becoming possible with modern facilities and detection systems. In this experiment, a ^102Rb beam was produced by 500 MeV, 10 μA protons impinging on a multilayer UCx target at TRIUMF-ISAC Facility. The beam of ^102Rb ions was implanted on a movable tape at the center of the 8π spectrometer. The 20 HPGe 8π γ-ray detectors were coupled with SCEPTAR, an hemispherical array of scintillators for β-tagging and DANTE, an array of five LaBr3 detectors for fast γ-ray timing. A preliminary analysis has allowed the first identification of the 4^+ to 2^+ transition in the daughter nucleus, ^102Sr. A near identical low-lying band structure of ^102Sr with ^98, 100Sr nuclei has been observed, indicating the rigidly deformed rotational nature continues towards to the N=66 midshell. The current experimental measurements of ^102Rb β-decay half life as well as the β-delayed neutron emission branching ratio compared with reported values, the shorter β-decay half life and the larger β-delayed neutron emission branching ratio will locally reshape astrophysical r-process predictions.

  5. Status of Neutron Beta Decay Asymmetry Studies from the UCNA Experiment

    NASA Astrophysics Data System (ADS)

    Phillips, David, II

    2013-04-01

    The UCNA experiment measures the neutron β decay asymmetry parameter A(E) using bottled polarized ultracold neutrons (UCN). UCN are produced from a pulsed spallation solid deuterium source coupled to the 800 MeV proton beam at LANSCE. The UCN spin states are selected via a 7 T polarizing field and an adiabatic fast passage spin flipper. The polarized UCN are then transported to a 1 T 2x2π spectrometer where the emitted electrons are measured. In the Standard Model, the leading order value of A(E), A0, is a function of the axial-vector to vector coupling ratio λ≡gA/gV, providing complementary data to the physics probed by measurements of the neutron lifetime τn. When taken together with τn, measurements of the beta decay asymmetry permit a nuclear structure independent determination of the CKM matrix element Vud. This talk presents an overview of the UCNA experiment, the status of the analysis of our 2011 dataset, the work performed in 2012 and the path forward.

  6. β -decay properties of the very neutron-rich isotopes 86Ge and 86As

    NASA Astrophysics Data System (ADS)

    Mazzocchi, C.; Rykaczewski, K. P.; Grzywacz, R.; Bączyk, P.; Bingham, C. R.; Brewer, N. T.; Gross, C. J.; Jost, C.; Karny, M.; Korgul, A.; Madurga, M.; Mendez, A. J.; Miernik, K.; Miller, D.; Padgett, S.; Paulauskas, S. V.; Sonzogni, A. A.; Stracener, D. W.; Wolińska-Cichocka, M.

    2015-11-01

    The β -decay properties of very neutron rich nuclei 86Ge and 86As were measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Spectroscopic information on new excited states in 86As and in 86Se was obtained and is interpreted within an advanced shell model approach. These calculations, previously explaining well the structure of 84Ge and 85Ge , are not able to reproduce all the experimentally determined features of the measured level schemes of 86As and 86Se . The Gamow-Teller decay of 86Ge and 86As is also investigated in a shell-model framework. The fission yield for 86Ge is discussed.

  7. {alpha}-decay properties of the new neutron deficient isotope {sup 212}Pa

    SciTech Connect

    Mitsuoka, S.; Ikezoe, H.; Ikuta, T.; Nagame, Y.; Tsukada, K.; Nishinaka, I.; Oura, Y.; Zhao, Y.L.

    1997-03-01

    The new neutron deficient isotope {sup 212}Pa has been produced in the {sup 182}W({sup 35}Cl,5n) reaction at a beam energy of 182.5 MeV. Evaporation residues have been separated with the JAERI recoil mass separator and identified on the basis of time- and position-correlated {alpha}-decay chains. The {alpha} decay from the ground state of {sup 212}Pa has been observed with an {alpha}-particle energy of 8.270(30) MeV and a half-life of 5.1{sub {minus}1.9}{sup +6.1} ms. {copyright} {ital 1997} {ital The American Physical Society}

  8. β-DECAY Studies around 78Ni: Investigation of Neutron-Rich ni Isotopes

    NASA Astrophysics Data System (ADS)

    Morales, A. I.; Benzoni, G.; Watanabe, H.; Sohler, D.; Sahin, E.; de Angelis, G.; Nishimura, S.; Lorusso, G.; Sumikama, T.; Doornenbal, P.; Xu, Z. Y.; Isobe, T.; Söderström, P. A.; Browne, F.; Wu, J.; Baba, H.; Patel, Z.; Rice, S.; Sinclair, L.; Yokoyama, R.; Daido, R.; Fang, Y.; Niikura, M.; Avigo, R.; Bello Garrote, F. L.; Blasi, N.; Bracco, A.; Ceruti, S.; Crespi, F. C. L.; Delattre, M.-C.; Dombradi, Zs.; Gottardo, A.; Kuti, I.; Matsui, K.; Melon, B.; Mengoni, D.; Miyazaki, T.; Modamio-Hoybjor, V.; Momiyama, S.; Napoli, D. R.; Orlandi, R.; Sakurai, H.; Taniuchi, R.; Taprogge, J.; Vajta, Zs.; Valiente-Dobòn, J. J.; Wieland, O.; Yagi, A.; Yalcinkaya, M.

    2015-06-01

    This The β- decay of 70-74Co and other species in the vicinity of 78Ni has been investigated following the relativistic fission of a 238U primary beam at the Radioactive Ion Beam Factory facility in RIKEN, as part of the EURICA campaign. Extremely neutron-rich nuclei from Mn to Cu were produced and stopped in a state-of-the-art β-decay spectroscopy setup after their in-flight identification. The unprecedented high intensity of the primary beam, I = 10 pnA, ensures the access to a broad number of low-lying excited states in their daughters. In the present contribution, specific details on the setup and the experimental techniques employed are described. As well, the preliminary results are discussed.

  9. Disordered Nuclear Pasta, Magnetic Field Decay, and Crust Cooling in Neutron Stars

    NASA Astrophysics Data System (ADS)

    Horowitz, C. J.; Berry, D. K.; Briggs, C. M.; Caplan, M. E.; Cumming, A.; Schneider, A. S.

    2015-01-01

    Nuclear pasta, with nonspherical shapes, is expected near the base of the crust in neutron stars. Large-scale molecular dynamics simulations of pasta show long lived topological defects that could increase electron scattering and reduce both the thermal and electrical conductivities. We model a possible low-conductivity pasta layer by increasing an impurity parameter Qimp . Predictions of light curves for the low-mass x-ray binary MXB 1659-29, assuming a large Qimp, find continued late time cooling that is consistent with Chandra observations. The electrical and thermal conductivities are likely related. Therefore, observations of late time crust cooling can provide insight on the electrical conductivity and the possible decay of neutron star magnetic fields (assuming these are supported by currents in the crust).

  10. Disordered nuclear pasta, magnetic field decay, and crust cooling in neutron stars

    NASA Astrophysics Data System (ADS)

    Horowitz, C. J.; Berry, D. K.; Briggs, C. M.; Caplan, M. E.; Cumming, A.; Schneider, A. S.

    2015-04-01

    Nuclear pasta, with non-spherical shapes, is expected near the base of the crust in neutron stars. Large scale molecular dynamics simulations of pasta show long lived topological defects that could increase electron scattering and reduce both the thermal and electrical conductivities. We model a possible low conductivity pasta layer by increasing an impurity parameter Qimp. Predictions of light curves for the low mass X-ray binary MXB 1659-29, assuming a large Qimp, find continued late time cooling that is consistent with Chandra observations. The electrical and thermal conductivities are likely related. Therefore observations of late time crust cooling can provide insight on the electrical conductivity and the possible decay of neutron star magnetic fields (assuming these are supported by currents in the crust). This research was supported in part by DOE Grants DE-FG02-87ER40365 (Indiana University) and DE-SC0008808 (NUCLEI SciDAC Collaboration).

  11. Neutron capture by (94,96)Zr and the decays of (97)Zr and (97)Nb.

    PubMed

    Krane, K S

    2014-12-01

    Cross sections for radiative neutron capture have been determined for (94)Zr and (96)Zr using the activation technique with samples of naturally occurring Zr metal. The sensitivity to the correction for epithermal neutrons in the determination of small thermal cross sections is discussed, particularly in view of the variation in the resonance integral at different sites in the reactor. Gamma-ray spectroscopic studies of the decays of (97)Zr and its daughter (97)Nb have been performed, leading to improved values of the energies and intensities of the emitted γ rays, and correspondingly improved values for the energy levels and β feedings of excited states populated in (97)Nb and (97)Mo. PMID:25103250

  12. Neutrino mass, proton decay, and neutron oscillations as crucial tests of unification models (A Review)

    PubMed Central

    Marshak, R. E.

    1982-01-01

    Several crucial tests of three popular unification models (of strong, electromagnetic, and weak interactions) are described. The models are SU(5) and SO(10) at the grand unification theory (GUT) level and SU(4)C × SU(2)L × SU(2)R at the partial unification theory (PUT) level. The tests selected for discussion are the finiteness of the neutrino mass in the electron volt region, the decay of protons into antileptons in the range of 1031± yr, and the detectability of neutron oscillations at all. The PUT group can also be tested by establishing the existence of four generations of quarks and leptons.

  13. Neutron capture cross-section studies of Tellurium isotopes for neutrinoless double beta decay applications

    NASA Astrophysics Data System (ADS)

    Bhike, Megha; Tornow, Werner

    2014-09-01

    The CUORE detector at Gran Sasso, aimed at searching for neutrinoless double-beta decay of 130Te, employs an array of TeO2 bolometer modules. To understand and identify the contribution of muon and (α,n) induced neutrons to the CUORE background, fast neutron cature cross-section data of the tellurium isotopes 126Te, 128Te and 130Te have been measured with the activation method at eight different energies in the neutron energy range 0.5-7.5 MeV. Plastic pill boxes of diameter 1.6 cm and width 1 cm containing Te were irradiated with mono-energetic neutrons produced via the 3H(p,n)3He and 2H(d,n)3He reactions. The cross-sections were determined relative to the 197Au(n, γ)198Au and 115In(n,n')115m In standard cross sections. The activities of the products were measured using 60% lead-shielded HPGe detectors at TUNL's low background counting facility. The present results are compared with the evaluated data from TENDL-2012, ENDF/B-VII.1, JEFF-3.2 and JENDL-4.0, as well as with literature data.

  14. Nuclear-decay studies of neutron-rich rare-earth nuclides

    SciTech Connect

    Chasteler, R.M. . Dept. of Chemistry Lawrence Berkeley Lab., CA )

    1990-04-26

    Neutron-rich rare-earth nuclei were produced in multinucleon transfer reactions of {sup 170}Er and {sup 176}Yb projectiles on {sup nat}W targets at the Lawrence Berkeley Laboratory SuperHILAC and their radioactive decays properties studied at the on-line mass separation facility OASIS. Two unknown isotopes, {sup 169}Dy (t {sub 1/2} {equals} 39 {plus minus} 8 s) and {sup 174}Er(t{sub 1/2} {equals} 3.3 {plus minus} 0.2 m) were discovered and their decay characteristics determined. The decay schemes for two previously identified isotopes, {sup 168}Dy (t{sub 1/2} {equals} 8.8 {plus minus} 0.3 m) and {sup 171}Ho (t{sub 1/2} {equals} 55 {plus minus} 3 s), were characterized. Evidence for a new isomer of 3.0 m {sup 168}Ho{sup g}, {sup 168}Ho{sup m} (t{sub 1/2} {equals} 132 {plus minus} 4 s) which decays by isomeric transition (IT) is presented. Beta particle endpoint energies were determined for the decay of {sup 168}Ho{sup g}, {sup 169}Dy, {sup 171}Ho, and {sup 174}Er, the resulting Q{beta}-values are: 2.93 {plus minus} 0.03, 3.2 {plus minus} 0.3, 3.2 {plus minus} 0.6, and 1.8 {plus minus} 0.2 MeV, respectively. These values were compared with values calculated using recent atomic mass formulae. Comparisons of various target/ion source geometries used in the OASIS mass separator facility for these multinucleon transfer reactions were performed. 73 refs., 40 figs., 11 tabs.

  15. Precision Measurement of the Radiative β Decay of the Free Neutron

    NASA Astrophysics Data System (ADS)

    Bales, M. J.; Alarcon, R.; Bass, C. D.; Beise, E. J.; Breuer, H.; Byrne, J.; Chupp, T. E.; Coakley, K. J.; Cooper, R. L.; Dewey, M. S.; Gardner, S.; Gentile, T. R.; He, D.; Mumm, H. P.; Nico, J. S.; O'Neill, B.; Thompson, A. K.; Wietfeldt, F. E.; RDK Collaboration, II

    2016-06-01

    The standard model predicts that, in addition to a proton, an electron, and an antineutrino, a continuous spectrum of photons is emitted in the β decay of the free neutron. We report on the RDK II experiment which measured the photon spectrum using two different detector arrays. An annular array of bismuth germanium oxide scintillators detected photons from 14 to 782 keV. The spectral shape was consistent with theory, and we determined a branching ratio of 0.00335 ±0.00005 [stat ]±0.00015 [syst ] . A second detector array of large area avalanche photodiodes directly detected photons from 0.4 to 14 keV. For this array, the spectral shape was consistent with theory, and the branching ratio was determined to be 0.00582 ±0.00023 [stat ]±0.00062 [syst ] . We report the first precision test of the shape of the photon energy spectrum from neutron radiative decay and a substantially improved determination of the branching ratio over a broad range of photon energies.

  16. Precision Measurement of the Radiative β Decay of the Free Neutron.

    PubMed

    Bales, M J; Alarcon, R; Bass, C D; Beise, E J; Breuer, H; Byrne, J; Chupp, T E; Coakley, K J; Cooper, R L; Dewey, M S; Gardner, S; Gentile, T R; He, D; Mumm, H P; Nico, J S; O'Neill, B; Thompson, A K; Wietfeldt, F E

    2016-06-17

    The standard model predicts that, in addition to a proton, an electron, and an antineutrino, a continuous spectrum of photons is emitted in the β decay of the free neutron. We report on the RDK II experiment which measured the photon spectrum using two different detector arrays. An annular array of bismuth germanium oxide scintillators detected photons from 14 to 782 keV. The spectral shape was consistent with theory, and we determined a branching ratio of 0.00335±0.00005[stat]±0.00015[syst]. A second detector array of large area avalanche photodiodes directly detected photons from 0.4 to 14 keV. For this array, the spectral shape was consistent with theory, and the branching ratio was determined to be 0.00582±0.00023[stat]±0.00062[syst]. We report the first precision test of the shape of the photon energy spectrum from neutron radiative decay and a substantially improved determination of the branching ratio over a broad range of photon energies. PMID:27367385

  17. Simulation of Charged Particle Trajectories in the Neutron Decay Correlation Experiment abBA

    PubMed Central

    Desai, Dharmin; Greene, Geoffrey; Mahurin, Rob; Bowman, David; Calarco, John

    2005-01-01

    The proposed neutron decay correlation experiment, abBA, will directly detect the direction of emission of decay protons and electrons as well as providing spectroscopic information for both particles. In order to provide this information, the abBA experiment incorporates spatially varying electric and magnetic fields. We report on detailed simulations of the decay particle trajectories in order to assess the impact of various systematic effects on the experimental observables. These include among others; adiabaticity of particle orbits, tracking of orbits, reversal of low energy protons due to inhomogeneous electric field, and accuracy of proton time of flight measurements. Several simulation methods were used including commercial software (Simion), custom software, as well as analytical tools based on the use of adiabatic invariants. Our results indicate that the proposed field geometry of the abBA spectrometer will be substantially immune to most systematic effects and that transport calculations using adiabatic invariants agree well with solution of the full equations of motion. PMID:27308165

  18. Naked-eye optical flash from gamma-ray burst 080319B: Tracing the decaying neutrons in the outflow

    SciTech Connect

    Fan Yizhong; Zhang Bing; Wei Daming

    2009-01-15

    For an unsteady baryonic gamma-ray burst (GRB) outflow, the fast and slow proton shells collide with each other and produce energetic soft gamma-ray emission. If the outflow has a significant neutron component, the ultrarelativistic neutrons initially expand freely until decaying at a larger radius. The late-time proton shells ejected from the GRB central engine, after powering the regular internal shocks, will sweep these {beta}-decay products and give rise to very bright UV/optical emission. The naked-eye optical flash from GRB 080319B, an energetic explosion in the distant Universe, can be well explained in this way.

  19. A measurement of correlation parameters in the decay of polarized free neutrons: The abBA experiment

    NASA Astrophysics Data System (ADS)

    Barrón-Palos, L.; Chávez, E.; Crawford, C.; Curiel-García, Q.; Huerta, A.; Juárez-Rosete, M. A.; Marín-Lámbarri, D. J.; Martin, E.; Ortiz, M. E.; Penttilä, S. I.; Rodríguez-Zamora, P.; Salas, A.; Tang, Z.; Wilburn, W. S.

    2010-07-01

    The abBA experiment will measure, in the same apparatus, four correlation parameters in the free neutron β-decay: the electron-antineutrino angular correlation (a), the Fierz interference term (6), and the asymmetries, with respect to the neutron spin direction, of the electron (A)and antineutrino (B).The precise determination of these parameters, together with the neutron lifetime, will provide important information about the Standard Model (SM) and will establish constraints for new physics. In this paper we describe the experimental methodology of abBA as well as some of the advances that have been done so far.

  20. Possible ground-level measurements of solar neutron decay protons during the 19 October 1989 solar cosmic ray event

    SciTech Connect

    Flueckiger, E.O. ); Shea, M.A.; Smart, D.F.; Wilson, M.D.

    1991-05-01

    The high energy solar proton event of 19 October 1989 had an atypical particle anisotropy during the initial phase with the Deep River, Ottawa and Goose Bay neutron monitors in the Eastern Canadian region recording the intensity increase about 25 minutes before comparable detectors in Europe and Western Canada. Using the asymptotic cones of acceptance for these neutron monitors, the authors show that this early onset in the particle intensity increase may be the detection of relativistic protons that are the decay product of solar flare generated relativistic neutrons.

  1. The first cosmic ray albedo proton map of the Moon

    NASA Astrophysics Data System (ADS)

    Wilson, Jody K.; Spence, Harlan E.; Kasper, Justin; Golightly, Michael; Bern Blake, J.; Mazur, Joe E.; Townsend, Lawrence W.; Case, Anthony W.; Dixon Looper, Mark; Zeitlin, Cary; Schwadron, Nathan A.

    2012-06-01

    Neutrons emitted from the Moon are produced by the impact of galactic cosmic rays (GCRs) within the regolith. GCRs are high-energy particles capable of smashing atomic nuclei in the lunar regolith and producing a shower of energetic protons, neutrons and other subatomic particles. Secondary particles that are ejected out of the regolith become “albedo” particles. The neutron albedo has been used to study the hydrogen content of the lunar regolith, which motivates our study of albedo protons. In principle, the albedo protons should vary as a function of the input GCR source and possibly as a result of surface composition and properties. During the LRO mission, the total detection rate of albedo protons between 60 MeV and 150 MeV has been declining since 2009 in parallel with the decline in the galactic cosmic ray flux, which validates the concept of an albedo proton source. On the other hand, the average yield of albedo protons has been increasing as the galactic cosmic ray spectrum has been hardening, consistent with a disproportionately stronger modulation of lower energy GCRs as solar activity increases. We construct the first map of the normalized albedo proton emission rate from the lunar surface to look for any albedo variation that correlates with surface features. The map is consistent with a spatially uniform albedo proton yield to within statistical uncertainties.

  2. Recent activities for β-decay half-lives and β-delayed neutron emission of very neutron-rich isotopes

    SciTech Connect

    Dillmann, Iris; Abriola, Daniel; Singh, Balraj

    2014-05-02

    Beta-delayed neutron (βn) emitters play an important, two-fold role in the stellar nucleosynthesis of heavy elements in the 'rapid neutron-capture process' (r process). On one hand they lead to a detour of the material β-decaying back to stability. On the other hand, the released neutrons increase the neutron-to-seed ratio, and are re-captured during the freeze-out phase and thus influence the final solar r-abundance curve. A large fraction of the isotopes inside the r-process reaction path are not yet experimentally accessible and are located in the (experimental) 'Terra Incognita'. With the next generation of fragmentation and ISOL facilities presently being built or already in operation, one of the main motivation of all projects is the investigation of these very neutron-rich isotopes. A short overview of one of the planned programs to measure βn-emitters at the limits of the presently know isotopes, the BRIKEN campaign (Beta delayed neutron emission measurements at RIKEN) will be given. Presently, about 600 β-delayed one-neutron emitters are accessible, but only for a third of them experimental data are available. Reaching more neutron-rich isotopes means also that multiple neutron-emission becomes the dominant decay mechanism. About 460 β-delayed two-, three-or four-neutron emitters are identified up to now but for only 30 of them experimental data about the neutron branching ratios are available, most of them in the light mass region below A=30. The International Atomic and Energy Agency (IAEA) has identified the urgency and picked up this topic recently in a 'Coordinated Research Project' on a 'Reference Database for Beta-Delayed Neutron Emission Data'. This project will review, compile, and evaluate the existing data for neutron-branching ratios and half-lives of β-delayed neutron emitters and help to ensure a reliable database for the future discoveries of new isotopes and help to constrain astrophysical and theoretical models.

  3. Neutron β -decay as the origin of IceCube's PeV (anti)neutrinos

    NASA Astrophysics Data System (ADS)

    Anchordoqui, Luis A.

    2015-01-01

    Motivated by the indications of a possible deficit of muon tracks in the first three-year equivalent data set of IceCube we investigate the possibility that the astrophysical (anti)neutrino flux (in the PeV energy range) could originate from β -decay of relativistic neutrons. We show that to accommodate IceCube observations it is necessary that only about 1% to 10% of the emitted cosmic rays in the energy decade 108.5≲ECR/GeV ≲109.5 , yielding antineutrinos on Earth (1 05.5≲Eν ¯/GeV ≲1 06.5 ), are observed. Such a strong suppression can be explained assuming magnetic shielding of the secondary protons which diffuse in extragalactic magnetic fields of strength 10 ≲B /nG ≲100 and coherence length ≲Mpc .

  4. {beta}-decay half-lives of new neutron-rich lanthanide isotopes

    SciTech Connect

    Ichikawa, S.; Tsukada, K.; Asai, M.; Nishinaka, I.; Nagame, Y.; Osa, A.; Sakama, M.; Oura, Y.; Kojima, Y.; Shibata, M.; Kawade, K.

    1998-12-21

    New neutron-rich lanthanide isotopes produced in the proton-induced fission of {sup 238}U have been identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The observed K x-rays following the {beta}{sup -}decay of products in the mass separated fraction provided direct isotopic identifications. New isotopes observed, with values of their half-lives given in parentheses, are {sup 159}Pm(2{+-}1 s), {sup 161}Sm(4.8{+-}0.8 s), {sup 165}Gd(10.3{+-}1.6 s), {sup 166}Tb(21{+-}6 s), {sup 167}Tb(19.4{+-}2.7 s) and {sup 168}Tb(8.2{+-}1.3 s). The half-life values are compared to the results of theoretical predictions.

  5. Beta decay of neutron-rich Co: Probing single-particle states at and above the N=40 subshell closure

    SciTech Connect

    Mueller, W. F.; Bruyneel, B.; Franchoo, S.; Huyse, M.; Kruglov, K.; Kudryavtsev, Y.; Raabe, R.; Reusen, I.; Duppen, P. van; Roosbroeck, J. van; Vermeeren, L.; Weissman, L.; Woehr, A.; Koester, U.; Kratz, K.-L.; Pfeiffer, B.; Thirolf, P.; Walters, W. B.

    1999-09-02

    Neutron-rich Co nuclei with A=66-70 were produced by the laser-ionization isotope-separation on-line method. The {beta} decay from these nuclei has been studied. A case example is given by reporting on the observed decay scheme of {sup 68}Co. The half life of the ground-state decay of this nucleus was measured to be 0.21(3) seconds. In addition, a new {beta} decaying isomer half life of 1.16(25) seconds was discovered. The level scheme of {sup 68}Ni has been significantly extended, and an interpretation of the observed levels is made by assuming that the N=40 gap has the characteristics of a shell closure.

  6. Albedo in the ATIC Experiment

    NASA Technical Reports Server (NTRS)

    Sokolskaya, N. V.; Adams, J. H., Jr.; Ahn, H. S.; Bashindzhagyan, G. L.; Batkov, K. E.; Case, G.; Christl, M.; Chang, J.; Fazely, A. R.; Ganel, O.; Six, N. Frank (Technical Monitor)

    2002-01-01

    ATIC(Advanced Thin Ionization Calorimeter) is a balloon borne experiment designed to measure the cosmic ray composition for elements from hydrogen to iron and their energy spectra from approx.50 GeV to near 100 TeV. It consists of a Si-matrix detector to determine the charge of a CR particle, a scintillator hodoscope for tracking, carbon interaction targets and a fully active BGO calorimeter. ATIC had its first 16-day flight from McMurdo, Antarctica from 28/12/2000 to 13/01/2000. The ATIC flight collected approximately 25 million events. To measure charge of primary particle in presence of radiation scattered back from the interaction and subsequent shower development in the calorimeter a charge detector must be a mosaic of small detector pads so that the pad containing the signal from the incident particle has no additional signal from albedo particles. Therefore the silicon matrix was built of 4480 individual silicon pads each 2 cm x 1.5 cm. The matrix consists of four planes of detectors and the active detector area, in these planes are partially overlapped to completely cover the aperture. The lateral and amplitude distributions of albedo signals in Si-matrix are analyzed for different primary nuclei and different energy deposits in BGO calorimeter. The greater part of albedo signals has Q near 1, where Q = square root of Amplitude(MIP). The albedo distribution exponentially decreases up to Q near 8. These high values are produced by slow protons and plans. There are also a small number of signals of Q > 8, mainly for heavy nucleus primaries. These signals are apparently generated by neutrons. The comparison of the experimental data and simulations with GEANT 3-21 code using QGSM generator for nucleus-nucleus interactions is presented.

  7. Earth's Reflection: Albedo

    ERIC Educational Resources Information Center

    Gillette, Brandon; Hamilton, Cheri

    2011-01-01

    When viewing objects of different colors, you might notice that some appear brighter than others. This is because light is reflected differently from various surfaces, depending on their physical properties. The word "albedo" is used to describe how reflective a surface is. The Earth-atmosphere has a combined albedo of about 30%, a number that is…

  8. Calculation of Beta Decay Half-Lives and Delayed Neutron Branching Ratio of Fission Fragments with Skyrme-QRPA

    NASA Astrophysics Data System (ADS)

    Minato, Futoshi

    2016-06-01

    Nuclear β-decay and delayed neutron (DN) emission is important for the r-process nucleosynthesis after the freeze-out, and stable and safe operation of nuclear reactors. Even though radioactive beam facilities have enabled us to measure β-decay and branching ratio of neutron-rich nuclei apart from the stability line in the nuclear chart, there are still a lot of nuclei which one cannot investigate experimentally. In particular, information on DN is rather scarce than that of T1/2. To predict T1/2 and the branching ratios of DN for next JENDL decay data, we have developed a method which comprises the quasiparticle-random-phase-approximation (QRPA) and the Hauser-Feshbach statistical model (HFSM). In this work, we calculate fission fragments with T1/2 ≤ 50 sec. We obtain the rms deviation from experimental half-life of 3:71. Although the result is still worse than GT2 which has been adopted in JENDL decay data, DN spectra are newly calculated. We also discuss further subjects to be done in future for improving the present approach and making next generation of JENDL decay data.

  9. On the Measurement of the Electron-Neutrino Correlation in Neutron Beta Decay

    PubMed Central

    Bowman, J. David

    2005-01-01

    I present a new approach to the measurement of a, the electron-neutrino correlation, in neutron beta decay. A precise measurement of a can lead to a precise determination of ratio of the axial vector and vector coupling constants, Ga/Gv. Coincidences between electrons and protons are detected in a field-expansion spectrometer. The field-expansion spectrometer is designed to make 1/TOF ≈ | pp|. TOF and pp are the proton time of flight and momentum. Two segmented Si detectors view both electrons and protons in 4π geometry. The time of flight between the electron and proton are accurately measured in a long, ≈ 1 m, drift distance. The electron energy is accurately measured in the Si detectors. The proton momentum and electron energy determine the electron-neutrino opening angle. I have shown that by sorting the data on proton time of flight and electron energy, a can be determined with a statistical relative standard uncertainty of ≈2.4/n, where n is the number of decays observed. The approach has a number of advantages. The acceptance of the spectrometer is 4π for both particles. Thin-dead-layer segmented Si detectors as well as all other components in the apparatus, are commercially available. There are no material apertures to determine the acceptance of the apparatus. The charged particles interact only with electric and magnetic fields before striking the detectors. Coincident detection of electrons and protons reduces backgrounds, and allows the in situ determination of backgrounds. In the analysis, it is not necessary to sort on the relative electron and proton direction and hence electron back scattering does not cause systematic uncertainties. A time of flight spectrum is obtained for each electron energy. Different parts of the spectra have different sensitivities to a. The medium time of flight parts of the spectra that are insensitive to a can be used to verify the accuracy of the electric and magnetic field determinations. PMID:27308158

  10. Albedos. Final report

    SciTech Connect

    Hansen, F.V.

    1993-07-01

    The albedo of the earth's surface varies dramatically from values of about 3 to 4 percent for calm bodies of water up to about 55 percent for gypsum sands. This rather broad range of reflected incoming solar radiation presents difficulties when attempting to define an average albedo for terrain over a large region from locally determined values. The patchwork, or checkerboard, appearance of the earth's surface as viewed from above is the result of various human activities, such as agriculture, the proliferation of urban sprawl, and road building. Each of these variable appearing surfaces will have individual albedos, rendering any attempt to determine an a real albedo almost an impossibility on the mesoscale. However, a vast data base exists for microscale applications for individual acreages, for example. A compilation of these data is presented.... Albedo, Solar radiation, Crops, Urban areas, Land uses.

  11. Decay of the neutron-rich isotope sup 171 Ho and the identification of sup 169 Dy

    SciTech Connect

    Chasteler, R.M.; Nitschke, J.M.; Firestone, R.B.; Vierinen, K.S.; Wilmarth, P.A. )

    1990-10-01

    Neutron-rich rare-earth isotopes were produced in multinucleon transfer reactions between {sup 170}Er ions and {sup nat}W targets. On-line mass separation was used together with {beta}- and {gamma}-ray spectroscopy in these studies. At mass {ital A}=169, the heaviest known dysprosium isotope, 39(8) s,{sup 169}Dy, was identified. It was observed to {beta}{sup {minus}} decay to the ground state of {sup 169}Ho or through a level at 1578 keV. In the {ital A}=171 mass chain, a partial decay scheme for 55(3)-s {sup 171}Ho was determined.

  12. β-Decay of Neutron-Rich Nuclei around 158Nd and the Origin of Rare-Earth Elements

    NASA Astrophysics Data System (ADS)

    Wu, J.; Nishimura, S.; Lorusso, G.; Xu, Z. Y.; Ideguchi, E.; Simpson, G. S.; Baba, H.; Browne, F.; Daido, R.; Doornenbal, P.; Fang, Y. F.; Isobe, T.; Li, Z.; Patel, Z.; Rice, S.; Sinclair, L.; Söderström, P.-A.; Sumikama, T.; Watanabe, H.; Yagi, A.; Yokoyama, R.; Aoi, N.; Bello Garrote, F. L.; Benzoni, G.; Gey, G.; Gottardo, A.; Nishibata, H.; Odahara, A.; Sakurai, H.; Tanaka, M.; Taprogge, J.; Yamamoto, T.

    A large fraction of the rare-earth elements around mass number A = 160 observed in the solar system are produced in the astrophysical rapid (r-) neutron capture process. However, current stellar models cannot completely explain the relative abundance of these elements partially because of nuclear physics uncertainties. To address this problem, a β-decay spectroscopy experiment was performed at the RI Beam Factory (RIBF), aimed at studying a wide region of very neutron-rich nuclei around 158Nd. The data from this experiment provides a test of nuclear models as well as experimental inputs for r-process calculations.

  13. Quality assurance of temporal variability of natural decay chain and neutron induced background for low-level NORM analysis

    SciTech Connect

    Yoho, Michael; Porterfield, Donivan R.; Landsberger, Sheldon

    2015-09-22

    In this study, twenty-one high purity germanium (HPGe) background spectra were collected over 2 years at Los Alamos National Laboratory. A quality assurance methodology was developed to monitor spectral background levels from thermal and fast neutron flux levels and naturally occurring radioactive material decay series radionuclides. 238U decay products above 222Rn demonstrated minimal temporal variability beyond that expected from counting statistics. 238U and 232Th progeny below Rn gas displayed at most twice the expected variability. Further, an analysis of the 139 keV 74Ge(n, γ) and 691 keV 72Ge(n, n') spectral features demonstrated temporal stability for both thermal and fast neutron fluxes.

  14. Experimental study of β and β -n decay of the neutron-rich N =54 isotone 87As

    NASA Astrophysics Data System (ADS)

    Korgul, A.; Rykaczewski, K. P.; Grzywacz, R.; Bingham, C. R.; Brewer, N. T.; Ciemny, A. A.; Gross, C. J.; Jost, C.; Karny, M.; Madurga, M.; Mazzocchi, C.; Mendez, A. J.; Miernik, K.; Miller, D.; Padgett, S.; Paulauskas, S. V.; Stracener, D. W.; Wolińska-Cichocka, M.

    2015-11-01

    The β -decay properties of neutron-rich 87As produced in the proton-induced fission of 238U were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The low-energy excited states in N =53 87Se and N =52 86Se were identified through β -γ and β -delayed neutrondecay of 87As, respectively. The experimental systematics of low-energy levels of N =53 isotones, Z =34 Se87, and Z =32 85Ge, and along with an analysis of shell-model calculations, allow us to discuss the main features of excited states expected for the next N =53 isotone, 83Zn.

  15. E2 transition probabilities for decays of isomers observed in neutron-rich odd Sn isotopes

    DOE PAGESBeta

    Iskra, Ł. W.; Broda, R.; Janssens, R. V.F.; Wrzesiński, J.; Chiara, C. J.; Carpenter, M. P.; Fornal, B.; Hoteling, N.; Kondev, F. G.; Królas, W.; et al

    2015-01-01

    High-spin states were investigated with gamma coincidence techniques in neutron-rich Sn isotopes produced in fission processes following ⁴⁸Ca + ²⁰⁸Pb, ⁴⁸Ca + ²³⁸U, and ⁶⁴Ni + ²³⁸U reactions. By exploiting delayed and cross-coincidence techniques, level schemes have been delineated in odd ¹¹⁹⁻¹²⁵Sn isotopes. Particular attention was paid to the occurrence of 19/2⁺ and 23/2⁺ isomeric states for which the available information has now been significantly extended. Reduced transition probabilities, B(E2), extracted from the measured half-lives and the established details of the isomeric decays exhibit a striking regularity. This behavior was compared with the previously observed regularity of the B(E2) amplitudesmore » for the seniority ν = 2 and 3, 10⁺ and 27/2⁻ isomers in even- and odd-Sn isotopes, respectively.« less

  16. The magnetic shielding for the neutron decay spectrometer aSPECT

    NASA Astrophysics Data System (ADS)

    Konrad, Gertrud; Ayala Guardia, Fidel; Baeßler, Stefan; Borg, Michael; Glück, Ferenc; Heil, Werner; Hiebel, Stefan; Muñoz Horta, Raquel; Sobolev, Yury

    2014-12-01

    Many experiments in nuclear and neutron physics are confronted with the problem that they use a superconducting magnetic spectrometer which potentially affects other experiments by their stray magnetic field. The retardation spectrometer aSPECT consists, inter alia, of a superconducting magnet system that produces a strong longitudinal magnetic field of up to 6.2 T. In order not to disturb other experiments in the vicinity of aSPECT, we had to develop a magnetic field return yoke for the magnet system. While the return yoke must reduce the stray magnetic field, the internal magnetic field and its homogeneity should not be affected. As in many cases, the magnetic shielding for aSPECT must manage with limited space. In addition, we must ensure that the additional magnetic forces on the magnet coils are not destructive. In order to determine the most suitable geometry for the magnetic shielding for aSPECT, we simulated a variety of possible geometries and combinations of shielding materials of non-linear permeability. The results of our simulations were checked through magnetic field measurements both with Hall and nuclear magnetic resonance probes. The experimental data are in good agreement with the simulated values: the mean deviation from the simulated exterior magnetic field is (-1.7±4.8)%. However, in the two critical regions, the internal magnetic field deviates by 0.2% (decay volume) and < 1 ×10-4 (analyzing plane) from the simulated values.

  17. Overall picture of the cascade gamma decay of neutron resonances within a modified practical model

    NASA Astrophysics Data System (ADS)

    Sukhovoj, A. M.; Mitsyna, L. V.; Jovancevic, N.

    2016-05-01

    The intensities of two-step cascades in 43 nuclei of mass number in the range of 28 ≤ A ≤ 200 were approximated to a high degree of precision within a modified version of the practical cascade-gammadecay model introduced earlier. In this version, the rate of the decrease in the model-dependent density of vibrational levels has the same value for any Cooper pair undergoing breakdown. The most probable values of radiative strength functions both for E1 and for M1 transitions are determined by using one or two peaks against a smooth model dependence on the gamma-transition energy. The statement that the thresholds for the breaking of Cooper pairs are higher for spherical than for deformed nuclei is a basic result of the respective analysis. The parameters of the cascade-decay process are now determined to a precision that makes it possible to observe the systematic distinctions between them for nuclei characterized by different parities of neutrons and protons.

  18. E2 transition probabilities for decays of isomers observed in neutron-rich odd Sn isotopes

    SciTech Connect

    Iskra, Ł. W.; Broda, R.; Janssens, R. V.F.; Wrzesiński, J.; Chiara, C. J.; Carpenter, M. P.; Fornal, B.; Hoteling, N.; Kondev, F. G.; Królas, W.; Lauritsen, T.; Pawłat, T.; Seweryniak, D.; Stefanescu, I.; Walters, W. B.; Zhu, S.

    2015-01-01

    High-spin states were investigated with gamma coincidence techniques in neutron-rich Sn isotopes produced in fission processes following ⁴⁸Ca + ²⁰⁸Pb, ⁴⁸Ca + ²³⁸U, and ⁶⁴Ni + ²³⁸U reactions. By exploiting delayed and cross-coincidence techniques, level schemes have been delineated in odd ¹¹⁹⁻¹²⁵Sn isotopes. Particular attention was paid to the occurrence of 19/2⁺ and 23/2⁺ isomeric states for which the available information has now been significantly extended. Reduced transition probabilities, B(E2), extracted from the measured half-lives and the established details of the isomeric decays exhibit a striking regularity. This behavior was compared with the previously observed regularity of the B(E2) amplitudes for the seniority ν = 2 and 3, 10⁺ and 27/2⁻ isomers in even- and odd-Sn isotopes, respectively.

  19. Observations of Surfzone Albedo

    NASA Astrophysics Data System (ADS)

    Sinnett, G.; Feddersen, F.

    2014-12-01

    The surfzone environment (where waves break) contains several unique and previously unconsidered processes that affect the heat budget. Entering short-wave radiation is a dominant term in both shelf and surfzone heat budgets. In contrast to the shelf, however, depth limited wave breaking in the surfzone generates spray, whitewater and suspended sediments, elevating the surface albedo (ratio of reflected to incident short-wave radiation). Elevated albedo reduces the level of solar short-wave radiation entering the water, potentially resulting in less heating. Additionally, surfzone water quality is often impacted by fecal bacteria contamination. As bacteria mortality is related to short-wave solar radiation, elevated surfzone albedo could reduce pathogen mortality, impacting human health. Albedo in the open ocean has been frequently studied and parameterizations often consider solar zenith angle, wind speed and ocean chlorophyll concentration, producing albedo values typically near 0.06. However, surfzone albedo observations have been extremely sparse, yet show depth limited wave breaking may increase the albedo by nearly a factor of 10 up to 0.5. Here, we present findings from a field study at the Scripps Institution of Oceanography pier to observe the affect of waves on surfzone albedo. Concurrent measurements were taken with a four-way radiometer (to measure both downwelling and upwelling short-wave and long wave radiation) mounted above the surfzone. A co-located GoPro camera was used to relate visual aspects of the surfzone to measured reflectance, and wave height and period were observed with a bottom mounted pressure sensor in 5 m water depth just outside the surfzone. Wind speed and direction were observed on the pier 10 m above the water surface. Here, we will examine the surfzone albedo dependence on surfzone parameters, such as wave height.

  20. Fast-neutron-induced potential background near the Q value of neutrinoless double-β decay of 76Ge

    NASA Astrophysics Data System (ADS)

    Tornow, W.; Bhike, Megha; Fallin, B.; Krishichayan

    2016-01-01

    The 76Ge (n,p)76Ga reaction and the subsequent β decay of 76Ga to 76Ge has been used to excite the 3951.89-keV state of 76Ge , which decays by the emission of a 2040.70-keV γ ray. Using high-purity germanium detectors, the associated pulse-height signal may be undistinguishable from the potential signal produced in neutrinoless double-β decay of 76Ge with its Q value of 2039.0 keV. At 20-MeV neutron energy the production cross section of the 2040.70-keV γ ray is approximately 0.1 mb.

  1. Detecting Low-Contrast Features in the Cosmic Ray Albedo Proton Map of the Moon

    NASA Technical Reports Server (NTRS)

    Wilson, J. K.; Schwadron, N.; Spence, H. E.; Golightly, M. J.; Case, A. W.; Smith, S.; Blake, J. B.; Kasper, J.; Looper, M. D.; Mazur, J. E.; Townsend, L. W.; Zeitlin, C.; Stubbs, T. J.

    2014-01-01

    High energy cosmic rays constantly bombard the lunar regolith, producing (via nuclear evaporation) secondary 'albedo' or 'splash' particles like protons and neutrons, some of which escape back to space. Lunar Prospector and the Lunar Reconnaissance Orbiter (LRO), have shown that the energy distribution of albedo neutrons is modulated by the elemental composition of the lunar regolith, and by ice deposits in permanently shadowed polar craters. Here we investigate an analogous phenomenon with high energy ((is) approximately 100 MeV) lunar albedo protons.

  2. -decay measurements for N > 40 Mn nuclei and inference of collectivity for neutron-rich Fe isotopes

    SciTech Connect

    Daugas, J; Delaroche, J. P.; Pfutzner, M.; Sawicka, M.; Becker, F.; Belier, G.; Bingham, C. R.; Borcea, C.; Bouchez, E.; Buta, A.; Dragulescu, E.; Georgiev, G.; Giovinazzo, J.; Grawe, H.; Grzywacz, R.; Hammache, F.; Libert, J.; Meot, V.; Negoita, F.; de Oliveira Santos, F.; Perru, O.; Roig, O.; Rykaczewski, Krzysztof Piotr; Saint-Laurent, M. G.; Sauvestre, J. E.; Sorlin, O.; Stanoiu, M.; Stefan, I.; Theisen, Ch.

    2011-01-01

    A decay spectroscopic study of the neutron-rich isotopes has been performed using fragmentation of a 86Kr primary beam. Fragments from this reaction have been selected by the LISE2000 spectrometer at the Grand Acc el erateur National d Ions Lourds (GANIL). Half-lives of 29 isotopes, including the first ones identified for 61Ti (15 4 ms), 64V (19 8 ms), and 71Fe (28 5 ms), have been determined and compared with model predictions. 67,68Mn -delayed rays were observed for the first time. The branching for the -delayed neutron emission was measured to be greater than 10(5)% in the 67Mn decay. The 67Fe isomeric level is firmly determined at higher energy than assigned in previous works. The excitation energies of the first (2+) and (4+) states of 68Fe are suggested to lie at 522(1) and 1389(1) keV, respectively, thus bringing confirmation of assignments based on in-beam -ray spectroscopy. Beyond-mean-field calculations with the Gogny D1S force have been performed for even-mass nuclei through the Fe isotopic chain. Not only 68Fe but most of the neutron-rich Fe isotopes with neutron numbers below N = 50 are interpreted as soft rotors. The calculated mean occupancy of the neutron g9/2 and d5/2 orbitals in correlated ground states is steadily growing with increasing neutron number throughout the isotopic chain. Interpretation of 67Fe data is based upon the present calculations for the 66Fe and 68Fe even cores.

  3. Greenland Glacier Albedo Variability

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The program for Arctic Regional Climate Assessment (PARCA) is a NASA-funded project with the prime goal of addressing the mass balance of the Greenland ice sheet. Since the formal initiation of the program in 1995, there has been a significant improvement in the estimates of the mass balance of the ice sheet. Results from this program reveal that the high-elevation regions of the ice sheet are approximately in balance, but the margins are thinning. Laser surveys reveal significant thinning along 70 percent of the ice sheet periphery below 2000 m elevations, and in at least one outlet glacier, Kangerdlugssuaq in southeast Greenland, thinning has been as much as 10 m/yr. This study examines the albedo variability in four outlet glaciers to help separate out the relative contributions of surface melting versus ice dynamics to the recent mass balance changes. Analysis of AVHRR Polar Pathfinder albedo shows that at the Petermann and Jakobshavn glaciers, there has been a negative trend in albedo at the glacier terminus from 1981 to 2000, whereas the Stor+strommen and Kangerdlugssuaq glaciers show slightly positive trends in albedo. These findings are consistent with recent observations of melt extent from passive microwave data which show more melt on the western side of Greenland and slightly less on the eastern side. Significance of albedo trends will depend on where and when the albedo changes occur. Since the majority of surface melt occurs in the shallow sloping western margin of the ice sheet where the shortwave radiation dominates the energy balance in summer (e.g. Jakobshavn region) this region will be more sensitive to changes in albedo than in regions where this is not the case. Near the Jakobshavn glacier, even larger changes in albedo have been observed, with decreases as much as 20 percent per decade.

  4. Decays of 110Rh and 112Rh to the near neutron midshell isotopes 110Pd and 112Pd

    NASA Astrophysics Data System (ADS)

    Lhersonneau, G.; Wang, J. C.; Hankonen, S.; Dendooven, P.; Jones, P.; Julin, R.; Äystö, J.

    1999-07-01

    The decays 110Rh and 112Rh have been investigated using on-line mass separation with the ion-guide technique. Extended decay schemes have been constructed for both the low- and high-spin states in 112Rh. Mixing ratios for the collective transitions from the 2+2 and 3+1 states in 112Pd have been measured by γ-γ angular correlation. The presence of two sets of 0+ and 2+ states in the 1.1-1.4 MeV range suggests the existence of an intruder band, the energy of which is the lowest in 110Pd with two neutrons fewer than the midshell. The quasiparticle levels at 2195 and 2755 keV are assigned I=4 and I=5, respectively. The corresponding levels in 110Pd are a new level at 2261 keV and the 2805 keV level. Systematics of logft values and excitation energies of these quasiparticle levels is remarkably smooth. The strong β feeding to the I=5 quasiparticle state can be regarded as similar to the main branch in the decay of odd Rh isotopes, while a neutron is a spectator.

  5. Decays of New Nuclides and Isomers Beyond the Proton Drip Line--The Influence of Neutron Configurations

    SciTech Connect

    Page, R. D.; Bianco, L.; Darby, I. G.; Joss, D. T.; Cooper, R. J.; Grahn, T.; Judson, D. S.; Sapple, P. J.; Thomson, J.; Simpson, J.; Labiche, M.; O'Donnell, D.; Al-Khalili, J. S.; Cannon, A. J.; Stevenson, P. D.; Suckling, E. B.; Eeckhaudt, S.; Greenlees, P. T.; Jones, P. M.; Julin, R.

    2008-11-11

    The energy of the vh{sub 9/2} orbital in nuclei above N = 82 drops rapidly in energy relative to the vf{sub 7/2} orbital as the occupancy of the {pi}h{sub 11/2} orbital increases. These two neutron orbitals become nearly degenerate as the proton drip line is approached. In this work, we have discovered the new nuclides {sup 161}Os and {sup 157}W, and studied the decays of the proton emitter {sup 160}Re in detail. The {sup 161}Os and {sup 160}Re nuclei were produced in reactions of 290, 300 and 310 MeV {sup 58}Ni ions with an isotopically enriched {sup 106}Cd target, separated in-flight using the RITU separator and implanted into the GREAT spectrometer. The {sup 161}Os{alpha} a decays populated the new nuclide {sup 157}W, which decayed by {beta}-particle emission. The {beta} decay fed the known {alpha}-decaying 1/2{sup +} and 11/2{sup -} states in {sup 157}Ta, which is consistent with a vf{sub 7/2} ground state in {sup 157}W. The measured {alpha}-decay energy and half-life for {sup 161}Os correspond to a reduced {alpha}-decay width that is compatible with s-wave {alpha}-particle emission, implying that its ground state is also a vf{sub 7/2} state. Over 7000 {sup 160}Re nuclei were produced and the {gamma} decays of a new isomeric state feeding the {pi}d{sub 3/2} level in {sup 160}Re were discovered, but no evidence for the proton or a decay of the expected {pi}h{sub 11/2} state could be found. The isomer decays offer a natural explanation for this non-observation and provides a striking example of the influence of the near degeneracy of the vh{sub 9/2} and vf{sub 7/2} orbitals on the properties of nuclei in this region.

  6. Program for Computing Albedo

    NASA Technical Reports Server (NTRS)

    Justus, Carl G.

    2003-01-01

    Simple Thermal Environment Model (STEM) is a FORTRAN-based computer program that provides engineering estimates of top-of-atmosphere albedo and outgoing long-wave radiation (OLR) for use in analyzing thermal loads on spacecraft near Earth. The thermal environment of a spacecraft is represented in STEM as consisting of direct solar radiation; short-wave radiation reflected by the atmosphere of the Earth, as characterized in terms of the albedo of the Earth; and OLR emitted by the atmosphere of the Earth. STEM can also address effects of heat loads internal to a spacecraft. Novel features of STEM include (1) the use of Earth albedo and OLR information based on time series of measurements by Earth Radiation Budget Experiment satellites in orbit; (2) the ability to address thermal time constants of spacecraft systems by use of albedo and OLR values representing averages over a range of averaging times; and (3) the ability to address effects, on albedo and OLR values, of satellite orbital inclination, the angle between the plane of a spacecraft orbit and the line between the centers of the Earth and Sun, the solar zenith angle, and latitude.

  7. Calculations of neutron flux spectra induced in the earth's atmosphere by galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Chandler, K. C.; Barish, J.

    1972-01-01

    Calculations have been carried out to determine the neutron flux induced in the earth's atmosphere by galactic protons and alpha particles at solar minimum for a geomagnetic latitude of 42 N. Neutron flux spectra were calculated using Monte Carlo and discrete ordinates methods, and various comparisons with experimental data are presented. The magnitude and shape of the calculated neutron-leakage spectrum at the particular latitude considered support the theory that the cosmic-ray-albedo-neutron-decay mechanism is the source of the protons and electrons trapped in the Van Allen belts.

  8. Quality assurance of temporal variability of natural decay chain and neutron induced background for low-level NORM analysis

    DOE PAGESBeta

    Yoho, Michael; Porterfield, Donivan R.; Landsberger, Sheldon

    2015-09-22

    In this study, twenty-one high purity germanium (HPGe) background spectra were collected over 2 years at Los Alamos National Laboratory. A quality assurance methodology was developed to monitor spectral background levels from thermal and fast neutron flux levels and naturally occurring radioactive material decay series radionuclides. 238U decay products above 222Rn demonstrated minimal temporal variability beyond that expected from counting statistics. 238U and 232Th progeny below Rn gas displayed at most twice the expected variability. Further, an analysis of the 139 keV 74Ge(n, γ) and 691 keV 72Ge(n, n') spectral features demonstrated temporal stability for both thermal and fast neutronmore » fluxes.« less

  9. β+/EC decay rates of deformed neutron-deficient nuclei in the deformed QRPA with realistic interactions

    NASA Astrophysics Data System (ADS)

    Ni, Dongdong; Ren, Zhongzhou

    2015-05-01

    The weak-decay (β+ and EC) rates of neutron-deficient Kr, Sr, Zr, and Mo isotopes are investigated within the deformed quasiparticle random-phase approximation with realistic nucleon-nucleon interactions. The particle-particle and particle-hole channels of residual interactions are handled in large single-particle model spaces, based on the Brückner G-matrix with charge-dependent Bonn nucleon-nucleon forces. Contributions from allowed Gamow-Teller and Fermi transitions as well as first-forbidden transitions are calculated. The calculated half-lives show good agreement with the experimental data over a wide range of magnitude, from 10-2 to 107 s. Moreover, predictions of β-decay half-lives are made for some extremely proton-rich isotopes, which could be useful for future experiments.

  10. β-decay of neutron-rich Zâ¼60 nuclei and the origin of rare earth elements

    NASA Astrophysics Data System (ADS)

    Wu, J.; Nishimura, S.; Lorusso, G.; Xu, Z. Y.; Baba, H.; Browne, F.; Daido, R.; Doornenbal, P.; Fang, Y. F.; Ideguchi, E.; Isobe, T.; Li, Z.; Patel, Z.; Rice, S.; Simpson, G.; Sinclair, L.; Söderström, P. A.; Sumikama, T.; Watanabe, H.; Yagi, A.; Yokoyama, R.; Aoi, N.; Garrote, F. L. Bello; Benzoni, G.; Gey, G.; Gottardo, A.; Nishibata, H.; Odahara, A.; Sakurai, H.; Tanaka, M.; Taprogge, J.; Yamamoto, T.; Eurica Collaboration

    2014-05-01

    A large fraction of the rare-earth elements observed in the solar system is produced in the astrophysical rapid neutron capture process (r-process). However, current stellar models cannot completely explain the relative abundance of these elements partially because of nuclear physics uncertainties. To address this problem, a β-decay spectroscopy experiment was performed at RI Beam Factory (RIBF) at RIKEN, aimed at studying a wide range of very neutron-rich nuclei with Z˜60 that are progenitors of the rare-earth elements with mass number A˜460. The experiment provides a test of nuclear models as well as experimental inputs for r-process calculations. This contribution presents the experimental setup and some preliminary results of the experiment.

  11. β-decay of neutron-rich Z∼60 nuclei and the origin of rare earth elements

    SciTech Connect

    Wu, J.; Nishimura, S.; Lorusso, G.; Baba, H.; Doornenbal, P.; Isobe, T.; Söderström, P. A.; Sakurai, H.; Xu, Z. Y.; Browne, F.; Daido, R.; Fang, Y. F.; Yagi, A.; Nishibata, H.; Odahara, A.; Yamamoto, T.; Ideguchi, E.; Aoi, N.; Tanaka, M.; Collaboration: EURICA Collaboration; and others

    2014-05-02

    A large fraction of the rare-earth elements observed in the solar system is produced in the astrophysical rapid neutron capture process (r-process). However, current stellar models cannot completely explain the relative abundance of these elements partially because of nuclear physics uncertainties. To address this problem, a β-decay spectroscopy experiment was performed at RI Beam Factory (RIBF) at RIKEN, aimed at studying a wide range of very neutron-rich nuclei with Z∼60 that are progenitors of the rare-earth elements with mass number A∼460. The experiment provides a test of nuclear models as well as experimental inputs for r-process calculations. This contribution presents the experimental setup and some preliminary results of the experiment.

  12. Deformation in the neutron-deficient rare earth isotopes: Radioactive decay scheme studies in the neodymium, promethium, and samarium isotopes

    SciTech Connect

    Breitenbach, J.B.

    1993-12-31

    Several experiments were performed at the UNISOR isotope separator facility at HHIRF at the Oak Ridge National Laboratory on the {beta}{sup +}/EC decay of neutron-deficient rare earth isotopes. Data for the decay chain {sup 133}Sm {yields} {sup 133}Pm {yields} {sup 133}Nd was obtained, consisting of multiscaled spectra of {gamma} rays, X rays, and conversion electrons, as well as {gamma}{gamma}t, X{gamma}t, e{gamma}t and eXt coincidences. Gamma rays associated with the decay of {sup 133}Sm and {sup 133}Pm were observed for the first time. The decay of a new low-spin (1/2) isomeric state, with a half life of about 70 sec was established for {sup 133}Nd. The level schemes for {sup 133}Nd and {sup 133}Pr were constructed. An M3 and two E1 isomers are established in {sup 133}Nd and an E3 isomer is confirmed in {sup 133}Pr. The energy level systematics for the nuclear region bounded by Z {ge} 58 and N {le} 78 is discussed. Theoretical interpretations are based on the particle-plus-triaxial rotor model calculations. In the framework of these calculations, the {beta}{sub 2} deformation is moderate for these nuclei ({beta}{sub 2} {approx} 0.20-0.25). A sudden onset of strong deformation is not observed, in contrast with the theoretical predictions by Leander and Moeller [Lea82].

  13. Theory and use of GIRAFFE for analysis of decay characteristics of delayed-neutron precursors in an LMFBR

    SciTech Connect

    Gross, K. C.

    1980-07-01

    The application of the computer code GIRAFFE (General Isotope Release Analysis For Failed Elements) written in FORTRAN IV is described. GIRAFFE was designed to provide parameter estimates of the nonlinear discrete-measurement models that govern the transport and decay of delayed-neutron precursors in a liquid-metal fast breeder reactor (LMFBR). The code has been organized into a set of small, relatively independent and well-defined modules to facilitate modification and maintenance. The program logic, the numerical techniques, and the methods of solution used by the code are presented, and the functions of the MAIN program and of each subroutine are discussed.

  14. Inelastic neutron scattering studies of 76Ge and 76Se: relevance to elevance to neutrinoless double-β decay

    NASA Astrophysics Data System (ADS)

    Crider, B. P.; Peters, E. E.; Ross, T. J.; McEllistrem, M. T.; Prados-Estévez, F. M.; Allmond, J. M.; Vanhoy, J. R.; Yates, S. W.

    2015-05-01

    Inelastic neutron scattering measurements were performed at the University of Kentucky Accelerator Laboratory on enriched 76Ge and 76Se scattering samples. From measurements at incident neutron energies from 2.0 to 4.0 MeV, many new levels were identified and characterized in each nucleus; level lifetimes, transition probabilities, multipole mixing ratios, and other properties were determined. In addition, γ-ray cross sections for the 76Ge(n,n'γ) reaction were measured at neutron energies up to 5.0 MeV, with the goal of determining the cross sections of γ rays in 2040-keV region, which corresponds to the region of interest in the neutrinoless double β decay of 76Ge. Gamma rays from the three strongest branches from the 3952-keV level were observed, but the previously reported 2041-keV γ ray was not. Population cross sections across the range of incident neutron energies were determined for the 3952-keV level, resulting in a cross section of ~0.1 mb for the 2041-keV branch using the previously determined branching ratios. Beyond this, the data from these experiments indicate that previously unreported γ rays from levels in 76Ge can be found in the 2039-keV region.

  15. Inelastic neutron scattering studies of Ge-76 and Se-76: relevance to neutrinoless double-beta decay

    SciTech Connect

    Crider, Ben; Peters, Erin; Ross, T.J.; McEllistrem, M; Prados-Estevez, F.; Allmond, James M; Vanhoy, J.R.; Yates, S.W.

    2015-01-01

    Inelastic neutron scattering measurements were performed at the University of Kentucky Accelerator Laboratory on enriched Ge-76 and Se-76 scattering samples. From measurements at incident neutron energies from 2.0 to 4.0 MeV, many new levels were identified and characterized in each nucleus; level lifetimes, transition probabilities, multipole mixing ratios, and other properties were determined. In addition, gamma-ray cross sections for the Ge-76(n,n'gamma) reaction were measured at neutron energies up to 5.0 MeV, with the goal of determining the cross sections of gamma rays in 2040-keV region, which corresponds to the region of interest in the neutrinoless double beta decay of Ge-76. Gamma rays from the three strongest branches from the 3952-keV level were observed, but the previously reported 2041-keV gamma ray was not. Population cross sections across the range of incident neutron energies were determined for the 3952-keV level, resulting in a cross section of similar to 0.1 mb for the 2041-keV branch using the previously determined branching ratios. Beyond this, the data from these experiments indicate that previously unreported gamma rays from levels in Ge-76 can be found in the 2039-keV region.

  16. Nuclear structure from radioactive decay

    SciTech Connect

    Wood, J.L.

    1990-09-30

    This report discusses the nuclear structure of the following isotopes as a result of radioactive decays: neutron-deficient iridium isotopes; neutron-deficient platinum isotopes; neutron-deficient gold isotopes; neutron-deficient mercury isotopes; neutron-deficient thallium isotopes; neutron-deficient lead isotopes; neutron-deficient promethium isotopes; and neutron-deficient samarium isotopes.

  17. Inelastic neutron scattering cross sections for 76Ge relevant to background in neutrinoless double-beta decay experiments

    DOE PAGESBeta

    Crider, Ben; Peters, Erin; Allmond, James M; McEllistrem, M; Prados-Estevez, F.; Ross, T.J.; Vanhoy, J.R.; Yates, S.W.

    2015-01-01

    The experimental signature in searches for the neutrinoless double- decay of 76Ge is a peak near 2039 keV in the spectrum. Given the low probability of the process, it is important that the background in this region be well understood. Inelastic scattering reactions with neutrons from muon-induced interactions and ( ,n) reactions in the surrounding materials or in the detector can provide contributions to the background. We have measured the production cross sections for rays from the 76Ge(n,n ) reaction in the 2039-keV region at incident neutron energies up to 4.9 MeV. In addition to determining that the cross sectionsmore » of a previously known 2040.7-keV ray from the 3952-keV level in 76 Ge are rather small, we find that a larger contribution arises from a 2037.5-keV ray which is attributed to a newly identified level at 3147 keV in 76Ge. A third contribution is also possible from another new level at 3577 keV. These results indicate that the 2039-keV region in 76Ge neutrinoless double- decay searches is more complex than was previously thought.« less

  18. Inelastic neutron scattering cross sections for Ge76 relevant to background in neutrinoless double- β decay experiments

    DOE PAGESBeta

    Crider, B. P.; Peters, E. E.; Allmond, J. M.; McEllistrem, M. T.; Prados-Estévez, F. M.; Ross, T. J.; Vanhoy, J. R.; Yates, S. W.

    2015-09-11

    The experimental signature in searches for the neutrinoless double- decay of 76Ge is a peak near 2039 keV in the spectrum. Given the low probability of the process, it is important that the background in this region be well understood. Moreover, inelastic scattering reactions with neutrons from muon-induced interactions and ( ,n) reactions in the surrounding materials or in the detector can provide contributions to the background. We also measured the production cross sections for rays from the 76Ge(n,n ) reaction in the 2039-keV region at incident neutron energies up to 4.9 MeV. In addition to determining that the crossmore » sections of a previously known 2040.7-keV ray from the 3952-keV level in 76 Ge are rather small, we find that a larger contribution arises from a 2037.5-keV ray which is attributed to a newly identified level at 3147 keV in 76Ge. Finally, a third contribution is also possible from another new level at 3577 keV. These results indicate that the 2039-keV region in 76Ge neutrinoless double- decay searches is more complex than was previously thought.« less

  19. Inelastic neutron scattering cross sections for 76Ge relevant to background in neutrinoless double-β decay experiments

    NASA Astrophysics Data System (ADS)

    Crider, B. P.; Peters, E. E.; Allmond, J. M.; McEllistrem, M. T.; Prados-Estévez, F. M.; Ross, T. J.; Vanhoy, J. R.; Yates, S. W.

    2015-09-01

    The experimental signature in searches for the neutrinoless double-β decay of 76Ge is a peak near 2039 keV in the spectrum. Given the low probability of the process, it is important that the background in this region be well understood. Inelastic scattering reactions with neutrons from muon-induced interactions and (α ,n ) reactions in the surrounding materials or in the detector can provide contributions to the background. We have measured the production cross sections for γ rays from the 76Ge(n ,n'γ ) reaction in the 2039-keV region at incident neutron energies up to 4.9 MeV. In addition to determining that the cross sections of a previously known 2040.7-keV γ ray from the 3952-keV level in 76Ge are rather small, we find that a larger contribution arises from a 2037.5-keV γ ray which is attributed to a newly identified level at 3147 keV in 76Ge. A third contribution is also possible from another new level at 3577 keV. These results indicate that the 2039-keV region in 76Ge neutrinoless double-β decay searches is more complex than was previously thought.

  20. Beta-Decay Spectroscopy of Neutron-Rich Isotopes Utilizing a Planar Ge Double-Sided Strip Detector

    NASA Astrophysics Data System (ADS)

    Larson, N.; Liddick, S. N.; Prokop, C. J.; Kondev, F. G.; Kumar, S.; Crider, B. P.; Paulauskas, S. V.; Suchyta, S.

    2015-10-01

    In nuclear science, rapid changes in the structure of the atomic nucleus have been inferred with small changes in the neutron and proton numbers. These changes are manifested in variations of the low-energy level schemes of exotic isotopes. One region of the nuclear chart where rapid changes in deformation have been suggested based on the behavior of the first excited 2 + states is in neutron-rich nuclei near A = 110. Beta-decay spectroscopy is a sensitive and selective technique that can be used to investigate the low-energy level schemes exotic nuclei at low production rates. At the National Superconducting Cyclotron Laboratory (NSCL), a recently commissioned planar Ge double-sided strip detector (GeDSSD) is used in a novel application for these studies. Preliminary results from the decay of Tc isotopes in an experiment aimed at nuclei near A = 110 will be presented. This work was supported by the DOE NNSA DE-NA0000979 and the NSF Grant PHY1102511.

  1. The Crucial Role of Neutron β-DECAY Experiments in Establishing the Fundamental Symmetries of the V-A Description of Weak Interactions

    NASA Astrophysics Data System (ADS)

    Byrne, J.

    2011-03-01

    Experimental data from unpolarized and polarized neutron beta -decay yield accurate values for the basic parameters of the P-violating T-conserving charged current weak interaction, thereby posing a potentially stringent unitarity test of the CKM quark mixing matrix. Experimental studies of the radiative (BR ~3.10-3) and two-body (BR ~ 4.10-6) decay branches are currently in progress.

  2. Earth Albedo and the orbit of LAGEOS

    NASA Technical Reports Server (NTRS)

    Rubincam, D. P.; Weiss, N. R.

    1985-01-01

    The long-period perturbations in the orbit of the Lageos satellite due to the Earth's albedo have been found using a new analytical formalism. The Earth is assumed to be a sphere whose surface diffusely reflects sunlight according to Lambert's law. Specular reflection is not considered. The formalism is based on spherical harmonics; it produces equations which hold regardless of whether the terminator is seen by the satellite or not. Specializing to the case of a realistic zonal albedo shows that Lageos' orbital semimajor axis changes periodically by only the a few millimeters and the eccentricity by one part in 100,000. The longitude of the node increases secularly. The effect considered here can explain neither the secular decay of 1.1 mm/day in the semimajor axis nor the observed along-track variations in acceleration of order 2 x 10 to the minus 12 power/sq ms.

  3. Neutron inelastic scattering processes as a background for double-{beta} decay experiments

    SciTech Connect

    Mei, D.-M.; Elliott, S. R.; Hime, A.; Gehman, V.; Kazkaz, K.

    2008-05-15

    We investigate several Pb(n,n{sup '}{gamma}) and Ge(n,n{sup '}{gamma}) reactions. We measure {gamma}-ray production from Pb(n,n{sup '}{gamma}) reactions that can be a significant background for double-{beta} decay experiments which use lead as a massive inner shield. Particularly worrisome for Ge-based double-{beta} decay experiments are the 2041-keV and 3062-keV {gamma} rays produced via Pb(n,n{sup '}{gamma}). The former is very close to the {sup 76}Ge double-{beta} decay endpoint energy and the latter has a double escape peak energy near the endpoint. We discuss the implications of these {gamma} rays on past and future double-{beta} decay experiments and estimate the cross section to excite the level that produces the 3062-keV {gamma} ray. Excitation {gamma}-ray lines from Ge(n,n{sup '}{gamma}) reactions are also observed. We consider the contribution of such backgrounds and their impact on the sensitivity of next-generation searches for neutrinoless double-{beta} decay using enriched germanium detectors.

  4. The Gamma-ray Albedo of the Moon

    SciTech Connect

    Moskalenko, Igor V.; Porter, Troy A.; /UC, Santa Cruz

    2007-09-28

    We use the GEANT4 Monte Carlo framework to calculate the {gamma}-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of {gamma}-rays from the Moon is very steep with an effective cutoff around 3-4 GeV (600 MeV for the inner part of the Moon disk) and exhibits a narrow pion-decay line at 67.5 MeV, perhaps unique in astrophysics. Apart from other astrophysical sources, the albedo spectrum of the Moon is well understood, including its absolute normalization; this makes it a useful 'standard candle' for {gamma}-ray telescopes. The steep albedo spectrum also provides a unique opportunity for energy calibration of {gamma}-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). Since the albedo flux depends on the incident CR spectrum which changes over the solar cycle, it is possible to monitor the CR spectrum using the albedo {gamma}-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter-Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo {gamma}-rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the LAT to monitor the CR spectrum near the Earth beyond the lifetime of the PAMELA.

  5. The Gamma-Ray Albedo of the Moon

    SciTech Connect

    Moskalenko, I.V.; Porter, T.A.; /UC, Santa Cruz

    2008-03-25

    We use the GEANT4 Monte Carlo framework to calculate the {gamma}-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of {gamma}-rays from the Moon is very steep with an effective cutoff around 3-4 GeV (600 MeV for the inner part of the Moon disk) and exhibits a narrow pion-decay line at 67.5 MeV, perhaps unique in astrophysics. Apart from other astrophysical sources, the albedo spectrum of the Moon is well understood, including its absolute normalization; this makes it a useful 'standard candle' for {gamma}-ray telescopes. The steep albedo spectrum also provides a unique opportunity for energy calibration of {gamma}-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). Since the albedo flux depends on the incident CR spectrum which changes over the solar cycle, it is possible to monitor the CR spectrum using the albedo {gamma}-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter-Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo {gamma}-rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the LAT to monitor the CR spectrum near the Earth beyond the lifetime of the PAMELA.

  6. Neutron capture by Ru: Neutron cross sections of {sup 96,102,104}Ru and gamma-ray spectroscopy in the decays of {sup 97,103,105}Ru

    SciTech Connect

    Krane, K. S.

    2010-04-15

    Cross sections for radiative capture of neutrons have been measured for stable isotopes of Ru with mass numbers 96,102, and 104. From separate irradiations using thermal and epithermal neutrons, independent values for the thermal cross section and effective resonance integral have been determined. Spectroscopic studies of the gamma rays emitted in the decays of {sup 97,103,105}Ru have enabled improvements in the precision of the energies and intensities of the radiations along with corresponding improvements in the beta-decay feeding intensities and the energies of the levels in the respective daughter nuclei. Similar spectroscopic measurements of the decays of {sup 105}Rh (daughter of {sup 105}Ru) and {sup 96}Tc (produced from n,p reactions on {sup 96}Ru) have resulted in improved gamma-ray energies and intensities in those decays.

  7. Measurement result of the neutron monitor onboard the Space Environment Data Acquisition Equipment - Attached Payload (SEDA-AP)

    NASA Astrophysics Data System (ADS)

    Koga, K.; Muraki, Y.; Shibata, S.; Yamamoto, T.; Matsumoto, H.; Okudaira, O.; Kawano, H.; Yumoto, K.

    2013-12-01

    decays are thought to originate from the radiation belt. This theory is called CRAND (Cosmic Ray Albedo Neutron Decay). Our observation result is consistent with the CRAND theory prediction in the case of low-energy parts. Moreover, the flux and angular distribution of local neutrons were estimated using the nuclear simulation code 'PHITS' to evaluate the influence of local neutrons on the structure of SEDA-AP and 'Kibo'. The results of our analyses on solar and albedo neutrons are reported in this paper.

  8. Nuclear Structure Relevant to Double-beta Decay: Studies of 76Ge and 76Se using Inelastic Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Crider, Benjamin P.

    While neutrino oscillations indicate that neutrino flavors mix and that neutrinos have mass, they do not supply information on the absolute mass scale of the three flavors of neutrinos. Currently, the only viable way to determine this mass scale is through the observation of the theoretically predicted process of neutrinoless double-beta decay (0nubetabeta). This yet-to-be-observed decay process is speculated to occur in a handful of nuclei and has predicted half-lives greater than 1025 years. Observation of 0nubetabeta is the goal of several large-scale, multinational efforts and consists of detecting a sharp peak in the summed energies at the Q-value of the reaction. An exceptional candidate for the observation of 0nubetabeta is 76Ge, which offers an excellent combination of capabilities and sensitivities, and two such collaborations, MAJORANA and GERDA, propose tonne-scale experiments that have already begun initial phases using a fraction of the material. The absolute scale of the neutrino masses hinges on a matrix element, which depends on the ground-state wave functions for both the parent (76Ge) and daughter (76Se) nuclei in the 0nubetabeta decay and can only be calculated from nuclear structure models. Efforts to provide information on the applicability of these models have been undertaken at the University of Kentucky Accelerator Laboratory using gamma-ray spectroscopy following inelastic scattering reactions with monoenergetic, accelerator-produced fast neutrons. Information on new energy levels and transitions, spin and parity assignments, lifetimes, multipole mixing ratios, and transition probabilities have been determined for 76Se, the daughter of 76Ge 0nubetabeta, up to 3.0 MeV. Additionally, inaccuracies in the accepted level schemes have been addressed. Observation of 0nubetabeta requires precise knowledge of potential contributors to background within the region of interest, i.e., approximately 2039 keV for 76Ge. In addition to backgrounds

  9. Enhanced γ -Ray Emission from Neutron Unbound States Populated in β Decay

    SciTech Connect

    Tain, J. L.; Valencia, E.; Algora, A.; Agramunt, J.; Rubio, B.; Rice, S.; Gelletly, W.; Regan, P.; Zakari-Issoufou, A. -A.; Fallot, M.; Porta, A.; Rissanen, J.; Eronen, T.; Äystö, J.; Batist, L.; Bowry, M.; Bui, V. M.; Caballero-Folch, R.; Cano-Ott, D.; Elomaa, V. -V.; Estevez, E.; Farrelly, G. F.; Garcia, A. R.; Gomez-Hornillos, B.; Gorlychev, V.; Hakala, J.; Jordan, M. D.; Jokinen, A.; Kolhinen, V. S.; Kondev, F. G.; Martínez, T.; Mendoza, E.; Moore, I.; Penttilä, H.; Podolyák, Zs.; Reponen, M.; Sonnenschein, V.; Sonzogni, A. A.

    2015-08-01

    Total absorption spectroscopy was used to investigate the β -decay intensity to states above the neutron separation energy followed by γ -ray emission in 87,88Br and 94Rb. Accurate results were obtained thanks to the careful control of systematic errors. An unexpectedly large γ intensity was observed in all three cases extending well beyond the excitation energy region where neutron penetration is hindered by low neutron energy. The γ branching as a function of excitation energy was compared to Hauser-Feshbach model calculations. For 87Br and 88Br the branching reaches 57% and 20% respectively, and could be explained as a nuclear structure effect. Some of the states populated in the daughter can only decay through the emission of a large orbital angular momentum neutron with a strongly reduced barrier penetrability. In the case of neutron-rich 94Rb the observed 4.5% branching is much larger than the calculations performed with standard nuclear statistical model parameters, even after proper correction for fluctuation effects on individual transition widths. The difference can be reconciled introducing an enhancement of one order-of-magnitude in the photon strength to neutron strength ratio. An increase in the photon strength function of such magnitude for very neutron-rich nuclei, if it proved to be correct, leads to a similar increase in the (n, γ) cross section that would have an impact on r process abundance calculations.

  10. {alpha}-decay of the new isotope {sup 187}Po: Probing prolate structures beyond the neutron mid-shell at N = 104

    SciTech Connect

    Andreyev, A.N.; Antalic, S.

    2006-04-15

    The new neutron-deficient isotope {sup 187}Po has been identified in the complete fusion reaction {sup 46}Ti+{sup 144}Sm{yields}{sup 187}Po+3n at the velocity filter SHIP. Striking features of the {sup 187}Po {alpha} decay are the strongly-hindered decay to the spherical ground state and unhindered decay to a surprisingly low-lying deformed excited state at 286 keV in the daughter nucleus {sup 183}Pb. Based on the potential energy surface calculations, the {sup 187}Po ground state and the 286 keV excited state in {sup 183}Pb were interpreted as being of prolate origin. The systematic deviation of the {alpha}-decay properties in the lightest odd-A Po isotopes relative to the smooth behavior in the even-A neighbors is discussed. Improved data for the decay of {sup 187}Bi{sup m,g} were also obtained.

  11. Rapid optical decay of the neutron star transient MAXI J0556-332

    NASA Astrophysics Data System (ADS)

    Jin, Ruolan; Kong, Albert K. H.

    2016-01-01

    We observed the neutron star X-ray transient MAXI J0556-332 currently in outburst with the 1m telescope at the Lulin Observatory in Taiwan. The observations were taken on 2016 January 9 (MJD 57396.66) and 10 (MJD 57397.67) with the SDSS g and r-band filters.

  12. Nuclear structure from radioactive decay

    SciTech Connect

    Wood, J.L.

    1991-09-30

    This report discusses nuclear structure from radioactive decay of the following: Neutron-Deficient Iridium Isotopes; Neutron-Deficient Platinum Isotopes; Neutron-Deficient Gold Isotopes; Neutron-Deficient Mercury Isotopes; Neutron-Deficient Thallium Isotopes; Neutron-Deficient Lead Isotopes; Neutron-Deficient Samarium Isotopes; Neutron-Deficient Promethium Isotopes; Neutron-Deficient Neodymium Isotopes; and Neutron-Deficient Praseodymium Isotopes. Also discussed are Nuclear Systematics and Models.

  13. ANITA-2000 activation code package - updating of the decay data libraries and validation on the experimental data of the 14 MeV Frascati Neutron Generator

    NASA Astrophysics Data System (ADS)

    Frisoni, Manuela

    2016-03-01

    ANITA-2000 is a code package for the activation characterization of materials exposed to neutron irradiation released by ENEA to OECD-NEADB and ORNL-RSICC. The main component of the package is the activation code ANITA-4M that computes the radioactive inventory of a material exposed to neutron irradiation. The code requires the decay data library (file fl1) containing the quantities describing the decay properties of the unstable nuclides and the library (file fl2) containing the gamma ray spectra emitted by the radioactive nuclei. The fl1 and fl2 files of the ANITA-2000 code package, originally based on the evaluated nuclear data library FENDL/D-2.0, were recently updated on the basis of the JEFF-3.1.1 Radioactive Decay Data Library. This paper presents the results of the validation of the new fl1 decay data library through the comparison of the ANITA-4M calculated values with the measured electron and photon decay heats and activities of fusion material samples irradiated at the 14 MeV Frascati Neutron Generator (FNG) of the NEA-Frascati Research Centre. Twelve material samples were considered, namely: Mo, Cu, Hf, Mg, Ni, Cd, Sn, Re, Ti, W, Ag and Al. The ratios between calculated and experimental values (C/E) are shown and discussed in this paper.

  14. Kilonovae: Electromagnetic Counterparts of Neutron Star Mergers Powered by the Radioactive Decay of R-Process Nuclei

    NASA Astrophysics Data System (ADS)

    Metzger, Brian

    2014-03-01

    The coalescence of binary neutron stars (NSs) are the most promising sources for the direct detection of gravitational waves by Advanced LIGO and Virgo. However, maximizing the scientific opportunities from such a discovery will require the detection of a coincident electromagnetic counterpart. One possible counterpart is a short gamma-ray burst (GRB), powered by the accretion of NS debris left over from the merger onto the newly-formed black hole. However, GRBs are thought to be relativistically beamed and hence to accompany only a small fraction of mergers. NS mergers also produce isotropic supernova-like emission, powered by the radioactive decay of heavy (r-process) elements which are synthesized in the neutron-rich ejecta from the merger. I will describe the first calculations of such ``kilonovae'' which include realistic nuclear physics and radiative transport. In addition to providing a smoking gun for detecting binary NS mergers, kilonovae inform the unknown origin of the heaviest elements in the Universe. The first kilonova may have been discovered by the Hubble Space Telescope last year.

  15. Project of Neutron Beta-Decay A-Asymmetry Measurement With Relative Accuracy of (1–2)×10−3

    PubMed Central

    Serebrov, A.; Rudnev, Yu.; Murashkin, A.; Zherebtsov, O.; Kharitonov, A.; Korolev, V.; Morozov, T.; Fomin, A.; Pusenkov, V.; Schebetov, A.; Varlamov, V.

    2005-01-01

    We are going to use a polarized cold neutron beam and an axial magnetic field in the shape of a bottle formed by a superconducting magnetic system. Such a configuration of magnetic fields allows us to extract the decay electrons inside a well-defined solid angle with high accuracy. An electrostatic cylinder with a potential of 25 kV defines the detected region of neutron decays. The protons, which come from this region will be accelerated and registered by a proton detector. The use of coincidences between electron and proton signals will allow us to considerably suppress the background. The final accuracy of the A-asymmetry will be determined by the uncertainty of the neutron beam polarization measurement which is at the level of (1–2) × 10−3, as shown in previous studies. PMID:27308154

  16. Nuclear Structure Between N = 20 and N = 28: Beta-Decay in the Neutron-Rich Mg and Al Isotopes

    NASA Astrophysics Data System (ADS)

    Crawford, Heather; NSCL Experiment E14063 Team

    2015-10-01

    The structure of nuclei in the vicinity of expected nuclear shell closures away from stability has been, and continues to be, a cornerstone for nuclear structure study. The confirmation of certain ``magic numbers'' in exotic nuclei provides insight into the evolution of nucleon configurations with isospin, but perhaps even more light is shed into the structure of the atomic nucleus when expected shell closures are found to be weakened, or entirely disappear. Two instances where this has been the case are the N = 20 and N = 28 neutron shell closures in the neutron-rich Mg, Si and S nuclei. However, a question which is only beginning to be answered is the nature of the transitional nuclei between N = 20 and 28. Recent experimental work in the Mg isotopes has suggested a chain of prolate-deformed nuclei at Z = 12, but the nature of the Al and Si isotopes just above remains a question. An experiment was conducted at NSCL to study the β-decay of neutron-rich Na, Mg, Al and Si isotopes to provide additional, and in some cases, first information on the level structures of the daughter isotopes in the region between N = 20 and N = 28. First results from this work will be presented, and the implications for nuclear structural evolution in this region discussed. This work was supported by the NSF under Grant No. PHY-1068217 (NSCL) and by the U. S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC02-05CH11231 (LBNL).

  17. Neutron inelastic scattering and reactions in natural Pb as a background in neutrinoless double-{beta}-decay experiments

    SciTech Connect

    Guiseppe, V. E.; Devlin, M.; Elliott, S. R.; Fotiades, N.; Hime, A.; Nelson, R. O.; Perepelitsa, D. V.; Mei, D.-M.

    2009-05-15

    Inelastic neutron scattering and reactions on Pb isotopes can result in {gamma} rays near the signature end-point energy in a number of {beta}{beta} isotopes. In particular, there are {gamma}-ray transitions in {sup 206,207,208}Pb that might produce energy deposits at the {sup 76}GeQ{sub {beta}}{sub {beta}} in Ge detectors used for 0{nu}{beta}{beta} searches. The levels that produce these {gamma} rays can be excited by (n,n{sup '}{gamma}) or (n,xn{gamma}) reactions, but the cross sections are small and previously unmeasured. This work uses the pulsed neutron beam at the Los Alamos Neutron Science Center to directly measure reactions of interest to {beta}{beta}-decay experiments. The cross section on {sup nat}Pb to produce the 2041-keV {gamma} ray from {sup 206}Pb is measured to be 3.6 {+-} 0.7 (stat.) {+-} 0.3 (syst.) mb at {approx_equal}9.6 MeV. The cross section on {sup nat}Pb to produce the 3061,3062-keV {gamma} rays from {sup 207}Pb and {sup 208}Pb is measured to be 3.9 {+-} 0.8 (stat.) {+-} 0.4 (syst.) mb at the same energy. We report cross sections or place upper limits on the cross sections for exciting some other levels in Pb that have transition energies corresponding to Q{sub {beta}}{sub {beta}} in other {beta}{beta} isotopes.

  18. Elastic and Inelastic Scattering of Neutrons from Neon and Argon: Impact on Neutrinoless Double-Beta Decay and Dark Matter Experimental Programs

    NASA Astrophysics Data System (ADS)

    MacMullin, Sean Patrick

    In underground physics experiments, such as neutrinoless double-beta decay and dark matter searches, fast neutrons may be the dominant and potentially irreducible source of background. Experimental data for the elastic and inelastic scattering cross sections of neutrons from argon and neon, which are target and shielding materials of interest to the dark matter and neutrinoless double-beta decay communities, were previously unavailable. Unmeasured neutron scattering cross sections are often accounted for incorrectly in Monte-Carlo simulations. Elastic scattering cross sections were measured at the Triangle Universities Nuclear Laboratory (TUNL) using the neutron time-of-flight technique. Angular distributions for neon were measured at 5.0 and 8.0 MeV. One full angular distribution was measured for argon at 6.0 MeV. The cross-section data were compared to calculations using a global optical model. Data were also fit using the spherical optical model. These model fits were used to predict the elastic scattering cross section at unmeasured energies and also provide a benchmark where the global optical models are not well constrained. Partial gamma-ray production cross sections for (n,xngamma ) reactions in natural argon and neon were measured using the broad spectrum neutron beam at the Los Alamos Neutron Science Center (LANSCE). Neutron energies were determined using time of flight and resulting gamma rays from neutron-induced reactions were detected using the GErmanium Array for Neutron Induced Excitations (GEANIE). Partial gamma-ray production cross sections for six transitions in 40Ar, two transitions in 39Ar and the first excited state transitions is 20Ne and 22Ne were measured from threshold to a neutron energy where the gamma-ray yield dropped below the detection sensitivity. Measured (n,xngamma) cross sections were compared with calculations using the TALYS and CoH3 nuclear reaction codes. These new measurements will help to identify potential backgrounds in

  19. Particle decay of very neutron deficient nuclei near {sup 100}Sn

    SciTech Connect

    Tighe, R.J.; Moltz, D.M.; Batchelder, J.C.; Ognibene, T.J.; Rowe, M.W.; Cerny, J.

    1993-10-01

    Proton emission from the nuclear ground state (gs) not only determines the limit of nuclear stability, but yields information on nuclear masses and structure very far from stability. There has been much recent experimental work in the region of the expected doubly-magic nucleus {sup 100}Sn (N=Z=50). This includes the discovery of the lightest known gs proton emitters, {sup 109}I and {sup 113}CS. We have used the compound nuclear reaction {sup 58}Ni + {sup 50}Cr to search for the gs particle decay of {sup 104}Sb and {sup 105}Sb. The evaporation residues were transported via our He-jet system and collected on a thin tape at the center of our new detector ball. This detector ball consists of six gas-{Delta}E gas-{Delta}E Si-E triple telescopes each capable of detecting protons with energies down to {approx}200 keV. Previous attempts to identify the gs proton decay of {sup 105}Sb had a lower energy threshold of {approx}500 keV. We have observed several low-energy ({approx}350-800 keV) proton groups at {sup 58}Ni bombarding energies of 223 MeV, 244 MeV, and 259 MeV.

  20. Decay radioactivity induced in plasma-facing materials by deutrium-tritium neutrons

    SciTech Connect

    Kumar, A.; Abdou, M.A.; Youssef, M.Z.; Ikeda, Y.; Konno, C.; Kosako, K.; Oyama, Y.; Nakamura, T.; Maekawa, H.

    1995-08-01

    Deuterium-tritium (D-T) neutron-induced radioactivity constitutes one of the foremost issues in fusion reactor design. Designers have been using radioactivity codes and associated nuclear data libraries for nucleonic designs of fusion reactors. However, in the past, there was hardly any experimental validation of these codes/libraries. An elaborate, experimental program was initiated in 1988 under a U.S. Department of Energy/Japan Atomic Energy Research Institute collaborative program to validate the radioactivity codes/libraries. As many as 14 neutron energy spectra were covered for a number of materials. The analyses of the isotopic activities of the irradiated materials using the activation cross-section libraries of four leading radioactivity codes, i.e., ACT4/THIDA-1, REAC-3. DKR-ICF; and RACC, have shown large discrepancies among the calculations on one hand and between the calculations and the measurements, on the other. Vanadium, Co, Ni, Zn, Zr, Mo, In, Sn, and W each count the largest number of discrepant isotopic activities. In addition to providing detailed results of the status of predictability of individual isotopic activities using the ACT4, REAC-3, DKR-ICF, and RACC activation cross-section libraries, safety factors cum quality factors characterizing each library are presented and discussed. The related issues of confidence level and associated uncertainty are also highlighted. 37 refs., 112 figs., 24 tabs.

  1. MISR Level 3 Albedo and Cloud Versioning

    Atmospheric Science Data Center

    2016-09-07

    ... 2:  CLOUD - Wind Vectors, Height Histogram Stage 1:  ALBEDO - Expansive, Restrictive and Local Albedo (except over snow and ... Stage 2 CLOUD - Height Histogram Stage 1 CLOUD - Wind Vectors Stage 1 ALBEDO - Expansive and Restrictive ...

  2. Radioactive decay products in neutron star merger ejecta: heating efficiency and γ-ray emission

    NASA Astrophysics Data System (ADS)

    Hotokezaka, K.; Wanajo, S.; Tanaka, M.; Bamba, A.; Terada, Y.; Piran, T.

    2016-06-01

    The radioactive decay of the freshly synthesized r-process nuclei ejected in compact binary mergers powers optical/infrared macronovae (kilonovae) that follow these events. The light curves depend critically on the energy partition among the different decay products and it plays an important role in estimates of the amount of ejected r-process elements from a given observed signal. We show that 20-50 per cent of the total radioactive energy is released in γ-rays on time-scales from hours to a month. The number of emitted γ-rays per unit energy interval has roughly a flat spectrum between a few dozen keV and 1 MeV so that most of the energy is carried by ˜1 MeV γ-rays. However, at the peak of macronova emission the optical depth of the γ-rays is ˜0.02 and most of the γ-rays escape. The loss of these γ-rays reduces the heat deposition into the ejecta and hence reduces the expected macronova signals if those are lanthanides dominated. This implies that the ejected mass is larger by a factor of 2-3 than what was previously estimated. Spontaneous fission heats up the ejecta and the heating rate can increase if a sufficient amount of transuranic nuclei are synthesized. Direct measurements of these escaping γ-rays may provide the ultimate proof for the macronova mechanisms and an identification of the r-process nucleosynthesis sites. However, the chances to detect these signals are slim with current X-ray and γ-ray missions. New detectors, more sensitive by at least a factor of 10, are needed for a realistic detection rate.

  3. β - γ and β-neutron- γ emission in mass A=137 Decay Chain Studied with the Modular Total Absorption Spectrometer (MTAS)

    NASA Astrophysics Data System (ADS)

    Rasco, Charles; Fijałkowska, Aleksandra; Karny, Marek; Rykaczewski, Krzysztof; Wolińska-Cichocka, Marzena; Grzywacz, Robert

    2013-10-01

    The Modular Total Absorption Spectrometer (MTAS) is a detector made up of 19 separate hexagon modules of NaI which results in over a ton of NaI in the MTAS detector. MTAS was designed to capture as much of the electromagnetic energy release in β-decays as possible. MTAS was constructed at the Holifield Radioactive Ion Beam Facility and measured over 20 decay products of 238U fission products in its inaugural measurement campaign in January 2012. The measurements were focused on nuclei identified as important for decay heat analysis of the nuclear fuel cycle. Silicon detectors placed at the center of MTAS to provide β triggers, make for extremely clean signals in MTAS. Preliminary results on the average electromagnetic energy release in the β decay of 137Xe and 137I isotopes will be presented. These isotopes are among the priority 1 cases listed by the NEA. The 137I also has a beta -neutron decay branch that is detected in MTAS. Neutron detection in a large NaI detector will also be discussed. This work was supported by the US DOE by award no. DE-FG02-96ER40978 and by US DOE, Office of Nuclear Physics.

  4. Dose point kernel for boron-11 decay and the cellular S values in boron neutron capture therapy

    SciTech Connect

    Ma Yunzhi; Geng Jinpeng; Gao Song; Bao Shanglian

    2006-12-15

    The study of the radiobiology of boron neutron capture therapy is based on the cellular level dosimetry of boron-10's thermal neutron capture reaction {sup 10}B(n,{alpha}){sup 7}Li, in which one 1.47 MeV helium-4 ion and one 0.84 MeV lithium-7 ion are spawned. Because of the chemical preference of boron-10 carrier molecules, the dose is heterogeneously distributed in cells. In the present work, the (scaled) dose point kernel of boron-11 decay, called {sup 11}B-DPK, was calculated by GEANT4 Monte Carlo simulation code. The DPK curve drops suddenly at the radius of 4.26 {mu}m, the continuous slowing down approximation (CSDA) range of a lithium-7 ion. Then, after a slight ascending, the curve decreases to near zero when the radius goes beyond 8.20 {mu}m, which is the CSDA range of a 1.47 MeV helium-4 ion. With the DPK data, S values for nuclei and cells with the boron-10 on the cell surface are calculated for different combinations of cell and nucleus sizes. The S value for a cell radius of 10 {mu}m and a nucleus radius of 5 {mu}m is slightly larger than the value published by Tung et al. [Appl. Radiat. Isot. 61, 739-743 (2004)]. This result is potentially more accurate than the published value since it includes the contribution of a lithium-7 ion as well as the alpha particle.

  5. {beta}-decay half-lives and {beta}-delayed neutron emission probabilities of nuclei in the region A < or approx. 110, relevant for the r process

    SciTech Connect

    Pereira, J.; Galaviz, D.; Matos, M.; Montes, F.; Hennrich, S.; Kessler, R.; Schertz, F.; Aprahamian, A.; Quinn, M.; Woehr, A.; Arndt, O.; Pfeiffer, B.; Becerril, A.; Elliot, T.; Estrade, A.; Lorusso, G.; Schatz, H.; Kratz, K.-L.; Mantica, P. F.; Moeller, P.

    2009-03-15

    Measurements of {beta}-decay properties of A < or approx. 110 r-process nuclei have been completed at the National Superconducting Cyclotron Laboratory at Michigan State University. {beta}-decay half-lives for {sup 105}Y, {sup 106,107}Zr, and {sup 111}Mo, along with {beta}-delayed neutron emission probabilities of {sup 104}Y, {sup 109,110}Mo and upper limits for {sup 105}Y, {sup 103-107}Zr, and {sup 108,111}Mo have been measured for the first time. Studies on the basis of the quasi-random-phase approximation are used to analyze the ground-state deformation of these nuclei.

  6. Beta-decay half-lives and beta-delayed neutron emisison probabilities of nuclei in the region A. 110, relevant for the r-process

    SciTech Connect

    Moller, Peter; Pereira, J; Hennrich, S; Aprahamian, A; Arndt, O; Becerril, A; Elliot, T; Estrade, A; Galaviz, D; Kessler, R; Kratz, K - L; Lorusso, G; Mantica, P F; Matos, M; Montes, F; Pfeiffer, B; Schatz, F; Schnorrenberger, L; Smith, E; Stolz, A; Quinn, M; Walters, W B; Wohr, A

    2009-01-01

    Measurements of the {beta}-decay properties of A {approx}< 110 r-process nuclei have been completed at the National Superconducting Cyclotron Laboratory, at Michigan State University. {beta}-decay half-lives for {sup 105}Y, {sup 106,107}Zr and {sup 108,111}Mo, along with ,B-delayed neutron emission probabilities of 104Y, 109,11OMo and upper limits for 105Y, 103-107Zr and 108,111 Mo have been measured for the first time. Studies on the basis of the quasi-random phase approximation are used to analyze the ground-state deformation of these nuclei.

  7. Observation of a large β -delayed neutron emission component in 102Rb decay and identification of excited states in 102Sr

    NASA Astrophysics Data System (ADS)

    Wang, Z. M.; Garnsworthy, A. B.; Andreoiu, C.; Ball, G. C.; Bender, P. C.; Bildstein, V.; Cross, D. S.; Demand, G.; Dunlop, R.; Evitts, L. J.; Garrett, P. E.; Hackman, G.; Hadinia, B.; Ketelhut, S.; Krücken, R.; Leach, K. G.; Laffoley, A. T.; Miller, D.; Moukaddam, M.; Pore, J.; Radich, A. J.; Rajabali, M. M.; Svensson, C. E.; Tan, A.; Tardiff, E.; Unsworth, C.; Voss, A.; Voss, P.

    2016-05-01

    The β decay and β -delayed neutron emission of 102Rb have been studied using the 8 π spectrometer at TRIUMF-ISAC. The level scheme of 102Sr has been expanded from results of a γ -γ coincidence analysis, including the identification of the (4+ ) member of the ground-state band. The β -delayed neutron branching ratio of 102Rb was found to be significantly larger than previously reported. This larger value has the potential to modify the results of r -process calculations and motivates further measurements as well as refinements of theoretical models.

  8. Neutron inelastic scattering in natural Pb as a background in neutrinoless double-beta decay experiments

    SciTech Connect

    Guiseppe, Vincente E; Elliott, Steve R; Hime, Andrew; Perepelitsa, Dennis V

    2008-01-01

    Inelastic neutron scattering on Pb isotopes can result in {gamma} rays near the signature endpoint energy in a number of {beta}{beta} isotopes. In particular, there are {gamma}-ray transitions in {sup 206}Pb and {sup 207}Pb that might produce energy deposits at the {sup 76}Ge Q{sub {beta}{beta}} in Ge detectors used for 0{nu}{beta}{beta} searches. The levels that produce these {gamma} rays can be excited by n,n'{gamma} reactions, but the cross sections are small and previously unmeasured. The cross section on {sup nat}Pb to produce the 2041-keV {gamma} ray from {sup 206}Pb is measured to be 3.1 {+-} 0.6 (stat.) {+-} 0.3 (syst.) mb at {approx} 9.6 MeV. The cross section on {sup nat}Pb to produce the 3062-keV {gamma} ray from {sup 207}Pb is measured to be 4.3 {+-} 0.8 (stat.) {+-} 0.4 (syst.) mb at the same energy. We place upper limits on the cross sections for exciting some other levels in Pb that have transition energies corresponding to Q{sub {beta}{beta}} in orhter {beta}{beta} isotopes.

  9. Characterization of large area, thick, and segmented silicon detector for electron and proton detection from neutron beta decay experiments in the cold and ultracold energies

    NASA Astrophysics Data System (ADS)

    Salas Bacci, Americo; McGaughey, Patrick; Baessler, Stefan; Broussard, Leah; Makela, Mark; Mirabal, Jacqueline; Pattie, Robert; Pocanic, Dinko; Hoedl, Seth; Sjue, Sky; Penttila, Seppo; Hasan, Syed; Wilburn, Scott; Young, Albert; Zeck, Bryan; Wang, Zhehui

    2012-10-01

    The ``Nab'' and ``UCNB'' collaborations have proposed to measure the correlation parameters in neutron β-decay at Oak Ridge and Los Alamos National Laboratory, using a novel detector design and electromagnetic spectrometers. Two large area, thick, hexagonal-segmented Silicon detectors containing 128 pixels per detector are going to be used to detect the electron and proton from neutron decay. Both Silicon detectors are connected by magnetic field lines of few Tesla field strength, and set on an electrostatic potential, such that protons can be accelerated up to 30 keV in order to be detected. We report the characterization, operation, proton detection from 15 to 30 keV, total pulse height defect, computation of atomic scattering defect, recombination defect, and evaluation of dead layer for these large area and thick Silicon detectors.

  10. Half-life systematics across the N=126 shell closure: role of first-forbidden transitions in the β decay of heavy neutron-rich nuclei.

    PubMed

    Morales, A I; Benlliure, J; Kurtukián-Nieto, T; Schmidt, K-H; Verma, S; Regan, P H; Podolyák, Z; Górska, M; Pietri, S; Kumar, R; Casarejos, E; Al-Dahan, N; Algora, A; Alkhomashi, N; Álvarez-Pol, H; Benzoni, G; Blazhev, A; Boutachkov, P; Bruce, A M; Cáceres, L S; Cullen, I J; Denis Bacelar, A M; Doornenbal, P; Estévez-Aguado, M E; Farrelly, G; Fujita, Y; Garnsworthy, A B; Gelletly, W; Gerl, J; Grebosz, J; Hoischen, R; Kojouharov, I; Kurz, N; Lalkovski, S; Liu, Z; Mihai, C; Molina, F; Mücher, D; Rubio, B; Shaffner, H; Steer, S J; Tamii, A; Tashenov, S; Valiente-Dobón, J J; Walker, P M; Wollersheim, H J; Woods, P J

    2014-07-11

    This Letter reports on a systematic study of β-decay half-lives of neutron-rich nuclei around doubly magic (208)Pb. The lifetimes of the 126-neutron shell isotone (204)Pt and the neighboring (200-202)Ir, (203)Pt, (204)Au are presented together with other 19 half-lives measured during the "stopped beam" campaign of the rare isotope investigations at GSI collaboration. The results constrain the main nuclear theories used in calculations of r-process nucleosynthesis. Predictions based on a statistical macroscopic description of the first-forbidden β strength reveal significant deviations for most of the nuclei with N<126. In contrast, theories including a fully microscopic treatment of allowed and first-forbidden transitions reproduce more satisfactorily the trend in the measured half-lives for the nuclei in this region, where the r-process pathway passes through during β decay back to stability. PMID:25062171

  11. Decay Properties and State Lifetimes in 128Te from an Inelastic Neutron Scattering (n,ng) Reaction.

    NASA Astrophysics Data System (ADS)

    Boehringer, John

    2002-03-01

    Gamma-ray spectroscopy following inelastic neutron scattering has been used to study the low-lying level structure of the 128Te nucleus. Measurements were made at the University of Kentucky Van de Graaff Laboratory; excited levels to 3.3 MeV excitation were studied. Gamma-ray angular distributions and Doppler shifts were measured at 2.2, 2.8 and 3.3 MeV, and g-ray excitation functions were measured between 2 MeV and 3.4 MeV in 90 keV steps. These data have been used to compile a level and decay scheme, deduce level spins and parities, lifetimes, branching ratios and multipole-mixing ratios. Electromagnetic transition rates determined from these data will be presented. Experimental results will be compared to model calculations from the interacting boson model and the particle-core coupling model. This work was supported in part by a grant from the National Science Foundation.

  12. The Ultraviolet Albedo of Ganymede

    NASA Technical Reports Server (NTRS)

    McGrath, Melissa; Hendrix, Amanda

    2013-01-01

    A large set of ultraviolet images of Ganymede have been acquired with the Hubble Space Telescope over the last 15 years. These images have been used almost exclusively to study Ganymede's stunning auroral emissions (Feldman et al. 2000; Eviatar et al. 2001; McGrath et al. 2004; Saur et al. 2011; McGrath et al. 2013), and even the most basic information about Ganymede's UV albedo has yet to be gleaned from these data. We will present a first-cut analysis of both disk-averaged and spatially-resolved UV albedos of Ganymede, with focus on the spatially-resolved Lyman-alpha albedo, which has never been considered previously for this satellite. Ganymede's visibly bright regions are known to be rich in water ice, while the visibly dark regions seem to be more carbonaceous (Carlson et al., 1996). At Lyman-alpha, these two species should also have very different albedo values.

  13. Cosmic Ray Albedo Proton Yield Correlated with Lunar Elemental Abundances

    NASA Astrophysics Data System (ADS)

    Wilson, J. K.; Spence, H. E.; Case, A. W.; Blake, J. B.; Golightly, M. J.; Kasper, J. C.; Looper, M. D.; Mazur, J. E.; Schwadron, N. A.; Townsend, L. W.; Zeitlin, C. J.

    2012-12-01

    High energy cosmic rays constantly bombard the lunar regolith, producing secondary "albedo" or "splash" particles like protons and neutrons, some of which escape back to space. Two lunar missions, Lunar Prospector and the Lunar Reconnaissance Orbiter (LRO), have shown that the energy distribution of albedo neutrons is modulated by the elemental composition of the lunar regolith[1-4], with reduced neutron fluxes near the lunar poles being the result of collisions with hydrogen nuclei in ice deposits[5] in permanently shadowed craters. Here we investigate an analogous phenomenon with high energy (~100 MeV) lunar albedo protons. LRO has been observing the surface and environment of the Moon since June of 2009. The CRaTER instrument (Cosmic Ray Telescope for the Effects of Radiation) on LRO is designed to characterize the lunar radiation environment and its effects on simulated human tissue. CRaTER's multiple solid-state detectors can discriminate the different elements in the galactic cosmic ray (GCR) population above ~10 MeV/nucleon, and can also distinguish between primary GCR protons arriving from deep space and albedo particles propagating up from the lunar surface. We use albedo protons with energies greater than 60 MeV to construct a cosmic ray albedo proton map of the Moon. The yield of albedo protons is proportional to the rate of lunar proton detections divided by the rate of incoming GCR detections. The map accounts for time variation in the albedo particles driven by time variations in the primary GCR population, thus revealing any true spatial variation of the albedo proton yield. Our current map is a significant improvement over the proof-of-concept map of Wilson et al.[6]. In addition to including twelve more months of CRaTER data here, we use more numerous minimum ionizing GCR protons for normalization, and we make use of all six of CRaTER's detectors to reduce contamination from spurious non-proton events in the data stream. We find find that the flux

  14. Variation in lunar neutron dose estimates.

    PubMed

    Slaba, Tony C; Blattnig, Steve R; Clowdsley, Martha S

    2011-12-01

    The radiation environment on the Moon includes albedo neutrons produced by primary particles interacting with the lunar surface. In this work, HZETRN2010 is used to calculate the albedo neutron contribution to effective dose as a function of shielding thickness for four different space radiation environments and to determine to what extent various factors affect such estimates. First, albedo neutron spectra computed with HZETRN2010 are compared to Monte Carlo results in various radiation environments. Next, the impact of lunar regolith composition on the albedo neutron spectrum is examined, and the variation on effective dose caused by neutron fluence-to-effective dose conversion coefficients is studied. A methodology for computing effective dose in detailed human phantoms using HZETRN2010 is also discussed and compared. Finally, the combined variation caused by environmental models, shielding materials, shielding thickness, regolith composition and conversion coefficients on the albedo neutron contribution to effective dose is determined. It is shown that a single percentage number for characterizing the albedo neutron contribution to effective dose can be misleading. In general, the albedo neutron contribution to effective dose is found to vary between 1-32%, with the environmental model, shielding material and shielding thickness being the driving factors that determine the exact contribution. It is also shown that polyethylene or other hydrogen-rich materials may be used to mitigate the albedo neutron exposure. PMID:21859325

  15. SCAP. Point Kernel Single or Albedo Scatter

    SciTech Connect

    Disney, R.K.; Bevan, S.E.

    1982-08-05

    SCAP solves for radiation transport in complex geometries using the single or albedo-scatter point kernel method. The program is designed to calculate the neutron or gamma-ray radiation level at detector points located within or outside a complex radiation scatter source geometry or a user-specified discrete scattering volume. The geometry is described by zones bounded by intersecting quadratic surfaces with an arbitrary maximum number of boundary surfaces per zone. The anisotropic point sources are described as point-wise energy dependent distributions of polar angles on a meridian; isotropic point sources may be specified also. The attenuation function for gamma rays is an exponential function on the primary source leg and the scatter leg with a buildup factor approximation to account for multiple scatter on the scatter leg. The neutron attenuation function is an exponential function using neutron removal cross sections on the primary source leg and scatter leg. Line or volumetric sources can be represented as distributions of isotropic point sources, with uncollided line-of-sight attenuation and buildup calculated between each source point and the detector point.

  16. Spectral albedos of midlatitude snowpacks

    NASA Technical Reports Server (NTRS)

    Choudhury, B.

    1981-01-01

    Spectral albedos of impure-nonhomogeneous snowpacks, typical of midlatitudes, from 400 to 2200 nm were modeled through a numerical solution of the radiative transfer equation in the two-stream approximation. Discrete depth-dependent values of density, grain size and impurity concentration were used to characterize the snowpacks. The model is for diffuse incident radiation, and the numerical method is based on doubling and invariant imbedding. The effect of soot impurities on snowpack albedos is illustrated when a snowpack is several centimeters deep and soot reduces the albedos at visible wavelengths, however, when a snowpack is only a few centimeters deep, soot may increase the albedos at visible wavelengths. By adjusting soot content and snow grain size, good quantitative agreement with some observations at the Cascade Mountains (Washington) and at Point Barrow (Alaska) are obtained; however, the model grain sizes are found to be fifty to four hundred percent larger than the measured values. For satellite snowcover observations, a model for effective albedo of partially snow-covered areas was developed and compared with some NOAA-2 observations of the southeastern United States.

  17. Signatures of volatiles in the lunar proton albedo

    NASA Astrophysics Data System (ADS)

    Schwadron, N. A.; Wilson, J. K.; Looper, M. D.; Jordan, A. P.; Spence, H. E.; Blake, J. B.; Case, A. W.; Iwata, Y.; Kasper, J. C.; Farrell, W. M.; Lawrence, D. J.; Livadiotis, G.; Mazur, J.; Petro, N.; Pieters, C.; Robinson, M. S.; Smith, S.; Townsend, L. W.; Zeitlin, C.

    2016-07-01

    We find evidence for hydrated material in the lunar regolith using "albedo protons" measured with the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO). Fluxes of these albedo protons, which are emitted from the regolith due to steady bombardment by high energy radiation (Galactic Cosmic Rays), are observed to peak near the poles, and are inconsistent with the latitude trends of heavy element enrichment (e.g., enhanced Fe abundance). The latitudinal distribution of albedo protons anti-correlates with that of epithermal or high energy neutrons. The high latitude enhancement may be due to the conversion of upward directed secondary neutrons from the lunar regolith into tertiary protons due to neutron-proton collisions in hydrated regolith that is more prevalent near the poles. The CRaTER instrument may thus provide important measurements of volatile distributions within regolith at the Moon and potentially, with similar sensors and observations, at other bodies within the Solar System.

  18. Decays of {sup 131}In, {sup 131}Sn, and the position of the h{sub 11/2} neutron hole state

    SciTech Connect

    Fogelberg, B.; Mach, H.; Sanchez-Vega, M.; Lindroth, A.; Ramstroem, E.; Gausemel, H.; Hoff, P.; Mezilev, K.A.; Genevey, J.; Pinston, J.A.

    2004-09-01

    The decays of the three isomers of {sup 131}In and the total decay energies of the two isomers of {sup 131}Sn have been studied in high sensitivity experiments at the OSIRIS mass separator. The main purpose of the investigation was to determine the position of the neutron hole h{sub 11/2} state, since a previous determination appeared to be in error. The present results support a small separation of the d{sub 3/2} and h{sub 11/2} neutron hole states. The new value obtained from measurements of decay energies is 69{+-}14 keV. A more precise value of 65.1 keV may be deduced from the level scheme of {sup 131}Sn obtained currently, however without firm support from coincidence data. This relatively low excitation energy of the h{sub 11/2} state is in agreement with systematics and in disagreement with the previous determination. A re-evaluation of the Q{sub {beta}} values and isomer spacings of {sup 131}In has been made.

  19. Evaluation of the β+-decay log ft value with inclusion of the neutron-proton pairing and particle-number projection

    NASA Astrophysics Data System (ADS)

    Kerrouchi, S.; Allal, N. H.; Fellah, M.; Oudih, M. R.

    2016-01-01

    The neutron-proton isovector pairing effect on the beta-plus decay log ft values is studied in typical mirror N≃Z nuclei. The log ft values are calculated by including or not the isovector pairing before and after a particle-number projection using the Sharp-Bardeen-Cooper-Schrieffer (SBCS) method. It is shown that the values obtained after projection in the isovector pairing case are the closest ones to experimental data. The effect of the deformation of the mother and daughter nuclei on the log ft is also studied.

  20. Decay studies of the neutron-rich isotopes sup 168 Dy and sup 168 Ho sup g and the identification of the new isomer sup 168 Ho sup m

    SciTech Connect

    Chasteler, R.M.; Nitschke, J.M.; Firestone, R.B.; Vierinen, K.S.; Wilmarth, P.A. )

    1990-11-01

    Multinucleon transfer reactions between {sup 170}Er ions and {sup nat}W targets with on-line mass separation were used to produce neutron-rich {ital A}=168 isotopes. {beta} and {gamma} spectroscopy was used to study the decay of these activities. A new isomer of holmium, {sup 168}Ho{sup {ital m}}, was identified to decay by an isomeric transition with a half-life of 132(4) s. A decay scheme for the most neutron-rich {ital A}=168 isotope, 8.8(3)-min {sup 168}Dy, was determined. Also, a new {ital Q}{sub {beta}}{sup {minus}} value of 2.93(3) MeV for the decay of 3.0-min {sup 168}Ho{sup {ital g}} has been obtained.

  1. Shape coexistence, shape evolution and Gamow-Teller {beta}-decay of neutron-rich A Asymptotically-Equal-To 100 nuclei

    SciTech Connect

    Petrovici, A.; Schmid, K. W.; Faessler, A.

    2012-11-20

    The structure of neutron-rich nuclei in the A Asymptotically-Equal-To 100 mass region relevant for the astrophysical r process manifests drastic changes in some isotopic chains and often sudden variations of particular nuclear properties have been identified. For a realistic description of the evolution in structure with increasing energy, spin, and isospin determined by shape coexistence and mixing beyond-mean-field approaches are required. Our recent studies represent an attempt to the self-consistent description of the shape coexistence phenomena in neutron-rich A Asymptotically-Equal-To 100 nuclei within the complex Excited Vampir variational model with symmetry projection before variation using a realistic effective interaction based on the Bonn A potential in a large model space. Results concerning the triple shape coexistence and the shape evolution in the N=58 Sr and Zr isotopes, the shape evolution in a chain of Zr nuclei, as well as the Gamow-Teller {beta}-decay properties of neutron-rich Zr and Tc nuclei are presented.

  2. Operational comparison of TLD albedo dosemeters and solid state nuclear tracks detectors in fuel fabrication facilities.

    PubMed

    Tsujimura, N; Takada, C; Yoshida, T; Momose, T

    2007-01-01

    The authors carried out an operational study that compared the use of TLD albedo dosemeters and solid state nuclear tracks detector in plutonium environments of Japan Nuclear Cycle Development Institute, Tokai Works. A selected group of workers engaged in the fabrication process of MOX (Plutonium-Uranium mixed oxide) fuel wore both TLD albedo dosemeters and solid state nuclear tracks detectors. The TL readings were generally proportional to the counted etch-pits, and thus the dose equivalent results obtained from TLD albedo dosemeter agreed with those from solid state nuclear tracks detector within a factor of 1.5. This result indicates that, in the workplaces of the MOX fuel plants, the neutron spectrum remained almost constant in terms of time and space, and the appropriate range of field-specific correction with spectrum variations was small in albedo dosimetry. PMID:17337735

  3. Accuracy of neutron self-activation method with iodine-containing scintillators for quantifying 128I generation using decay-fitting technique

    NASA Astrophysics Data System (ADS)

    Nohtomi, Akihiro; Wakabayashi, Genichiro

    2015-11-01

    We evaluated the accuracy of a self-activation method with iodine-containing scintillators in quantifying 128I generation in an activation detector; the self-activation method was recently proposed for photo-neutron on-line measurements around X-ray radiotherapy machines. Here, we consider the accuracy of determining the initial count rate R0, observed just after termination of neutron irradiation of the activation detector. The value R0 is directly related to the amount of activity generated by incident neutrons; the detection efficiency of radiation emitted from the activity should be taken into account for such an evaluation. Decay curves of 128I activity were numerically simulated by a computer program for various conditions including different initial count rates (R0) and background rates (RB), as well as counting statistical fluctuations. The data points sampled at minute intervals and integrated over the same period were fit by a non-linear least-squares fitting routine to obtain the value R0 as a fitting parameter with an associated uncertainty. The corresponding background rate RB was simultaneously calculated in the same fitting routine. Identical data sets were also evaluated by a well-known integration algorithm used for conventional activation methods and the results were compared with those of the proposed fitting method. When we fixed RB = 500 cpm, the relative uncertainty σR0 /R0 ≤ 0.02 was achieved for R0/RB ≥ 20 with 20 data points from 1 min to 20 min following the termination of neutron irradiation used in the fitting; σR0 /R0 ≤ 0.01 was achieved for R0/RB ≥ 50 with the same data points. Reasonable relative uncertainties to evaluate initial count rates were reached by the decay-fitting method using practically realistic sampling numbers. These results clarified the theoretical limits of the fitting method. The integration method was found to be potentially vulnerable to short-term variations in background levels, especially

  4. Measurements and analyses of decay radioactivity induced in simulated deuterium-tritium neutron environments for fusion reactor structural materials

    SciTech Connect

    Ikeda, Y.; Konno, C.; Kosako, K.; Oyama, Y.; Maekawa, F.; Maekawa, H.; Kumar, A.; Youssef, M.Z.; Abdou, M.A.

    1995-08-01

    To meet urgent requirements for data validation, an experimental analysis has been carried out for isotopic radioactivity induced by deuterium-tritium neutron irradiation in structural materials. The primary objective is to examine the adequacy of the activation cross sections implemented in the current activation calculation codes considered for use in fusion reactor nuclear design. Four activation cross-section libraries, namely, JENDL, LIB90, REAC{sup *}63, and REAC{sup *}175 were investigated in this current analysis. The isotopic induced radioactivity calculations using these four libraries are compared with experimental values obtained in the Japan Atomic Energy Research Institute/U.S. Department of Energy collaborative program on fusion blanket neutronics. The nine materials studied are aluminum, silicon, titanium, vanadium, chromium, MnCu alloy, iron, nickel, niobium, and Type 316 stainless steel. The adequacy of the cross sections is investigated through the calculation to experiment analysis. As a result, most of the discrepancies in the calculations from experiments can be explained by inadequate activation cross sections. In addition, uncertainties due to neutron energy groups and neutron transport calculation are considered. The JENDL library gives the best agreement with experiments, followed by REAC{sup *}175, LIB90, and REAC{sup *}63, in this order. 45 refs., 32 figs., 5 tabs.

  5. β-decay half-lives of new neutron-rich rare-earth isotopes 159Pm,162Sm, and 166Gd

    NASA Astrophysics Data System (ADS)

    Ichikawa, S.; Asai, M.; Tsukada, K.; Haba, H.; Nagame, Y.; Shibata, M.; Sakama, M.; Kojima, Y.

    2005-06-01

    The new neutron-rich rare-earth isotopes 159Pm, 162Sm, and 166Gd produced in the proton-induced fission of 238U were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The half-lives of 159Pm, 162Sm, and 166Gd were determined to be 1.5 ± 0.2, 2.4 ± 0.5, and 4.8 ± 1.0 s respectively. The partial decay scheme of 166Gd was constructed from γγ-coincidence data. A more accurate half-life value of 25.6 ± 2.2 s was obtained for the previously identified isotope 166Tb. The half-lives measured in the present study are in good agreement with the theoretical predictions calculated by the second generation of the gross theory with the atomic masses evaluated by Audi and Wapstra.

  6. Effect of the electron decay of metallic fission products on the chemical and phase compositions of an uranium-plutonium fuel irradiated by fast neutrons

    NASA Astrophysics Data System (ADS)

    Bondarenko, G. G.; Bulatov, G. S.; Gedgovd, K. N.; Lyubimov, D. Yu.; Yakushkin, M. M.

    2011-11-01

    After fast-neutron irradiation, uranium-plutonium nitride U0.8Pu0.2N is shown to acquire a complex structure consisting of a solid solution that is based on the nitrides of uranium, plutonium, americium, neptunium, zirconium, yttrium, and lanthanides and contains condensed phases U2N3, CeRu2, BaTe, Ba3N2, CsI, Sr3N2, LaSe, metallic molybdenum, technetium, and U(Ru, Rh, Pd)3 intermetallics. The contents and compositions of these phases are calculated at a temperature of 900 K and a burn-up fraction up to 14% (U + Pu). The change in the composition of the irradiated uranium-plutonium nitride is studied during the electron decay of metallic radionuclides. The kinetics of transformation of U103Ru3, 137CsI, 140Ba3N2, and 241PuN is calculated.

  7. The Ultraviolet Albedo of Ganymede

    NASA Astrophysics Data System (ADS)

    McGrath, Melissa; Hendrix, A.

    2013-10-01

    A large set of ultraviolet images of Ganymede have been acquired with the Hubble Space Telescope over the last 15 years. These images have been used almost exclusively to study Ganymede’s stunning auroral emissions (Feldman et al. 2000; Eviatar et al. 2001; McGrath et al. 2004; Saur et al. 2011; McGrath et al. 2013), and even the most basic information about Ganymede’s UV albedo has yet to be gleaned from these data. We will present a first-cut analysis of both disk-averaged and spatially-resolved UV albedos of Ganymede, with focus on the spatially-resolved Lyman-alpha albedo, which has never been considered previously for this satellite. Ganymede's visibly bright regions are known to be rich in water ice, while the visibly dark regions seem to be more carbonaceous (Carlson et al., 1996). At Lyman-alpha, these two species should also have very different albedo values. References Carlson, R. and 39 co-authors, Near-infrared spectroscopy and spectral mapping of Jupiter and the Galilean satellites: Results from Galileo’s initial orbit, Science, 274, 385-388, 1996. Eviatar, A., D. F. Strobel, B. C. Wolven, P. D. Feldman, M. A. McGrath, and D. J. Williams, Excitation of the Ganymede ultraviolet aurora, Astrophys. J, 555, 1013-1019, 2001. Feldman, P. D., M. A. McGrath, D. F. Strobel, H. W. Moos, K. D. Retherford, and B. C. Wolven, HST/STIS imaging of ultraviolet aurora on Ganymede, Astrophys. J, 535, 1085-1090, 2000. McGrath M. A., Lellouch E., Strobel D. F., Feldman P. D., Johnson R. E., Satellite Atmospheres, Chapter 19 in Jupiter: The Planet, Satellites and Magnetosphere, ed. F. Bagenal, T. Dowling, W. McKinnon, Cambridge University Press, 2004. McGrath M. A., Jia, Xianzhe; Retherford, Kurt; Feldman, Paul D.; Strobel, Darrell F.; Saur, Joachim, Aurora on Ganymede, J. Geophys. Res., doi: 10.1002/jgra.50122, 2013. Saur, J., S. Duling, S., L. Roth, P. D. Feldman, D. F. Strobel, K. D. Retherford, M. A. McGrath, A. Wennmacher, American Geophysical Union, Fall Meeting

  8. Long-term Passive Mode Data Measured by the Dynamic Albedo of Neutrons (DAN) Instrument onboard Mars Science Laboratory (MSL) and Comparison to REMS Surface Pressure and Temperature Measurements

    NASA Astrophysics Data System (ADS)

    Jun, I.; Mitrofanov, I. G.; Litvak, M. L.; Sanin, A. B.; Martín-Torres, J.; Zorzano, M. P.; Boynton, W. V.; Fedosov, F.; Golovin, D.; Hardgrove, C. J.; Harshman, K.; Kozyrev, A.; Kuzmin, R.; Malakhov, A. V.; Mischna, M. A.; Moersch, J.; Mokrousov, M.; Nikiforov, S.; Tate, C. G.

    2014-12-01

    Since the landing in August 2012, DAN has provided a wealth of scientific data from the successful surface operation in both Active mode and Passive mode. While the main DAN science investigation so far has focused in estimating the contents of water-equivalent-hydrogen (WEH) and chlorine-equivalent-neutron-absorption in the surface, here we will provide/discuss low energy (less than about 1 keV) background neutron environment at the Martian surface as measured by DAN Passive mode operation. Passive mode measurements have been done on almost every sols with durations ranging from 1 hour to ~9 hour, covering different times of a day. Neutrons from the onboard power source Multi Mission Radioisotope Thermonuclear Generator (MMRTG) and induced by Galactic Cosmic Ray (GCR)/Solar Energetic Particles (SEP) interactions with the Martian atmosphere and the surface material contribute to the DAN passive data. An approach to separate out the respective contributions from the DAN total count rates was developed previously (Jun et al., 2013) using the data collected at Rocknest (where the rover stayed from sol 60 to sol 100). The main goal of this paper is to extend the same analysis to other locations encountered during the rover traverse especially to understand the long-term (through Sol 800, covering more than 1 Martian year) behavior of the neutron environment at the Martian surface as measured by DAN in response to variation of the free space GCR/SEP environment. Extensive Monte Carlo transport simulations using Monte Carlo N-Particle eXtended (MCNPX) have been performed to support the analysis and to aid interpretation of the DAN passive data. In addition, the DAN passive data are compared to the long-term surface temperature and pressure data (both measured and modeled) from Rover Environmental Monitoring Station (REMS) to investigate possible correlation of the DAN data with ambient environmental conditions.

  9. Tentative study of nuclear charge radii for neutron-deficient nuclei around the Z = 82 shell from experimental α decay data

    NASA Astrophysics Data System (ADS)

    Qian, Yibin; Ren, Zhongzhou

    2016-01-01

    We tentatively investigate the root-mean-square (rms) nuclear charge radii of odd-A Po and Pb isotopes plus Tl isotopes, particularly concerning these difficultly-detected nuclei along with short lifetimes, via various data on α decay. Within the density-dependent cluster model, the density distributions of studied daughter nuclei are determined by exactly reproducing the corresponding experimental α decay half-lives, which leads the final results of nuclear charge radii. In addition, our recently proposed formula deducing the charge radii is extended to this study for comparison. Whether it concerns the ground or isomeric state of target nuclei, the extracted nuclear charge radii are found to be in good agreement with the measured values. Sequential predictions on the rms charge radii are subsequently made for these neutron-deficient nuclei and especially for the rarely detected Bi isotopic chain, which are expected to be useful for future measurements. Moreover, the variety of α-preformation factors is analyzed in the scheme of valence nucleon number to pursue the further improvement of the model. This may be considered as an effective effort to obtain the charge radii of ground and even low-lying excited states for exotic nuclei near the proton-dripline.

  10. Neutron-Induced Partial Cross-Section Measurements on ^76Ge Motivated by The Majorana Project 0νββ Decay Search

    NASA Astrophysics Data System (ADS)

    Hilderbrand, S.; Kwan, E.; Angell, C.; Fallin, B.; Howell, C. R.; Hutcheson, A.; Karwowski, H. J.; Kelley, J. H.; Tonchev, A. P.; Tornow, W.; Masters, D. B.; Pedroni, R. S.; Weisel, G. J.

    2007-10-01

    The goal of the Majorana Collaboration is to study 0νββ in order to verify that the neutrino is its own anti-particle; and if so, what is the mass ofthe electron neutrino. Observation of a sharp peak at the ββ endpoint energy will confirm 0νββ as a decay mode, and determination of the partial width will determine the matrix element which depends directly on the electron neutrino mass. In order to observe and verify the existence of 0νββ, it is important to reduce intrinsic, extrinsic,& cosmogenic backgrounds. The Majorana Project will operate with HPGe detectors deep underground to achieve a low-background environment. Recent advances in signal processing and detector design have also enabled scientists to further understand background sources. γ-ray spectra from the interaction of pulsed mono-energetic neutrons with ^76Ge were measured at TUNL using segmented HPGe clover detectors. The neutron-induced partial cross-sections for γ transitions in ^76Ge were measured at En = 8 and 12MeV.

  11. The temporal scale research of MODIS albedo product authenticity verification

    NASA Astrophysics Data System (ADS)

    Cao, Yongxing; Xue, Zhihang; Cheng, Hui; Xiong, Yajv; Chen, Yunping; Tong, Ling

    2016-06-01

    This study introduces a method that normalizes the inversed ETM+ albedo to the local solar noon albedo for the temporal scale of the MODIS albedo validation. Firstly, the statistical relation model between the surface albedo and the solar elevation angle was set up, and then deducing relationship between ETM+ albedo and the solar elevation angle, so the ETM+ albedo at local solar noon could be got. Secondly, the ground measurement albedo at the local solar noon was used to assess the inversed ETM+ albedo and the normalized albedo. The experiment results show that the method can effectively improve the accuracy of product certification.

  12. Nuclear structure from radioactive decay. Annual progress report

    SciTech Connect

    Wood, J.L.

    1991-09-30

    This report discusses nuclear structure from radioactive decay of the following: Neutron-Deficient Iridium Isotopes; Neutron-Deficient Platinum Isotopes; Neutron-Deficient Gold Isotopes; Neutron-Deficient Mercury Isotopes; Neutron-Deficient Thallium Isotopes; Neutron-Deficient Lead Isotopes; Neutron-Deficient Samarium Isotopes; Neutron-Deficient Promethium Isotopes; Neutron-Deficient Neodymium Isotopes; and Neutron-Deficient Praseodymium Isotopes. Also discussed are Nuclear Systematics and Models.

  13. Weak decay of hypernuclei

    SciTech Connect

    Grace, R.

    1983-01-01

    The Moby Dick spectrometer (at BNL) in coincidence with a range spectrometer and a TOF neutron detector will be used to study the weak decay modes of /sup 12/C. The Moby Dick spectrometer will be used to reconstruct and tag events in which specific hypernuclear states are formed in the reaction K/sup -/ + /sup 12/C ..-->.. ..pi../sup -/ + /sup 12/C. Subsequent emission of decay products (pions, protons and neutrons) in coincidence with the fast forward pion will be detected in a time and range spectrometer, and a neutron detector.

  14. Lunar Proton Albedo Anomalies: Soil, Surveyors, and Statistics

    NASA Astrophysics Data System (ADS)

    Wilson, J. K.; Schwadron, N.; Spence, H. E.; Case, A. W.; Golightly, M. J.; Jordan, A.; Looper, M. D.; Petro, N. E.; Robinson, M. S.; Stubbs, T. J.; Zeitlin, C. J.; Blake, J. B.; Kasper, J. C.; Mazur, J. E.; Smith, S. S.; Townsend, L. W.

    2014-12-01

    Since the launch of LRO in 2009, the CRaTER instrument has been mapping albedo protons (~100 MeV) from the Moon. These protons are produced by nuclear spallation, a consequence of galactic cosmic ray (GCR) bombardment of the lunar regolith. Just as spalled neutrons and gamma rays reveal elemental abundances in the lunar regolith, albedo protons may be a complimentary method for mapping compositional variations. We presently find that the lunar maria have an average proton yield 0.9% ±0.3% higher than the average yield in the highlands; this is consistent with neutron data that is sensitive to the regolith's average atomic weight. We also see cases where two or more adjacent pixels (15° × 15°) have significantly anomalous yields above or below the mean. These include two high-yielding regions in the maria, and three low-yielding regions in the far-side highlands. Some of the regions could be artifacts of Poisson noise, but for completeness we consider possible effects from compositional anomalies in the lunar regolith, including pyroclastic flows, antipodes of fresh craters, and so-called "red spots". We also consider man-made landers and crash sites that may have brought elements not normally found in the lunar regolith.

  15. {beta}-decay half-lives of new neutron-rich isotopes of elements from Pm to Tb

    SciTech Connect

    Ichikawa, S.; Asai, M.; Tsukada, K.; Nishinaka, I.; Nagame, Y.; Osa, A.; Sakama, M.; Oura, Y.; Kojima, Y.; Shibata, M.; Kawade, K.

    1999-11-16

    Eight new neutron-rich lanthanide isotopes produced in the proton-induced fission of {sup 238}U have been identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. For six of these, each half-life was determined: {sup 159}Pm (2{+-}1 s), {sup 161}Sm (4.8{+-}0.8 s), {sup 165}Gd (10.3{+-}1.6 s), {sup 166}Tb (21{+-}6 s), {sup 167}Tb (19.4{+-}2.7 s) and {sup 168}Tb (8.2{+-}1.3 s). The observed half-lives were compared with theoretical calculations. The recent calculation by the gross theory with the new one-particle strength function shows quite good agreement with the experimental half-lives.

  16. {beta}-Decay Half-Lives of New Neutron-Rich Isotopes of Elements from Pm to Tb

    SciTech Connect

    S. Ichikawa; M. Asai; K. Tsukada; A. Osa; M. Sakama; Y. Kojima; M. Shibata; I. Nishinaka; Y. Nagame; Y. Oura; K. Kawade

    1999-12-31

    Eight new neutron-rich lanthanide isotopes produced in the proton-induced fission of {sup 238}U have been identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. For six of these, each half-life was determined: {sup 159}Pm (2 {+-} 1 s), {sup 161}Sm (4.8 {+-} 0.8 s), {sup 165}Gd (10.3 {+-} 1.6 s), {sup 166}Tb (21 {+-} 6 s), {sup 167}Tb (19.4 {+-} 2.7 s) and {sup 168}Tb (8.2 {+-} 1.3 s). The observed half-lives were compared with theoretical calculations. The recent calculation by the gross theory with the new one-particle strength function shows quite good agreement with the experimental half-lives.

  17. Variability of albedo and utility of the MODIS albedo product in forested wetlands

    USGS Publications Warehouse

    Sumner, David M.; Wu, Qinglong; Pathak, Chandra S.

    2011-01-01

    Albedo was monitored over a two-year period (beginning April 2008) at three forested wetland sites in Florida, USA using up- and down-ward facing pyranometers. Water level, above and below land surface, is the primary control on the temporal variability of daily albedo. Relatively low reflectivity of water accounts for the observed reductions in albedo with increased inundation of the forest floor. Enhanced canopy shading of the forest floor was responsible for lower sensitivity of albedo to water level at the most dense forest site. At one site, the most dramatic reduction in daily albedo was observed during the inundation of a highly-reflective, calcareous periphyton-covered land surface. Satellite-based Moderate-Resolution Imaging Spectroradiometer (MODIS) estimates of albedo compare favorably with measured albedo. Use of MODIS albedo values in net radiation computations introduced a root mean squared error of less than 4.7 W/m2 and a mean, annual bias of less than 2.3 W/m2 (1.7%). These results suggest that MODIS-estimated albedo values can reliably be used to capture areal and temporal variations in albedo that are important to the surface energy balance.

  18. Arctic sea ice albedo from AVHRR

    SciTech Connect

    Lindsay, R.W.; Rothrock, D.A.

    1994-11-01

    The seasonal cycle of surface albedo of sea ice in the Arctic is estimated from measurements made with the Advanced Very High Resolution Radiometer (AVHRR) on the polar-orbiting satellites NOAA-10 and NOAA-11. The albedos of 145 200-km-square cells are analyzed. The cells are from March through September 1989 and include only those for which the sun is more than 10 deg above the horizon. Cloud masking is performed manually. Corrections are applied for instrument calibration, nonisotropic reflection, atmospheric interference, narrowband to broadband conversion, and normalization to a common solar zenith angle. The estimated albedos are relative, with the instrument gain set to give an albedo of 0.80 for ice floes in March and April. The mean values for the cloud-free portions of individual cells range from 0.18 to 0.91. Monthly averages of cells in the central Arctic range from 0.76 in April to 0.47 in August. The monthly averages of the within-cell standard deviations in the central Arctic are 0.04 in April and 0.06 in September. The surface albedo and surface temperature are correlated most strongly in March (R = -0.77) with little correlation in the summer. The monthly average lead fraction is determined from the mean potential open water, a scaled representation of the temperature or albedo between 0.0 (for ice) and 1.0 (for water); in the central Arctic it rises from an average 0.025 in the spring to 0.06 in September. Sparse data on aerosols, ozone, and water vapor in the atmospheric column contribute uncertainties to instantaneous, area-average albedos of 0.13, 0.04, and 0.08. Uncertainties in monthly average albedos are not this large. Contemporaneous estimation of these variables could reduce the uncertainty in the estimated albedo considerably.

  19. Detecting Low-Contrast Features in the Cosmic Ray Albedo Proton Yield Map of the Moon

    NASA Astrophysics Data System (ADS)

    Wilson, J. K.; Schwadron, N.; Spence, H.; Smith, S. S.; Golightly, M. J.; Case, A. W.; Stubbs, T. J.; Blake, J. B.; Kasper, J. C.; Looper, M. D.; Mazur, J. E.; Townsend, L. W.; Zeitlin, C. J.

    2013-12-01

    High energy cosmic rays constantly bombard the lunar regolith, producing (via nuclear evaporation[1]) secondary 'albedo' or 'splash' particles like protons and neutrons, some of which escape back to space. Lunar Prospector and the Lunar Reconnaissance Orbiter (LRO), have shown that the energy distribution of albedo neutrons is modulated by the elemental composition of the lunar regolith[2-5], and by ice deposits[6] in permanently shadowed polar craters. Here we investigate an analogous phenomenon with high energy lunar albedo protons. Using the CRaTER instrument (Cosmic Ray Telescope for the Effects of Radiation) on LRO, we measure albedo protons (60 to 150 MeV) to construct a cosmic ray albedo proton map of the Moon. Our current map is a significant improvement over the proof-of-concept map of Wilson et al.[7]. In addition to using more numerous minimum ionizing GCR protons for normalization, we filter out all solar particle enhancement periods and make use of all six of CRaTER's detectors to reduce contamination from spurious non-proton events in the data stream. The average yield of albedo protons from the maria is 0.8% × 0.4% higher than the yield from the highlands. In addition there appear to be localized peaks in the albedo proton yield that are co-located with peaks in trace elemental abundances as measured by the Lunar Prospector Gamma Ray Spectrometer. More data may reveal subtler proton yield variations correlated with latitude, time of day, or the locations of permanently shadowed craters, due to the presence of water frost. Given that the most obvious features in the map have a proton yield only 2σ above average, the search for more subtle regions of enhancement or reduction in proton yield will require precise corrections for small but systematic effects of time and spacecraft altitude on the apparent proton yield. We will show the effects of these trends as well as the latest version of the albedo proton map. References: [1] Bethe (1937) Rev. Mod

  20. {beta}-decay half-lives of new neutron-rich rare-earth isotopes {sup 159}Pm,{sup 162}Sm, and {sup 166}Gd

    SciTech Connect

    Ichikawa, S.; Asai, M.; Tsukada, K.; Nagame, Y.; Haba, H.; Shibata, M.; Sakama, M.; Kojima, Y.

    2005-06-01

    The new neutron-rich rare-earth isotopes {sup 159}Pm, {sup 162}Sm, and {sup 166}Gd produced in the proton-induced fission of {sup 238}U were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The half-lives of {sup 159}Pm, {sup 162}Sm, and {sup 166}Gd were determined to be 1.5 {+-} 0.2, 2.4 {+-} 0.5, and 4.8 {+-} 1.0 s respectively. The partial decay scheme of {sup 166}Gd was constructed from {gamma}{gamma}-coincidence data. A more accurate half-life value of 25.6 {+-} 2.2 s was obtained for the previously identified isotope {sup 166}Tb. The half-lives measured in the present study are in good agreement with the theoretical predictions calculated by the second generation of the gross theory with the atomic masses evaluated by Audi and Wapstra.

  1. β -Decay Half-Lives of 110 Neutron-Rich Nuclei across the N =82 Shell Gap: Implications for the Mechanism and Universality of the Astrophysical r Process

    NASA Astrophysics Data System (ADS)

    Lorusso, G.; Nishimura, S.; Xu, Z. Y.; Jungclaus, A.; Shimizu, Y.; Simpson, G. S.; Söderström, P.-A.; Watanabe, H.; Browne, F.; Doornenbal, P.; Gey, G.; Jung, H. S.; Meyer, B.; Sumikama, T.; Taprogge, J.; Vajta, Zs.; Wu, J.; Baba, H.; Benzoni, G.; Chae, K. Y.; Crespi, F. C. L.; Fukuda, N.; Gernhäuser, R.; Inabe, N.; Isobe, T.; Kajino, T.; Kameda, D.; Kim, G. D.; Kim, Y.-K.; Kojouharov, I.; Kondev, F. G.; Kubo, T.; Kurz, N.; Kwon, Y. K.; Lane, G. J.; Li, Z.; Montaner-Pizá, A.; Moschner, K.; Naqvi, F.; Niikura, M.; Nishibata, H.; Odahara, A.; Orlandi, R.; Patel, Z.; Podolyák, Zs.; Sakurai, H.; Schaffner, H.; Schury, P.; Shibagaki, S.; Steiger, K.; Suzuki, H.; Takeda, H.; Wendt, A.; Yagi, A.; Yoshinaga, K.

    2015-05-01

    The β -decay half-lives of 110 neutron-rich isotopes of the elements from Rb 37 to Sn 50 were measured at the Radioactive Isotope Beam Factory. The 40 new half-lives follow robust systematics and highlight the persistence of shell effects. The new data have direct implications for r -process calculations and reinforce the notion that the second (A ≈130 ) and the rare-earth-element (A ≈160 ) abundance peaks may result from the freeze-out of an (n ,γ )⇄(γ ,n ) equilibrium. In such an equilibrium, the new half-lives are important factors determining the abundance of rare-earth elements, and allow for a more reliable discussion of the r process universality. It is anticipated that universality may not extend to the elements Sn, Sb, I, and Cs, making the detection of these elements in metal-poor stars of the utmost importance to determine the exact conditions of individual r -process events.

  2. β -decay rates of odd-mass neutron-rich isotopes in the deformed quasiparticle random-phase approximation with realistic interactions

    NASA Astrophysics Data System (ADS)

    Ni, Dongdong; Ren, Zhongzhou

    2015-09-01

    The deformed quasiparticle random-phase approximation with realistic nucleon-nucleon interactions is extended for the β- decay of odd-mass neutron-rich Kr, Sr, Zr, and Mo isotopes, from their longest-lived isotopes to the experimentally unknown nuclei. The particle-particle and particle-hole channels of residual interactions are handled in large single-particle model spaces, based on the Brückner G matrix with charge-dependent Bonn nucleon-nucleon forces. Both allowed Gamow-Teller and first-forbidden transitions are considered and different treatments for odd-mass systems are emphasized. The sensitivity of the calculated results to the single-particle level scheme and the particle-particle strength is discussed. The calculated Gamow-Teller strengths are analyzed, together with the contributions from first-forbidden transitions. The calculated half-lives are found to agree well with the experimental data over the orders of magnitude from 10-2 to 103 s.

  3. Response of TLD-albedo and nuclear track dosimeters exposed to plutonium sources

    SciTech Connect

    Brackenbush, L.W.; Baumgartner, W.V.; Fix, J.J.

    1991-12-01

    Neutron dosimetry has been extensively studied at Hanford since the mid-1940s. At the present time, Hanford contractors use thermoluminescent dosimeter (TLD)-albedo dosimeters to record the neutron dose equivalent received by workers. The energy dependence of the TLD-albedo dosimeter has been recognized and documented since introduced at Hanford in 1964 and numerous studies have helped assure the accuracy of dosimeters. With the recent change in Hanford`s mission, there has been a significant decrease in the handling of plutonium tetrafluoride, and an increase in the handling of plutonium metal and plutonium oxide sources. This study was initiated to document the performance of the current Hanford TLD-albedo dosimeter under the low scatter conditions of the calibration laboratory and under the high scatter conditions in the work place under carefully controlled conditions at the Plutonium Finishing Plant (PFP). The neutron fields at the PFP facility were measured using a variety of instruments, including a multisphere spectrometer, tissue equivalent proportional counters, and specially calibrated rem meters. Various algorithms were used to evaluate the TLD-albedo dosimeters, and the results are given in this report. Using current algorithms, the dose equivalents evaluated for bare sources and sources with less than 2.5 cm (1 in.) of acrylic plastic shielding in high scatter conditions typical of glove box operations are reasonably accurate. Recently developed CR-39 track etch dosimeters (TEDs) were also exposed in the calibration laboratory and at the PFP. The results indicate that the TED dosimeters are quite accurate for both bare and moderated neutron sources. Until personnel dosimeter is available that incorporates a direct measure of the neutron dose to a person, technical uncertainties in the accuracy of the recorded data will continue.

  4. Response of TLD-albedo and nuclear track dosimeters exposed to plutonium sources

    SciTech Connect

    Brackenbush, L.W.; Baumgartner, W.V.; Fix, J.J.

    1991-12-01

    Neutron dosimetry has been extensively studied at Hanford since the mid-1940s. At the present time, Hanford contractors use thermoluminescent dosimeter (TLD)-albedo dosimeters to record the neutron dose equivalent received by workers. The energy dependence of the TLD-albedo dosimeter has been recognized and documented since introduced at Hanford in 1964 and numerous studies have helped assure the accuracy of dosimeters. With the recent change in Hanford's mission, there has been a significant decrease in the handling of plutonium tetrafluoride, and an increase in the handling of plutonium metal and plutonium oxide sources. This study was initiated to document the performance of the current Hanford TLD-albedo dosimeter under the low scatter conditions of the calibration laboratory and under the high scatter conditions in the work place under carefully controlled conditions at the Plutonium Finishing Plant (PFP). The neutron fields at the PFP facility were measured using a variety of instruments, including a multisphere spectrometer, tissue equivalent proportional counters, and specially calibrated rem meters. Various algorithms were used to evaluate the TLD-albedo dosimeters, and the results are given in this report. Using current algorithms, the dose equivalents evaluated for bare sources and sources with less than 2.5 cm (1 in.) of acrylic plastic shielding in high scatter conditions typical of glove box operations are reasonably accurate. Recently developed CR-39 track etch dosimeters (TEDs) were also exposed in the calibration laboratory and at the PFP. The results indicate that the TED dosimeters are quite accurate for both bare and moderated neutron sources. Until personnel dosimeter is available that incorporates a direct measure of the neutron dose to a person, technical uncertainties in the accuracy of the recorded data will continue.

  5. Mimas - Photometric roughness and albedo map

    NASA Technical Reports Server (NTRS)

    Verbiscer, Anne J.; Veverka, Joseph

    1992-01-01

    The backscattering phase function asssociated with bright icy satellites may render Hapke's (1986) isotropic approximation to multiple scattering inadequate. A reanalysis is accordingly conducted here of the Voyager observations of Mimas, using a modification to Hapke's equation that accommodates anisotropic multiple scattering, in order to characterize the physical and photometric properties of the heavily cratered icy surface. The roughness parameter of Mimas is in this way redefined, and an accurate albedo map is obtained which deminstrates small latitudinal and longitudinal albedo variations.

  6. The Albedo 'system' in the Cryosphere

    NASA Astrophysics Data System (ADS)

    Burkhart, J. F.; Storvold, R.; Solbo, S.; Pedersen, C. A.; Bogren, W.; Gerland, S.; Kylling, A.

    2012-12-01

    An Unmanned Aerial Vehicle (UAV) equipped with spectrometers making upward and downward measurements between 320-950nm was flown in Ny-Ålesund and Summit providing measurements of sea ice, ice sheet, and snow-covered tundra conditions. Concurrent with the flights, ground based stations with identical instrumentation were established. Micro snow pits and snow samples for black carbon analysis were collected at each measurement location. Preliminary analysis of the data show reflectance variability larger than albedo variability and more sensitive at longer wavelengths. This variability is driven by both the light absorbing aerosol component of the black carbon as well as physical aspects of the snow pack properties. At the each location, grain size variability, stratigraphy, and other physical snow pack properties are recorded. Analysis of black carbon content of the snow and inter-comparison with satellite retrieved measurements of albedo is ongoing. In this presentation the multiple measurements of albedo show that traditional measurements and estimates of albedo lack adequate characterization of the system within which the measurements are being made. Albedo is not a property of the surface being measured, but rather a property of a system and dependent on multiple parameters within the system that change seasonally, daily, and even hourly. We examine this system, and identify areas for improvement in current albedo parameterizations in the cryosphere.

  7. Sea ice-albedo climate feedback mechanism

    SciTech Connect

    Schramm, J.L.; Curry, J.A.; Ebert, E.E.

    1995-02-01

    The sea ice-albedo feedback mechanism over the Arctic Ocean multiyear sea ice is investigated by conducting a series of experiments using several one-dimensional models of the coupled sea ice-atmosphere system. In its simplest form, ice-albedo feedback is thought to be associated with a decrease in the areal cover of snow and ice and a corresponding increase in the surface temperature, further decreasing the area cover of snow and ice. It is shown that the sea ice-albedo feedback can operate even in multiyear pack ice, without the disappearance of this ice, associated with internal processes occurring within the multiyear ice pack (e.g., duration of the snow cover, ice thickness, ice distribution, lead fraction, and melt pond characteristics). The strength of the ice-albedo feedback mechanism is compared for several different thermodynamic sea ice models: a new model that includes ice thickness distribution., the Ebert and Curry model, the Mayjut and Untersteiner model, and the Semtner level-3 and level-0 models. The climate forcing is chosen to be a perturbation of the surface heat flux, and cloud and water vapor feedbacks are inoperative so that the effects of the sea ice-albedo feedback mechanism can be isolated. The inclusion of melt ponds significantly strengthens the ice-albedo feedback, while the ice thickness distribution decreases the strength of the modeled sea ice-albedo feedback. It is emphasized that accurately modeling present-day sea ice thickness is not adequate for a sea ice parameterization; the correct physical processes must be included so that the sea ice parameterization yields correct sensitivities to external forcing. 22 refs., 6 figs., 1 tab.

  8. Surface Albedo and Spectral Variability of Ceres

    NASA Astrophysics Data System (ADS)

    Li, Jian-Yang; Reddy, Vishnu; Nathues, Andreas; Le Corre, Lucille; Izawa, Matthew R. M.; Cloutis, Edward A.; Sykes, Mark V.; Carsenty, Uri; Castillo-Rogez, Julie C.; Hoffmann, Martin; Jaumann, Ralf; Krohn, Katrin; Mottola, Stefano; Prettyman, Thomas H.; Schaefer, Michael; Schenk, Paul; Schröder, Stefan E.; Williams, David A.; Smith, David E.; Zuber, Maria T.; Konopliv, Alexander S.; Park, Ryan S.; Raymond, Carol A.; Russell, Christopher T.

    2016-02-01

    Previous observations suggested that Ceres has active, but possibly sporadic, water outgassing as well as possibly varying spectral characteristics over a timescale of months. We used all available data of Ceres collected in the past three decades from the ground and the Hubble Space Telescope, as well as the newly acquired images by the Dawn  Framing Camera, to search for spectral and albedo variability on Ceres, on both a global scale and in local regions, particularly the bright spots inside the Occator crater, over timescales of a few months to decades. Our analysis has placed an upper limit on the possible temporal albedo variation on Ceres. Sporadic water vapor venting, or any possibly ongoing activity on Ceres, is not significant enough to change the albedo or the area of the bright features in the Occator crater by >15%, or the global albedo by >3% over the various timescales that we searched. Recently reported spectral slope variations can be explained by changing Sun-Ceres-Earth geometry. The active area on Ceres is less than 1 km2, too small to cause global albedo and spectral variations detectable in our data. Impact ejecta due to impacting projectiles of tens of meters in size like those known to cause observable changes to the surface albedo on Asteroid Scheila cannot cause detectable albedo change on Ceres due to its relatively large size and strong gravity. The water vapor activity on Ceres is independent of Ceres’ heliocentric distance, ruling out the possibility of the comet-like sublimation process as a possible mechanism driving the activity.

  9. Surface Albedo and Spectral Variability of Ceres

    NASA Astrophysics Data System (ADS)

    Li, Jian-Yang; Reddy, Vishnu; Nathues, Andreas; Le Corre, Lucille; Izawa, Matthew R. M.; Cloutis, Edward A.; Sykes, Mark V.; Carsenty, Uri; Castillo-Rogez, Julie C.; Hoffmann, Martin; Jaumann, Ralf; Krohn, Katrin; Mottola, Stefano; Prettyman, Thomas H.; Schaefer, Michael; Schenk, Paul; Schröder, Stefan E.; Williams, David A.; Smith, David E.; Zuber, Maria T.; Konopliv, Alexander S.; Park, Ryan S.; Raymond, Carol A.; Russell, Christopher T.

    2016-02-01

    Previous observations suggested that Ceres has active, but possibly sporadic, water outgassing as well as possibly varying spectral characteristics over a timescale of months. We used all available data of Ceres collected in the past three decades from the ground and the Hubble Space Telescope, as well as the newly acquired images by the Dawn  Framing Camera, to search for spectral and albedo variability on Ceres, on both a global scale and in local regions, particularly the bright spots inside the Occator crater, over timescales of a few months to decades. Our analysis has placed an upper limit on the possible temporal albedo variation on Ceres. Sporadic water vapor venting, or any possibly ongoing activity on Ceres, is not significant enough to change the albedo or the area of the bright features in the Occator crater by >15%, or the global albedo by >3% over the various timescales that we searched. Recently reported spectral slope variations can be explained by changing Sun–Ceres–Earth geometry. The active area on Ceres is less than 1 km2, too small to cause global albedo and spectral variations detectable in our data. Impact ejecta due to impacting projectiles of tens of meters in size like those known to cause observable changes to the surface albedo on Asteroid Scheila cannot cause detectable albedo change on Ceres due to its relatively large size and strong gravity. The water vapor activity on Ceres is independent of Ceres’ heliocentric distance, ruling out the possibility of the comet-like sublimation process as a possible mechanism driving the activity.

  10. A more accurate and penetrating method to measure the enrichment and mass of UF6 storage containers using passive neutron self-interrogation

    SciTech Connect

    Menlove, Howard O; Swinhoe, Martyn T; Miller, Karen A

    2010-01-01

    This paper describes an unattended mode neutron measurement that can provide the enrichment of the uranium in UF{sub 6} cylinders. The new passive neutron measurement provides better penetration into the uranium mass than prior gamma-ray enrichment measurement methods. The Passive Neutron Enrichment Monitor (PNEM) provides a new measurement technique that uses passive neutron totals and coincidence counting together with neutron self-interrogation to measure the enrichment in the cylinders. The measurement uses the neutron rates from two detector pods. One of the pods has a bare polyethylene surface next to the cylinder and the other polyethylene surface is covered with Cd to prevent thermal neutrons from returning to the cylinder. The primary neutron source from the enriched UF{sub 6} is the alpha-particle decay from the {sub 234}U that interacts with the fluorine to produce random neutrons. The singles neutron counting rate is dominated by the {sub 234}U neutrons with a minor contribution from the induced fissions in the {sub 235}U. However, the doubles counting rate comes primarily from the induced fissions (i.e., multiplication) in the {sub 235}U in enriched uranium. The PNEM concept makes use of the passive neutrons that are initially produced from the {sub 234}U reactions that track the {sub 235}U enrichment during the enrichment process. The induced fission reactions from the thermal-neutron albedo are all from the {sub 235}U and provide a measurement of the {sub 235}U. The Cd ratio has the desirable feature that all of the thermal-neutron-induced fissions in {sub 235}U are independent of the original neutron source. Thus, the ratio is independent of the uranium age, purity, and prior reactor history.

  11. The Search for Proton Decay.

    ERIC Educational Resources Information Center

    Marshak, Marvin L.

    1984-01-01

    Provides the rationale for and examples of experiments designed to test the stability of protons and bound neutrons. Also considers the unification question, cosmological implications, current and future detectors, and current status of knowledge on proton decay. (JN)

  12. Gamma-ray Albedo of the Moon

    SciTech Connect

    Moskalenko, Igor V.; Porter, Troy A.

    2007-06-14

    We use the GEANT4 Monte Carlo framework to calculate the gamma-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of gamma-rays from the Moon is very steep with an effective cutoff around 3 GeV (600 MeV for the inner part of the Moon disc). Since it is the only (almost) black spot in the gamma-ray sky, it provides a unique opportunity for calibration of gamma-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). The albedo flux depends on the incident CR spectrum which changes over the solar cycle. Therefore, it is possible to monitor the CR spectrum using the albedo gamma-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo -rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the GLAST LAT to monitor the CR spectrum near the Earth beyond the lifetime of PAMELA.

  13. Albedo and color contrasts on asteroid surfaces

    NASA Technical Reports Server (NTRS)

    Degewij, J.; Tedesco, E. F.; Zellner, B.

    1979-01-01

    Asteroids in general display only small or negligible variations in spectrum or albedo during a rotational cycle. Color variations with rotation are described in the literature but are usually comparable to the noise in the measurements. Twenty-four asteroids have been systematically monitored for such color changes. Only 3 Juno, 4 Vesta, 6 Hebe, 71 Niobe, 349 Dembowska, and 944 Hidalgo display color variations larger than 0.03 mag. In each of these cases the asteroid appears redder near maximum brightness. Of seven asteroids monitored polarimetrically, only 4 Vesta shows a convincing variation, attributed to an albedo change with rotation. The lightcurve can be explained by albedo differences alone; Vesta apparently has a nearly spheroidal shape. Nothwithstanding the above results, the degree of uniformity of most asteroid surfaces is remarkable. If asteroids exist with large discrete domains of ferrosilicate, metallic, and/or carbonaceous material together on their surfaces, they have not yet been identified.

  14. The determination of surface albedo from meteorological satellites

    NASA Technical Reports Server (NTRS)

    Johnson, W. T.

    1977-01-01

    A surface albedo was determined from visible data collected by the NOAA-4 polar orbiting meteorological satellite. To filter out the major cause of atmospheric reflectivity, namely clouds, techniques were developed and applied to the data resulting in a map of global surface albedo. Neglecting spurious surface albedos for regions with persistent cloud cover, sun glint effects, insufficient reflected light and, at this time, some unresolved influences, the surface albedos retrieved from satellite data closely matched those of a global surface albedo map produced from surface and aircraft measurements and from characteristic albedos for land type and land use.

  15. Multiscale climatological albedo look-up maps derived from moderate resolution imaging spectroradiometer BRDF/albedo products

    NASA Astrophysics Data System (ADS)

    Gao, Feng; He, Tao; Wang, Zhuosen; Ghimire, Bardan; Shuai, Yanmin; Masek, Jeffrey; Schaaf, Crystal; Williams, Christopher

    2014-01-01

    Surface albedo determines radiative forcing and is a key parameter for driving Earth's climate. Better characterization of surface albedo for individual land cover types can reduce the uncertainty in estimating changes to Earth's radiation balance due to land cover change. This paper presents albedo look-up maps (LUMs) using a multiscale hierarchical approach based on moderate resolution imaging spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF)/albedo products and Landsat imagery. Ten years (2001 to 2011) of MODIS BRDF/albedo products were used to generate global albedo climatology. Albedo LUMs of land cover classes defined by the International Geosphere-Biosphere Programme (IGBP) at multiple spatial resolutions were generated. The albedo LUMs included monthly statistics of white-sky (diffuse) and black-sky (direct) albedo for each IGBP class for visible, near-infrared, and shortwave broadband under both snow-free and snow-covered conditions. The albedo LUMs were assessed by using the annual MODIS IGBP land cover map and the projected land use scenarios from the Intergovernmental Panel on Climate Change land-use harmonization project. The comparisons between the reconstructed albedo and the MODIS albedo data product show good agreement. The LUMs provide high temporal and spatial resolution global albedo statistics without gaps for investigating albedo variations under different land cover scenarios and could be used for land surface modeling.

  16. Monitoring surface albedo change with Landsat

    NASA Technical Reports Server (NTRS)

    Otterman, J.

    1977-01-01

    A pronounced decrease of the surface albedo (reflectivity) has been observed in an area in the Northern Sinai, fenced-in in the summer of 1974. Analysis of the Landsat Multispectral Scanner System digital data from an April 1977 pass indicates a reduction in the albedo in the exclosure by 13%, as compared to the outside, which continues to be subjected to overgrazing and anthropogenic pressures. The reduction of reflectivity is approximately the same in all the spectral bands, and is therefore attributable to accumulation of dead plants and plant debris, and not directly to live vegetation.

  17. The diameter and albedo of 1943 Anteros

    NASA Technical Reports Server (NTRS)

    Veeder, G. J.; Tedesco, E. F.; Tholen, D. J.; Tokunaga, A.; Matthews, K.; Neugebauer, G.; Soifer, B. T.; Kowal, C.

    1981-01-01

    The results of broadband visual and infrared photometry of the Apollo-Amor asteroid 1943 Anteros during its 1980 apparition are reported. By means of a radiometric model, a diameter of 2.3 + or - 0.2 km and a visual geometric albedo of 0.13 + or - 0.03 is calculated. The albedo and reflectance spectrum of Anteros imply that it is a type S asteroid. Thus, Anteros may have a silicate surface similar to other Apollo-Amor asteroids as well as some stony-iron meteorites.

  18. The ultraviolet continuum albedo of Uranus

    SciTech Connect

    Cochran, W.D.; Wagener, R.; Caldwell, J.; Fricke, K.H. New York State Univ., Stony Brook York Univ., Toronto Bonn Universitaet )

    1990-01-01

    A radiative transfer code explicitly treating the Raman scattering of solar protons by H{sub 2} is presently used to analyze the Uranus geometric albedo in the 2000-5000 A range. The Baines and Bergstralh (1986) baseline model used reproduces the geometric albedo peak produced by Raman scattering filling of solar absorption line cores, but is found to be excessively bright for wavelengths below 2400 A. This discrepancy is resolvable through inclusion of an absorbing stratospheric haze layer, and results are thereby obtained which are consistent with the Pollack et al. (1987) model, in which aerosols are generated stratospherically through photochemical effects on hydrocarbons. 20 refs.

  19. The ultraviolet spectral albedo of planet earth

    NASA Technical Reports Server (NTRS)

    Frederick, John E.; Serafino, George N.

    1987-01-01

    The solar backscattered ultraviolet spectral radiometer on the Nimbus 7 satellite provides a unique set of radiation measurements which allows an evaluation of the spectral albedo of the earth and its atmosphere in the wavelength range 300 to 340 nm. Near 340 nm, the derived spectral albedo expressed as a function of latitude and month exceeds that in the visible part of the spectrum, with values near 45 percent existing equatorward of 30 deg and an increase to 60-80 percent toward the poles. At middle to high latitudes, the monthly mean spectral albedo exceeds the contribution from Rayleigh scattering alone by factors of 1.4 to 2.2. At wavelengths from 300 to 310 nm, where absorption by stratospheric ozone is significant, the daylight averaged spectral albedos receive negligible contribution from scattering by tropospheric clouds, yet the derived values exceed those predicted for Rayleigh scattering from a clean stratosphere. These observations are consistent with the presence of an atmospheric scattering layer, distinct from cloudiness, located at an altitude above the tropopause.

  20. The low energy atmospheric antiproton albedo

    NASA Technical Reports Server (NTRS)

    Cole, J. B.; Ormes, J. F.

    1989-01-01

    The flux of albedo antiprotons in the 100-1000 MeV kinetic energy range produced by the cosmic ray primaries in the atmosphere is calculated. It is shown that this is not a significant background to measurements of the low energy anti-proton cosmic ray flux.

  1. Optimizing VANDLE for Decay Spectroscopy

    NASA Astrophysics Data System (ADS)

    Brewer, N. T.; Taylor, S. Z.; Grzywacz, R.; Madurga, M.; Paulauskas, S. V.; Cizewski, J. A.; Peters, W. A.; Vandle Collaboration

    2013-10-01

    Understanding the decay properties of neutron rich isotopes has well established importance to the path of the r-process and to the total decay heat for reactor physics. Specifically, the half-life, branching ratio and spectra for β-n decay is of particular interest. With that in mind, we have continued attempts to improve upon the Versatile Array of Neutron Detectors at Low Energy (VANDLE) in terms of efficiency and TOF resolution through the use of new and larger scintillators. Details of the new implementation, design and characterization of the array will be shown and compared to previous results.

  2. The albedo of fractal stratocumulus clouds

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Ridgway, William; Wiscombe, Warren J.; Bell, Thomas L.; Snider, Jack B.

    1994-01-01

    An increase in the planetary albedo of the earth-atmosphere system by only 10% can decrease the equilibrium surface temperature to that of the last ice age. Nevertheless, albedo biases of 10% or greater would be introduced into large regions of current climate models if clouds were given their observed liquid water amounts, because of the treatment of clouds as plane parallel. The focus on marine stratocumulus clouds is due to their important role in cloud radiative forcing and also that, of the wide variety of earth's cloud types, they are most nearly plane parallel, so that they have the least albedo bias. The fractal model employed here reproduces both the probability distribution and the wavenumber spectrum of the stratocumulus liquid water path, as observed during the First ISCCP Regional Experiment (FIRE). A single new fractal parameter 0 less than or equal to f less than or equal to 1, is introduced and determined empirically by the variance of the logarithm of the vertically integrated liquid water. The reduced reflectivity of fractal stratocumulus clouds is approximately given by the plane-parallel reflectivity evaluated at a reduced 'effective optical thickness,' which when f = 0.5 is tau(sub eff) approximately equal to 10. Study of the diurnal cycle of stratocumulus liquid water during FIRE leads to a key unexpected result: the plane-parallel albedo bias is largest when the cloud fraction reaches 100%, that is, when any bias associated with the cloud fraction vanishes. This is primarily due to the variability increase with cloud fraction. Thus, the within-cloud fractal structure of stratocumulus has a more significant impact on estimates of its mesoscale-average albedo than does the cloud fraction.

  3. Albedo boundaries on Mars in 1972: Results from Mariner 9

    USGS Publications Warehouse

    Batson, R.M.; Inge, J.L.

    1976-01-01

    A map of "albedo" boundaries (light and dark markings) on Mars was prepared from Mariner 9 images. After special digital processing, these pictures provide detailed locations of albedo boundaries, which is significant in interpreting recent eolian activity. Derivation of absolute albedo values from the spacecraft data was not attempted. The map correlates well with telescopic observations of Mars after the 1971 dust storm. ?? 1976.

  4. Saturn Neutron Exosphere as Source for Inner and Innermost Radiation Belts

    NASA Technical Reports Server (NTRS)

    Cooper, John; Lipatov, Alexander; Sittler, Edward; Sturner, Steven

    2011-01-01

    Energetic proton and electron measurements by the ongoing Cassini orbiter mission are expanding our knowledge of the highest energy components of the Saturn magnetosphere in the inner radiation belt region after the initial discoveries of these belts by the Pioneer 11 and Voyager 2 missions. Saturn has a neutron exosphere that extends throughout the magnetosphere from the cosmic ray albedo neutron source at the planetary main rings and atmosphere. The neutrons emitted from these sources at energies respectively above 4 and 8 eV escape the Saturn system, while those at lower energies are gravitationally bound. The neutrons undergo beta decay in average times of about 1000 seconds to provide distributed sources of protons and electrons throughout Saturn's magnetosphere with highest injection rates close to the Saturn and ring sources. The competing radiation belt source for energetic electrons is rapid inward diffusion and acceleration of electrons from the middle magnetosphere and beyond. Minimal losses during diffusive transport across the moon orbits, e.g. of Mimas and Enceladus, and local time asymmetries in electron intensity, suggest that drift resonance effects preferentially boost the diffusion rates of electrons from both sources. Energy dependences of longitudinal gradient-curvature drift speeds relative to the icy moons are likely responsible for hemispheric differences (e.g., Mimas, Tethys) in composition and thermal properties as at least partly produced by radiolytic processes. A continuing mystery is the similar radial profiles of lower energy (<10 MeV) protons in the inner belt region. Either the source of these lower energy protons is also neutron decay, but perhaps alternatively from atmospheric albedo, or else all protons from diverse distributed sources are similarly affected by losses at the moon' orbits, e.g. because the proton diffusion rates are extremely low. Enceladus cryovolcanism, and radiolytic processing elsewhere on the icy moon and

  5. Inelastic neutron scattering cross sections for Ge76 relevant to background in neutrinoless double- β decay experiments

    SciTech Connect

    Crider, B. P.; Peters, E. E.; Allmond, J. M.; McEllistrem, M. T.; Prados-Estévez, F. M.; Ross, T. J.; Vanhoy, J. R.; Yates, S. W.

    2015-09-11

    The experimental signature in searches for the neutrinoless double- decay of 76Ge is a peak near 2039 keV in the spectrum. Given the low probability of the process, it is important that the background in this region be well understood. Moreover, inelastic scattering reactions with neutrons from muon-induced interactions and ( ,n) reactions in the surrounding materials or in the detector can provide contributions to the background. We also measured the production cross sections for rays from the 76Ge(n,n ) reaction in the 2039-keV region at incident neutron energies up to 4.9 MeV. In addition to determining that the cross sections of a previously known 2040.7-keV ray from the 3952-keV level in 76 Ge are rather small, we find that a larger contribution arises from a 2037.5-keV ray which is attributed to a newly identified level at 3147 keV in 76Ge. Finally, a third contribution is also possible from another new level at 3577 keV. These results indicate that the 2039-keV region in 76Ge neutrinoless double- decay searches is more complex than was previously thought.

  6. The LLNL CR-39 personnel neutron dosimeter

    SciTech Connect

    Hankins, D.E.; Homann, S.; Westermark, J.

    1987-09-29

    We developed a personnel neutron dosimetry system based on the electrochemical etching of CR-39 plastic at elevated temperatures. The doses obtained using this dosimeter system are more accurate than those obtained using other dosimetry systems, especially when varied neutron spectra are encountered. This CR-39 dosimetry system does not have the severe energy dependence that exists with albedo neutron dosimeters or the fading and reading problems encountered with NTA film. 3 refs., 4 figs.

  7. Estimating big bluestem albedo from directional reflectance measurements

    NASA Technical Reports Server (NTRS)

    Irons, J. R.; Ranson, K. J.; Daughtry, C. S. T.

    1988-01-01

    Multidirectional reflectance factor measurements acquired in the summer of 1986 are used to make estimates of big bluestem grass albedo, evaluating the variation of albedo with changes in solar zenith angle and phenology. On any given day, the albedo was observed to increase by at least 19 percent as solar zenith angle increased. Changes in albedo were found to correspond to changes in the green leaf area index of the grass canopy. Estimates of albedo made using reflectance data acquired within only one or two azimuthal planes and at a restricted range of view zenith angle were evaluated and compared to 'true' albedos derived from all available reflectance factor data. It was found that even a limited amount of multiple direction reflectance data was preferable to a single nadir reflectance factor for the estimation of prarie grass albedo.

  8. The albedo of particles in reflection nebulae

    NASA Technical Reports Server (NTRS)

    Rush, W. F.

    1974-01-01

    The relation between the apparent angular extent of a reflection nebula and the apparent magnitude of its illuminating star was reconsidered under a less restrictive set of assumptions. A computational technique was developed which permits the use of fits to the observed m-log a values to determine the albedo of particles composing reflection nebulae, providing only that a phase function and average optical thickness are assumed. Multiple scattering, anisotropic phase functions, and illumination by the general star field are considered, and the albedo of reflection nebular particles appears to be the same as that for interstellar particles in general. The possibility of continuous fluorescence contributions to the surface brightness is also considered.

  9. Geomorphological related albedo features on Ceres

    NASA Astrophysics Data System (ADS)

    Krohn, K.; Matz, K.-D.; Jaumann, R.; Otto, K.; Li, J.-Y.; Buczkowski, D.; Mest, S.; Scully, J. E. C.; Williams, D. A.; Raymond, C. A.; Russell, C. T.

    2015-10-01

    NASA's Dawn spacecraft entered orbit of Ceres on March 6, 2015, to spend one year characterizing the geology, elemental and mineralogical composition, topography, shape, and internal structure of the Ceres [1]. Ceres is supposed to be differentiated into a silicate core, a liquid water mantle and a solid ice crust with a surface temperature from 130K to 235K [2,3]. At the time of writing, the acquired image data from Ceres provide a spatial resolution of up to 2.1 km/pixel. The surface of Ceres reveals some albedo features that seem to be related to geomorphology. Those features show either a high or a low albedo compared to the surrounding.

  10. Climatic effects of surface albedo geoengineering

    NASA Astrophysics Data System (ADS)

    Irvine, Peter J.; Ridgwell, Andy; Lunt, Daniel J.

    2011-12-01

    Various surface albedo modification geoengineering schemes such as those involving desert, urban, or agricultural areas have been proposed as potential strategies for helping counteract the warming caused by greenhouse gas emissions. However, such schemes tend to be inherently limited in their potential and would create a much more heterogeneous radiative forcing than propositions for space-based "reflectors" and enhanced stratospheric aerosol concentrations. Here we present results of a series of atmosphere-ocean general circulation model (GCM) simulations to compare three surface albedo geoengineering proposals: urban, cropland, and desert albedo enhancement. We find that the cooling effect of surface albedo modification is strongly seasonal and mostly confined to the areas of application. For urban and cropland geoengineering, the global effects are minor but, because of being colocated with areas of human activity, they may provide some regional benefits. Global desert geoengineering, which is associated with significant global-scale changes in circulation and the hydrological cycle, causes a smaller reduction in global precipitation per degree of cooling than sunshade geoengineering, 1.1% K-1 and 2.0% K-1 respectively, but a far greater reduction in the precipitation over land, 3.9% K-1 compared with 1.0% K-1. Desert geoengineering also causes large regional-scale changes in precipitation with a large reduction in the intensity of the Indian and African monsoons in particular. None of the schemes studied reverse the climate changes associated with a doubling of CO2, with desert geoengineering profoundly altering the climate and with urban and cropland geoengineering providing only some regional amelioration at most.

  11. β-decay and β-delayed Neutron Emission Measurements at GSI-FRS Beyond N=126, for r-process Nucleosynthesis

    SciTech Connect

    Caballero-Folch, R.; Domingo-Pardo, C.; Cortès, G.; Taín, J.L.; Agramunt, J.; Algora, A.; Ameil, F.; Ayyad, Y.; Benlliure, J.; Bowry, M.; Calviño, F.; Cano-Ott, D.; Davinson, T.; and others

    2014-06-15

    New measurements of very exotic nuclei in the neutron-rich region beyond N=126 have been performed at the GSI facility with the fragment separator (FRS). The aim of the experiment is to determine half-lives and β-delayed neutron emission branching ratios of isotopes of Hg, Tl and Pb in this region. This contribution summarizes final counting statistics for identification and for implantation, as well as the present status of the data analysis of the half-lives. In summary, isotopes of Pt, Au, Hg, Tl, Pb, Bi, Po, At, Rn and Fr were clearly identified and several of them ({sup 208-211}Hg, {sup 211-215}Tl, {sup 214-218}Pb) were implanted with enough statistics to determine their half-lives. About half of them are expected to be neutron emitters, in such cases it will become possible to obtain the neutron emission probabilities, Pn.

  12. Operational comparison of bubble (super heated drop) dosimetry with routine albedo TLD for a selected group of Pu-238 workers at Los Alamos National Laboratory

    SciTech Connect

    Romero, L.L.; Hoffman, J.M.; Foltyn, E.M.; Buhl, T.E.

    1998-09-01

    Personnel neutron dosimetry continues to be a difficult science due to the lack of availability of robust passive dosimeters that exhibit tissue- or near-tissue- equivalent response. This paper is an operational study that compares the use of albedo thermoluminescent dosimeters with bubble dosimeters to determine whether bubble dosimeters do provide a useful daily ALARA tool that can yield measurements close to the dose-of-record. A group of workers at Los Alamos National Laboratory (LANL) working on the Radioisotopic Thermoelectric Generators (RTG) for the NASA Cassini space mission wore both bubble dosimeters and albedo dosimeters over a period from 1993 through 1996. The personal albedo dosimeter was processed on a monthly basis and used as the dose-of-record. The results of this study indicated that cumulative daily bubble dosimetry results agreed with whole-body albedo dosimetry results within about 37% on average.

  13. Neutron-capture cross-section measurements of 74Ge and 76Ge in the energy region 0.4-14.8 MeV for neutrinoless double β decay applications

    NASA Astrophysics Data System (ADS)

    Bhike, Megha; Tornow, Werner

    2013-10-01

    Fast neutron capture cross sections for the reactions 74Ge(n, γ)75Ge and 76Ge(n, γ)77Ge have been measured in the neutron energy region 0.4-14.8 MeV with the activation method. The results are important to identify backgrounds in the neutrinoless double- β decay experiments GERDA and MAJORANA, which use germanium as both source and detector. Isotopically enriched targets which consisted of 86% of 76Ge and 14% of 74Ge were irradiated with mono-energetic neutrons produced via 3H(p,n)3He, 2H(d,n)3He and 3H(d,n)4He reactions. The cross sections were determined relative to 197Au(n, γ)198Au, 115In(n,n')115mIn and 197Au(n,2n)196Au standard cross sections. The activities of the products were measured using high-resolution γ-ray spctroscopy. The present results are compared with the evaluated data from ENDF/B-VII.1 and TALYS.

  14. Determination of the Neutron Lifetime Using Magnetically Trapped Neutrons

    PubMed Central

    Dzhosyuk, S. N.; Copete, A.; Doyle, J. M.; Yang, L.; Coakley, K. J.; Golub, R.; Korobkina, E.; Kreft, T.; Lamoreaux, S. K.; Thompson, A. K.; Yang, G. L.; Huffman, P. R.

    2005-01-01

    We report progress on an experiment to measure the neutron lifetime using magnetically trapped neutrons. Neutrons are loaded into a 1.1 T deep superconducting Ioffe-type trap by scattering 0.89 nm neutrons in isotopically pure superfluid 4He. Neutron decays are detected in real time using the scintillation light produced in the helium by the beta-decay electrons. The measured trap lifetime at a helium temperature of 300 mK and with no ameliorative magnetic ramping is substantially shorter than the free neutron lifetime. This is attributed to the presence of neutrons with energies higher than the magnetic potential of the trap. Magnetic field ramping is implemented to eliminate these neutrons, resulting in an 833−63+74s trap lifetime, consistent with the currently accepted value of the free neutron lifetime. PMID:27308147

  15. Half space albedo problem for the nonconservative vector equation of transfer with a combination of Rayleigh and isotropic scattering

    NASA Astrophysics Data System (ADS)

    Şenyiğit, M.

    2016-09-01

    The half-space albedo problem has been solved for a combination of Rayleigh and isotropic scattering using HN method which is developed for the neutron transport studies. The numerical results are compared with exact values obtained using variational method and Chandrasekhar's equation for the {H}-matrix. The analytical solutions of HN method are easy to handle in comparison with the other methods. The numerical results are in good agreement with previous works in literature.

  16. Global color and albedo variations on Io

    NASA Technical Reports Server (NTRS)

    Mcewen, Alfred S.

    1988-01-01

    The present Voyager imaging data multispectral mosaics of Io include global mosaics from each of the Voyager 1 and 2 data sets and a high-resolution mosaic of the region centered on the Ra Patera volcano. The constancy of the disk-integrated color and albedo of Io over recent decades despite volcanic activity may be due to the regular occurrence of large Pele-type plumes with relatively dark, red deposits. Io's intrinsic spectral variability involves continuous variation among three major spectral end members. Attention is given to the mapping of the data into five spectral units for the purposes of comparison with laboratory measurements of Io surface material candidates.

  17. Albedo and transmittance of inhomogeneous stratus clouds

    SciTech Connect

    Zuev, V.E.; Kasyanov, E.I.; Titov, G.A.

    1996-04-01

    A highly important topic is the study of the relationship between the statistical parameters of optical and radiative charactertistics of inhomogeneous stratus clouds. This is important because the radiation codes of general circulation models need improvement, and it is important for geophysical information. A cascade model has been developed at the Goddard Space Flight Center to treat stratocumulus clouds with the simplest geometry and horizontal fluctuations of the liquid water path (optical thickness). The model evaluates the strength with which the stochastic geometry of clouds influences the statistical characteristics of albedo and the trnasmittance of solar radiation.

  18. Impact of Atmospheric Albedo on Amazon Evapotranspiration

    NASA Astrophysics Data System (ADS)

    Lopes, A. V.; Thompson, S. E.; Dracup, J. A.

    2013-12-01

    The vulnerability of the Amazon region to climate and anthropogenic driven disturbances has been the subject of extensive research efforts, given its importance in the global and regional climate and ecologic systems. The evaluation of such vulnerabilities requires the proper understanding of physical mechanisms controlling water and energy balances and how the disturbances change them. Among those mechanisms, the effects of atmospheric albedo on evapotranspiration have not been fully explored yet and are explored in this study. Evapotranspiration in the Amazon is sustained at high levels across all seasons and represents a large fraction of water and energy surface budgets. In this study, statistical analysis of data from four flux towers installed at Amazon primary forest sites was employed to quantify the impact of atmospheric albedo, mostly resulted from cloudiness, on evapotranspiration and to compare it to the effect of water limitation. Firstly, the difference in eddy-flux derived evapotranspiration at the flux towers under rainy and non-rainy antecedent conditions was tested for significance. Secondly, the same statistical comparison was performed under cloudy and clear sky conditions at hourly and daily time scales, using the reduction in incoming solar radiation as an indicator of cloudiness. Finally, the sensitivity of seasonal evapotranspiration totals to atmospheric albedo resulted from rainfall patterns is evaluated. That was done by sampling daily evapotranspiration estimates from empirical probability distribution functions conditioned to rainfall occurrence and then varying the number of dry days in each season. It was found that light limitation is much more important than water limitation in the Amazon, resulting in up to 43% reduction in daily evapotranspiration. Also, this effect varies by location and by season, the largest impact being in wet season, from December do January. Moreover, seasonal evapotranspiration totals were found to be

  19. Albedo maps of Pluto and Charon - Initial mutual event results

    NASA Technical Reports Server (NTRS)

    Buie, Marc W.; Tholen, David J.; Horne, Keith

    1992-01-01

    By applying the technique of maximum entropy image reconstruction to invert observed lightcurves, surface maps of single-scattering albedo are obtained for the surfaces of Pluto and Charon from 1954 to 1986. The albedo features of the surface of Pluto are similar to those of the Buie and Tholen (1989) spot model maps; a south polar cap is evident. The map of Charon is somewhat darker, with single-scattering albedos as low as 0.03.

  20. Correlation of Far Ultraviolet Lunar Albedo with Solar Activity

    NASA Technical Reports Server (NTRS)

    Maddox, Will; Spann, James F.; Germany, Glynn

    2004-01-01

    We present a correlative analysis between the variability of the lunar albedo in the far ultraviolet wavelength range (130- 190 nm) and various solar activity indices for a two-week period. We also report lunar albedo measurements in four separate wavelength ranges, corresponding to four filters on the Polar Ultraviolet Imager. To our knowledge this is the first reported long term measurements of the lunar albedo in this wavelength range.

  1. γ-ray decay from neutron-bound and unbound states in 95Mo and a novel technique for spin determination

    DOE PAGESBeta

    Wiedeking, M.; Krticka, M.; Bernstein, L. A.; Allmond, James M.; Basunia, M. S.; Bleuel, D. L.; Burke, J. T.; Daub, B. H.; Fallon, P.; Firestone, R. B.; et al

    2016-02-01

    The emission of γ rays from neutron-bound and neutron-unbound states in 95Mo, populated in the 94Mo(d,p) reaction, has been investigated. Charged particles and γ radiation were detected with arrays of annular silicon and Clover-type high-purity Germanium detectors, respectively. Utilizing p-γ and p-γ-γ coincidences, the 95Mo level scheme was greatly enhanced with 102 new transitions and 43 new states. It agrees well with shell model calculations for excitation energies below ≈2 MeV. From p-γ coincidence data, a new method for the determination of spins of discrete levels is proposed. The method exploits the suppression of high-angular momentum neutron emission from levelsmore » with high spins populated in the (d,p) reaction above the neutron separation energy. As a result, spins for almost all 95Mo levels below 2 MeV (and for a few levels above) have been determined with this method.« less

  2. Impact of weather events on Arctic sea ice albedo evolution

    NASA Astrophysics Data System (ADS)

    Arntsen, A. E.; Perovich, D. K.; Polashenski, C.; Stwertka, C.

    2015-12-01

    Arctic sea ice undergoes a seasonal evolution from cold snow-covered ice to melting snow to bare ice with melt ponds. Associated with this physical evolution is a decrease in the albedo of the ice cover. While the change in albedo is often considered as a steady seasonal decrease, weather events during melt, such as rain or snow, can impact the albedo evolution. Measurements on first year ice in the Chukchi Sea showed a decrease in visible albedo to 0.77 during the onset of melt. New snow from 4 - 6 June halted melting and increased the visible albedo to 0.87. It took 12 days for the albedo to decrease to levels prior to the snowfall. Incident solar radiation is large in June and thus a change in albedo has a large impact on the surface heat budget. The snowfall increased the albedo by 0.1 and reduced the absorbed sunlight from 5 June to 17 June by approximately 32 MJ m-2. The total impact of the snowfall will be even greater, since the delay in albedo reduction will be propagated throughout the entire summer. A rain event would have the opposite impact, increasing solar heat input and accelerating melting. Snow or rain in May or June can impact the summer melt cycle of Arctic sea ice.

  3. THE ALBEDO-COLOR DIVERSITY OF TRANSNEPTUNIAN OBJECTS

    SciTech Connect

    Lacerda, Pedro; Rengel, Miriam; Fornasier, Sonia; Lellouch, Emmanuel; Delsanti, Audrey; Kiss, Csaba; Vilenius, Esa; Müller, Thomas; Santos-Sanz, Pablo; Duffard, René; Guilbert-Lepoutre, Aurélie

    2014-09-20

    We analyze albedo data obtained using the Herschel Space Observatory that reveal the existence of two distinct types of surface among midsized trans-Neptunian objects. A color-albedo diagram shows two large clusters of objects, one redder and higher albedo and another darker and more neutrally colored. Crucially, all objects in our sample located in dynamically stable orbits within the classical Kuiper Belt region and beyond are confined to the bright red group, implying a compositional link. Those objects are believed to have formed further from the Sun than the dark neutral bodies. This color-albedo separation is evidence for a compositional discontinuity in the young solar system.

  4. Enhancement of the MODIS Daily Snow Albedo Product

    NASA Technical Reports Server (NTRS)

    Hall, Dorothy K.; Schaaf, Crystal B.; Wang, Zhuosen; Riggs, George A.

    2009-01-01

    The MODIS daily snow albedo product is a data layer in the MOD10A1 snow-cover product that includes snow-covered area and fractional snow cover as well as quality information and other metadata. It was developed to augment the MODIS BRDF/Albedo algorithm (MCD43) that provides 16-day maps of albedo globally at 500-m resolution. But many modelers require daily snow albedo, especially during the snowmelt season when the snow albedo is changing rapidly. Many models have an unrealistic snow albedo feedback in both estimated albedo and change in albedo over the seasonal cycle context, Rapid changes in snow cover extent or brightness challenge the MCD43 algorithm; over a 16-day period, MCD43 determines whether the majority of clear observations was snow-covered or snow-free then only calculates albedo for the majority condition. Thus changes in snow albedo and snow cover are not portrayed accurately during times of rapid change, therefore the current MCD43 product is not ideal for snow work. The MODIS daily snow albedo from the MOD10 product provides more frequent, though less robust maps for pixels defined as "snow" by the MODIS snow-cover algorithm. Though useful, the daily snow albedo product can be improved using a daily version of the MCD43 product as described in this paper. There are important limitations to the MOD10A1 daily snow albedo product, some of which can be mitigated. Utilizing the appropriate per-pixel Bidirectional Reflectance Distribution Functions (BRDFs) can be problematic, and correction for anisotropic scattering must be included. The BRDF describes how the reflectance varies with view and illumination geometry. Also, narrow-to-broadband conversion specific for snow on different surfaces must be calculated and this can be difficult. In consideration of these limitations of MOD10A1, we are planning to improve the daily snow albedo algorithm by coupling the periodic per-pixel snow albedo from MCD43, with daily surface ref|outanoom, In this paper, we

  5. Colloquium: The neutron lifetime

    SciTech Connect

    Greene, Geoffrey L; Wietfeldt, F

    2011-01-01

    The decay of the free neutron into a proton, electron, and antineutrino is the prototype semileptonic weak decay and is the simplest example of nuclear beta decay. It played a key role in the early Universe as it determined the ratio of neutrons to protons during the era of primordial light element nucleosynthesis. Neutron decay is physically related to important processes in solar physics and neutrino detection. The mean neutron lifetime has been the subject of more than 20 major experiments done, using a variety of methods, between 1950 and the present. The most precise recent measurements have stated accuracies approaching 0.1%, but are not in good agreement as they differ by as much as 5 sigma using quoted uncertainties. The history of neutron lifetime measurements is reviewed and the different methods used are described, giving important examples of each. The discrepancies and some systematic issues in the experiments that may be responsible are discussed, and it is shown by means of global averages that the neutron lifetime is likely to lie in the range of 880 884 s. Plans and prospects for future experiments are considered that will address these systematic issues and improve our knowledge of the neutron lifetime.

  6. Applications of {sup 3}He neutron detectors

    SciTech Connect

    Testov, D. A.; Briancon, Ch.; Dmitriev, S. N.; Yeremin, A. V.; Penionzhkevich, Yu. E.; Pyatkov, Yu. V.; Sokol, E. A.

    2009-01-15

    Neutron detectors with {sup 3}He-filled proportional counters are described. The use of these detectors in measuring the probability of neutron emission (in particular, multiparticle neutron emission) after the {beta} decay of neutron-rich nuclei and in studying rare events of spontaneous fission of superheavy nuclei is considered.

  7. Entrainment, Drizzle, and Stratocumulus Cloud Albedo

    NASA Technical Reports Server (NTRS)

    Ackerman, A. S.; Kirkpatrick, M. P.; Stevens, D. E.; Toon, O. B.

    2004-01-01

    Globally averaged cloud changes from GCMs on average show a doubling of the Twomey effect, which is the change in cloud albedo with respect to changes in droplet concentrations for fixed cloud water and droplet dispersion. In contrast, ship-track measurements show a much more modest amplification of the Twomey effect, suggesting that the GCMs are exaggerating the indirect aerosol effect. We have run large-eddy simulations with bin microphysics of marine stratocumulus from multiple field campaigns, and find that the large-eddy simulations are in much better agreement with the ship-track measurements. The inversion strength over N. Pacific stratocumulus (as measured during DYCOMS-II) is generally much stronger than over N. Atlantic stratocumulus (as measured during ASTEX), and we have found that the response of cloud water to increasing droplet concentration changes sign as the inversion strengthens. For the different environmental conditions, we will show the overall response of cloud albedo to droplet concentrations, and decompose the response into its contributing factors of changes in cloud water, droplet dispersion, and horizontal inhomogeneity.

  8. Surface Albedo Variations Across Opportunity's Traverse in Meridiani Planum

    NASA Astrophysics Data System (ADS)

    Studer-Ellis, G. L.; Rice, M. S.; Johnson, J. R.; Bell, J. F., III

    2015-12-01

    Surface albedo measurements from the Mars Exploration Rover (MER) Opportunity mission can be used to help understand surface-atmosphere interactions at Meridiani Planum. Opportunity has acquired 117 albedo panoramas with the Pancam instrument as of sol 3870, across the first 40 km of its traverse. To date, only the first 32 panoramas have been reported upon in previous studies [1]. Here we present an analysis of the full set of PDS-released albedo observations from Opportunity and correlate our measurements with terrain type and known atmospheric events. To acquire a 360-degree albedo observation, Pancam's L1 ("clear") filter is used to take 27 broad-spectrum images, which are stitched into a mosaic. Pancam images are calibrated to reflectance factor (R*), which is taken as an approximation of the Lambertian albedo. Areas of interest are selected and average albedo calculations are applied to all of the selections. Results include the average albedo of each scene, as well as equal-area corrections where applicable, in addition to measurements of specific classes of surface features (e.g., outcrops, dusty terrain, and rover tracks). Average scene albedo measurements range from 0.11 ± 0.04 to 0.30 ± 0.04, with the highest value observed on sol 1290 (immediately after the planet-encircling dust storm of 2007). We compare these results to distance traveled, surface morphologies, local wind driven events, and dust opacity measurements. Future work will focus on correlating Pancam albedo values with orbital data from cameras such as HiRISE, CTX, MOC, THEMIS-VIS, and MARCI, and completion of the same analysis for the full Pancam albedo dataset from Spirit. References: [1] Bell, J. F., III, M. S. Rice, J. R. Johnson, and T. M. Hare (2008), Surface albedo observations at Gusev Crater and Meridiani Planum, Mars, J. Geophys. Res., 113, E06S18, doi:10.1029/2007JE002976.

  9. From Regional Cloud-Albedo to a Global Albedo Footprint - Studying Aerosol Effects on the Radiation Budget Using the Relation Between Albedo and Cloud Fraction

    NASA Astrophysics Data System (ADS)

    Bender, F.; Engström, A.; Karlsson, J.; Wood, R.; Charlson, R. J.

    2015-12-01

    Earth's albedo is the primary determinant of the amount of energy absorbed by the Earth-atmosphere system. The main factor controlling albedo is the amount of clouds present, but aerosols can affect and alter both clear-sky and cloudy-sky reflectance. How albedo depends on cloud fraction and how albedo varies at a given cloud fraction and a given cloud water content, reveals information about these aerosol effects on the radiation budget. Hence, the relation between total albedo and cloud fraction can be used for illustration and quantification of aerosol effects, and as a diagnostic tool, to test model performance. Here, we show examples of the utilisation of this relation focusing on satellite observations from CERES and MODIS on Aqua, as well as from Calipso and CloudSat, and performing comparisons with climate models on the way: In low-cloud regions in the subtropics, we find that climate models well represent a near-constant regional cloud albedo, and this representation has improved from CMIP3 to CMIP5. CMIP5 models indicate more reflective clouds in present-day climate than pre-industrial, as a result of increased aerosol burdens. On monthly mean time scale, models are found to over-estimate the regional cloud-brightening due to aerosols. On the global scale we find an increasing cloud albedo with increasing cloud fraction - a relation that is very well defined in observations, and less so in CMIP5 models. Cloud brightening from pre-industrial to present day is also seen on global scale. Further, controlling for both cloud fraction and cloud water content we can trace small variations in albedo, or perturbations of solar reflectivity, that create a near-global coherent geographical pattern that is consistent with aerosol impacts on climate, with albedo enhancement in regions dominant of known aerosol sources and suppression of albedo in regions associated with high rates of aerosol removal (deduced using CloudSat precipitation estimates). This mapping can be

  10. γ-decay of {}_{8}^{16}{{\\rm{O}}}_{8}\\,{and}\\,{}_{7}^{16}{{\\rm{N}}}_{9} in proton–neutron Tamm–Dancoff and random phase approximations with optimized surface δ interaction

    NASA Astrophysics Data System (ADS)

    Pahlavani, M. R.; Firoozi, B.

    2016-09-01

    γ-ray transitions from excited states of {}16{{N}} and {}16{{O}} isomers that appear in the γ spectrum of the {}616{{{C}}}10\\to {}716{{{N}}}9\\to {}816{{{O}}}8 beta decay chain are investigated. The theoretical approach used in this research starts with a mean-field potential consisting of a phenomenological Woods–Saxon potential including spin-orbit and Coulomb terms (for protons) in order to obtain single-particle energies and wave functions for nucleons in a nucleus. A schematic residual surface delta interaction is then employed on the top of the mean field and is treated within the proton–neutron Tamm–Dancoff approximation (pnTDA) and the proton–neutron random phase approximation. The goal is to use an optimized surface delta interaction interaction, as a residual interaction, to improve the results. We have used artificial intelligence algorithms to establish a good agreement between theoretical and experimental energy spectra. The final results of the ‘optimized’ calculations are reasonable via this approach.

  11. Halley's comet - Its size and decay rate

    NASA Astrophysics Data System (ADS)

    Wallis, M. K.; Wickramasinghe, N. C.

    1985-09-01

    The outgassing rates inferred from the 1910 apparition and the brightness decay over the previous two millenia are compatible with the minimum nuclear brightness currently observed if the comet nucleus is small, 1.8 - 2.7 km radius with an albedo of 0.1 - 0.2. Outgassing is faster than from a bare nucleus of dirty H2O-ice, which is attributed either to a hot microdust coma or to an organic polymer composition. Halley's comet will decay away within another 45 - 65 apparitions.

  12. 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.

  13. 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.

  14. β-decay half-lives of neutron-rich nuclei around 158Nd, relevant to the formation of the A≈165 rare-earth element peak

    NASA Astrophysics Data System (ADS)

    Wu, J.; Nishimura, S.; Lorusso, G.; Xu, Z. Y.; Ideguchi, E.; Simpson, G. S.; Baba, H.; Browne, F.; Daido, R.; Doornebal, P.; Fang, Y. F.; Isobe, T.; Li, Z.; Patel, Z.; Rice, S.; Sinclair, L.; Söderström, P.-A.; Sumikama, T.; Watanabe, H.; Yagi, A.; Yokoyama, R.; Aoi, N.; Bello Garrote, F. L.; Benzoni, G.; Gey, G.; Gottardo, A.; Nishibata, H.; Odahara, A.; Sakurai, H.; Tanaka, M.; Taprogge, J.; Yamamoto, T.

    2016-02-01

    A β-decay spectroscopy experiment around 158Nd was performed at RI Beam Factory (RIBF), RIKEN Nishina Center, in order to understand the production mechanism of the A≈165 rare-earth element (REE) peak in the r-process mass abundance pattern. In this experiment, 53 half-lives are measured including 34 new results, which could be employed in a fully dynamic r-process network calculation.

  15. The albedo of snow for partially cloudy skies

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.; Chang, A. T. C.

    1980-01-01

    The input parameters of the model are atmospheric precipitable water, ozone content, turbidity, cloud optical thickness, size and shape of ice crystal of snow and surface pressure. The model outputs spectral and integrated solar flux snow reflectance as a function of solar elevation and fractional cloudcover. The model is illustrated using representative parameters for the Antarctic coastal regions. The albedo for a clear sky depends inversely on the solar elevation. At high elevation the albedo depends primarily upon the grain size; at low elevation this dependence is on grain size and shape. The gradient of the albedo-elevation curve increases as the grains get larger and faceted. The albedo for a dense overcast is a few percent higher than the clear sky albedo at high elevations. A simple relation between the grain size and the overcast albedo is obtained. For a set of grain size and shape, the albedo matrices (the albedo as a function of solar elevation and fractional cloudcover) are tabulated.

  16. Shallow Lunar Hydrogen and Forward-Scattered Albedo Protons

    NASA Astrophysics Data System (ADS)

    Wilson, J. K.; Schwadron, N.; Jordan, A. P.; Spence, H. E.; Looper, M. D.; Townsend, L. W.

    2015-11-01

    The CRaTER instrument sees a ~40% higher flux of lunar albedo protons (>65 MeV) at grazing angles compared to the nadir direction. A shallow layer (<10 cm) of hydrated lunar regolith may enhance the yield of forward-scattered albedo protons.

  17. Effect of shaddock albedo addition on the properties of frankfurters.

    PubMed

    Shan, Bing; Li, Xingmin; Pan, Teng; Zheng, Limin; Zhang, Hao; Guo, Huiyuan; Jiang, Lu; Zhen, Shaobo; Ren, Fazheng

    2015-07-01

    To explore the potential as a natural auxiliary emulsifier, shaddock albedo was added into frankfurters at six different levels: 0.0, 2.5, 5.0, 7.5, 10 and 12.5 %. The emulsion capacity (EC) of meat batters and cooking properties of frankfurters were evaluated. EC of meat batters was improved with the addition of shaddock albedo and the maximum value was reached at the 5 % albedo concentration. The addition of shaddock albedo resulted in lower cooking losses of frankfurters, with the lowest value obtained at the 7.5 % level. The presence of shaddock albedo decreased the total expressible fluid (TEF) and the proportion of fat in total expressible fluid (PF) which indicated the emulsion stability of frankfurters and the lowest values both occurred at the concentration of 7.5 %. Shaddock albedo inclusion increased the lightness and yellowness of frankfurters and decreased redness. Texture profile analysis showed increased hardness and decreased chewiness of frankfurters with the addition of shaddock albedo. Consequently, shaddock albedo could be a potential source of auxiliary emulsifier filler for emulsion-type meat products. PMID:26139927

  18. Anthropogenic desertification by high-albedo pollution Observations and modeling

    NASA Technical Reports Server (NTRS)

    Otterman, J.; Rosenberg, N. W.; Rosenberg, E.

    1974-01-01

    ERTS-1 MSS albedo data of Western Negev, Sinai and the Gaza strip are presented. A sharp contrast in albedo exists across the Negev-Sinai and Negev-Gaza strip borders. Anthropogenic desertification has occurred on the Arab side due to overgrazing and Bedouin agriculture, whereas natural vegetation grows much more abundantly on the Israeli side.

  19. Greenland surface albedo changes 1981-2012 from satellite observations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Significant melt over Greenland has been observed during the last several decades associated with extreme warming events over the northern Atlantic Ocean. An analysis of surface albedo change over Greenland is presented, using a 32-year consistent satellite albedo product from the Global Land Surfac...

  20. Asymmetry in the Diurnal Variation of Surface Albedo

    NASA Technical Reports Server (NTRS)

    Mayor, S.; Smith, W. L., Jr.; Nguyen, L.; Alberta, T. A.; Minnis, P.; Whitlock, C. H.; Schuster, G. L.

    1996-01-01

    Remote sensing of surface properties and estimation of clear-sky and surface albedo generally assumes that the albedo depends only on the solar zenith angle. The effects of dew, frost, and precipitation as well as evaporation and wind can lead to some systematic diurnal variability resulting in an asymmetric diurnal cycle of albedo. This paper examines the symmetry of both surface-observed albedos and top-of-the-atmosphere (TOA) albedos derived from satellite data. Broadband and visible surface albedos were measured at the Department of Energy Atmospheric Radiation Measurement (ARM) Program Southern Great Plains Central Facility, at some fields near the ARM site, and over a coniferous forest in eastern Virginia. Surface and wind conditions are available for most cases. GOES-8 satellite radiance data are converted to broadband albedo using bidirectional reflectance functions and an empirical narrowband-to-broadband relationship. The initial results indicate that surface moisture has a significant effect and can change the albedo in the afternoon by 20% relative to its morning counterpart. Such effects may need to be incorporated in mesoscale and even large-scale models of atmospheric processes.

  1. Correlation of Neutron Data Taken at Commercial Nuclear Sites

    SciTech Connect

    Rathbun, L. A.; Endres, G. W.R.

    1983-10-01

    In this report, data from neutron measurement and dosimetry studies performed by Pacific Northwest Laboratory, the Environmental Measurements Laboratory, and Rensselaer Polytechnic Institute are examined and compared. The purpose of this data correlation effort is to determine whether useful relationships exist between the actual neutron dose equivalent in a typical commercial nuclear power reactor and various measurement parameters, such as ratios of the response of 9-in. to 3-in. spheres, neutron/gamma ratios, albedo dosimeter response and neutron spectrometer readings. In most neutron radiation fields found in the reactors visited, the response of albedo dosimeters can be brought into reasonable agreement with dose equivalents measured with multispheres, tissue equivalent proportional counters (TEPCs) or remmeters. Because the responses of the remmeters, like the responses of albedo dosimeters, are energy dependent, it is preferable to correct the responses of the albedo dosimeters to agree with dose equivalents measured with either TEPCs or multispheres. If one of these laboratory systems has been used to measure neutron dose equivalents at a specific pressurized water reactor, a calculated average albedo dosimeter correction factor can be used for most locations at that reactor. However, if the measured 9-in. to 3-in. remmeter ratio is greater than 0.20, it is advisable to use a plot of 9-in. to 3-in. remmeter ratios versus albedo dosimeter correction factors to obtain an albedo dosimeter correction factor. Because 9-in. to 3-in. remmeter ratios at boiling water reactors are typically greater than 0.20, the latter approach applies to this type of reactor.

  2. NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos

    NASA Astrophysics Data System (ADS)

    Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; Masiero, J.; Sonnett, S.; Wright, E. L.

    2016-09-01

    The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids (NEAs) and 8885 other asteroids. Of the NEAs, 84% NEAs did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within ±∼20% and ±∼40%, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large (>100 m), and have low albedos.

  3. NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos

    NASA Astrophysics Data System (ADS)

    Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; Masiero, J.; Sonnett, S.; Wright, E. L.

    2016-09-01

    The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids (NEAs) and 8885 other asteroids. Of the NEAs, 84% NEAs did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within ±˜20% and ±˜40%, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large (>100 m), and have low albedos.

  4. Global color and albedo variations on Io

    USGS Publications Warehouse

    McEwen, A.S.

    1988-01-01

    Three multispectral mosaics of Io have been produced from Voyager imaging data: a global mosaic from each of the Voyager 1 and Voyager 2 data sets and a high-resolution mosaic of the region surrounding the volcano Ra Patera. The mosaics are maps of normal albedo and color in accurate geometric map formats. Io's photometric behavior, mapped with a two-image technique, is spatially variable, especially in the bright white areas. The disk-integrated color and albedo of the satellite have been remarkably constant over recent decades, despite the volcanic activity and the many differences between Voyager 1 and 2 images (acquired just 4 months apart). This constancy is most likely due to the consistent occurrence of large Pele-type plumes with relatively dark, red deposits in the region from long 240 to 360??. A transient brightening southeast of Pele during the Voyager 1 encounter was probably due to real changes in surface and/or atmospheric materials, rather than to photometric behavior. The intrinsic spectral variability of Io, as seen in a series of two-dimensional histograms of the multispectral mosaics, consists of continuous variation among three major spectral end members. The data were mapped into five spectral units to compare them with laboratory measurements of candidate surface materials and to show the planimetric distributions. Unit 1 is best fit by the spectral reflectance of ordinary elemental sulfur, and it is closely associated with the Peletype plume deposits. Unit 2 is strongly confined to the polar caps above about latitude ??50??, but its composition is unknown. Unit 5 is probably SO2 with relatively minor contamination; it is concentrated in the equatorial region and near the long-lived Prometheus-type plumes. Units 3 and 4 are gradational between units 1 and 5. In addition to SO2 and elemental sulfur, other plausible components of the surface are polysulfur oxides, FeCl2, Na2S, and NaHS. ?? 1988.

  5. Fire disturbance effects on land surface albedo in Alaskan tundra

    NASA Astrophysics Data System (ADS)

    French, Nancy H. F.; Whitley, Matthew A.; Jenkins, Liza K.

    2016-03-01

    The study uses satellite Moderate Resolution Imaging Spectroradiometer albedo products (MCD43A3) to assess changes in albedo at two sites in the treeless tundra region of Alaska, both within the foothills region of the Brooks Range, the 2007 Anaktuvuk River Fire (ARF) and 2012 Kucher Creek Fire (KCF). Results are compared to each other and other studies to assess the magnitude of albedo change and the longevity of impact of fire on land surface albedo. In both sites there was a marked decrease of albedo in the year following the fire. In the ARF, albedo slowly increased until 4 years after the fire, when it returned to albedo values prior to the fire. For the year immediately after the fire, a threefold difference in the shortwave albedo decrease was found between the two sites. ARF showed a 45.3% decrease, while the KCF showed a 14.1% decrease in shortwave albedo, and albedo is more variable in the KCF site than ARF site 1 year after the fire. These differences are possibly the result of differences in burn severity of the two fires, wherein the ARF burned more completely with more contiguous patches of complete burn than KCF. The impact of fire on average growing season (April-September) surface shortwave forcing in the year following fire is estimated to be 13.24 ± 6.52 W m-2 at the ARF site, a forcing comparable to studies in other treeless ecosystems. Comparison to boreal studies and the implications to energy flux are discussed in the context of future increases in fire occurrence and severity in a warming climate.

  6. Generating multi-scale albedo look-up maps using MODIS BRDF/Albedo products and landsat imagery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface albedo determines radiative forcing and is a key parameter for driving Earth’s climate. Better characterization of surface albedo for individual land cover types can reduce the uncertainty in estimating changes to Earth’s radiation balance due to land cover change. This paper presents a mult...

  7. Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

    SciTech Connect

    Liu, Y.; Wu, W.; Jensen, M. P.; Toto, T.

    2011-07-21

    This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surface-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fraction, and cloud albedo. The analytical expression is then used to deduce a new approach for inferring cloud albedo from concurrent surface-based measurements of downwelling surface shortwave radiation and cloud fraction. High-resolution decade-long data on cloud albedos are obtained by use of this surface-based approach over the US Department of Energy's Atmospheric Radiaton Measurement (ARM) Program at the Great Southern Plains (SGP) site. The surface-based cloud albedos are further compared against those derived from the coincident GOES satellite measurements. The three long-term (1997-2009) sets of hourly data on shortwave cloud radiative forcing, cloud fraction and cloud albedo collected over the SGP site are analyzed to explore the multiscale (diurnal, annual and inter-annual) variations and covariations. The analytical formulation is useful for diagnosing deficiencies of cloud-radiation parameterizations in climate models.

  8. Tooth Decay

    MedlinePlus

    ... decay starts in the outer layer, called the enamel. Without a filling, the decay can get deep into the tooth and its nerves and cause a toothache or abscess. To help prevent cavities Brush your teeth every day with a fluoride toothpaste Clean between ...

  9. Arid land monitoring using Landsat albedo difference images

    USGS Publications Warehouse

    Robinove, Charles J.; Chavez, Pat S., Jr.; Gehring, Dale G.; Holmgren, Ralph

    1981-01-01

    The Landsat albedo, or percentage of incoming radiation reflected from the ground in the wavelength range of 0.5 [mu]m to 1.1 [mu]m, is calculated from an equation using the Landsat digital brightness values and solar irradiance values, and correcting for atmospheric scattering, multispectral scanner calibration, and sun angle. The albedo calculated for each pixel is used to create an albedo image, whose grey scale is proportional to the albedo. Differencing sequential registered images and mapping selected values of the difference is used to create quantitative maps of increased or decreased albedo values of the terrain. All maps and other output products are in black and white rather than color, thus making the method quite economical. Decreases of albedo in arid regions may indicate improvement of land quality; increases may indicate degradation. Tests of the albedo difference mapping method in the Desert Experimental Range in southwestern Utah (a cold desert with little long-term terrain change) for a four-year period show that mapped changes can be correlated with erosion from flash floods, increased or decreased soil moisture, and increases or decreases in the density of desert vegetation, both perennial shrubs and annual plants. All terrain changes identified in this test were related to variations in precipitation. Although further tests of this method in hot deserts showing severe "desertification" are needed, the method is nevertheless recommended for experimental use in monitoring terrain change in other arid and semiarid regions of the world.

  10. The Temporal Evolution of the Albedo of Seasonal Sea Ice

    NASA Astrophysics Data System (ADS)

    Perovich, D. K.; Polashenski, C.; Eicken, H.; Grenfell, T. C.

    2009-12-01

    The ice-albedo feedback mechanism plays a key role in the heat budget of the Arctic sea ice cover and has climate implications. Seasonal ice is now the dominant Arctic ice type and has a significant impact on the large-scale albedo. The albedo of shorefast, seasonal ice was measured from April through late June for five field seasons. There was considerable interannual variability in the seasonal evolution of albedo, and consequently the solar heat input to the ice and upper ocean. In one year there was a monotonic decrease in areally averaged albedo after the onset of melt, while in others there were significant fluctuations of up to 0.4 over periods of only a few days. For all of the different evolutionary pathways there were two key drivers of albedo; the timing of the onset of melt and the areal coverage of melt ponds. Melt ponds on undeformed seasonal ice have been observed to reach coverages as large as 80% in only a few days. Just as rapidly coverages have been observed to drop to 7% as the ponds drained. The evolution of melt ponds is the key to understanding the evolution of seasonal ice albedo during the early stages of melt.

  11. ALBEDOS OF SMALL HILDA GROUP ASTEROIDS AS REVEALED BY SPITZER

    SciTech Connect

    Ryan, Erin Lee; Woodward, Charles E. E-mail: chelsea@astro.umn.edu

    2011-06-15

    We present thermal 24 {mu}m observations from the Spitzer Space Telescope of 62 Hilda asteroid group members with diameters ranging from 3 to 12 km. Measurements of the thermal emission, when combined with reported absolute magnitudes, allow us to constrain the albedo and diameter of each object. From our Spitzer sample, we find the mean geometric albedo, p{sub V} = 0.07 {+-} 0.05, for small (D < 10 km) Hilda group asteroids. This Spitzer-derived value of p{sub V} is greater than and spans a larger range in albedo space than the mean albedo of large (D {approx}> 10 km) Hilda group asteroids which is p{sub V} = 0.04 {+-} 0.01. Though this difference may be attributed to space weathering, the small Hilda group population reportedly displays greater taxonomic range from C-, D-, and X-type whose albedo distributions are commensurate with the range of determined albedos. We discuss the derived Hilda size-frequency distribution, color-color space, and geometric albedo for our survey sample in the context of the expected migration induced 'seeding' of the Hilda asteroid group with outer solar system proto-planetesimals as outlined in the 'Nice' formalism.

  12. Albedo reduction by dirty snow: measurements and implications

    NASA Astrophysics Data System (ADS)

    Zender, C. S.; Gallet, J.; Domine, F.; Picard, G.

    2008-12-01

    Industrial and biomass burning emissions of black carbon (BC) from low- and mid-latitudes dominate the radiative forcing by absorbing impurities trapped in snow and ice at mid- and high- northern latitudes. Correct model representation of albedo reduction by BC-contaminated snow is crucial because our GCM simulations show that dirty snow can explain about 30% of the observed 20th century Arctic warming. Until now, measurements of actual snow darkening by BC have been attempted only in the field, under non- reproducible conditions, and limited to the environmental BC concentration. We have conducted the first measurements of the direct effect of BC-contamination on snow albedo by in a controlled environment. We doped natural snow with a commercially available BC-analogue and measured the resulting albedo change at visible and near-infrared wavelengths. Snow albedo was measured in a (portable) integrating sphere system. Snow grain size is estimated from the near-infrared albedo. Snow density, temperature, and BC properties were known a priori. The albedo measurement reproducibility is about 1% for natural snow. Our measurements agree with model predictions that BC concentrations from 250 ppbm to 200 ppmm darken snow albedo by 1--70%. Our results lend confidence to the current model representations of surface darkening in the cryosphere. Applying these methods to impurity records in polar ice cores yields surface radiative forcing estimates that can be extrapolated to regional scales.

  13. β -decay study of 94Kr

    NASA Astrophysics Data System (ADS)

    Miernik, K.; Rykaczewski, K. P.; Grzywacz, R.; Gross, C. J.; Madurga, M.; Miller, D.; Stracener, D. W.; Batchelder, J. C.; Brewer, N. T.; Cartegni, L.; Fijałkowska, A.; Karny, M.; Korgul, A.; Królas, W.; Mazzocchi, C.; Mendez, A. J., II; Padgett, S. W.; Paulauskas, S. V.; Winger, J. A.; Wolińska-Cichocka, M.; Zganjar, E. F.

    2016-08-01

    β decay of neutron-rich nuclide 94Kr was reinvestigated by means of a high resolution on-line mass separator and β -γ spectroscopy. In total 22 γ -ray transitions were assigned to the decay of 94Kr, and a new isomeric state was identified. The new information allows us to build detailed levels systematics in a chain of odd-odd rubidium isotopes and draw conclusions on nuclear structure for some of the observed states. The discussed level structure affects the evolution of β -decay half-lives for neutron-rich selenium, krypton, and strontium isotopes.

  14. Yrast structure of the two-proton - and three-neutron-hole nucleus {sup 203}Hg from the decay of a 53/2+ isomer.

    SciTech Connect

    Szpak, B.; Maier, K. H.; Smolkowska, A. S.; Fornal, B.; Broda, R.; Carpenter, M. P.; Cieplicka, N.; Janssens, R. V. F.; Krolas, W.; Pawlat, T.; Wrzesinski, J.; Zhu, S.

    2011-06-15

    The decay of a new, 53/2{sup +}, isomer at 8281 keV in {sup 203}Hg has been studied by {gamma} coincidence spectroscopy. A half-life of 146(30) ns was measured. In addition, another isomeric, 39/2{sup +}, level with a half-life of 7.8(1.5) ns was observed. Some elements of the Rydstroem shell-model interaction have been adjusted to reproduce level energies in nuclei with two to four holes in the {sup 208}Pb core. With this interaction, the new states in the five-hole nucleus {sup 203}Hg are reproduced with an rms error of 105 keV.

  15. Lunar Terrain and Albedo Reconstruction from Apollo Imagery

    NASA Technical Reports Server (NTRS)

    Nefian, Ara V.; Kim, Taemin; Broxton, Michael; Moratto, Zach

    2010-01-01

    Generating accurate three dimensional planetary models and albedo maps is becoming increasingly more important as NASA plans more robotics missions to the Moon in the coming years. This paper describes a novel approach for separation of topography and albedo maps from orbital Lunar images. Our method uses an optimal Bayesian correlator to refine the stereo disparity map and generate a set of accurate digital elevation models (DEM). The albedo maps are obtained using a multi-image formation model that relies on the derived DEMs and the Lunar- Lambert reflectance model. The method is demonstrated on a set of high resolution scanned images from the Apollo era missions.

  16. Global color and albedo variations on Triton

    NASA Technical Reports Server (NTRS)

    Mcewen, Alfred S.

    1990-01-01

    Global multispectral mosaics of Triton have been produced from Voyager approach images; six spectral units are defined and mapped. The margin of the south polar cap (SPC) is scalloped and ranges in latitude from + 10 deg to -30 deg. A bright fringe is closely associated with the cap's margin; form it, diffuse bright rays extend north-northeast for hundreds of kilometers. Thus, the rays may consist of fringe materials that were redistributed by northward-going Coriolis-deflected winds. From 1977 to 1989, Triton's full-disk spectrum changed from markedly red and UV-dark to nearly neutral white and UV-bright. This spectral change can be explained by new deposition of nitrogen frost over both the northern hemisphere and parts of a formerly redder SPC. Frost deposition in the southern hemisphere during southern summer is possible over relatively high albedo areas of the cap (Stansberry et al., 1990), which helps to explain the apparent stability of the unexpectedly large SPC and the presence of the bright fringe.

  17. Neutron recognition in the LAND detector for large neutron multiplicity

    NASA Astrophysics Data System (ADS)

    Pawłowski, P.; Brzychczyk, J.; Leifels, Y.; Trautmann, W.; Adrich, P.; Aumann, T.; Bacri, C. O.; Barczyk, T.; Bassini, R.; Bianchin, S.; Boiano, C.; Boretzky, K.; Boudard, A.; Chbihi, A.; Cibor, J.; Czech, B.; De Napoli, M.; Ducret, J.-E.; Emling, H.; Frankland, J. D.; Gorbinet, T.; Hellström, M.; Henzlova, D.; Hlavac, S.; Immè, J.; Iori, I.; Johansson, H.; Kezzar, K.; Kupny, S.; Lafriakh, A.; Le Fèvre, A.; Le Gentil, E.; Leray, S.; Łukasik, J.; Lühning, J.; Lynch, W. G.; Lynen, U.; Majka, Z.; Mocko, M.; Müller, W. F. J.; Mykulyak, A.; Orth, H.; Otte, A. N.; Palit, R.; Panebianco, S.; Pullia, A.; Raciti, G.; Rapisarda, E.; Rossi, D.; Salsac, M.-D.; Sann, H.; Schwarz, C.; Simon, H.; Sfienti, C.; Sümmerer, K.; Tsang, M. B.; Verde, G.; Veselsky, M.; Volant, C.; Wallace, M.; Weick, H.; Wiechula, J.; Wieloch, A.; Zwiegliński, B.

    2012-12-01

    The performance of the LAND neutron detector is studied. Using an event-mixing technique based on one-neutron data obtained in the S107 experiment at the GSI laboratory, we test the efficiency of various analytic tools used to determine the multiplicity and kinematic properties of detected neutrons. A new algorithm developed recently for recognizing neutron showers from spectator decays in the ALADIN experiment S254 is described in detail. Its performance is assessed in comparison with other methods. The properties of the observed neutron events are used to estimate the detection efficiency of LAND in this experiment.

  18. Cloud condensation nucleus-sulfate mass relationship and cloud albedo

    NASA Technical Reports Server (NTRS)

    Hegg, Dean A.

    1994-01-01

    Analysis of previously published, simultaneous measurements of cloud condensation nucleus number concentration and sulfate mass concentration suggest a nonlinear relationship between the two variables. This nonlinearity reduces the sensitivity of cloud albedo to changes in the sulfur cycle.

  19. Disappearance of the Propontis Regional Dark Albedo Feature on Mars

    NASA Astrophysics Data System (ADS)

    Lee, S. W.; Thomas, P. C.; Cantor, B. A.

    2014-07-01

    In Aug. 2009, repeated local dust storms deposited sufficient bright dust to reduce the contrast of the Propontis dark albedo feature dramatically — effectively “erasing” this distinct and long-observed feature. Propontis has yet to "recover".

  20. Interpretation of surface and planetary directional albedos for vegetated regions

    NASA Technical Reports Server (NTRS)

    Cess, Robert D.; Vulis, Inna L.

    1989-01-01

    An atmospheric solar radiation model has been coupled with surface reflectance measurements for two vegetation types, pasture land and savannah, in order to address several issues associated with understanding the directional planetary albedo; i.e., the dependence of planetary albedo upon solar zenith angle. These include an elucidation of processes that influence the variation of planetary albedo with solar zenith angle, as well as emphasizing potential problems associated with converting narrowband planetary albedo measurements to broadband quantities. It is suggested that, for vegetated surfaces, this latter task could be somewhat formidable, since the model simulations indicate that narrowband to broadband conversions strongly depend upon vegetation type. A further aspect of this paper is to illustrate a procedure by which reciprocity inconsistencies within a bidirectional reflectance dataset, if they are not too severe, can be circumvented.

  1. Greenland ice sheet albedo variability and feedback: 2000-2015

    NASA Astrophysics Data System (ADS)

    Box, J. E.; van As, D.; Fausto, R. S.; Mottram, R.; Langen, P. P.; Steffen, K.

    2015-12-01

    Absorbed solar irradiance represents the dominant source of surface melt energy for Greenland ice. Surface melting has increased as part of a positive feedback amplifier due to surface darkening. The 16 most recent summers of observations from the NASA MODIS sensor indicate a darkening exceeding 6% in July when most melting occurs. Without the darkening, the increase in surface melting would be roughly half as large. A minority of the albedo decline signal may be from sensor degradation. So, in this study, MOD10A1 and MCD43 albedo products from MODIS are evaluated for sensor degradation and anisotropic reflectance errors. Errors are minimized through calibration to GC-Net and PROMICE Greenland snow and ice ground control data. The seasonal and spatial variability in Greenland snow and ice albedo over a 16 year period is presented, including quantifying changing absorbed solar irradiance and melt enhancement due to albedo feedback using the DMI HIRHAM5 5 km model.

  2. A preliminary global oceanic cloud climatology from satellite albedo observations

    NASA Technical Reports Server (NTRS)

    Hughes, N. A.; Henderson-Sellers, A.

    1983-01-01

    A predictive relationship is developed between over-ocean cloud system albedo and the cloud amount present, using as a data base ERB satellite microwave readings at 0.5-0.7 micron and the USAF three-dimensional nephanalysis archive. The ERB data provided global coverage at a resolution of 2.5 x 2.5 deg during the 1974-78 period. Regression analyses were performed on the amounts and albedos for several years of data for one month in order to detect seasonal variations. A logarithmic relationship was found between the cloud system albedo and cloud amount over the oceans, with negligible seasonal variance. The analysis is noted to apply only where low surface albedos are encountered, and further work to extend the study to continental vegetated areas is indicated.

  3. Albedo Pattern Recognition and Time-Series Analyses in Malaysia

    NASA Astrophysics Data System (ADS)

    Salleh, S. A.; Abd Latif, Z.; Mohd, W. M. N. Wan; Chan, A.

    2012-07-01

    Pattern recognition and time-series analyses will enable one to evaluate and generate predictions of specific phenomena. The albedo pattern and time-series analyses are very much useful especially in relation to climate condition monitoring. This study is conducted to seek for Malaysia albedo pattern changes. The pattern recognition and changes will be useful for variety of environmental and climate monitoring researches such as carbon budgeting and aerosol mapping. The 10 years (2000-2009) MODIS satellite images were used for the analyses and interpretation. These images were being processed using ERDAS Imagine remote sensing software, ArcGIS 9.3, the 6S code for atmospherical calibration and several MODIS tools (MRT, HDF2GIS, Albedo tools). There are several methods for time-series analyses were explored, this paper demonstrates trends and seasonal time-series analyses using converted HDF format MODIS MCD43A3 albedo land product. The results revealed significance changes of albedo percentages over the past 10 years and the pattern with regards to Malaysia's nebulosity index (NI) and aerosol optical depth (AOD). There is noticeable trend can be identified with regards to its maximum and minimum value of the albedo. The rise and fall of the line graph show a similar trend with regards to its daily observation. The different can be identified in term of the value or percentage of rises and falls of albedo. Thus, it can be concludes that the temporal behavior of land surface albedo in Malaysia have a uniform behaviours and effects with regards to the local monsoons. However, although the average albedo shows linear trend with nebulosity index, the pattern changes of albedo with respects to the nebulosity index indicates that there are external factors that implicates the albedo values, as the sky conditions and its diffusion plotted does not have uniform trend over the years, especially when the trend of 5 years interval is examined, 2000 shows high negative linear

  4. Earth albedo effects in the motion of artificial earth satellites

    NASA Astrophysics Data System (ADS)

    Lala, P.

    Different models of the earth albedo values and geographical distribution are compared. Effects of the local cloud cover on the satellite perturbing acceleration are investigated. Resulting changes of the satellite orbit obtained by the method of numerical integration in the spherical coordinate system are given. It is shown that a sufficiently sensitive microaccelerometer on board a special satellite could significantly improve existing models of the earth albedo.

  5. NEOWISE Diameters and Albedos V1.0

    NASA Astrophysics Data System (ADS)

    Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; Nugent, C. R.; Sonnett, S. M.; Stevenson, R. A.; Wright, E. L.

    2016-06-01

    This PDS data set represents a compilation of published diameters, optical albedos, near-infrared albedos, and beaming parameters for minor planets detected by NEOWISE during the fully cryogenic, 3-band cryo, post-cryo and NEOWISE-Reactivation Year 1 operations. It contains data covering near-Earth asteroids, Main Belt asteroids, active Main Belt objects, Hildas, Jupiter Trojans, Centaurs, and Jovian and Saturnian irregular satellites. Methodology for physical property determination is described in the referenced articles.

  6. Surface albedo observations at Gusev Crater and Meridiani Planum, Mars

    USGS Publications Warehouse

    Bell, J.F., III; Rice, M.S.; Johnson, J. R.; Hare, T.M.

    2008-01-01

    During the Mars Exploration Rover mission, the Pancam instrument has periodically acquired large-scale panoramic images with its broadband (739??338 nm) filter in order to estimate the Lambert bolometric albedo of the surface along each rover's traverse. In this work we present the full suite of such estimated albedo values measured to date by the Spirit and Opportunity rovers along their traverses in Gusev Crater and Meridiani Planum, respectively. We include estimated bolometric albedo values of individual surface features (e.g., outcrops, dusty plains, aeolian bed forms, wheel tracks, light-toned soils, and crater walls) as well as overall surface averages of the 43 total panoramic albedo data sets acquired to date. We also present comparisons to estimated Lambert albedo values taken from the Mars Global Surveyor Mars Orbiter Camera (MOC) along the rovers' traverses, and to the large-scale bolometric albedos of the sites from the Viking Orbiter Infrared Thermal Mapper (IRTM) and Mars Global Surveyor/Thermal Emission Spectrometer (TES). The ranges of Pancam-derived albedos at Gusev Crater (0.14 to 0.25) and in Meridiani Planum. (0.10 to 0.18) are in good agreement with IRTM, TES, and MOC orbital measurements. These data sets will be a useful tool and benchmark for future investigations of albodo variations with time, including measurements from orbital instruments like the Context Camera and High Resolution Imaging Science Experiment on Mars Reconnaissance Orbiter. Long-term, accurate albedo measurements could also be important for future efforts in climate modeling as well as for studies of active surface processes. Copyright 2008 by the American Geophysical Union.

  7. IAU nomenclature for albedo features on the planet Mercury

    NASA Technical Reports Server (NTRS)

    Dollfus, A.; Chapman, C. R.; Davies, M. E.; Gingerich, O.; Goldstein, R.; Guest, J.; Morrison, D.; Smith, B. A.

    1978-01-01

    The International Astronomical Union has endorsed a nomenclature for the albedo features on Mercury. Designations are based upon the mythological names related to the god Hermes; they are expressed in Latin form. The dark-hued albedo features are associated with the generic term Solitudo. The light-hued areas are designated by a single name without generic term. The 32 names adopted are allocated on the Mercury map.

  8. Improving modeled snow albedo estimates during the spring melt season

    NASA Astrophysics Data System (ADS)

    Malik, M. Jahanzeb; Velde, Rogier; Vekerdy, Zoltan; Su, Zhongbo

    2014-06-01

    Snow albedo influences snow-covered land energy and water budgets and is thus an important variable for energy and water fluxes calculations. Here, we quantify the performance of the three existing snow albedo parameterizations under alpine, tundra, and prairie snow conditions when implemented in the Noah land surface model (LSM)—Noah's default and ones from the Biosphere-Atmosphere Transfer Scheme (BATS) and the Canadian Land Surface Scheme (CLASS) LSMs. The Noah LSM is forced with and its output is evaluated using in situ measurements from seven sites in U.S. and France. Comparison of the snow albedo simulations with the in situ measurements reveals that the three parameterizations overestimate snow albedo during springtime. An alternative snow albedo parameterization is introduced that adopts the shape of the variogram for the optically thick snowpacks and decreases the albedo further for optically thin conditions by mixing the snow with the land surface (background) albedo as a function of snow depth. In comparison with the in situ measurements, the new parameterization improves albedo simulation of the alpine and tundra snowpacks and positively impacts the simulation of snow depth, snowmelt rate, and upward shortwave radiation. An improved model performance with the variogram-shaped parameterization can, however, not be unambiguously detected for prairie snowpacks, which may be attributed to uncertainties associated with the simulation of snow density. An assessment of the model performance for the Upper Colorado River Basin highlights that with the variogram-shaped parameterization Noah simulates more evapotranspiration and larger runoff peaks in Spring, whereas the Summer runoff is lower.

  9. Simultaneous Spectral Albedo Measurements Near the Atmospheric Radiation Measurement Southern Great Plains (ARM SGP) Central Facility

    SciTech Connect

    Michalsky, Joseph J.; Min, Qilong; Barnard, James C.; Marchand, Roger T.; Pilewskie, Peter

    2003-04-30

    In this study, a data analysis is performed to determine the area-averaged, spectral albedo at ARM's SGP central facility site. The spectral albedo is then fed into radiation transfer models to show that the diffuse discrepancy is diminished when the spectral albedo is used (as opposed to using the broadband albedo).

  10. β-Decay Half-Lives of 110 Neutron-Rich Nuclei across the N=82 Shell Gap: Implications for the Mechanism and Universality of the Astrophysical r Process.

    PubMed

    Lorusso, G; Nishimura, S; Xu, Z Y; Jungclaus, A; Shimizu, Y; Simpson, G S; Söderström, P-A; Watanabe, H; Browne, F; Doornenbal, P; Gey, G; Jung, H S; Meyer, B; Sumikama, T; Taprogge, J; Vajta, Zs; Wu, J; Baba, H; Benzoni, G; Chae, K Y; Crespi, F C L; Fukuda, N; Gernhäuser, R; Inabe, N; Isobe, T; Kajino, T; Kameda, D; Kim, G D; Kim, Y-K; Kojouharov, I; Kondev, F G; Kubo, T; Kurz, N; Kwon, Y K; Lane, G J; Li, Z; Montaner-Pizá, A; Moschner, K; Naqvi, F; Niikura, M; Nishibata, H; Odahara, A; Orlandi, R; Patel, Z; Podolyák, Zs; Sakurai, H; Schaffner, H; Schury, P; Shibagaki, S; Steiger, K; Suzuki, H; Takeda, H; Wendt, A; Yagi, A; Yoshinaga, K

    2015-05-15

    The β-decay half-lives of 110 neutron-rich isotopes of the elements from _{37}Rb to _{50}Sn were measured at the Radioactive Isotope Beam Factory. The 40 new half-lives follow robust systematics and highlight the persistence of shell effects. The new data have direct implications for r-process calculations and reinforce the notion that the second (A≈130) and the rare-earth-element (A≈160) abundance peaks may result from the freeze-out of an (n,γ)⇄(γ,n) equilibrium. In such an equilibrium, the new half-lives are important factors determining the abundance of rare-earth elements, and allow for a more reliable discussion of the r process universality. It is anticipated that universality may not extend to the elements Sn, Sb, I, and Cs, making the detection of these elements in metal-poor stars of the utmost importance to determine the exact conditions of individual r-process events. PMID:26024165

  11. Spectral albedo and transmittance of thin young Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Taskjelle, Torbjørn; Hudson, Stephen R.; Granskog, Mats A.; Nicolaus, Marcel; Lei, Ruibo; Gerland, Sebastian; Stamnes, Jakob J.; Hamre, Børge

    2016-01-01

    Spectral albedo and transmittance in the range were measured on three separate dates on less than thick new Arctic sea ice growing on Kongsfjorden, Svalbard at , . Inherent optical properties, including absorption coefficients of particulate and dissolved material, were obtained from ice samples and fed into a radiative transfer model, which was used to analyze spectral albedo and transmittance and to study the influence of clouds and snow on these. Integrated albedo and transmittance for photosynthetically active radiation () were in the range 0.17-0.21 and 0.77-0.86, respectively. The average albedo and transmittance of the total solar radiation energy were 0.16 and 0.51, respectively. Values inferred from the model indicate that the ice contained possibly up to 40% brine and only 0.6% bubbles. Angular redistribution of solar radiation by clouds and snow was found to influence both the wavelength-integrated value and the spectral shape of albedo and transmittance. In particular, local peaks and depressions in the spectral albedo and spectral transmittance were found for wavelengths within atmospheric absorption bands. Simulated and measured transmittance spectra were within 5% for most of the wavelength range, but deviated up to 25% in the vicinity of , indicating the need for more optical laboratory measurements of pure ice, or improved modeling of brine optical properties in this near-infrared wavelength region.

  12. Postfire influences of snag attrition on albedo and radiative forcing

    NASA Astrophysics Data System (ADS)

    O'Halloran, Thomas L.; Acker, Steven A.; Joerger, Verena M.; Kertis, Jane; Law, Beverly E.

    2014-12-01

    This paper examines albedo perturbation and radiative forcing after a high-severity fire in a mature forest in the Oregon Cascade Range. Correlations between postfire albedo and seedling, sapling, and snag (standing dead tree) density were investigated across fire severity classes and seasons for years 4-15 after fire. Albedo perturbation was 14 times larger in winter compared to summer and increased with fire severity class for the first several years. Albedo perturbation increased linearly with time over the study period. Correlations between albedo perturbations and the vegetation densities were strongest with snags, and significant in all fire classes in both summer and winter (R < -0.92, p < 0.01). The resulting annual radiative forcing at the top of the atmosphere became more negative linearly at a rate of -0.86 W m-2 yr-1, reaching -15 W m-2 in year 15 after fire. This suggests that snags can be the dominant controller of postfire albedo on decadal time scales.

  13. Albedo as a modulator of climate response to tropical deforestation

    NASA Technical Reports Server (NTRS)

    Dirmeyer, Paul A.; Shukla, J.

    1994-01-01

    An atmospheric general circulation model with land surface properties represented by the simplified Simple Biosphere model is used to investigate the effects on local climate due to tropical deforestation for the Amazon basin. One control and three anomaly integrations of 4 years' duration are performed. In the anomaly integrations, rain forest in South America is replaced by degraded grassland. The anomaly integrations differ only in the optical properties of the grassland vegetation, with net surface albedos ranging from the same as to 0.09 lighter than that of rain forest. It is found that the change in climate, particularly rainfall, is strongly dependent on the change in surface albedo that accompanies deforestation. Replacement of forest by grass causes a reduction in transpiration and reduces frictional convergence by decreasing surface roughness. However, precipitation averaged over the deforested area is not necessarily reduced. Average precipitation decreases when the increase in albedo is greater than 0.03. If surface albedo is not increased appreciably as a result of deforestation, moisture flux convergence driven by the increase in surface temperature can offset the other effects, and average precipitation increases. As albedo is increased, surface temperature does not change, but surface latent and sensible heat flux decreases due to reduced radiational energy absorbed at the surface, resulting in a reduction in convection and precipitation. A change in the distribution of precipitation due to deforestation that appears to be independent of the albedo is observed.

  14. Albedo as a modulator of climate response to tropical deforestation

    SciTech Connect

    Dirmeyer, P.A.; Shukla, J.

    1994-10-01

    An atmospheric general circulation model with land surface properties represented by the simplified Simple Biosphere model is used to investigate the effects on local climate due to tropical deforestation for the Amazon basin. One control and three anomaly integrations of 4 years` duration are performed. In the anomaly integrations, rain forest in South America is replaced by degraded grassland. The anomaly integrations differ only in the optical properties of the grassland vegetation, with net surface albedos ranging from the same as to 0.09 lighter than that of rain forest. It is found that the change in climate, particularly rainfall, is strongly dependent on the change in surface albedo that accompanies deforestation. Replacement of forest by grass causes a reduction in transpiration and reduces frictional convergence by decreasing surface roughness. However, precipitation averaged over the deforested area is not necessarily reduced. Average precipitation decreases when the increase in albedo is greater than 0.03. If surface albedo is not increased appreciably as a result of deforestation, moisture flux convergence driven by the increase in surface temperature can offset the other effects, and average precipitation increases. As albedo is increased, surface temperature does not change, but surface latent and sensible heat flux decreases due to reduced radiational energy absorbed at the surface, resulting in a reduction in convection and precipitation. A change in the distribution of precipitation due to deforestation that appears to be independent of the albedo is observed.

  15. The Fundamental Neutron Physics Beamline at the Spallation Neutron Source

    PubMed Central

    Greene, Geoffrey; Cianciolo, Vince; Koehler, Paul; Allen, Richard; Snow, William Michael; Huffman, Paul; Gould, Chris; Bowman, David; Cooper, Martin; Doyle, John

    2005-01-01

    The Spallation Neutron Source (SNS), currently under construction at Oak Ridge National Laboratory with an anticipated start-up in early 2006, will provide the most intense pulsed beams of cold neutrons in the world. At a projected power of 1.4 MW, the time averaged fluxes and fluences of the SNS will approach those of high flux reactors. One of the flight paths on the cold, coupled moderator will be devoted to fundamental neutron physics. The fundamental neutron physics beamline is anticipated to include two beam-lines; a broad band cold beam, and a monochromatic beam of 0.89 nm neutrons for ultracold neutron (UCN) experiments. The fundamental neutron physics beamline will be operated as a user facility with experiment selection based on a peer reviewed proposal process. An initial program of five experiments in neutron decay, hadronic weak interaction and time reversal symmetry violation have been proposed. PMID:27308112

  16. Single Scattering Albedo Monitor for Airborne Particulates

    NASA Astrophysics Data System (ADS)

    Onasch, Timothy; Massoli, Paola; Kebabian, Paul; Hills, Frank; Bacon, Fred; Freedman, Andrew

    2015-04-01

    We describe a robust, compact, field deployable instrument (the CAPS PMssa) that simultaneously measures airborne particle light extinction and scattering coefficients and thus the single scattering albedo (SSA) on the same sample volume. With an appropriate change in mirrors and light source, measurements have been made at wavelengths ranging from 450 to 780 nm. The extinction measurement is based on cavity attenuated phase shift (CAPS) techniques as employed in the CAPS PMex particle extinction monitor; scattering is measured using a integrating nephelometry by incorporating a Lambertian integrating sphere within the sample cell. The scattering measurement is calibrated using the extinction measurement. Measurements using ammonium sulfate particles of various sizes indicate that the response of the scattering channel with respect to measured extinction is linear to within 1% up to 1000 Mm-1 and can be extended further (4000 Mm-1) with additional corrections. The precision in both measurement channels is less than 1 Mm-1 (1s, 1σ). The truncation effect in the scattering channel, caused by light lost at extreme forward/backward scattering angles, was measured as a function of particle size using monodisperse polystyrene latex particles (n=1.59). The results were successfully fit using a simple geometric model allowing for reasonable extrapolation to a given wavelength, particle index of refraction and particle size distribution, assuming spherical particles. For sub-micron sized particles, the truncation corrections are comparable to those reported for commercial nephelometers. Measurements of the optical properties of ambient aerosol indicate that the values of the SSA of these particles measured with this instrument (0.91±0.03) using scattering and extinction agreed within experimental uncertainty with those determined using extinction measured by this instrument and absorption measured using a Multi-Angle Absorption Spectrometer (0.89±0.03) where the

  17. High-albedo materials for reducing building cooling energy use

    SciTech Connect

    Taha, H.; Sailor, D.; Akbari, H.

    1992-01-01

    One simple and effective way to mitigate urban heat islands, i.e., the higher temperatures in cities compared to those of the surrounds, and their negative impacts on cooling energy consumption is to use high-albedo materials on major urban surfaces such as rooftops, streets, sidewalks, school yards, and the exposed surfaces of parking lots. High-albedo materials can save cooling energy use by directly reducing the heat gain through a building`s envelope (direct effect) and also by lowering the urban air temperature in the neighborhood of the building (indirect effect). This project is an attempt to address high-albedo materials for buildings and to perform measurements of roof coatings. We search for existing methods and materials to implement fighter colors on major building and urban surfaces. Their cost effectiveness are examined and the possible related technical, maintenance, and environmental problems are identified. We develop a method for measuring albedo in the field by studying the instrumentation aspects of such measurements. The surface temperature impacts of various albedo/materials in the actual outdoor environment are studied by measuring the surface temperatures of a variety of materials tested on an actual roof. We also generate an albedo database for several urban surfaces to serve as a reference for future use. The results indicate that high-albedo materials can have a large impact on the surface temperature regime. On clear sunny days, when the solar noon surface temperatures of conventional roofing materials were about 40{degrees}C (72{degrees}F) warmer than air, the surface temperature of high-albedo coatings were only about 5{degrees}C warmer than air. In the morning and in the late afternoon, the high-albedo materials were as cool as the air itself. While conventional roofing materials warm up by an average 0.055{degrees}C/(W m{sup {minus}2}), the high-albedo surfaces warm up by an average 0.015{degrees}C/(W m{sup {minus}2}).

  18. High-albedo materials for reducing building cooling energy use

    SciTech Connect

    Taha, H.; Sailor, D.; Akbari, H.

    1992-01-01

    One simple and effective way to mitigate urban heat islands, i.e., the higher temperatures in cities compared to those of the surrounds, and their negative impacts on cooling energy consumption is to use high-albedo materials on major urban surfaces such as rooftops, streets, sidewalks, school yards, and the exposed surfaces of parking lots. High-albedo materials can save cooling energy use by directly reducing the heat gain through a building's envelope (direct effect) and also by lowering the urban air temperature in the neighborhood of the building (indirect effect). This project is an attempt to address high-albedo materials for buildings and to perform measurements of roof coatings. We search for existing methods and materials to implement fighter colors on major building and urban surfaces. Their cost effectiveness are examined and the possible related technical, maintenance, and environmental problems are identified. We develop a method for measuring albedo in the field by studying the instrumentation aspects of such measurements. The surface temperature impacts of various albedo/materials in the actual outdoor environment are studied by measuring the surface temperatures of a variety of materials tested on an actual roof. We also generate an albedo database for several urban surfaces to serve as a reference for future use. The results indicate that high-albedo materials can have a large impact on the surface temperature regime. On clear sunny days, when the solar noon surface temperatures of conventional roofing materials were about 40{degrees}C (72{degrees}F) warmer than air, the surface temperature of high-albedo coatings were only about 5{degrees}C warmer than air. In the morning and in the late afternoon, the high-albedo materials were as cool as the air itself. While conventional roofing materials warm up by an average 0.055{degrees}C/(W m{sup {minus}2}), the high-albedo surfaces warm up by an average 0.015{degrees}C/(W m{sup {minus}2}).

  19. Standards for the validation of remotely sensed albedo products

    NASA Astrophysics Data System (ADS)

    Adams, Jennifer

    2015-04-01

    Land surface albedo is important component of the Earth's energy balance, defined as the fraction of shortwave radiation absorbed by a surface, and is one many Essential Climate Variables (ECVS) that can be retrieved from space through remote sensing. To quantify the accuracy of these products, they must be validated with respect to in-situ measurements of albedo using an albedometer. Whilst accepted standards exist for the calibration of albedometers, standards for the use of in-situ measurement schemes, and their use in validation procedures have yet to be developed. It is essential that we can assess the quality of remotely sensed albedo data, and to identify traceable sources of uncertainty during process of providing these data. As a result of the current lack of accepted standards for in-situ albedo retrieval and validation procedures, we are not yet able to identify and quantify traceable sources of uncertainty. Establishing standard protocols for in-situ retrievals for the validation of global albedo products would allow inter-product use and comparison, in addition to product standardization. Accordingly, this study aims to assess the quality of in-situ albedo retrieval schemes and identify sources of uncertainty, specifically in vegetation environments. A 3D Monte Carlo Ray Tracing Model will be used to simulate albedometer instruments in complex 3D vegetation canopies. To determine sources of uncertainty, factors that influence albedo measurement uncertainty were identified and will subsequently be examined: 1. Time of day (Solar Zenith Angle) 2. Ecosytem type 3. Placement of albedometer within the ecosystem 4. Height of albedometer above the canopy 5. Clustering within the ecosystem A variety of 3D vegetation canopies have been generated to cover the main ecosystems found globally, different seasons, and different plant distributions. Canopies generated include birchstand and pinestand forests for summer and winter, savanna, shrubland, cropland and

  20. Neutron measurements in near-Earth orbit with COMPTEL

    NASA Technical Reports Server (NTRS)

    Morris, D. J.; Aarts, H.; Bennett, K.; Lockwood, J. A.; Mcconnell, M. L.; Ryan, J. M.; Schoenfelder, V.; Steinle, H.; Peng, X.

    1995-01-01

    The fast neutron flux in near-Earth orbit has been measured with the COMPTEL instrument on the Compton Gamma Ray Observatory (CGRO). For this measurement one of COMPTEL's seven liquid scintillator modules was used as an uncollimated neutron detector with threshold of 12.8 MeV. The measurements cover a range of 4.8 to 15.5 GV in vertical cutoff rigidity and 3 deg to 177 deg in spacecraft geocenter zenith angle. One of the measurements occurred near the minimum of the deepest Forbush decrease ever observed by ground-level neutron monitors. After correction for solar modulation, the total flux is well fitted by separable functions in rigidity and zenith angle. With the spacecraft pointed near the nadir the flux is consistent with balloon measurements of the atmospheric neutron albedo. The flux varies by about a factor of 4 between the extremes of rigidity and a factor of 2 between the extremes of zenith angle. The effect of the spacecraft mass in shielding the detector from the atmospheric neutron albedo is much more important than its role as a source of additional secondary neutrons. The neutron spectral hardness varies little with rigidity or zenith angle and lies in the range spanned by earlier atmospheric neutron albedo measurements.

  1. Precision Neutron Polarimetry

    NASA Astrophysics Data System (ADS)

    Sharma, Monisha; Barron-Palos, L.; Bowman, J. D.; Chupp, T. E.; Crawford, C.; Danagoulian, A.; Klein, A.; Penttila, S. I.; Salas-Bacci, A. F.; Wilburn, W. S.

    2008-04-01

    Proposed PANDA and abBA experiments aim to measure the correlation coefficients in the polarized neutron beta decay at the SNS. The goal of these experiments is 0.1% measurement which will require neutron polarimetry at 0.1% level. The FnPB neutron beam will be polarized either using a ^3He spin filter or a supermirror polarizer and the neutron polarization will be measured using a ^3He spin filter. Experiment to establish the accuracy to which neutron polarization can be determined using ^3He spin fliters was performed at Los Alamos National Laboratory in Summer 2007 and the analysis is in progress. The details of the experiment and the results will be presented.

  2. Pulsed neutron detector

    DOEpatents

    Robertson, deceased, J. Craig; Rowland, Mark S.

    1989-03-21

    A pulsed neutron detector and system for detecting low intensity fast neutron pulses has a body of beryllium adjacent a body of hydrogenous material the latter of which acts as a beta particle detector, scintillator, and moderator. The fast neutrons (defined as having En>1.5 MeV) react in the beryllium and the hydrogenous material to produce larger numbers of slow neutrons than would be generated in the beryllium itself and which in the beryllium generate hellium-6 which decays and yields beta particles. The beta particles reach the hydrogenous material which scintillates to yield light of intensity related to the number of fast neutrons. A photomultiplier adjacent the hydrogenous material (scintillator) senses the light emission from the scintillator. Utilization means, such as a summing device, sums the pulses from the photo-multiplier for monitoring or other purposes.

  3. First measurement of the neutron beta asymmetry with ultracold neutrons.

    PubMed

    Pattie, R W; Anaya, J; Back, H O; Boissevain, J G; Bowles, T J; Broussard, L J; Carr, R; Clark, D J; Currie, S; Du, S; Filippone, B W; Geltenbort, P; García, A; Hawari, A; Hickerson, K P; Hill, R; Hino, M; Hoedl, S A; Hogan, G E; Holley, A T; Ito, T M; Kawai, T; Kirch, K; Kitagaki, S; Lamoreaux, S K; Liu, C-Y; Liu, J; Makela, M; Mammei, R R; Martin, J W; Melconian, D; Meier, N; Mendenhall, M P; Morris, C L; Mortensen, R; Pichlmaier, A; Pitt, M L; Plaster, B; Ramsey, J C; Rios, R; Sabourov, K; Sallaska, A L; Saunders, A; Schmid, R; Seestrom, S; Servicky, C; Sjue, S K L; Smith, D; Sondheim, W E; Tatar, E; Teasdale, W; Terai, C; Tipton, B; Utsuro, M; Vogelaar, R B; Wehring, B W; Xu, Y P; Young, A R; Yuan, J

    2009-01-01

    We report the first measurement of an angular correlation parameter in neutron beta decay using polarized ultracold neutrons (UCN). We utilize UCN with energies below about 200 neV, which we guide and store for approximately 30 s in a Cu decay volume. The interaction of the neutron magnetic dipole moment with a static 7 T field external to the decay volume provides a 420 neV potential energy barrier to the spin state parallel to the field, polarizing the UCN before they pass through an adiabatic fast passage spin flipper and enter a decay volume, situated within a 1 T field in a 2x2pi solenoidal spectrometer. We determine a value for the beta-asymmetry parameter A_{0}=-0.1138+/-0.0046+/-0.0021. PMID:19257182

  4. THE HIGH ALBEDO OF THE HOT JUPITER KEPLER-7 b

    SciTech Connect

    Demory, Brice-Olivier; Seager, Sara; Madhusudhan, Nikku; Kjeldsen, Hans; Christensen-Dalsgaard, Joergen; Gillon, Michael; Rowe, Jason F.; Borucki, William J.; Koch, David G.; Welsh, William F.; Adams, Elisabeth R.; Dupree, Andrea; McCarthy, Don; Kulesa, Craig

    2011-07-01

    Hot Jupiters are expected to be dark from both observations (albedo upper limits) and theory (alkali metals and/or TiO and VO absorption). However, only a handful of hot Jupiters have been observed with high enough photometric precision at visible wavelengths to investigate these expectations. The NASA Kepler mission provides a means to widen the sample and to assess the extent to which hot Jupiter albedos are low. We present a global analysis of Kepler-7 b based on Q0-Q4 data, published radial velocities, and asteroseismology constraints. We measure an occultation depth in the Kepler bandpass of 44 {+-} 5 ppm. If directly related to the albedo, this translates to a Kepler geometric albedo of 0.32 {+-} 0.03, the most precise value measured so far for an exoplanet. We also characterize the planetary orbital phase light curve with an amplitude of 42 {+-} 4 ppm. Using atmospheric models, we find it unlikely that the high albedo is due to a dominant thermal component and propose two solutions to explain the observed planetary flux. First, we interpret the Kepler-7 b albedo as resulting from an excess reflection over what can be explained solely by Rayleigh scattering, along with a nominal thermal component. This excess reflection might indicate the presence of a cloud or haze layer in the atmosphere, motivating new modeling and observational efforts. Alternatively, the albedo can be explained by Rayleigh scattering alone if Na and K are depleted in the atmosphere by a factor of 10-100 below solar abundances.

  5. Preferential cooling of hot extremes from cropland albedo management

    PubMed Central

    Davin, Edouard L.; Seneviratne, Sonia I.; Ciais, Philippe; Olioso, Albert; Wang, Tao

    2014-01-01

    Changes in agricultural practices are considered a possible option to mitigate climate change. In particular, reducing or suppressing tillage (no-till) may have the potential to sequester carbon in soils, which could help slow global warming. On the other hand, such practices also have a direct effect on regional climate by altering the physical properties of the land surface. These biogeophysical effects, however, are still poorly known. Here we show that no-till management increases the surface albedo of croplands in summer and that the resulting cooling effect is amplified during hot extremes, thus attenuating peak temperatures reached during heat waves. Using a regional climate model accounting for the observed effects of no-till farming on surface albedo, as well as possible reductions in soil evaporation, we investigate the potential consequences of a full conversion to no-till agriculture in Europe. We find that the summer cooling from cropland albedo increase is strongly amplified during hot summer days, when surface albedo has more impact on the Earth’s radiative balance due to clear-sky conditions. The reduced evaporation associated with the crop residue cover tends to counteract the albedo-induced cooling, but during hot days the albedo effect is the dominating factor. For heatwave summer days the local cooling effect gained from no-till practice is of the order of 2 °C. The identified asymmetric impact of surface albedo change on summer temperature opens new avenues for climate-engineering measures targeting high-impact events rather than mean climate properties. PMID:24958872

  6. Preferential cooling of hot extremes from cropland albedo management.

    PubMed

    Davin, Edouard L; Seneviratne, Sonia I; Ciais, Philippe; Olioso, Albert; Wang, Tao

    2014-07-01

    Changes in agricultural practices are considered a possible option to mitigate climate change. In particular, reducing or suppressing tillage (no-till) may have the potential to sequester carbon in soils, which could help slow global warming. On the other hand, such practices also have a direct effect on regional climate by altering the physical properties of the land surface. These biogeophysical effects, however, are still poorly known. Here we show that no-till management increases the surface albedo of croplands in summer and that the resulting cooling effect is amplified during hot extremes, thus attenuating peak temperatures reached during heat waves. Using a regional climate model accounting for the observed effects of no-till farming on surface albedo, as well as possible reductions in soil evaporation, we investigate the potential consequences of a full conversion to no-till agriculture in Europe. We find that the summer cooling from cropland albedo increase is strongly amplified during hot summer days, when surface albedo has more impact on the Earth's radiative balance due to clear-sky conditions. The reduced evaporation associated with the crop residue cover tends to counteract the albedo-induced cooling, but during hot days the albedo effect is the dominating factor. For heatwave summer days the local cooling effect gained from no-till practice is of the order of 2 °C. The identified asymmetric impact of surface albedo change on summer temperature opens new avenues for climate-engineering measures targeting high-impact events rather than mean climate properties. PMID:24958872

  7. Global Cooling: Effect of Urban Albedo on Global Temperature

    SciTech Connect

    Akbari, Hashem; Menon, Surabi; Rosenfeld, Arthur

    2007-05-22

    In many urban areas, pavements and roofs constitute over 60% of urban surfaces (roof 20-25%, pavements about 40%). The roof and the pavement albedo can be increased by about 0.25 and 0.10, respectively, resulting in a net albedo increase for urban areas of about 0.1. Many studies have demonstrated building cooling-energy savings in excess of 20% upon raising roof reflectivity from an existing 10-20% to about 60%. We estimate U.S. potential savings in excess of $1 billion (B) per year in net annual energy bills. Increasing albedo of urban surfaces can reduce the summertime urban temperature and improve the urban air quality. Increasing the urban albedo has the added benefit of reflecting more of the incoming global solar radiation and countering the effect of global warming. We estimate that increasing albedo of urban areas by 0.1 results in an increase of 3 x 10{sup -4} in Earth albedo. Using a simple global model, the change in air temperature in lowest 1.8 km of the atmosphere is estimated at 0.01K. Modelers predict a warming of about 3K in the next 60 years (0.05K/year). Change of 0.1 in urban albedo will result in 0.01K global cooling, a delay of {approx}0.2 years in global warming. This 0.2 years delay in global warming is equivalent to 10 Gt reduction in CO2 emissions.

  8. A Continental United States High Resolution NLCD Land Cover – MODIS Albedo Database to Examine Albedo and Land Cover Change Relationships

    EPA Science Inventory

    Surface albedo influences climate by affecting the amount of solar radiation that is reflected at the Earth’s surface, and surface albedo is, in turn, affected by land cover. General Circulation Models typically use modeled or prescribed albedo to assess the influence of land co...

  9. Neutron Absorption Measurements Constrain Eucrite-Diogenite Mixing in Vesta's Regolith

    NASA Technical Reports Server (NTRS)

    Prettyman, T. H.; Mittlefehldt, D. W.; Feldman, W. C.; Hendricks, J. S.; Lawrence, D. J.; Peplowski, P. N.; Toplis, M. J.; Yamashita, N.; Beck, A.; LeCorre, L.; McCoy, T. J.; McSween, H. Y.; Reedy, R. C.; Titus, T. N.; Mizzon, H.; Reddy, V.; Joy, S. P.; Raymond, C. A.; Russell, C. T.

    2013-01-01

    The NASA Dawn Mission s Gamma Ray and Neutron Detector (GRaND) [1] acquired mapping data during 5 months in a polar, low altitude mapping orbit (LAMO) with approx.460-km mean radius around main-belt asteroid Vesta (264-km mean radius) [2]. Neutrons and gamma rays are produced by galactic cosmic ray interactions and by the decay of natural radioelements (K, Th, U), providing information about the elemental composition of Vesta s regolith to depths of a few decimeters beneath the surface. From the data acquired in LAMO, maps of vestan neutron and gamma ray signatures were determined with a spatial resolution of approx.300 km full-width-at-half-maximum (FWHM), comparable in scale to the Rheasilvia impact basin (approx.500 km diameter). The data from Vesta encounter are available from the NASA Planetary Data System. Based on an analysis of gamma-ray spectra, Vesta s global-average regolith composition was found to be consistent with the Howardite, Eucrite, and Diogenite (HED) meteorites, reinforcing the HED-Vesta connection [2-7]. Further, an analysis of epithermal neutrons revealed variations in the abundance of hydrogen on Vesta s surface, reaching values up to 400 micro-g/g [2]. The association of high concentrations of hydrogen with equatorial, low-albedo surface regions indicated exogenic delivery of hydrogen by the infall of carbonaceous chondrite (CC) materials. This finding was buttressed by the presence of minimally-altered CC clasts in howardites, with inferred bulk hydrogen abundances similar to that found by GRaND, and by studies using data from Dawn s Framing Camera (FC) and VIR instruments [8-10]. In addition, from an analysis of neutron absorption, spatial-variations in the abundance of elements other than hydrogen were detected [2].

  10. Relating black carbon content to reduction of snow albedo

    NASA Astrophysics Data System (ADS)

    Brandt, R. E.; Warren, S. G.; Clarke, A. D.

    2011-12-01

    In remote snow of the Northern Hemisphere, the levels of soot pollution are in the parts-per-billion (ppb) range, where the effect on albedo is at the level of a few percent. A reduction of albedo by 1-2% is significant for climate but is difficult to detect experimentally, because snow albedo depends on several other variables. In our work to quantify the climatic effect of black carbon (BC) in snow, we therefore do not directly measure the albedo reduction. Instead, we use a two-step procedure: (1) We collect snow samples, melt and filter them, and analyze the filters spectrophotometrically for BC concentration. (2) We use the BC amount from the filter measurement, together with snow grain size, in a radiative transfer model to compute the albedo reduction. Our radiative transfer model uses the discrete ordinates algorithm DISORT 2.0. We have chosen a representative BC size distribution and optical constants, and have incorporated those of mineral dust as well. While a given mass of BC causes over an order of magnitude more snow albedo reduction compared to dust, a snowpack containing dust mutes the albedo-reducing effect of BC. Because the computed reduction of snow albedo is model-based, it requires experimental verification. We doubt that direct measurement of albedo-reduction will be feasible in nature, because of the vertical variation of both snow grain size and soot content, and because the natural soot content is small. We conclude that what is needed is an artificial snowpack, with uniform grain size and large uniform soot content (ppm not ppb), to produce a large signal on albedo. We have chosen to pursue this experiment outdoors rather than in the laboratory, for the following reasons: (1) The snowpack in the field of view is uniformly illuminated if the source of radiation is the Sun. (2) Visible radiation penetrates into the snow, so photons emerge horizontally distant from where they entered. In the limited width of a laboratory snowpack, radiation

  11. Potential effects of forest management on surface albedo

    NASA Astrophysics Data System (ADS)

    Otto, J.; Bréon, F.-M.; Schelhaas, M.-J.; Pinty, B.; Luyssaert, S.

    2012-04-01

    Currently 70% of the world's forests are managed and this figure is likely to rise due to population growth and increasing demand for wood based products. Forest management has been put forward by the Kyoto-Protocol as one of the key instruments in mitigating climate change. For temperate and boreal forests, the effects of forest management on the stand-level carbon balance are reasonably well understood, but the biophysical effects, for example through changes in the albedo, remain elusive. Following a modeling approach, we aim to quantify the variability in albedo that can be attributed to forest management through changes in canopy structure and density. The modelling approach chains three separate models: (1) a forest gap model to describe stand dynamics, (2) a Monte-Carlo model to estimate the probability density function of the optical path length of photons through the canopy and (3) a physically-based canopy transfer model to estimate the interaction between photons and leaves. The forest gap model provides, on a monthly time step the position, height, diameter, crown size and leaf area index of individual trees. The Monte-Carlo model computes from this the probability density function of the distance a photon travels through crown volumes to determine the direct light reaching the forest floor. This information is needed by the canopy transfer model to calculate the effective leaf area index - a quantity that allows it to correctly represent a 3D process with a 1D model. Outgoing radiation is calculated as the result of multiple processes involving the scattering due to the canopy layer and the forest floor. Finally, surface albedo is computed as the ratio between incident solar radiation and calculated outgoing radiation. The study used two time series representing thinning from below of a beech and a Scots pine forest. The results show a strong temporal evolution in albedo during stand establishment followed by a relatively stable albedo once the canopy

  12. Understanding the Factors That Control Snow Albedo Over Central Greenland

    NASA Astrophysics Data System (ADS)

    Wright, P.; Bergin, M. H.; Dibb, J. E.; Domine, F.; Carmagnola, C.; Courville, Z.; Sokolik, I. N.; Lefer, B. L.

    2011-12-01

    Snow albedo plays a critical role in the energy balance of the Greenland Ice Sheet. In particular, the snow albedo influences the extent to which absorbing aerosols over Greenland (i.e. dust and black carbon) force climate. With this in mind the spectral snow albedo, physical snow properties, and snow chemistry were measured during May, June, and July 2011 at Summit, Greenland to investigate the variability in snow spectral albedo and its impact on aerosol direct radiative forcing. Optical and chemical properties of aerosol and aerosol optical depth were also measured as part of this study. Strellis et. al. will present a preliminary assessment of aerosol radiative forcing at Summit in summer 2011, in a separate presentation at this meeting. Spectral albedo was measured from 350-2500 nm with an ASD FieldSpec Pro spectroradiometer daily at four permanent sites and a moving fifth site where snow was sampled for characterization, as well as in more intensive diurnal and spatial surveys. Snow specific surface area (SSA), the ratio of snow crystal surface area to mass, was measured with a Dual Frequency Integrating Sphere (DUFISSS) at 1310 nm and 1550 nm, as well as with dyed and cast samples collected for stereology analysis. Snow stratigraphy, crystal size, and density were also measured on a daily basis, and snow samples will be analyzed for microstructural parameters determined from micro-CT imaging. Snow chemistry measurements include specific elements, major ions, and elemental and organic carbon. The time series of daily albedo measurements ranged from 0.88 to nearly 1.0 in visible wavelengths and from 0.42 to 0.65 in the near infrared. Changes as large as 0.1 were observed between consecutive daily measurements across the spectrum. Preliminary results show a strong correlation between variation in albedo and co-located measurements of snow specific surface area, specifically in the near infrared. By conducting our measurements near solar noon every day, and

  13. Occurrence of lower cloud albedo in ship tracks

    NASA Astrophysics Data System (ADS)

    Chen, Y.-C.; Christensen, M. W.; Xue, L.; Sorooshian, A.; Stephens, G. L.; Rasmussen, R. M.; Seinfeld, J. H.

    2012-05-01

    The concept of geoengineering by marine cloud brightening is based on seeding marine stratocumulus clouds with sub-micrometer sea-salt particles to enhance the cloud droplet number concentration and cloud albedo, thereby producing a climate cooling effect. The efficacy of this as a strategy for global cooling rests on the extent to which aerosol-perturbed marine clouds will respond with increased albedo. Ship tracks, cloud regions impacted by ship exhaust, are a well-known manifestation of the effect of aerosol injection on marine clouds. We present here an analysis of the albedo responses in ship tracks, based on in situ aircraft measurements and three years of satellite observations of 589 individual ship tracks. It is found that the sign (increase or decrease) and magnitude of the albedo response in ship tracks depends on the mesoscale cloud structure, the free tropospheric humidity, and cloud top height. In a closed cell structure (cloud cells ringed by a perimeter of clear air), nearly 30% of ship tracks exhibited a decreased albedo. Detailed cloud responses must be accounted for in global studies of the potential efficacy of sea-spray geoengineering as a means to counteract global warming.

  14. Occurrence of lower cloud albedo in ship tracks

    NASA Astrophysics Data System (ADS)

    Chen, Y.-C.; Christensen, M. W.; Xue, L.; Sorooshian, A.; Stephens, G. L.; Rasmussen, R. M.; Seinfeld, J. H.

    2012-09-01

    The concept of geoengineering by marine cloud brightening is based on seeding marine stratocumulus clouds with sub-micrometer sea-salt particles to enhance the cloud droplet number concentration and cloud albedo, thereby producing a climate cooling effect. The efficacy of this as a strategy for global cooling rests on the extent to which aerosol-perturbed marine clouds will respond with increased albedo. Ship tracks, quasi-linear cloud features prevalent in oceanic regions impacted by ship exhaust, are a well-known manifestation of the effect of aerosol injection on marine clouds. We present here an analysis of the albedo responses in ship tracks, based on in situ aircraft measurements and three years of satellite observations of 589 individual ship tracks. It is found that the sign (increase or decrease) and magnitude of the albedo response in ship tracks depends on the mesoscale cloud structure, the free tropospheric humidity, and cloud top height. In a closed cell structure (cloud cells ringed by a perimeter of clear air), nearly 30% of ship tracks exhibited a decreased albedo. Detailed cloud responses must be accounted for in global studies of the potential efficacy of sea-spray geoengineering as a means to counteract global warming.

  15. Climate change due to anthropogenic surface albedo modification

    SciTech Connect

    Potter, G.L.; Ellsaesser, H.W.; MacCracken, M.C.; Ellis, J.S.; Luther, F.M.

    1980-02-01

    Using a statistical dynamic climate model with more realistic surface albedo changes than used in previous experiments, we have conducted a numerical experiment combining desertification of the Sahara and deforestation of the tropical rain forest. Over an area of 9 x 10/sup 6/ km/sup 2/ at 20/sup 0/N the desert albedo was increased from 0.16 to 0.35 and over 7 x 10/sup 6/ km/sup 2/ at the equator and 10/sup 0/S the rain forest albedo was increased from 0.07 to 0.16. While the most significant direct climatic responses were observed in the modified zones, high northern latitudes exhibited the greatest cooling through activation of the ice-albedo feedback process. In contrast to Sagan et al., this experiment suggests that anthropogenic modification of surface albedo over the past few thousand years has had an impact on global climate which is likely quite small and probably undetectable.

  16. THE ALBEDOS OF KEPLER'S CLOSE-IN SUPER-EARTHS

    SciTech Connect

    Demory, Brice-Olivier

    2014-07-01

    Exoplanet research focusing on the characterization of super-Earths is currently limited to the handful of targets orbiting bright stars that are amenable to detailed study. This Letter proposes to look at alternative avenues to probe the surface and atmospheric properties of this category of planets, known to be ubiquitous in our galaxy. I conduct Markov Chain Monte Carlo light-curves analyses for 97 Kepler close-in R{sub P} ≲ 2.0 R {sub ⊕} super-Earth candidates with the aim of detecting their occultations at visible wavelengths. Brightness temperatures and geometric albedos in the Kepler bandpass are constrained for 27 super-Earth candidates. A hierarchical Bayesian modeling approach is then employed to characterize the population-level reflective properties of these close-in super-Earths. I find median geometric albedos A{sub g} in the Kepler bandpass ranging between 0.16 and 0.30, once decontaminated from thermal emission. These super-Earth geometric albedos are statistically larger than for hot Jupiters, which have medians A{sub g} ranging between 0.06 and 0.11. A subset of objects, including Kepler-10b, exhibit significantly larger albedos (A{sub g} ≳ 0.4). I argue that a better understanding of the incidence of stellar irradation on planetary surface and atmospheric processes is key to explain the diversity in albedos observed for close-in super-Earths.

  17. Spectral surface albedo derived from GOME-2/Metop measurements

    NASA Astrophysics Data System (ADS)

    Pflug, Bringfried; Loyola, Diego

    2009-09-01

    Spectral surface albedo is an important input for GOME-2 trace gas retrievals. An algorithm was developed for estimation of spectral surface albedo from top-of-atmosphere (TOA)-radiances measured by the Global Ozone Monitoring Experiment GOME-2 flying on-board MetOp-A. The climatologically version of this algorithm estimates Minimum Lambert-Equivalent Reflectivity (MLER) for a fixed time window and can use data of many years in contrast to the Near-real time version. Accuracy of surface albedo estimated by MLER-computation increases with the amount of available data. Unfortunately, most of the large GOME pixels are partly covered by clouds, which enhance the LER-data. A plot of LER-values over cloud fraction is used within this presentation to account for this influence of clouds. This "cloud fraction plot" can be applied over all surface types. Surface albedo obtained using the "cloud fraction plot" is compared with reference surface albedo spectra and with the FRESCO climatology. There is a general good agreement; however there are also large differences for some pixels.

  18. MORSE/STORM: A generalized albedo option for Monte Carlo calculations

    SciTech Connect

    Gomes, I.C.; Stevens, P.N. )

    1991-09-01

    The advisability of using the albedo procedure for the Monte Carlo solution of deep penetration shielding problems that have ducts and other penetrations has been investigated. The use of albedo data can dramatically improve the computational efficiency of certain Monte Carlo calculations. However, the accuracy of these results may be unacceptable because of lost information during the albedo event and serious errors in the available differential albedo data. This study was done to evaluate and appropriately modify the MORSE/BREESE package, to develop new methods for generating the required albedo data, and to extend the adjoint capability to the albedo-modified calculations. Major modifications to MORSE/BREESE include an option to save for further use information that would be lost at the albedo event, an option to displace the point of emergence during an albedo event, and an option to use spatially dependent albedo data for both forward and adjoint calculations, which includes the point of emergence as a new random variable to be selected during an albedo event. The theoretical basis for using TORT-generated forward albedo information to produce adjuncton albedos was derived. The MORSE/STORM package was developed to perform both forward and adjoint modes of analysis using spatially dependent albedo data. Results obtained with MORSE/STORM for both forward and adjoint modes were compared with benchmark solutions. Excellent agreement and improved computational efficiency were achieved, demonstrating the full utilization of the albedo option in the MORSE code. 7 refs., 17 figs., 15 tabs.

  19. Direct determination of surface albedos from satellite imagery

    NASA Technical Reports Server (NTRS)

    Mekler, Y.; Joseph, J. H.

    1983-01-01

    An empirical method to measure the spectral surface albedo of surfaces from Landsat imagery is presented and analyzed. The empiricism in the method is due only to the fact that three parameters of the solution must be determined for each spectral photograph of an image on the basis of independently known albedos at three points. The approach is otherwise based on exact solutions of the radiative transfer equation for upwelling intensity. Application of the method allows the routine construction of spectral albedo maps from satelite imagery, without requiring detailed knowledge of the atmospheric aerosol content, as long as the optical depth is less than 0.75, and of the calibration of the satellite sensor.

  20. A new parameterization of spectral and broadband ocean surface albedo.

    PubMed

    Jin, Zhonghai; Qiao, Yanli; Wang, Yingjian; Fang, Yonghua; Yi, Weining

    2011-12-19

    A simple yet accurate parameterization of spectral and broadband ocean surface albedo has been developed. To facilitate the parameterization and its applications, the albedo is parameterized for the direct and diffuse incident radiation separately, and then each of them is further divided into two components: the contributions from surface and water, respectively. The four albedo components are independent of each other, hence, altering one will not affect the others. Such a designed parameterization scheme is flexible for any future update. Users can simply replace any of the adopted empirical formulations (e.g., the relationship between foam reflectance and wind speed) as desired without a need to change the parameterization scheme. The parameterization is validated by in situ measurements and can be easily implemented into a climate or radiative transfer model. PMID:22274228

  1. The two faces of Iapetus. [photometric and radiometric albedo observations

    NASA Technical Reports Server (NTRS)

    Morrison, D.; Jones, T. J.; Cruikshank, D. P.; Murphy, R. E.

    1975-01-01

    Radiometric and photometric observations of Iapetus are described, and a model is developed for the albedo distribution consistent with the visual light curves, color variations, and radiometric flux curve. The 20-micron infrared observations show that the radiometric variation differs by about 180 deg in phase from the visual light curve and has a peak-to-peak amplitude of about a factor of two, while the linear phase coefficient of the light curve varies, as the satellite rotates, from 0.028 to 0.068 mag/deg. Determination of the albedo distribution is described, and it is found to be characterized by a dark area covering most of the leading hemisphere, a bright trailing hemisphere, and a bright south polar cap. The radius is approximated as 800 to 850 km, and the mean geometric albedos for the light and dark faces are estimated as 0.35 and 0.07, respectively.

  2. Sample size and scene identification (cloud) - Effect on albedo

    NASA Technical Reports Server (NTRS)

    Vemury, S. K.; Stowe, L.; Jacobowitz, H.

    1984-01-01

    Scan channels on the Nimbus 7 Earth Radiation Budget instrument sample radiances from underlying earth scenes at a number of incident and scattering angles. A sampling excess toward measurements at large satellite zenith angles is noted. Also, at large satellite zenith angles, the present scheme for scene selection causes many observations to be classified as cloud, resulting in higher flux averages. Thus the combined effect of sampling bias and scene identification errors is to overestimate the computed albedo. It is shown, using a process of successive thresholding, that observations with satellite zenith angles greater than 50-60 deg lead to incorrect cloud identification. Elimination of these observations has reduced the albedo from 32.2 to 28.8 percent. This reduction is very nearly the same and in the right direction as the discrepancy between the albedoes derived from the scanner and the wide-field-of-view channels.

  3. Moon: lunar albedo for soft x-rays

    NASA Astrophysics Data System (ADS)

    Ibadov, Subhon

    2016-07-01

    Albedo of the Moon for soft X-rays (0.1-2 keV photons) is determined on the basis of the X-ray luminosity of the Moon detected and measured for the first time by orbital space telescope ROSAT in 1990. It is found that the lunar albedo for the solar soft X-rays is less than the lunar visual region albedo almost thousand times. The data allow to estimate more correctly X-ray luminosity of dusty comets like Hyakutake C/1996 B2 and Hale-Bopp C/1995 O1 due to scattering of solar soft X-rays and to reveal thus the dominant mechanism for production of X-rays in dusty comets.

  4. Cloud albedo control by cloud-top entrainment

    NASA Technical Reports Server (NTRS)

    Hanson, Howard P.

    1991-01-01

    Marine stratus and stratocumulus clouds exert a considerable influence on the earth's heat budget, mainly due to their high albedos relative to the ocean surface. It is therefore important to understand the processes that control the radiative properties of these extensive cloud systems, particularly during daylight hours. Aircraft measurements of a stratocumulus cloud deck taken around local noon during the 1987 field phase of the First International Satellite Cloud Climatology Project Regional Experiment are the topic of this paper. A mixing line analysis of data from a series of flight tracks across a strong gradient in cloud albedo provides evidence that variations in the water vapor content of the air above the marine inversion can be responsible for the albedo change. The implications of this unexpected result for climate modeling are discussed.

  5. Detailed spatiotemporal albedo observations at Greenland's Mittivakkat Gletscher

    NASA Astrophysics Data System (ADS)

    Mernild, Sebastian H.; Knudsen, Niels T.; Yde, Jacob C.; Malmros, Jeppe K.

    2015-04-01

    Surface albedo is defined as the reflected fraction of incoming solar shortwave radiation at the surface. On Greenland's Mittivakkat Gletscher the mean glacier-wide MODIS-estimated albedo dropped by 0.10 (2000-2013) from 0.43 to 0.33 by the end of the mass balance year (EBY). Hand-held albedo measurements as low as 0.10 were observed over debris-covered ice at the glacier margin at the EBY: these values were slightly below observed values for proglacial bedrock (~0.2). The albedo is highly variable in space - a significant variability occurred within few meters at the glacier margin area ranging from 0.10 to 0.39 due to variability in debris-cover thickness and composition, microbial activity (including algae and cyanobacteria), snow grain crystal metamorphism, bare ice exposure, and meltwater ponding. Huge dark-red-brown-colored ice algae colonies were observed. Albedo measurements on snow patches and bare glacier ice changed significant with increasing elevations (180-600 m a.s.l.) by lapse rates of 0.04 and 0.03 per 100 m, respectively, indicating values as high as 0.82 and 0.40 on the upper part of the glacier. Over a period of two weeks from early August to late August 2014 the hand-held observed mean glacier-wide albedo changed from 0.40 to 0.30 indicating that on average 10% more incoming solar shortwave radiation became available for surface ablation at the end of the melt season.

  6. Transformation of surface albedo to surface: Atmosphere surface and irradiance, and their spectral and temporal averages

    NASA Technical Reports Server (NTRS)

    Nack, M. L.; Curran, R. J.

    1978-01-01

    The dependence of the albedo at the top of a realistic atmosphere upon the surface albedo, solar zenith angle, and cloud optical thickness is examined for the cases of clear sky, total cloud cover, and fractional cloud cover. The radiative transfer calculations of Dave and Braslau (1975) for particular values of surface albedo and solar zenith angle, and a single value of cloud optical thickness are used as the basis of a parametric albedo model. The question of spectral and temporal averages of albedos and reflected irradiances is addressed, and unique weighting functions for the spectral and temporal albedo averages are developed.

  7. The search for proton decay

    SciTech Connect

    Haines, T.; Kaneyuki, K.; McGrew, C.; Mohapatra, R.; Peterson, E.; Cline, D.B.

    1994-12-31

    The conservation of the quantum number called baryon number, like lepton (or family) number, is an empirical fact even though there are very good reasons to expect otherwise. Experimentalists have been searching for baryon number violating decays of the proton and neutron for decades now without success. Theorists have evolved deep understanding of the relationship between the natural forces in the development of various Grand Unified Theories (GUTs) that nearly universally predict baryon number violating proton decay, or related phenomena like n-{bar n} oscillations. With this in mind, the Proton Decay Working Group reviewed the current experimental and theoretical status of the search for baryon number violation with an eye to the advancement in the next decade.

  8. Differential neutron energy spectra measured on spacecraft low Earth orbit

    NASA Technical Reports Server (NTRS)

    Benton, E. V.; Frank, A. L.; Dudkin, E. V.; Potapov, Yu. V.; Akopova, A. B.; Melkumyan, L. V.

    1995-01-01

    Two methods for measuring neutrons in the range from thermal energies to dozens of MeV were used. In the first method, alpha-particles emitted from the (sup 6) Li(n.x)T reaction are detected with the help of plastic nuclear track detectors, yielding results on thermal and resonance neutrons. Also, fission foils are used to detect fast neutrons. In the second method, fast neutrons are recorded by nuclear photographic emulsions (NPE). The results of measurements on board various satellites are presented. The neutron flux density does not appear to correlate clearly with orbital parameters. Up to 50% of neutrons are due to albedo neutrons from the atmosphere while the fluxes inside the satellites are 15-20% higher than those on the outside. Estimates show that the neutron contribution to the total equivalent radiation dose reaches 20-30%.

  9. Comparative global albedo and color maps of the Uranian satellites

    NASA Technical Reports Server (NTRS)

    Buratti, Bonnie J.; Mosher, Joel A.

    1991-01-01

    The surfaces of the Uranian satellites Ariel, Miranda, Oberon, Titania, and Umbriel are characterized on the basis of Voyager observations. Tables of spectrophotometric data and maps of normal reflectances, green/violet ratios, and possible geological formations are presented and discussed in detail. Variations in albedo are found to be associated with impact features, and it is inferred from color differences that the upper surface of Ariel contains a higher proportion of redder material (tentatively identified as accreted low-albedo meteoritic dust) than those of the other moons.

  10. Albedo, clouds and climate sensitivity in the CMIP3 models

    NASA Astrophysics Data System (ADS)

    Bender, F.; Rodhe, H.; Ekman, A. M.; Charlson, R.

    2010-12-01

    The albedo is a key parameter in the radiative budget of the Earth and a primary determinant of the planetary temperature and is therefore also central to questions regarding climate stability, climate change and climate sensitivity. Global climate models are essential for studying the albedo, and the parameters determining it (specifically clouds), on large spatial and temporal scales. Although models (here represented by the CMIP3 models) are able to capture the large-scale characteristics of the albedo, a bias is found between modelled and observed global albedo estimates, and on a regional scale particularly problematic regions can be identified. Many cloud parameters are poorly constrained by observations, and vary widely among models. This freedom of variability can be used in tuning models to the better constrained radiative budget, which may influence the model climate sensitivity. The effect can be kept small, compared to the range of climate sensitivities estimated by different models. Despite their different parameterizations of clouds, aerosols etc., models do have fundamental features in common, which can further the understanding of the real climate system. For instance, sensitivity to volcanic forcing is related to climate sensitivity in an ensemble of CMIP3 models. If this relation is valid for the real climate as well, observations of the volcanic sensitivity can help restrict estimates of climate sensitivity. The range of climate sensitivity estimates in models can largely be attributed to variations in cloud response to external forcing. In models with high (low) climate sensitivity, changes in cloud cover and cloud reflectivity generally enhance (counteract) a positive radiative forcing due to increased CO2 concentrations, feeding back on (damping) the warming, with a more (less) negative albedo response to the forcing. Cloud albedo is important in this regard, yet not well known. Regional cloud albedo, particularly for low-level marine

  11. Daily albedo estimation and comparison to MCD43 product

    NASA Astrophysics Data System (ADS)

    Franch, B.; Vermote, E.; Sobrino, J. A.

    2013-12-01

    Land surface broadband albedo is among the main radiative uncertainties in current climate modelling. An accuracy requirement of 5% and a daily temporal resolution is suggested by the Global Climate Observing System for albedo characterization at spatial and temporal scales compatible with climate studies. Satellite remote sensing provides the only practical way of producing high-quality global albedo data sets with high spatial and temporal resolutions. For view-ilumination geometries such as Moderate Resolution Imaging Spectroradiometer (MODIS), in order to retrieve the Bidirectional Reflectance Distribution Function (BRDF) parameters and, consequently, the albedo, a period of sequential measurement is needed to accumulate sufficient observations. This is used to derive the MODIS BRDF/Albedo product (MCD43), which consider a composite period of 16 days with a resulting temporal resolution of 8 days. Looking for an improvement in the albedo temporal resolution that mitigated the assumption of a stable target, Vermote et al. (2009) presented the VJB method that assumes that the BRDF shape variations throughout a year are limited and linked to the Normalized Difference Vegetation Index (NDVI). This method retains the highest temporal resolution (daily, cloud cover permitting). The purpose of this work is to compare the MCD43 product with the VJB method through the albedo. Additionally, we present and study a method based on the VJB assumption, the 5param Rsqr. In this study we focus our analysis on daily MODIS CMG Collection 6 data from both Aqua and Terra satellites over Europe from 2002 until 2011. Figure 1 shows the percentage of the total RMSE of the VJB and the 5param Rsqr method against the MCD43 product. They display that southern latitudes present lower errors while they increase for northern latitudes and mountainous areas. Comparing the methods, the VJB presents errors higher than 15% in 8.2% of total land pixels while they suppose 6.9% of pixels when

  12. Evaluation of neutron dosimetry techniques for well-logging operations

    SciTech Connect

    Cummings, F.M.; Haggard, D.L.; Endres, G.W.R.

    1985-07-01

    Neutron dose and energy spectral measurements from /sup 241/AmBe and a 14 MeV neutron generator were performed at a well-logging laboratory. The measurement technique included the tissue equivalent proportional counter, multisphere, two types of remmeters and five types of personnel neutron dosimeters. Several source configurations were used to attempt to relate data to field situations. The results of the measurements indicated that the thermoluminescent albedo dosimeter was the most appropriate personnel neutron dosimeter, and that the most appropriate calibration source would be the source normally employed in the field with the calibration source being used in the unmoderated configuration. 7 refs., 35 figs., 14 tabs.

  13. Determination of the sensitivity of thermoluminescent detectors to thermal neutrons

    SciTech Connect

    Zhilov, Y.N.; Erkin, V.G.; Kuchomov, V.A.; Lebedev, O.V.; Tyurin, G.A.

    1985-10-01

    The authors show how the considerable difference in sensitivity to thermal neutrons of the TLD-6-05 and TLD-7-05 detectors allows them to be used jointly for the separate recording of thermal neutrons and -radiation in mixed fields. For detectors with the natural content of lithium isotopes, the sensitivity to thermal neutrons is an order of magnitude lower than for the TLD-6-05, which corresponds to the ratio of the Li-6 concentrations in these detectors. These detectors may be found useful in individual neutron dosimeters of the albedo type for monitoring the radiation safety of personnel.

  14. Seal Out Tooth Decay

    MedlinePlus

    ... Topics > Tooth Decay (Caries) > Seal Out Tooth Decay Seal Out Tooth Decay Main Content What are dental ... back teeth decay so easily? Who should get seal​ants? Should sealants be put on baby teeth? ...

  15. Precision Polarization of Neutrons

    NASA Astrophysics Data System (ADS)

    Martin, Elise; Barron-Palos, Libertad; Couture, Aaron; Crawford, Christopher; Chupp, Tim; Danagoulian, Areg; Estes, Mary; Hona, Binita; Jones, Gordon; Klein, Andi; Penttila, Seppo; Sharma, Monisha; Wilburn, Scott

    2009-05-01

    Determining polarization of a cold neutron beam to high precision is required for the next generation neutron decay correlation experiments at the SNS, such as the proposed abBA and PANDA experiments. Precision polarimetry measurements were conducted at Los Alamos National Laboratory with the goal of determining the beam polarization to the level of 10-3 or better. The cold neutrons from FP12 were polarized using optically polarized ^3He gas as a spin filter, which has a highly spin-dependent absorption cross section. A second ^ 3He spin filter was used to analyze the neutron polarization after passing through a resonant RF spin rotator. A discussion of the experiment and results will be given.

  16. Intercomparison and interpretation of satellite-derived directional albedos over deserts

    NASA Technical Reports Server (NTRS)

    Cess, Robert D.; Vulis, Inna L.

    1989-01-01

    Issues related to the dependence of planetary albedo upon solar zenith angle are studied using Nimbus-7, GOES, and Meteosat data over deserts. Geographical variations of the planetary albedo are isolated from the albedo's solar zenith angle dependence. An atmospheric solar radiation model is coupled with desert surface bidirectional reflectance measurements to test the consistency of satellite-derived directional planetary albedos. Consideration is given to the use of narrowband versus broadband instruments, the impact of desert aerosols on the directional planetary albedo, and potential differences in the directional planetary albedo associated with different types of deserts. The results show that the directional planetary albedo is dominated by the directional surface albedo, although surface brightness influences the atmospheric limb brightening and limb darkening processes.

  17. Albedo and color maps of the Saturnian satellites

    SciTech Connect

    Buratti, B.J.; Mosher, J.A.; Johnson, T.V. )

    1990-10-01

    The paper discusses the production of maps of the albedos and colors of Mimas, Enceladus, Tethys, Dione, and Rhea over the full range of their imaged surfaces. Voyager images were used to prepare maps of the normal reflectances and color ratios (0.58/0.41 micron) of these satelites. 67 refs.

  18. The albedo of snow for partially cloudy skies

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.; Chang, A. T. C.

    1981-01-01

    The albedo of snow is defined as the ratio of reflected to incident solar energy, and it is an important parameter in the earth's radiation budget analysis and in the study of snowpack's thermal conditions. An approximate model for calculating the incident spectral flux for partially cloudy skies is presented. The input parameters for the calculation are atmospheric precipitable water, turbidity, ozone content, surface pressure, the optical thickness of clouds, and the grain size of snow crystals. The spectral snow reflectance model considers both specular surface reflection and volumetric multiple scattering. The surface reflection is calculated by using a crystal-shape-dependent bidirectional reflectance distribution function; the volumetric multiple scattering is calculated by using a crystal-size-dependent approximate solution in the radiative transfer equation. The model yields spectral and integrated solar flux and snow reflectance as a function of solar elevation and fractional cloud-cover. The illustrative insolation and albedo values were obtained from spectral reflectance and incident flux for representative parameters of Antarctic coastal regions. A simple relationship between grain size and the overcast albedo was obtained. For a set of grain size and shape, the albedo as a function of solar elevation and fractional cloud cover was tabulated.

  19. Asteroid magnitudes, UBV colors, and IRAS albedos and diameters

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    1989-01-01

    This paper lists absolute magnitudes and slope parameters for known asteroids numbered through 3318. The values presented are those used in reducing asteroid IR flux data obtained with the IRAS. U-B colors are given for 938 asteroids, and B-V colors are given for 945 asteroids. The IRAS albedos and diameters are tabulated for 1790 asteroids.

  20. Detection limits of albedo changes induced by climate engineering

    NASA Astrophysics Data System (ADS)

    Seidel, Dian J.; Feingold, Graham; Jacobson, Andrew R.; Loeb, Norman

    2014-02-01

    A key question surrounding proposals for climate engineering by increasing Earth's reflection of sunlight is the feasibility of detecting engineered albedo increases from short-duration experiments or prolonged implementation of solar-radiation management. We show that satellite observations permit detection of large increases, but interannual variability overwhelms the maximum conceivable albedo increases for some schemes. Detection of an abrupt global average albedo increase <0.002 (comparable to a ~0.7 W m-2 reduction in radiative forcing) would be unlikely within a year, given a five-year prior record. A three-month experiment in the equatorial zone (5° N-5° S), a potential target for stratospheric aerosol injection, would need to cause an ~0.03 albedo increase, three times larger than that due to the Mount Pinatubo eruption, to be detected. Detection limits for three-month experiments in 1° (latitude and longitude) regions of the subtropical Pacific, possible targets for cloud brightening, are ~0.2 larger than might be expected from some model simulations.

  1. Albedo in the ATIC Experiment: Results of Measurements and Simulation

    NASA Technical Reports Server (NTRS)

    Sokolskaya, N. V.; Adams, J. H., Jr.; Ahn, H. S.; Bashindzhagyan, G. L.; Batkov, K. E.; Chang, J.; Christl, M.; Fazely, A. R.; Ganel, O.; Gunasingha, R. M.

    2004-01-01

    Characteristics of albedo, or backscatter current, providing a 'background' for calorimeter experiments in high energy cosmic rays are analyzed. The comparison of experimental data obtained in the flights of the ATIC spectrometer is made with simulations performed using the GEANT 3.21 code. The influence of the backscatter on charge resolution in the ATIC experiment is discussed.

  2. Mimicking biochar-albedo feedback in complex Mediterranean agricultural landscapes

    NASA Astrophysics Data System (ADS)

    Bozzi, E.; Genesio, L.; Toscano, P.; Pieri, M.; Miglietta, F.

    2015-08-01

    Incorporation of charcoal produced by biomass pyrolysis (biochar) in agricultural soils is a potentially sustainable strategy for climate change mitigation. However, some side effects of large-scale biochar application need to be investigated. In particular a massive use of a low-reflecting material on large cropland areas may impact the climate via changes in surface albedo. Twelve years of MODIS-derived albedo data were analysed for three pairs of selected agricultural sites in central Italy. In each pair bright and dark coloured soil were identified, mimicking the effect of biochar application on the land surface albedo of complex agricultural landscapes. Over this period vegetation canopies never completely masked differences in background soil colour. This soil signal, expressed as an albedo difference, induced a local instantaneous radiative forcing of up to 4.7 W m-2 during periods of high solar irradiance. Biochar mitigation potential might therefore be reduced up to ˜30%. This study proves the importance of accounting for crop phenology and crop management when assessing biochar mitigation potential and provides more insights into the analysis of its environmental feedback.

  3. FLASH EXTRACTION OF PECTIN FROM ORANGE ALBEDO BY STEAM INJECTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pectin was acid extracted from orange albedo by steam injection heating under pressure. Extraction times ranged from 2 to 6 minutes at a pressure of about 15 psi. Solubilized pectin was characterized by HPSEC with online light scattering and viscosity detection. Molar mass (M), radius of gyration...

  4. Detection of light transformations and concomitant changes in surface albedo

    PubMed Central

    Gerhard, Holly E.; Maloney, Laurence T.

    2010-01-01

    We report two experiments demonstrating that (1) observers are sensitive to information about changes in the light field not captured by local scene statistics and that (2) they can use this information to enhance detection of changes in surface albedo. Observers viewed scenes consisting of matte surfaces at many orientations illuminated by a collimated light source. All surfaces were achromatic, all lights neutral. In the first experiment, observers attempted to discriminate small changes in direction of the collimated light source (light transformations) from matched changes in the albedos of all surfaces (non-light transformations). Light changes and non-light changes shared the same local scene statistics and edge ratios, but the latter were not consistent with any change in direction to the collimated source. We found that observers could discriminate light changes as small as 5 degrees with sensitivity d′ > 1 and accurately judge the direction of change. In a second experiment, we measured observers' ability to detect a change in the surface albedo of an isolated surface patch during either a light change or a surface change. Observers were more accurate in detecting isolated albedo changes during light changes. Measures of sensitivity d′ were more than twice as great. PMID:20884599

  5. Using BRDFs for accurate albedo calculations and adjacency effect corrections

    SciTech Connect

    Borel, C.C.; Gerstl, S.A.W.

    1996-09-01

    In this paper the authors discuss two uses of BRDFs in remote sensing: (1) in determining the clear sky top of the atmosphere (TOA) albedo, (2) in quantifying the effect of the BRDF on the adjacency point-spread function and on atmospheric corrections. The TOA spectral albedo is an important parameter retrieved by the Multi-angle Imaging Spectro-Radiometer (MISR). Its accuracy depends mainly on how well one can model the surface BRDF for many different situations. The authors present results from an algorithm which matches several semi-empirical functions to the nine MISR measured BRFs that are then numerically integrated to yield the clear sky TOA spectral albedo in four spectral channels. They show that absolute accuracies in the albedo of better than 1% are possible for the visible and better than 2% in the near infrared channels. Using a simplified extensive radiosity model, the authors show that the shape of the adjacency point-spread function (PSF) depends on the underlying surface BRDFs. The adjacency point-spread function at a given offset (x,y) from the center pixel is given by the integral of transmission-weighted products of BRDF and scattering phase function along the line of sight.

  6. Albedo and color maps of the Saturnian satellites

    NASA Technical Reports Server (NTRS)

    Buratti, Bonnie J.; Mosher, Joel A.; Johnson, Torrence V.

    1990-01-01

    The paper discusses the production of maps of the albedos and colors of Mimas, Enceladus, Tethys, Dione, and Rhea over the full range of their imaged surfaces. Voyager images were used to prepare maps of the normal reflectances and color ratios (0.58/0.41 micron) of these satelites.

  7. Albedo of Permanently Shadowed Regions of the Lunar Poles

    NASA Astrophysics Data System (ADS)

    Riner, M. A.; Lucey, P. G.; Bussey, B.; Cahill, J. T.; McGovern, A.

    2012-12-01

    Due to the slight tilt in the Moon's spin axis, some topographic depressions near the lunar poles experience permanent shadow and may serve as cold traps, harboring water ice and/or other volatile compounds [1]. Permanently shadowed regions (PSRs) provide an opportunity toward understanding the amount, nature and transport of volatiles on the Moon and may also be a potential resource for human exploration. While many different data sets have suggested the presence of water ice in PSRs near the lunar poles many questions remain. For example, ice does not appear to be uniformly distributed across identified PSRs. More work is needed to understand the distribution of ice in PSRs and how delivery and retention mechanisms influence the distribution. The active illumination of the Lunar Orbiter Laser Altimeter (LOLA) provides a unique contribution toward exploration PSR exploration. While LOLA is principally a laser altimeter used for quantitative topography and related cartographic and geodetic applications [2], LOLA also measures the intensity and width of the return laser pulse (1064 nm) from the surface. Here we use a global mosaic (4 pixels per degree) of LOLA albedo data corrected for instrumental drift, irregular variations, and calibrated to normal albedo using local equatorial measurements of normal albedo obtained by the Kaguya Multiband Imager [3]. Recent work using LOLA albedo shows the floor of Shackleton crater, near the lunar south pole, is brighter than the surrounding terrain (and the interior of nearby craters) at 1064 nm [4]. This albedo difference may be due to decreased space weathering due to shadowing from the Sun or to a 1 μm thick layer with 20% water ice a the surface of the crater floor [4]. Here we use LOLA dayside reflectance measurements to examine the albedo of PSRs catalogued by [5] derived from illumination modeling of a hybrid 100 m/pixel LOLA-LROC digital terrain model (DTM) up to 83° north and south latitudes. The upper latitude

  8. Effective Albedo of Vegetated Terrain at L-Band

    NASA Technical Reports Server (NTRS)

    Kurum, Mehmet; O'Neill, Peggy E.; Lang, Roger H.

    2011-01-01

    This paper derives an explicit expression for an effective albedo of vegetated terrain from the zero- and multiple- order radiative transfer (RT) model comparison. The formulation establishes a direct physical link between the effective vegetation parameterization and the theoretical description of absorption and scattering within the canopy. The paper will present an evaluation of the derived albedo for corn canopies with data taken during an experiment at Alabama A&M Winfield A. Thomas Agricultural Research Station near Huntsville, Alabama in June, 1998. The test site consisted of two 50-m x 60-m plots - one with a bare surface and the other with grass cover - and four 30-m x 50-m plots of corn at different planting densities. One corn field was planted at a full density of 9.5 plants/sq m while the others were planted at 1/3, 1/2 and 2/3 of the full density. The fields were observed with a truck-mounted L-band radiometer at incident angle of 15 degree for the period of two weeks. Soil moisture (SM) changed daily due to irrigation and natural rainfall. Variations in gravimetric SM from 18 % to 34 % were seen during this period. Ground truth data, including careful characterization of the corn size and orientation statistics, and its dielectric, was also collected and used to simulate the effective albedo for the vegetation. The single-scattering albedo is defined as the fractional power scattered from individual vegetation constituents with respect to canopy extinction. It represents single-scattering properties of vegetation elements only, and is independent of ground properties. The values of the albedo get higher when there is dense vegetation (i.e. forest, mature corn, etc.) with scatterers, such as branches and trunks (or stalks in the case of corn), which are large with respect to the wavelength. This large albedo leads to a reduction in brightness temperature in the zero-order RT solution (known as tau-omega model). Higher-order multiple-scattering RT

  9. Influence of polar-cap albedo on past and current Martian climate

    NASA Technical Reports Server (NTRS)

    Kieffer, Hugh H.; Paige, David A.

    1987-01-01

    The finding that the observed albedo of the Martian polar caps increase with increasing isolation is reviewed. Models of the Martian climate system are greatly stabilized when an insolation-dependent frost albedo instead of a constant albedo is used in the energy budget. The authors views on microphysics of the process is then presented. Long term climate models must account for the variability of CO2 frost albedo.

  10. Report on the ALPO LTP observing program. [for establishing albedo scale for lunar features

    NASA Technical Reports Server (NTRS)

    Cameron, W. S.

    1974-01-01

    Observations of lunar transient phenomena for the Association of Lunar and Planetary Observers (ALPO) are reported. The procedures for making visual observations for estimating albedo are described, and the reported albedo analyzed for lunar topographic features. It is shown that a catalog or scale of albedos can be established for each feature.

  11. The electromagnetic component of albedo from superhigh energy cascades in dense media

    NASA Technical Reports Server (NTRS)

    Golynskaya, R. M.; Hein, L. A.; Plyasheshnikov, A. V.; Vorobyev, K. V.

    1985-01-01

    Albedo from cascades induced in iron by high energy gamma quanta were Monte Carlo simulated. Thereafter the albedo electromagnetic component from proton induced cascades were calculated analytically. The calculations showed that the albedo electromagnetic component increases more rapidly than the nuclear active component and will dominate at sufficiently high energies.

  12. Albedo Response of Native and Artificial Soils to a Wetting Event: Implications for Critical Zone Processes

    NASA Astrophysics Data System (ADS)

    Lovell, L.; Sanchez-Mejia, Z. M.; Papuga, S. A.

    2012-12-01

    The Landscape Evolution Observatory (LEO) at Biosphere 2 is composed of three experimental hill slopes filled to one meter depth of a ground basaltic tephra soil, set up to investigate critical zone processes. Our goal is to understand the energy aspects of this artificial LEO soil; surfaces with a high surface reflectance (albedo) may limit energy available for critical zone processes. The albedo of a surface can change, e.g. by vegetation growth or soil wetting, which can further influence available energy. Here, we examine the soil moisture and albedo response of LEO soil to a 10 mm rainfall event, and compare the results to those found using traditional potting and native desert soils that differ in color and texture. We hypothesized that: 1) increased soil moisture would decrease albedo for all soil types; 2) a smaller wetting front would maximize any decrease in albedo, and 3) albedo will reach a minimum within hours of a rainstorm, returning to a maximum albedo value within the day. We found that albedo was lowest under wet conditions for all soils, regardless of initial color and texture. Additionally, the LEO soil experienced the shallowest wetting front and also showed the most significant decrease in albedo following rainfall. After the rainfall event, all soils showed an initial decrease in albedo, followed by an increase in albedo as the soil dried. While the albedo and soil moisture of each soil reacted similarly, the very dark and fine LEO soil showed the strongest response to wetting.

  13. Decay studies of neutron deficient nuclei near the Z=64 subshell: 142Dy, 140,142Tb, 140,142Gd, 140,142Eu, 142Sm, and 142Pm

    NASA Astrophysics Data System (ADS)

    Firestone, R. B.; Gilat, J.; Nitschke, J. M.; Wilmarth, P. A.; Vierinen, K. S.

    1991-03-01

    The electron-capture and β+-decay branchings (EC/β+) and delayed proton decays of A=142 isotopes with 61<=Z<=66 and A=140 isotopes with 63<=Z<=65 were investigated with the OASIS facility on-line at the Lawrence Berkeley Laboratory SuperHILAC. Electron capture and positron-decay emission probabilities have been determined for 142Pm and 142Sm decays, and extensive decay schemes have been constructed for 142Eug(2.34+/-0.12 s), 142Gd(70.2+/-0.6 s), 140Eu(1.51+/-0.02 s), and 140Gd(15.8+/-0.4 s). Decay schemes for the new isotopes 142Tbg(597+/-17 ms), 142Tbm(303+/-17 ms), 142Dy(2.3+/-0.3 s), 140Eum(125+/-2 ms), and 140Tb(2.4+/-0.2 s) are also presented. We have assigned γ rays to these isotopes on the basis of γγ and xγ coincidences, and from half-life determinations. Electron-capture and β+-decay branchings were measured for each decay, and β-delayed proton branchings were determined for 142Dy, 142Tb, and 140Tb decays. QEC values, derived from the measured EC/β+ branchings and the level schemes are compared with those from the Wapstra and Audi mass evaluation and the Liran and Zeldes mass calculation. The systematics of the N=77 isomer decays are discussed, and the intense 0+-->1+ and 1+-->0+ ground-state beta decays are compared with shell-model predictions for simple spin-flip transitions.

  14. Method of searching for neutron clusters

    NASA Astrophysics Data System (ADS)

    Dudkin, G. N.; Garapatskii, A. A.; Padalko, V. N.

    2014-10-01

    A new method of searching for neutron clusters (multineutrons) composed of neutrons bound by nuclear forces has been introduced and implemented. The method is based on the search for daughter nuclei that emerge at the nuclei cluster decay of 252Cf to neutron clusters. The effect of long-time build-up of daughter nuclei with a high atomic number and long half-life was utilized. The results are interpreted as evidence of the cluster decay of 252Cf to daughter nucleus 232U (half-life of T1/2= 68.9 years). The emergence of 232U is attributed to emission of neutron clusters consisting of eight neutrons - octaneutrons. The emission probability of octaneutrons against α-decay probability of 252Cf is defined equal to λC/λα=1.74×10-6.

  15. Nucleon-decay-like signatures of hylogenesis

    NASA Astrophysics Data System (ADS)

    Demidov, S. V.; Gorbunov, D. S.

    2016-02-01

    We consider nucleon-decay-like signatures of hylogenesis, a variant of the antibaryonic dark matter model. For the interaction between visible and dark matter sectors through the neutron portal, we calculate the rates of dark matter scatterings off a neutron which mimic neutron-decay processes n →ν γ and n →ν e+e- with richer kinematics. We obtain bounds on the model parameters from nonobservation of the neutron decays by applying the kinematical cuts adopted in the experimental analyses. The bounds are generally (much) weaker than those coming from the recently performed study of events with a single jet of high transverse momentum and missing energy observed at the LHC. Then we suggest several new nucleon-decay-like processes with two mesons in the final state and estimate (accounting for the LHC constraints) the lower limits on the nucleon lifetime with respect to these channels. The obtained values appear to be promising for probing the antibaryonic dark matter at future underground experiments like HyperK and DUNE.

  16. Neutronic reactor

    DOEpatents

    Wende, Charles W. J.; Babcock, Dale F.; Menegus, Robert L.

    1983-01-01

    A nuclear reactor includes an active portion with fissionable fuel and neutron moderating material surrounded by neutron reflecting material. A control element in the active portion includes a group of movable rods constructed of neutron-absorbing material. Each rod is movable with respect to the other rods to vary the absorption of neutrons and effect control over neutron flux.

  17. The weak decay of helium hypernuclei

    SciTech Connect

    Athanas, M.J.

    1992-08-01

    A {Lambda} hyperon replaces a neutron in a nucleus to form a hypernucleus via the {sup A}X(K{sup {minus}}, {pi}{sup {minus}}) {sub {Lambda}}{sup A}X reaction at 750 MeV/c (Brookhaven Experiment 788). The free {Lambda} decay rates {Gamma}({Lambda} {yields} p{pi}{sup {minus}}) and {Gamma}({Lambda} {yields} n{pi}{sup 0}) are diminished due to Pauli blocking; but a non-mesonic decay mode, nucleon stimulated decay N{Lambda} {yields} Nn, is present and is detected via the energetic decay nucleon(s) ({approx} 400MeV/c). Measurements of the various hypernuclear decay rates {Gamma}({Lambda} {yields} p{pi}{sup {minus}}), {Gamma}({Lambda} {yields} n{pi}{sup 0}) and {Gamma}({Lambda}n {yields} nn) provides insight into the strong modification of the weak interaction such as the baryon-baryon {Delta}I ={1/2} rule. The hypernuclear state is isolated by momentum analysis of (K{sup {minus}}, {pi}{sup {minus}}) target reaction. Out-of-beam large volume scintillation detectors and tracking chambers axe used to make particle identification of the hypernuclear decay products by time-of-flight, dE/dx, and range. The kinetic energy of the decay neutrons are measured by time of flight using the large volume 100 element neutron detector system. The hypernuclear lifetime is directly measured using precision scintillator counters and tracking chambers. Measurements of the various decay rates as well as the total lifetime are discussed for {sub {Lambda}}{sup 4}He.

  18. NEANDC specialists meeting on yields and decay data of fission product nuclides

    SciTech Connect

    Chrien, R.E.; Burrows, T.W.

    1983-01-01

    Separate abstracts were prepared for the 29 papers presented. Workshop reports on decay heat, fission yields, beta- and gamma-ray spectroscopy, and delayed neutrons are included. An appendix contains a survey of the most recent compilations and evaluations containing fission product yield, fission product decay data, and delayed neutron yield information. (WHK)

  19. Long term surface albedo datasets generated with Meteosat images

    NASA Astrophysics Data System (ADS)

    Lattanzio, A.; Govaerts, Y. M.; Theodore, B.

    2009-04-01

    The Global Climate Observing System (GCOS) has recognized the importance and the key-role of the surface albedo in the study of the climate change. This and the other climate variables, called Essential Climate Variables (ECVs), must satisfy the following requirements: (i) a global coverage over long-term periods with adequate spatial and temporal resolution, (ii) reliability and accuracy as well as a (iii) quality control. The Coordination Group for Meteorological Satellites (CGMS) assigned to EUMETSAT an action (T18 (TF7)) in order to prototype and test a new algorithm able to retrieve surface albedo using geostationary satellites as described in the "Implementation plan for the global observing system for climate in support of the UNFCCC" document (WMO/TD No. 1219). In this frame EUMETSAT decided to develop a new specific algorithm, named Meteosat Surface Albedo (MSA), based on a method proposed by Pinty et al. The MSA algorithm is currently running in the operational reprocessing facility of EUMETSAT in order to generate reliable albedo data set starting from 1982. These data have been acquired by six different radiometers. As Meteosat first generation satellites have not been designed for climate monitoring, before proceeding with the interpretation of the complete archive (~ 25 years of data), a detailed temporal consistency analysis of the albedo data set generated with the MSA algorithm has been performed in order to check the compliance with points (ii) and (iii). Specific efforts have been put on the estimation of the measurement error accounting for the observation uncertainties and retrieval method assumptions. Currently 100% of the archive for the prime mission at 0 degree has been processed and the albedo data set can be requested from the EUMETSAT archive facility. This paper will present the method elaborated for the evaluation of the temporal consistency of the MSA data set and illustrate typical problems raising from the processing of old data and

  20. Radiative transfer in dusty nebulae. III - The effects of dust albedo

    NASA Technical Reports Server (NTRS)

    Petrosian, V.; Dana, R. A.

    1980-01-01

    The effects of an albedo of internal dust, such as ionization structure and temperature of dust grain, were studied by the quasi-diffusion method with an iterative technique for solving the radiative heat transfer equations. It was found that the generalized on-the-spot approximation solution is adequate for most astrophysical applications for a zero albedo; for a nonzero albedo, the Eddington approximation is more accurate. The albedo increases the average energy of the diffuse photons, increasing the ionization level of hydrogen and heavy elements if the Eddington approximation is applied; the dust thermal gradient is reduced so that the infrared spectrum approaches blackbody spectrum with an increasing albedo.

  1. Neutron dosimetry at commercial nuclear plants. Final report of Subtask C: /sup 3/He neutron spectrometer

    SciTech Connect

    Brackenbush, L.W.; Reece, W.D.; Tanner, J.E.

    1984-09-01

    In commercial nuclear power plants, personnel routinely enter containment for maintenance and inspections while the reactor is operating and can be exposed to intense neutron fields. The low-energy neutron fields found in reactor containment cause problems in proper interpretation of TLD-albedo dosimeters and survey instrument readings. This report describes a technique that can aid plant health physicists to improve the accuracy of personnel neutron dosimetry programs. A /sup 3/He neutron spectrometer can be used to measure neutron energy spectra and determine dose equivalent rates at work locations inside containment. Energy correction factors for TLD-albedo dosimeters can be determined from the measured spectra if the dosimeter energy response is known, or from direct measurements with dosimeters placed on phantoms at locations where the dose equivalent rate has been measured. This report describes how to assemble a spectrometer system using only commercially available components, how to use it for reactor energy spectrum measurements, and how to analyze the data and interpret the results. Both /sup 3/He and multisphere spectrometers were used to measure neutron energy spectra and dose equivalent at three PWRs and one BWR. In general, the /sup 3/He spectrometer measures higher dose equivalent rates than the multisphere spectrometer. In the energy range from 10 keV to 1 MeV, the dose equivalents measured by the /sup 3/He spectrometer and multisphere spectrometer agree within about 35% for the spectra measured.

  2. First Delayed Neutron Emission Measurements at Alto with the Neutron Detector Tetra

    NASA Astrophysics Data System (ADS)

    Testov, D.; Ancelin, S.; Bettane, J.; Ibrahim, F.; Kolos, K.; Kuznetsova, E.; Mavilla, G.; Niikura, M.; Penionzhkevich, Yu.; Smirnov, V.; Sokol, E.; Verney, D.; Wilson, J.

    2013-06-01

    Beta decay properties are among the easiest and therefore, the first ones to be measured to study new neutron rich isotopes. Eventually it could be sufficient just a few number of nuclei to estimate its lifetime and neutron emission probability. With the new radioactive beam facilities which have been commissioned recently (or will have been constructed shortly) new areas of neutron rich isotopes are becoming reachable. To study beta decay properties of such nuclei at IPN Orsay in the frame of collaboration with JINR, Dubna a new experimental setup including the neutron detector TETRA of high efficiency was developed and commissioned.

  3. Albedo of coastal landfast sea ice in Prydz Bay, Antarctica: Observations and parameterization

    NASA Astrophysics Data System (ADS)

    Yang, Qinghua; Liu, Jiping; Leppäranta, Matti; Sun, Qizhen; Li, Rongbin; Zhang, Lin; Jung, Thomas; Lei, Ruibo; Zhang, Zhanhai; Li, Ming; Zhao, Jiechen; Cheng, Jingjing

    2016-05-01

    The snow/sea-ice albedo was measured over coastal landfast sea ice in Prydz Bay, East Antarctica (off Zhongshan Station) during the austral spring and summer of 2010 and 2011. The variation of the observed albedo was a combination of a gradual seasonal transition from spring to summer and abrupt changes resulting from synoptic events, including snowfall, blowing snow, and overcast skies. The measured albedo ranged from 0.94 over thick fresh snow to 0.36 over melting sea ice. It was found that snow thickness was the most important factor influencing the albedo variation, while synoptic events and overcast skies could increase the albedo by about 0.18 and 0.06, respectively. The in-situ measured albedo and related physical parameters (e.g., snow thickness, ice thickness, surface temperature, and air temperature) were then used to evaluate four different snow/ice albedo parameterizations used in a variety of climate models. The parameterized albedos showed substantial discrepancies compared to the observed albedo, particularly during the summer melt period, even though more complex parameterizations yielded more realistic variations than simple ones. A modified parameterization was developed, which further considered synoptic events, cloud cover, and the local landfast sea-ice surface characteristics. The resulting parameterized albedo showed very good agreement with the observed albedo.

  4. Comparison of spectral surface albedos and their impact on the general circulation model simulated surface climate

    NASA Astrophysics Data System (ADS)

    Roesch, A.; Wild, M.; Pinker, R.; Ohmura, A.

    2002-07-01

    This study investigates the impact of spectrally resolved surface albedo on the total surface albedo. The neglect of albedo variation within the shortwave spectrum may lead to substantial errors as the atmospheric water greatly influences the spectral distribution of the incoming radiation. It is shown that ignoring the spectral dependence of the surface albedo will affect the predicted climate. The study reveals substantial changes in the climate over northern Africa when modifying the surface albedo of the Sahara deserts. Detailed information is given how the European Center/Hamburg General Circulation Model (ECHAM4) can be extended to include surface boundary conditions for both the visible and near-infrared incoming radiation. This comprises global climatologies for both the visible and near-infrared albedo for snow-free conditions, as well as the corresponding albedo values over snow, land-/sea ice and over snow covered forests. Comparisons between several available surface albedo climatologies and a newly compiled albedo data set show substantial scatter in estimated albedos. The largest albedo differences are found in snow covered forest regions as well as in arid and semi-arid terrains.

  5. Evaluating biases in simulated land surface albedo from CMIP5 global climate models

    NASA Astrophysics Data System (ADS)

    Li, Yue; Wang, Tao; Zeng, Zhenzhong; Peng, Shushi; Lian, Xu; Piao, Shilong

    2016-06-01

    Land surface albedo is a key parameter affecting energy balance and near-surface climate. In this study, we used satellite data to evaluate simulated surface albedo in 37 models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). There was a systematic overestimation in the simulated seasonal cycle of albedo with the highest bias occurring during the Northern Hemisphere's winter months. The bias in surface albedo during the snow-covered season was classified into that in snow cover fraction (SCF) and albedo contrast (β1). There was a general overestimation of β1 due to the simulated snow-covered albedo being brighter than the observed value; negative biases in SCF were not always related to negative albedo biases, highlighting the need for realistic representation of snow-covered albedo in models. In addition, models with a lower leaf area index (LAI) tend to produce a higher surface albedo over the boreal forests during the winter, which emphasizes the necessity of improving LAI simulations in CMIP5 models. Insolation weighting showed that spring albedo biases were of greater importance for climate. The removal of albedo biases is expected to improve temperature simulations particularly over high-elevation regions.

  6. MISR Level 2 TOA/Cloud Albedo parameters (MIL2TCAL_V2)

    NASA Technical Reports Server (NTRS)

    Diner, David J. (Principal Investigator)

    The TOA/Cloud Albedo data contain albedo values, including finely-sampled or local (2.2 km) TOA albedos registered to the RLRA, and two coarsely-sampled (35.2 km resolution) TOA albedos projected to 30-km altitude. The local (2.2 km) albedos do not take the obscuration of cloud features into account, so they should only be treated as traditional albedos when the number of obscured pixels is low. The restrictive and expansive albedos are both available at 35.2 km resolution: the restrictive albedos are only calculated using the radiation upwelling from the pixel under consideration, whereas the expansive albedos use all the radiation emanating from the surrounding area. Therefore, the expansive albedo is closer to the traditional definition of top-of-atmosphere albedos. [Temporal_Coverage: Start_Date=2000-02-24; Stop_Date=] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1.1 km; Longitude_Resolution=1.1 km; Temporal_Resolution=about 15 orbits/day].

  7. Durability of high-albedo roof coatings and implications for cooling energy savings. Final report

    SciTech Connect

    Bretz, S.E.; Akbari, H.

    1994-06-01

    Twenty-six spot albedo measurements of roofs were made using a calibrated pyranometer. The roofs were surfaced with either an acrylic elastomeric coating, a polymer coating with an acrylic base, or a cementitious coating. Some of the roofs` albedos were measured before and after washing to determine whether the albedo decrease was permanent. Data indicated that most of the albedo degradation occurred within the first year, and even within the first two months. On one roof, 70% of one year`s albedo degradation occurred in the first two months. After the first year, the degradation slowed, with data indicating small losses in albedo after the second year. Measurements of seasonal cooling energy savings by Akbari et al. (1993) included the effects of over two months of albedo degradation. We estimated {approximately}20% loss in cooling-energy savings after the first year because of dirt accumulation. For most of the roofs we cleaned, the albedo was restored to within 90% of its initial value. Although washing is effective at restoring albedo, the increase in energy savings is temporary and labor costs are significant in comparison to savings. By our calculations, it is not cost-effective to hire someone to clean a high-albedo roof only to achieve energy savings. Thus, it would be useful to develop and identify dirt-resistant high-albedo coatings.

  8. Preliminary albedo map of the south polar region

    NASA Technical Reports Server (NTRS)

    Devaucouleurs, G.; Roth, J.; Mulholand, C.

    1973-01-01

    A preliminary albedo map of the Martian south polar region in stereographic projection was prepared mainly from mission test video system (MTVS) prints before rectified and gridded prints were received, but some adjustments were made to conform with a semi-controlled photomosaic. Wherever possible, use also was made of crater coordinates. Two versions of the map are presented: one with a coordinate grid overlay and one without it. The precision of the coordinates is generally within 1 deg in latitude and the corresponding are in longitude. The maps show both the albedo markings and, with subdued contrast, the craters and topographic features that are necessary to locate the former. The map covers the range of latitudes from - 65 deg to the south pole.

  9. Comparison of MISR and MODIS land surface albedos: Methodology

    NASA Astrophysics Data System (ADS)

    Taberner, M.; Pinty, B.; Govaerts, Y.; Liang, S.; Verstraete, M. M.; Gobron, N.; Widlowski, J.-L.

    2010-03-01

    The broadband white sky surface albedo (bihemispherical reflectance) products available from the Moderate Resolution Imaging Spectroradiometer (MODIS) are compared at regional and continental scales with similar products generated from the Multiangle Imaging Spectroradiometer (MISR) land surface bidirectional reflectance factor (BRF) parameters. This paper describes the methodology applied to derive MISR white sky albedos over four spectral broadbands of interest, namely, 0.3-0.7 μm, 0.4-1.1 μm, 0.7-3.0 μm, and 0.3-3.0 μm, as well as an evaluation of the strategy adopted to compare the MODIS and MISR products. The results are very encouraging since the two data sets show very good statistical agreement over large areas and over a full year of measurements, despite the many differences that exist in the suite of algorithms applied to retrieve these surface quantities from each of these instruments separately.

  10. Exogenic and endogenic albedo and color patterns on Europa

    NASA Technical Reports Server (NTRS)

    Mcewen, A. S.

    1986-01-01

    New global and high-resolution multispectral mosaics of Europa have been produced from the Voyager imaging data. Photometric normalizations are based on multiple-image techniques that explicitly account for intrinsic albedo variations through pixel-by-pixel solutions. The exogenic color and albedo pattern on Europa is described by a second-order function of the cosine of the angular distance from the apex of orbital motion. On the basis of this second-order function and of color trends that are different on the leading and trailing hemispheres, the exogenic pattern is interpreted as being due to equilibrium between two dominant processes: (1) impact gardening and (2) magnetospheric interactions, including sulfur-ion implantation and sputtering redistribution. Removal of the model exogenic pattern in the mosaics reveals the endogenic variations, consisting of only two major units: darker (redder) and bright materials. Therefore Europa's visual spectral reflectivity is simple, having one continuous exogenic pattern and two discrete endogenic units.

  11. Deriving Albedo from Coupled MERIS and MODIS Surface Products

    NASA Technical Reports Server (NTRS)

    Gao, Feng; Schaaf, Crystal; Jin, Yu-Fang; Lucht, Wolfgang; Strahler, Alan

    2004-01-01

    MERIS Level 2 surface reflectance products are now available to the scientific community. This paper demonstrates the production of MERIS-derived surface albedo and Nadir Bidirectional Reflectance Distribution Function (BRDF) adjusted reflectances by coupling the MERIS data with MODIS BRDF products. Initial efforts rely on the specification of surface anisotropy as provided by the global MODIS BRDF product for a first guess of the shape of the BRDF and then make use all of the coincidently available, partially atmospherically corrected, cloud cleared, MERIS observations to generate MERIS-derived BRDF and surface albedo quantities for each location. Comparisons between MODIS (aerosol-corrected) and MERIS (not-yet aerosol-corrected) surface values from April and May 2003 are also presented for case studies in Spain and California as well as preliminary comparisons with field data from the Devil's Rock Surfrad/BSRN site.

  12. Land Surface Albedo from MERIS Reflectances Using MODIS Directional Factors

    NASA Technical Reports Server (NTRS)

    Schaaf, Crystal L. B.; Gao, Feng; Strahler, Alan H.

    2004-01-01

    MERIS Level 2 surface reflectance products are now available to the scientific community. This paper demonstrates the production of MERIS-derived surface albedo and Nadir Bidirectional Reflectance Distribution Function (BRDF) adjusted reflectances by coupling the MERIS data with MODIS BRDF products. Initial efforts rely on the specification of surface anisotropy as provided by the global MODIS BRDF product for a first guess of the shape of the BRDF and then make use all of the coincidently available, partially atmospherically corrected, cloud cleared, MERIS observations to generate MERIS-derived BRDF and surface albedo quantities for each location. Comparisons between MODIS (aerosol-corrected) and MERIS (not-yet aerosol-corrected) surface values from April and May 2003 are also presented for case studies in Spain and California as well as preliminary comparisons with field data from the Devil's Rock Surfrad/BSRN site.

  13. Temporal Variations in the Uranian Near-IR Geometric Albedo

    NASA Astrophysics Data System (ADS)

    Walter, C. M.; Marley, M. S.; Baines, K. H.

    1996-09-01

    Over the period August 1995 -- August 1996 the near-infrared geometric albedo of Uranus showed distinct variation. We obtained images of the planet in 10 broad and narrowband filters using the ARC 3.5 meter telescope at Apache Point Observatory. Along with the albedo variations we saw significant changes in the contrast of the planet. Data acquired in August 1995 (Walter & Marley 1995) show the same high altitude hazes encircling the south polar region as seen by Baines et al. (1995) from the IRTF two days prior to our observations and by HST in August 1994. Followup images from June 1996 no longer contain this asymmetry, instead showing a homogeneous disk with corresponding lower albedos at matching wavelengths. Observations will also be made in late August 1996. We modeled this data by computing theoretical monochromatic albedos which were then integrated over the filter bandpasses. These filters were chosen to best probe a variety of atmospheric levels, with continuum filters probing down to the CH_4 tropospheric cloud and beyond. Filters selected in the deep H_2 and CH_4 absorption bands allow us to examine the structure of hazes in the upper stratosphere, whose small reflection contributions dominate in these dark filters. Preliminary analysis of information from two very different states of Uranian weather shows evidence for temporal variability in the vertical location and thickness of the CH_4 cloud as well as the incompatibility of extrapolating optical stratospheric haze characteristics in the near-infrared. This work was supported by NASA grant NGT-51383. Baines, K. H., Yanamandra-Fisher, P., Lebofsky, L. A., Momary, T. W., & Golisch, W. 1995, BAAS, 27, 1088. Walter, C & Marley, M. S. 1995, BAAS, 27, 1089.

  14. A wide angle earth albedo sensor for spacecraft attitude determinations

    NASA Astrophysics Data System (ADS)

    Cruise, A. M.; Barnsdale, K.; Bowles, J. A.; Coker, A. J.; Sheather, P. H.

    1991-03-01

    A design is proposed for an earth albedo sensor which meets the conflicting parameters of a wide field of view and high sensitivity by using large area photodiodes and a very low noise dc amplifier. Two units have been launched on the United Kingdom Satellite of the Active Magnetospheric Particle tracer Experiment mission and operated successfully, measuring spacecraft attitude to an accuracy of one degree.

  15. Extended HXR Sources - Albedo Patches or Coronal Sources

    NASA Technical Reports Server (NTRS)

    Dennis, Brian R.

    2011-01-01

    Extended HXR sources in the presence of compact footpoints have been reported based on visibility amplitudes from different detectors. Attempts have been made to determine the location and extent of these sources through direct imaging. Results of this work will be described for simulated sources and for specific flares at different solar longitudes, with a discussion of the possible nature of the extended sources as either albedo patches or coronal sources or a combination of the two.

  16. An Improved Degree-day Melt Model Considering Albedo

    NASA Astrophysics Data System (ADS)

    Pellicciotti, F.; Strasser, U.; Burlando, P.; Funk, M.; Brock, B.; Corripio, J.

    Albedo is a major controlling factor for the melting of snow and ice. Here, an en- hanced degree-day melt model for the point scale is presented, in which the classical dependency on temperature is extended by considering albedo and global radiation. Temperature based index melt methods have been widely used due to their good per- formances, the availability of temperature data and the ease of its spatial interpolation. Other authors have recently improved the standard approach by addition of a radiation term. Here, the latter is modified with albedo, which represents a physical property of the material, and accounts for the way the surface reacts to the energy input of global radiation. The formulation adopted is additive, being melt expressed as the sum of two components, one controlled by temperature and the second by short-wave incoming radiation. Such a representation allows to separate in a clear way the two important contributions to melt of long wave and global radiation The model was run at different sites where the necessary meteorological data are measured and melt values are avail- able. In the pre-alpine site of Col de Porte (French Alps, 1340m), melt was computed by use of a highly sophisticated, physically based energy balance model. An ultrasonic device was used at a glacier location on Haut Glacier d'Arolla (Swiss Alps, 2920 m). Both measured short-wave radiation and computed potential direct short-wave radia- tion were used, and different temporal resolutions were tested. Results are discussed with the purpose of evaluating the increased efficiency of the improved degree-day scheme, and in the light of extending it to a distributed model, which accounts for space-time albedo variability.

  17. Albedo feedback enhanced by smoother Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Landy, Jack C.; Ehn, Jens K.; Barber, David G.

    2015-12-01

    The ICESat operational period 2003-2008 coincided with a dramatic decline in Arctic sea ice—linked to prolonged melt season duration and enhanced melt pond coverage. Although melt ponds evolve in stages, sea ice with smoother surface topography typically allows the pond water to spread over a wider area, reducing the ice-albedo and accelerating further melt. Here we develop this theory into a quantitative relationship between premelt sea ice surface roughness and summer melt pond coverage. Our method, applied to ICESat observations of the end-of-winter sea ice roughness, can account for 85% of the variance in advanced very high resolution radiometer (AVHRR) observations of the summer ice-albedo. An Arctic-wide reduction in sea ice roughness from 2003 to 2008 explains a drop in ice-albedo that resulted in a 16% increase in solar heat input to the sea ice cover, which represents ten times the heat input contributed by earlier melt onset timing over the same period.

  18. Gamma-ray Albedo of Small Solar System Bodies

    SciTech Connect

    Moskalenko, I.V.

    2008-03-25

    We calculate the {gamma}-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the {gamma}-ray albedo for the Main Belt and KBOs strongly depends on the small-body mass spectrum of each system and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). If detected, it can be used to derive the mass spectrum of small bodies in the Main Belt and Kuiper Belt and to probe the spectrum of CR nuclei at close-to-interstellar conditions. The orbits of the Main Belt asteroids and KBOs are distributed near the ecliptic, which passes through the Galactic center and high Galactic latitudes. Therefore, the {gamma}-ray emission by the Main Belt and Kuiper Belt has to be taken into account when analyzing weak {gamma}-ray sources close to the ecliptic. The asteroid albedo spectrum also exhibits a 511 keV line due to secondary positrons annihilating in the rock. This may be an important and previously unrecognized celestial foreground for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of the Galactic 511 keV line emission including the direction of the Galactic center. For details of our calculations and references see [1].

  19. Leading/Trailing Albedo Asymmetries of Thebe, Amalthea, and Metis

    NASA Astrophysics Data System (ADS)

    Simonelli, Damon P.; Rossier, Laura; Thomas, Peter C.; Veverka, Joseph; Burns, Joseph A.; Belton, Michael J. S.

    2000-10-01

    Using Galileo clear-filter images (effective wavelength ≈0.64 μm), we have created the first albedo maps of the small inner jovian satellites Thebe, Amalthea, and Metis. These maps clearly show that the leading sides of all three satellites are significantly brighter than their corresponding trailing sides, confirming and extending a result first reported by P. C. Thomas et al. (1998, Icarus135, 360-371). In particular, on all three moons the leading side is brighter than the trailing side by 25 to 30%. The fact that the direction and size of this albedo asymmetry is identical from satellite to satellite suggests that one common physical mechanism is governing the global albedo patterns of all three moons. The most plausible such mechanism is the impact of macroscopic meteoroids that originated outside the jovian system. These impacts, which eject the dust that forms Jupiter's ring system (M. E. Ockert-Bell et al., 1999, Icarus138, 188-213; J. A. Burns et al., 1999, Science284, 1146-1150), are probably also responsible for brightening the leading sides of these small satellites.

  20. Supercritical Salt Spray for the Implementation of Cloud Albedo Modification

    NASA Astrophysics Data System (ADS)

    Neukermans, A. P.; Cooper, G.; Foster, J. D.; Galbraith, L.; Ormond, B.; Wang, Q.; Johnston, D.; Cloud Brightening Research

    2011-12-01

    Of all the geo-engineering schemes proposed so far, the Latham-Salter cloud albedo modification scheme is perhaps the most benign and "natural" method. In its full deployment, it proposes to densify and thereby modify the albedo of low-hanging marine boundary clouds by a few percent such that the overall earth albedo might be changed by 1%. The scheme would require the production of vast numbers of salt cloud condensation nuclei (CCN), in one implementation on the order of 10^17 per second from each of some 1500 autonomous sailing vessels. We have investigated a number of possible techniques to create these nuclei. We reported previously the laboratory production of suitable nuclei from saltwater using Taylor cones. This method would require about 10^8 Taylor cones per vessel to get to the required CCN production rate, and hence needs a very extensive scale-up effort. We report here on the use of saltwater sprayed at or near its critical temperature and pressure through small nozzles. Although a number of technical problems remain, results to date suggest that this method might be suitable, at least for research purposes. The mean particle size distributions of nuclei generated (40-100 nm) are acceptable, and the scale-up effort to the estimated number of nozzles required (1000-2000) seems reasonable.

  1. Semileptonic Decays

    SciTech Connect

    Luth, Vera G.; /SLAC

    2012-10-02

    The following is an overview of the measurements of the CKM matrix elements |V{sub cb}| and |V{sub ub}| that are based on detailed studies of semileptonic B decays by the BABAR and Belle Collaborations and major advances in QCD calculations. In addition, a new and improved measurement of the ratios R(D{sup (*)}) = {Beta}({bar B} {yields} D{sup (*)}{tau}{sup -}{bar {nu}}{sub {tau}})/{Beta}({bar B} {yields} D{sup (*)}{ell}{sup -}{bar {nu}}{sub {ell}}) is presented. Here D{sup (*)} refers to a D or a D* meson and {ell} is either e or {mu}. The results, R(D) = 0.440 {+-} 0.058 {+-} 0.042 and R(D*) = 0.332 {+-} 0.024 {+-} 0.018, exceed the Standard Model expectations by 2.0{sigma} and 2.7{sigma}, respectively. Taken together, they disagree with these expectations at the 3.4{sigma} level. The excess of events cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model.

  2. Dental Caries (Tooth Decay)

    MedlinePlus

    ... Find Data by Topic > Dental Caries (Tooth Decay) Dental Caries (Tooth Decay) Main Content Dental caries (tooth decay) remains the most prevalent chronic ... important source of information on oral health and dental care in the United States since the early ...

  3. Measurement of the Neutron Lifetime by Counting Trapped Protons

    PubMed Central

    Wietfeldt, F. E.; Dewey, M. S.; Gilliam, D. M.; Nico, J. S.; Fei, X.; Snow, W. M.; Greene, G. L.; Pauwels, J.; Eykens, R.; Lamberty, A.; Van Gestel, J.

    2005-01-01

    We measured the neutron decay lifetime by counting in-beam neutron decay recoil protons trapped in a quasi-Penning trap. The absolute neutron beam fluence was measured by capture in a thin 6LiF foil detector with known efficiency. The combination of these measurements gives the neutron lifetime: τn = (886.8 ± 1.2 ± 3.2) s, where the first (second) uncertainty is statistical (systematic) in nature. This is the most precise neutron lifetime determination to date using an in-beam method. PMID:27308145

  4. Decay studies of neutron deficient nuclei near the Z =64 subshell: sup 142 Dy, sup 140,142 Tb, sup 140,142 Gd, sup 140,142 Eu, sup 142 Sm, and

    SciTech Connect

    Firestone, R.B.; Gilat, J.; Nitschke, J.M.; Wilmarth, P.A.; Vierinen, K.S. )

    1991-03-01

    The electron-capture and {beta}{sup +}-decay branchings (EC/{beta}{sup +}) and delayed proton decays of {ital A}=142 isotopes with 61{le}{ital Z}{le}66 and {ital A}=140 isotopes with 63{le}{ital Z}{le}65 were investigated with the OASIS facility on-line at the Lawrence Berkeley Laboratory SuperHILAC. Electron capture and positron-decay emission probabilities have been determined for {sup 142}Pm and {sup 142}Sm decays, and extensive decay schemes have been constructed for {sup 142}Eu{sup {ital g}}(2.34{plus minus}0.12 s), {sup 142}Gd(70.2{plus minus}0.6 s), {sup 140}Eu(1.51{plus minus}0.02 s), and {sup 140}Gd(15.8{plus minus}0.4 s). Decay schemes for the new isotopes {sup 142}Tb{sup {ital g}}(597{plus minus}17 ms), {sup 142}Tb{sup {ital m}}(303{plus minus}17 ms), {sup 142}Dy(2.3{plus minus}0.3 s), {sup 140}Eu{sup {ital m}}(125{plus minus}2 ms), and {sup 140}Tb(2.4{plus minus}0.2 s) are also presented. We have assigned {gamma} rays to these isotopes on the basis of {gamma}{gamma} and {ital x}{gamma} coincidences, and from half-life determinations. Electron-capture and {beta}{sup +}-decay branchings were measured for each decay, and {beta}-delayed proton branchings were determined for {sup 142}Dy, {sup 142}Tb, and {sup 140}Tb decays. {ital Q}{sub EC} values, derived from the measured EC/{beta}{sup +} branchings and the level schemes are compared with those from the Wapstra and Audi mass evaluation and the Liran and Zeldes mass calculation. The systematics of the {ital N}=77 isomer decays are discussed, and the intense 0{sup +}{r arrow}1{sup +} and 1{sup +}{r arrow}0{sup +} ground-state beta decays are compared with shell-model predictions for simple spin-flip transitions.

  5. 2002 REVIEW OF NEUTRON AND NON NEUTRON NUCLEAR DATA.

    SciTech Connect

    HOLDEN,N.E.

    2002-08-18

    Review articles are in preparation for the 2003 edition of the CRC's Handbook of Chemistry and Physics dealing with both non-neutron and neutron nuclear data. Highlights include: withdrawal of the claim for discovery of element 118; new measurements of isotopic abundances have led to changes for many elements; a new set of recommended standards for calibration of {gamma}-ray energies have been published for many nuclides; new half-life measurements reported for very short lived isotopes, many long-lived nuclides and {beta}{beta} decay measurements for quasi-stable nuclides; a new reassessment of spontaneous fission (sf) half-lives for ground state nuclides, distinguishing half-lives from sf decay and cluster decay half-lives and the new cluster-fission decay; charged particle cross sections, (n,p) and (n,{alpha}) measurements for thermal neutrons incident on light nuclides; new thermal (n,{gamma}) cross sections and neutron resonance integrals measured. Details are presented.

  6. Quantifying the Impacts of Surface Albedo on Climate Using the WRF Model

    NASA Astrophysics Data System (ADS)

    Schlosser, C. A.; Xu, L.; Xu, X.; Gregory, J.; Kirchain, R.

    2015-12-01

    Surface albedo is an important part of the energy budget in shaping local and regional climate. It could also be a potential tool to mitigate the anthropogenic effect on climate change. However, the current level of scientific understanding of surface albedo on global warming potential is medium to low. In order to investigate the anthropogenic impact of surface albedo on climate, different scenarios of urban surface albedo over continental US using the WRF model are simulated. In this study, the change in surface albedo applies to rooftops, pavements, and walls of urban land cover grid cells. The two groups of simulations (low and high albedo) were compared to determine the impacts of elevating urban surface albedo and to account for the uncertainty in the errors or noise introduced by the slightly different initial conditions. The results are represented as the differences in surface temperature and the top of the atmosphere radiation between the two scenarios when urban surface albedos are elevated from 0.15 to 0.40. The ensemble mean of all potential outcomes as a whole, instead of individual initial conditions, shows that the impact of elevating surface albedo has a cooling effect that is robust at both local and regional scales during the summer season. More refined analyses of urban areas will provide insights on surface albedo impacts in specific regions. Future analyses may address changes in CO2 equivalence.

  7. Robust estimation of albedo for illumination-invariant matching and shape recovery.

    PubMed

    Biswas, Soma; Aggarwal, Gaurav; Chellappa, Rama

    2009-05-01

    We present a nonstationary stochastic filtering framework for the task of albedo estimation from a single image. There are several approaches in the literature for albedo estimation, but few include the errors in estimates of surface normals and light source direction to improve the albedo estimate. The proposed approach effectively utilizes the error statistics of surface normals and illumination direction for robust estimation of albedo, for images illuminated by single and multiple light sources. The albedo estimate obtained is subsequently used to generate albedo-free normalized images for recovering the shape of an object. Traditional Shape-from-Shading (SFS) approaches often assume constant/piecewise constant albedo and known light source direction to recover the underlying shape. Using the estimated albedo, the general problem of estimating the shape of an object with varying albedo map and unknown illumination source is reduced to one that can be handled by traditional SFS approaches. Experimental results are provided to show the effectiveness of the approach and its application to illumination-invariant matching and shape recovery. The estimated albedo maps are compared with the ground truth. The maps are used as illumination-invariant signatures for the task of face recognition across illumination variations. The recognition results obtained compare well with the current state-of-the-art approaches. Impressive shape recovery results are obtained using images downloaded from the Web with little control over imaging conditions. The recovered shapes are also used to synthesize novel views under novel illumination conditions. PMID:19299862

  8. [Temporal and Spatial Characteristics of Lake Taihu Surface Albedo and Its Impact Factors].

    PubMed

    Cao, Chang; Li, Xu-hui; Zhang, Mi; Liu, Shou-dong; Xiao, Wei; Xiao, Qi-tao; Xu, Jia-ping

    2015-10-01

    Lake surface albedo determines energy balance of water-atmospheric interface and water physical environment. Solar elevation angle, cloudiness, wind speed, water quality and other factors can affect lake surface albedo. Using solar radiation, wind speed, and water quality data (turbidity and chlorophyll-a concentration) which were observed in four eddy covariance sites (Meiliangwan, Dapukou, Bifenggang and Xiaoleishan i. e. MLW, DPK, BFG and XLS) in Lake Taihu and clearness index (k(t)), the influence of these factors on Lake Taihu surface albedo and the reasons that led to its spatial difference were investigated. The results showed that solar elevation angle played a leading role in the diurnal and seasonal change of lake surface albedo; lake surface albedo reached two peaks in 0 < k(t) < 0.1 and 0.4 < k(t) < 0.6 respectively, when solar elevation angle was below 35 degrees. The surface albedo increased with the increasing wind speed, turbidity and chlorophyll-a concentration. However, wind could indirectly affect surface albedo through leading to the changes in sediment resuspension and chlorophyll-a distribution. The sequence of albedo in the four sites was XLS > BFG > DPK > MLW. XLS and BFG belonged to the higher albedo group, while DPK and MLW belonged to the lower albedo group. The different biological environments caused by aquatic macrophytes and algae resulting in the spatial variation of Lake Taihu surface albedo. The relationship between albedo and chlorophyll-a concentration was not a very sensitive factor for indicating the outbreak of algae. This study can provide theoretical reference for lake albedo parameterization. PMID:26841592

  9. Probing the Planck Scale with Proton Decay

    SciTech Connect

    Harnik, Roni; Larson, Daniel T.; Murayama, Hitoshi; Thormeier, Marc

    2004-04-28

    We advocate the idea that proton decay may probe physics at the Planck scale instead of the GUT scale. This is possible because supersymmetric theories have dimension-5 operators that can induce proton decay at dangerous rates, even with R-parity conservation. These operators are expected to be suppressed by the same physics that explains the fermion masses and mixings. We present a thorough analysis of nucleon partial lifetimes in models with a string-inspired anomalous U(1)_X family symmetry which is responsible for the fermionic mass spectrum as well as forbidding R-parity violating interactions. Protons and neutrons can decay via R-parity conserving non-renormalizable superpotential terms that are suppressed by the Planck scale and powers of the Cabibbo angle. Many of the models naturally lead to nucleon decay near present limits without any reference to grand unification.

  10. Relativistic neutrons in active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Sikora, Marek; Begelman, Mitchell C.; Rudak, Bronislaw

    1989-01-01

    The acceleration of protons to relativistic energies in active galactic nuclei leads to the creation of relativistic neutrons which escape from the central engine. The neutrons decay at distances of up to 1-100 pc, depositing their energies and momenta in situ. Energy deposition by decaying neutrons may inhibit spherical accretion and drive a wind, which could be responsible for the velocity fields in emission-line regions and the outflow of broad absorption line systems. Enhanced pressure in the neutron decay region may also help to confine emission line clouds. A fraction of the relativistic proton energy is radiated in gamma-rays with energies which may be as large as about 100,000 GeV.

  11. Climatic Benefit of Swiss Forest Cover Change: Including Albedo Change into Net Carbon Balance

    NASA Astrophysics Data System (ADS)

    Schwaab, J.; Lehning, M.; Bebi, P.

    2012-12-01

    Forests influence climate through physical, chemical and biological processes. It has been shown that warming caused by the comparatively low albedo of forests (albedo-effect), can reduce or even exceed cooling caused by carbon storage in forests (CO2-effect). Although warming caused by albedo and the amount of carbon storage depend on local characteristics, studies are lacking that investigate the combined local patterns of albedo and CO2-effect. Our study area, Switzerland, provides a variety of geographical features and thus the possibility to show how different geographical variables influence the two effects. We used the concept of radiative forcing to compare the effect of a changing albedo and a change in atmospheric CO2 concentration due to land cover change in the past. The change of forest cover was analysed over a period of 12 years based on aerial photographs. We estimate the albedo-effect by combining albedo data derived from the satellite sensor MODIS and data on snow cover derived from the satellite sensor AVHRR. Changes in carbon storage were calculated as differences in biomass and soil stocks of specific land cover classes. We found carbon storage induced cooling to be higher than albedo induced warming everywhere in Switzerland. However, especially in altitudes over 1200 m the albedo-effect reduced the benefits of carbon storage by more than 50%. In lower altitudes the albedo change was less important. The albedo-effect in altitudes above 1200 m was more relevant because of a more persistent snow-cover, a slightly higher global radiation and less additional carbon storage. The relevance of warming caused by an albedo change did not only depend on altitude, but also on the characteristics of forest cover change. While transitions from open land to open forest were accompanied by high albedo changes, the albedo change was only marginal if open forest turned into closed forest. Since snow cover has a large influence on the albedo effect, we included

  12. 2013 Review of Neutron and Non-Neutron Nuclear Data

    SciTech Connect

    Holden, N. E.

    2014-05-23

    The results of a review and evaluation of neutron and non-neutron nuclear data published in the scientific literature over the past three years since the ISRD-14 Symposium has been performed and the highlights are presented. Included in the data review are the status of new chemical elements, new measurements of the isotopic composition for many chemical elements and the resulting change in the atomic weight values. New half-life measurements for both short-lived and longlived nuclides, some alpha decay and double beta decay measurements for quasistable nuclides are discussed. The latest evaluation of atomic masses has been published. Data from new measurements on the very heavy (trans-meitnerium) elements are discussed and tabulated. Data on various recent neutron cross section and resonance integral measurements are discussed and tabulated.

  13. 2013 Review of Neutron and Non-Neutron Nuclear Data

    NASA Astrophysics Data System (ADS)

    Holden, N. E.

    2016-02-01

    The results of a review and evaluation of neutron and non-neutron nuclear data published in the scientific literature over the past three years since the ISRD-14 Symposium has been performed and the highlights are presented. Included in the data review are the status of new chemical elements, new measurements of the isotopic composition for many chemical elements and the resulting change in the atomic weight values. New half-life measurements for both short-lived and long-lived nuclides, some alpha decay and double beta decay measurements for quasi-stable nuclides are discussed. The latest evaluation of atomic masses has been published. Data from new measurements on the very heavy (trans-meitnerium) elements are discussed and tabulated. Data on various recent neutron cross section and resonance integral measurements are discussed and tabulated.

  14. Martian Neutron Energy Spectrometer (MANES)

    NASA Technical Reports Server (NTRS)

    Maurer, R. H.; Roth, D. R.; Kinnison, J. D.; Goldsten, J. O.; Fainchtein, R.; Badhwar, G.

    2000-01-01

    High energy charged particles of extragalactic, galactic, and solar origin collide with spacecraft structures and planetary atmospheres. These primaries create a number of secondary particles inside the structures or on the surfaces of planets to produce a significant radiation environment. This radiation is a threat to long term inhabitants and travelers for interplanetary missions and produces an increased risk of carcinogenesis, central nervous system (CNS) and DNA damage. Charged particles are readily detected; but, neutrons, being electrically neutral, are much more difficult to monitor. These secondary neutrons are reported to contribute 30-60% of the dose equivalent in the Shuttle and MIR station. The Martian atmosphere has an areal density of 37 g/sq cm primarily of carbon dioxide molecules. This shallow atmosphere presents fewer mean free paths to the bombarding cosmic rays and solar particles. The secondary neutrons present at the surface of Mars will have undergone fewer generations of collisions and have higher energies than at sea level on Earth. Albedo neutrons produced by collisions with the Martian surface material will also contribute to the radiation environment. The increased threat of radiation damage to humans on Mars occurs when neutrons of higher mean energy traverse the thin, dry Martian atmosphere and encounter water in the astronaut's body. Water, being hydrogeneous, efficiently moderates the high energy neutrons thereby slowing them as they penetrate deeply into the body. Consequently, greater radiation doses can be deposited in or near critical organs such as the liver or spleen than is the case on Earth. A second significant threat is the possibility of a high energy heavy ion or neutron causing a DNA double strand break in a single strike.

  15. Proton decay theory

    SciTech Connect

    Marciano, W.J.

    1983-01-01

    Topics include minimal SU(5) predictions, gauge boson mediated proton decay, uncertainties in tau/sub p/, Higgs scalar effects, proton decay via Higgs scalars, supersymmetric SU(5), dimension 5 operators and proton decay, and Higgs scalars and proton decay. (WHK)

  16. UV signatures of carbonaceous species on low-albedo asteroids

    NASA Astrophysics Data System (ADS)

    Hendrix, A.; Vilas, F.

    2014-07-01

    Asteroids in the low-albedo classes (C, B, G, F) are known to have spectra that are relatively feature-free in the visible/near-infrared (VNIR) spectral region, making them classically difficult to study in terms of surface mineralogy. Many of these bodies exhibit a 3-micron absorption band (e.g., [1]), which can be used to study hydration and organics. The primary other spectrally active region --- less well studied so far --- is the ultraviolet (UV). In this study, we utilize UV spectra of low-albedo asteroids (C, B, G, and F class) to study surface composition. In particular, we investigate implications for the presence of carbonaceous compounds, including tholins and Polycyclic Aromatic Hydrocarbons (PAHs), which have unique spectral features in the UV. Low-albedo asteroids are typically rather bland spectrally at VNIR wavelengths. Many of these objects exhibit an absorption band near 3 microns, indicative of some type of hydration (OH and-or H_2O). A subset of the asteroids with the 3-micron features also exhibit absorption near 0.7 microns, due to a ferrous-ferric charge-transfer transition likely resulting from aqueous alteration (the interaction of material with liquid water formed by melting of water upon a heating event). Some asteroids likely do not exhibit these features due to a history of heating experienced at some point in the asteroid's evolution. Despite having little spectral activity in the VNIR, all low-albedo asteroids absorb at wavelengths shorter than ˜500 nm. This has been generally attributed to a ferric-iron intervalence charge-transfer transition absorption. Carbon-bearing phases have long been assumed to be important on low-albedo asteroids (e.g., [2]) due to the dark, mostly-featureless VNIR spectra of these bodies. However, there are many forms of carbonaceous species and the species are expected to undergo phase modifications (e.g., due to thermal, aqueous, and radiation processes) that affect the spectra [3,7]. Tholins are residues

  17. Effect of reflectance model choice on earthshine-based terrestrial albedo determinations.

    NASA Astrophysics Data System (ADS)

    Thejll, Peter; Gleisner, Hans; Flynn, Chris

    2016-04-01

    Earthshine observations can be used to determine near-hemispheric average terrestrial albedos by careful observation of the relative strength of the earthshine-lit half of the Moon coupled with correct modelling of the reflectances of Earth and Moon, as well as lunar single-scattering albedo maps. Using our own observations of the earthshine, from Mauna Loa Observatory in 2011-12, we investigate the influence of the choice of bidirectional reflectance models for the Moon on derived terrestrial albedos. We find a considerable dependence on albedo results in this choice, and discuss ways to determine what the origin of the dependence is - e.g is it in the joint choices of lunar and terrestrial BRDFs, or is the choice of terrestrial BRDF less important than the lunar one? We report on the results of modelling lunar reflectance and albedo in 6 ways and terrestrial reflectance in two ways, assuming a uniform single-scattering albedo on Earth.

  18. A REVISED ASTEROID POLARIZATION-ALBEDO RELATIONSHIP USING WISE/NEOWISE DATA

    SciTech Connect

    Masiero, Joseph R.; Mainzer, A. K.; Bauer, J. M.; Wright, E. L.; McMillan, R. S.; Tholen, D. J.; Blain, A. W.

    2012-04-20

    We present a reanalysis of the relationship between asteroid albedo and polarization properties using the albedos derived from the Wide-field Infrared Survey Explorer. We find that the function that best describes this relation is a three-dimensional linear fit in the space of log (albedo)-log (polarization slope)-log (minimum polarization). When projected to two dimensions, the parameters of the fit are consistent with those found in previous work. We also define p* as the quantity of maximal polarization variation when compared with the albedo and present the best-fitting albedo-p* relation. Some asteroid taxonomic types stand out in this three-dimensional space, notably the E, B, and M Tholen types, while others cluster in clumps coincident with the S- and C-complex bodies. We note that both low albedo and small (D < 30 km) asteroids are underrepresented in the polarimetric sample, and we encourage future polarimetric surveys to focus on these bodies.

  19. Earth's albedo variations 1998-2014 as measured from ground-based earthshine observations

    NASA Astrophysics Data System (ADS)

    Palle, E.; Goode, P. R.; Montañés-Rodríguez, P.; Shumko, A.; Gonzalez-Merino, B.; Lombilla, C. Martinez; Jimenez-Ibarra, F.; Shumko, S.; Sanroma, E.; Hulist, A.; Miles-Paez, P.; Murgas, F.; Nowak, G.; Koonin, S. E.

    2016-05-01

    The Earth's albedo is a fundamental climate parameter for understanding the radiation budget of the atmosphere. It has been traditionally measured not only from space platforms but also from the ground for 16 years from Big Bear Solar Observatory by observing the Moon. The photometric ratio of the dark (earthshine) to the bright (moonshine) sides of the Moon is used to determine nightly anomalies in the terrestrial albedo, with the aim of quantifying sustained monthly, annual, and/or decadal changes. We find two modest decadal scale cycles in the albedo, but with no significant net change over the 16 years of accumulated data. Within the evolution of the two cycles, we find periods of sustained annual increases, followed by comparable sustained decreases in albedo. The evolution of the earthshine albedo is in remarkable agreement with that from the Clouds and the Earth's Radiant Energy System instruments, although each method measures different slices of the Earth's Bond albedo.

  20. Splash and Re-entrant Albedo Fluxes Measured in the PAMELA Experiment

    NASA Astrophysics Data System (ADS)

    Mayorov, A. G.; Moiseeva, A. I.; Adriani, O.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; Boezio, M.; Bogomolov, E. A.; Bongi, M.; Bonvicini, V.; Bottai, S.; Bruno, A.; Cafagna, F.; Campana, D.; Carbone, R.; Carlson, P.; Casolino, M.; Castellini, G.; DeDonato, C.; DeSantis, C.; DeSimone, N.; DiFelice, V.; Formato, V.; Galper, A. M.; Karelin, A. V.; Koldashov, S. V.; Koldobskiy, S.; Kvashnin, A. A.; Kvashnin, A. N.; Leonov, A.; Malakhov, V.; Marcelli, L.; Martucci, M.; Mayorova, M. A.; Menn, W.; Merge', M.; Mikhailov, V. V.; Mocchiutti, E.; Monaco, A.; Mori, N.; Munini, R.; Osteria, G.; Palma, F.; Panico, B.; Papini, P.; Pearce, M.; Picozza, P.; Pizzolotto, C.; Ricci, M.; Ricciarini, S. B.; Sarkar, R.; Scotti, V.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stozhkov, Y. I.; Vacchi, A.; Vannuccini, E.; Voronov, S. A.; Yurkin, Y. T.; Zampa, G.; Zampa, N.; Zverev, V. G.

    This work devoted to the description of the method for splash albedo protons identification in the satellite-born experiment PAMELA. In contrast to the reentrant albedo particles, which enter into the main aperture of the instrument, the direct albedo particles enter from the opposite direction, so they pass a few detectors, including calorimeter, before being register by the magnetic spectrometer. The developed method take into account the influence of these detectors on the selection of events and measurements of their characteristics. To test this method the energy spectrum of reentrant albedo protons in various regions of the near-Earth space reconstructed; it is in a good agreement with the classical measurements in the main aperture. Therefore, this method can be useful to obtain a new physical data about fluxes of splash albedo protons in the PAMELA experiment, which, unlike the reentrant albedo, can be study even at high geomagnetic latitudes.

  1. Surface Albedo/BRDF Parameters (Terra/Aqua MODIS)

    DOE Data Explorer

    Trishchenko, Alexander

    2008-01-15

    Spatially and temporally complete surface spectral albedo/BRDF products over the ARM SGP area were generated using data from two Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on Terra and Aqua satellites. A landcover-based fitting (LBF) algorithm is developed to derive the BRDF model parameters and albedo product (Luo et al., 2004a). The approach employs a landcover map and multi-day clearsky composites of directional surface reflectance. The landcover map is derived from the Landsat TM 30-meter data set (Trishchenko et al., 2004a), and the surface reflectances are from MODIS 500m-resolution 8-day composite products (MOD09/MYD09). The MOD09/MYD09 data are re-arranged into 10-day intervals for compatibility with other satellite products, such as those from the NOVA/AVHRR and SPOT/VGT sensors. The LBF method increases the success rate of the BRDF fitting process and enables more accurate monitoring of surface temporal changes during periods of rapid spring vegetation green-up and autumn leaf-fall, as well as changes due to agricultural practices and snowcover variations (Luo et al., 2004b, Trishchenko et al., 2004b). Albedo/BRDF products for MODIS on Terra and MODIS on Aqua, as well as for Terra/Aqua combined dataset, are generated at 500m spatial resolution and every 10-day since March 2000 (Terra) and July 2002 (Aqua and combined), respectively. The purpose for the latter product is to obtain a more comprehensive dataset that takes advantages of multi-sensor observations (Trishchenko et al., 2002). To fill data gaps due to cloud presence, various interpolation procedures are applied based on a multi-year observation database and referring to results from other locations with similar landcover property. Special seasonal smoothing procedure is also applied to further remove outliers and artifacts in data series.

  2. Can increasing albedo of existing ship wakes reduce climate change?

    NASA Astrophysics Data System (ADS)

    Crook, Julia A.; Jackson, Lawrence S.; Forster, Piers M.

    2016-02-01

    Solar radiation management schemes could potentially alleviate the impacts of global warming. One such scheme could be to brighten the surface of the ocean by increasing the albedo and areal extent of bubbles in the wakes of existing shipping. Here we show that ship wake bubble lifetimes would need to be extended from minutes to days, requiring the addition of surfactant, for ship wake area to be increased enough to have a significant forcing. We use a global climate model to simulate brightening the wakes of existing shipping by increasing wake albedo by 0.2 and increasing wake lifetime by ×1440. This yields a global mean radiative forcing of -0.9 ± 0.6 Wm-2 (-1.8 ± 0.9 Wm-2 in the Northern Hemisphere) and a 0.5°C reduction of global mean surface temperature with greater cooling over land and in the Northern Hemisphere, partially offsetting greenhouse gas warming. Tropical precipitation shifts southward but remains within current variability. The hemispheric forcing asymmetry of this scheme is due to the asymmetry in the distribution of existing shipping. If wake lifetime could reach ~3 months, the global mean radiative forcing could potentially reach -3 Wm-2. Increasing wake area through increasing bubble lifetime could result in a greater temperature reduction, but regional precipitation would likely deviate further from current climatology as suggested by results from our uniform ocean albedo simulation. Alternatively, additional ships specifically for the purpose of geoengineering could be used to produce a larger and more hemispherically symmetrical forcing.

  3. Independent pixel and Monte Carlo estimates of stratocumulus albedo

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Ridgway, William; Wiscombe, Warren J.; Gollmer, Steven; HARSHVARDHAN

    1994-01-01

    Monte Carlo radiative transfer methods are employed here to estimate the plane-parallel albedo bias for marine stratocumulus clouds. This is the bias in estimates of the mesoscale-average albedo, which arises from the assumption that cloud liquid water is uniformly distributed. The authors compare such estimates with those based on a more realistic distribution generated from a fractal model of marine stratocumulus clouds belonging to the class of 'bounded cascade' models. In this model the cloud top and base are fixed, so that all variations in cloud shape are ignored. The model generates random variations in liquid water along a single horizontal direction, forming fractal cloud streets while conserving the total liquid water in the cloud field. The model reproduces the mean, variance, and skewness of the vertically integrated cloud liquid water, as well as its observed wavenumber spectrum, which is approximately a power law. The Monte Carlo method keeps track of the three-dimensional paths solar photons take through the cloud field, using a vectorized implementation of a direct technique. The simplifications in the cloud field studied here allow the computations to be accelerated. The Monte Carlo results are compared to those of the independent pixel approximation, which neglects net horizontal photon transport. Differences between the Monte Carlo and independent pixel estimates of the mesoscale-average albedo are on the order of 1% for conservative scattering, while the plane-parallel bias itself is an order of magnitude larger. As cloud absorption increases, the independent pixel approximation agrees even more closely with the Monte Carlo estimates. This result holds for a wide range of sun angles and aspect ratios. Thus, horizontal photon transport can be safely neglected in estimates of the area-average flux for such cloud models. This result relies on the rapid falloff of the wavenumber spectrum of stratocumulus, which ensures that the smaller

  4. Albedo, thermal inertia and rotation of ring particles (Invited)

    NASA Astrophysics Data System (ADS)

    Morishima, R.; Spilker, L. J.; Ohtsuki, K.; Cassini Cirs Ring Team

    2010-12-01

    Since the Saturn orbit insertion of the Cassini spacecraft in mid-2004 up to now, the Cassini composite infrared spectrometer (CIRS) has measured temperatures of Saturn's main rings at various observational geometries. We present results of parameter fits using our new thermal model (Morishima et al. 2009). Our model is based on classical radiative transfer and takes into account the heat transport due to particle motion in the azimuthal and vertical directions. The model assumes a bimodal size distribution consisting of small fast rotators and large slow rotators. Important parameters are the Bolometric bond albedo, A_V, the fraction of fast rotators in cross section, f_fast, and the thermal inertia, Γ. Two different data sets are used to estimate these parameters. The first set, which consists of four radial scans obtained at low and high solar phases both on the lit and unlit faces of rings (Spilker et al. 2006), is suitable for accurate estimations of A_V and f_fast with high radial resolution. Another one, which consists of azimuthal scans that include data in Saturn shadow (Leyrat et al. 2008), is suitable for estimations of Γ. The estimated parameters are shown in Fig.1. The albedo is 0.1-0.4, 0.5-0.7, 0.4, 0.5 for the C ring, the B ring, the Cassini division, and the A ring, respectively. The fraction of fast rotators is roughly half for all the rings. The thermal inertia is 7-21 in MKS units. For the mid B ring, values of parameters obtained from two data sets are consistent with each other if ring particles are assumed to bounce at the midplane due to mutual collisions. We also find that fits to azimuthal scans are improved if Γ for fast rotators is larger than that for slow rotators. Albedo, fraction of fast rotators in cross section, and thermal inertia estimated from parameter fits. Two different thermal data sets are used: radial scans at four different geometries (solid curves) and azimuthal scans including data in Saturn shadow (diamonds). Dashed

  5. Sizes and Albedos of Young C-type Asteroids

    NASA Astrophysics Data System (ADS)

    Tamblyn, Peter; Chapman, Clark; Durda, Dan; Merline, William; Nesvorny, David

    2005-06-01

    We propose to measure the sizes and albedos of 8 very young C-type asteroids with IRAC 8um and near-simultaneous ground-based visible photometry. Asteroid families are created from major collisions between asteroids and are identified from clustering of orbital elements. Co-I Nesvorny has recently identified an exceptionally-young family (Veritas) and precisely-dated it at only 8.3+/-0.5 Myr (just 0.2% of the age of the solar system). We will compare our results for this family with those obtained by our similar Spitzer GO-1 program where we study an even younger S-type family, Karin. C-type asteroids are composed of primitive material (as opposed to the more processed silicate-rich S-types) and comprise the majority of asteorids in the Main Belt, yet their compositions and properties remain elusive. These recent breakup events provide unparalleled opportunities to study compositions, dynamics, and collisions of asteroids. They allow tests of the rates of physical processes that happen on time scales comparable with the family age. Space weathering, for example, appears to affect C- and S-type asteroids very differently. We will test directly whether the Veritas fragments have similar albedos; we will also test if their albedos differ from those of similar asteroids with much older surfaces by study of a second C-type family, Themis. We will compare our observations with those made of larger asteroids of both families, from a companion ground-based program. We will quantify any correlation of size with albedo, a dominant uncertainty in standard size estimates. The size distribution will be used to calibrate hydrocode models of asteroid collisions. To do this will require observations at the smallest practical sizes. In addition, the measured sizes will be immediately applicable to a novel measurement of the Yarkovsky Effect. We have already demonstrated in our GO-1 program that we can make similar Spitzer observations and provide the ground-based visible support.

  6. The asteroid albedo scale. II - Laboratory polarimetry of dark carbon-bearing silicates

    NASA Technical Reports Server (NTRS)

    Zellner, B.; Lebertre, T.; Day, K.

    1977-01-01

    Laboratory reflection polarimetry is presented for eight samples of artificial, poorly crystalline magnesian silicates with varying admixtures of carbon black. The polarimetric slope-albedo law saturates for geometric albedos lower than about 0.05, and good agreement with the telescopic polarization-phase curves of C-type asteroids is found for albedos as low as 0.02. Thus the conclusion from thermal radiometry is confirmed that the C objects are very dark, darker than any known carbonaceous chondrite.

  7. Measuring the Neutron Lifetime using Magnetically Trapped Ultracold Neutrons

    NASA Astrophysics Data System (ADS)

    Mumm, H. P.; Coakley, K. J.; Dewey, M. S.; Huber, M. G.; Hughes, P. P.; Thompson, A. K.; Golub, R.; Huffer, C. R.; Huffman, P. R.; O'Shaughnessy, C. M.; Schelhammer, K. W.

    2010-11-01

    The neutron beta-decay lifetime is important in both theoretical predictions of the primordial abundance of ^4He and providing a strong unitarity test of the CKM mixing matrix. We have previously demonstrated trapping of Ultracold Neutrons (UCN) in a magnetic trap, and, though statistically limited, measured a lifetime consistent with the world average. A major upgrade of the apparatus has now been completed at NIST. In our unique approach, a 0.89 nm neutron beam is incident on a superfluid ^4He target within the minimum field region of an Ioffe-type magnetic trap. Neutrons are downscattered by single phonon scattering in liquid helium to near rest and trapped; at sufficiently low temperatures, the low phonon density in the helium suppresses upscatter. The electron accompanying neutron decay produces scintillation in the superfluid helium and can be detected in real time. Previous statistical limitations as well as systematics related to neutron material bottling will be reduced by significant increases in field strength and trap volume. Details of analyses of the systematics as well as the initial performance benchmarks of the new apparatus will be presented.

  8. Radii and albedos of asteroids 1, 2, 3, 4, 6, 15, 51, 433, and 511

    NASA Technical Reports Server (NTRS)

    Cruikshank, D. P.; Morrison, D.

    1973-01-01

    The following radii (in kilometers) and visual geometric albedos are derived for nine asteroids from 10- and 20-micron radiometry: 1 Ceres (540, .06); 2 Pallas (275, .08); 3 Juno (125, .14); 4 Vesta (270, .21); 6 Hebe (110, .16); 15 Eunomia (135, .15); 51 Nemausa (80, .05); 433 Eros (12, .07); and 511 Davida (180, .04). Vesta has the highest albedo measured for an asteroid, while Davida, the lowest-albedo object in the sample, is one of the darkest known objects in the solar system. The median of all asteroid albedos measured to date is 0.1.-

  9. Surface features on Mars: Ground-based albedo and radar compared with Mariner 9 topography

    NASA Technical Reports Server (NTRS)

    Frey, H.

    1973-01-01

    Earth-based albedo maps of Mars were compared with Mariner 9 television data and ground-based radar profiles to investigate the nature of the bright and dark albedo features. Little correlation was found except at the boundaries of classical albedo features, where some topographic control is indicated. Wind-blown dust models for seasonal and secular albedo variations are supported, but it is not clear whether the fines are derived from bright or dark parent rock. Mars, like the Earth and Moon, has probably generated two distinct types of crustal material.

  10. Investigating the spread in surface albedo for snow-covered forests in CMIP5 models

    NASA Astrophysics Data System (ADS)

    Wang, Libo; Cole, Jason N. S.; Bartlett, Paul; Verseghy, Diana; Derksen, Chris; Brown, Ross; Salzen, Knut

    2016-02-01

    This study investigates the role of leaf/plant area index (LAI/PAI) specification on the large spread of winter albedo simulated by climate models. To examine the sensitivity of winter albedo to LAI, we perform a sensitivity analysis using two methods commonly used to compute albedo in snow-covered forests as well as diagnostic calculations within version 4.2 of the Canadian Atmospheric Model for which PAI is systematically varied. The results show that the simulated albedo is very sensitive to negative PAI biases, especially for smaller PAI values. The LAI and surface albedo of boreal forests in the presence of snow simulated by the Coupled Model Intercomparison Project Phase 5 (CMIP5) models are evaluated using satellite observations. The evaluation of CMIP5 models suggest that inaccurate tree cover fraction due to improper plant functional type specification or erroneous LAI parameterization in some models explains, in part, an observed positive bias in winter albedo over boreal forest regions of the Northern Hemisphere. This contributes to a large intermodel spread in simulated surface albedo in the presence of snow over these regions and is largely responsible for uncertainties in simulated snow-albedo feedback strength. Errors are largest (+20-40%) in models with large underestimation of LAI but are typically within ±15% when simulated LAI is within the observed range. This study underscores the importance of accurate representation of vegetation distribution and parameters in realistic simulation of surface albedo.

  11. Investigating the spread of surface albedo in snow covered forests in CMIP5 models

    NASA Astrophysics Data System (ADS)

    Wang, Libo; Cole, Jason; Bartlett, Paul; Verseghy, Diana; Derksen, Chris; Brown, Ross; von Salzen, Knut

    2016-04-01

    This study investigates the role of leaf/plant area index (LAI/PAI) specification on the large spread of winter albedo simulated by climate models. To examine the sensitivity of winter albedo to LAI, we perform a sensitivity analysis using two methods commonly used to compute albedo in snow-covered forests as well as diagnostic calculations within version 4.2 of the Canadian Atmospheric Model for which PAI is systematically varied. The results show that the simulated albedo is very sensitive to negative PAI biases, especially for smaller PAI values. The LAI and surface albedo of boreal forests in the presence of snow simulated by the Coupled Model Intercomparison Project Phase 5 (CMIP5) models are evaluated using satellite observations. The evaluation of CMIP5 models suggest that inaccurate tree cover fraction due to improper plant functional type specification or erroneous LAI parameterization in some models explains, in part, an observed positive bias in winter albedo over boreal forest regions of the Northern Hemisphere. This contributes to a large intermodel spread in simulated surface albedo in the presence of snow over these regions and is largely responsible for uncertainties in simulated snow-albedo feedback strength. Errors are largest (+20-40 %) in models with large underestimation of LAI but are typically within ±15% when simulated LAI is within the observed range. This study underscores the importance of accurate representation of vegetation distribution and parameters in realistic simulation of surface albedo.

  12. Vegetation controls on northern high latitude snow-albedo feedback: observations and CMIP5 model simulations.

    PubMed

    Loranty, Michael M; Berner, Logan T; Goetz, Scott J; Jin, Yufang; Randerson, James T

    2014-02-01

    The snow-masking effect of vegetation exerts strong control on albedo in northern high latitude ecosystems. Large-scale changes in the distribution and stature of vegetation in this region will thus have important feedbacks to climate. The snow-albedo feedback is controlled largely by the contrast between snow-covered and snow-free albedo (Δα), which influences predictions of future warming in coupled climate models, despite being poorly constrained at seasonal and century time scales. Here, we compare satellite observations and coupled climate model representations of albedo and tree cover for the boreal and Arctic region. Our analyses reveal consistent declines in albedo with increasing tree cover, occurring south of latitudinal tree line, that are poorly represented in coupled climate models. Observed relationships between albedo and tree cover differ substantially between snow-covered and snow-free periods, and among plant functional type. Tree cover in models varies widely but surprisingly does not correlate well with model albedo. Furthermore, our results demonstrate a relationship between tree cover and snow-albedo feedback that may be used to accurately constrain high latitude albedo feedbacks in coupled climate models under current and future vegetation distributions. PMID:24039000

  13. A comparative study of the effects of albedo change on drought in semi-arid regions

    NASA Technical Reports Server (NTRS)

    Charney, J.; Quirk, W. J.; Chow, S.-H.; Kornfield, J.

    1977-01-01

    Numerical simulation studies of the effects of changes in albedo on rainfall involve comparisons of semiarid areas, lying at the boundary between a major desert and an adjacent monsoonal region, with areas of the same size located within the monsoonal region itself. The sensitivity of the rainfall to the ground hydrology was determined by performing the albedo simulations with two different evapotranspiration parameterizations, one giving too high evaporation over land and the other giving negligible evaporation over land. The evaporation rate is, in general, found to have as important an effect as changes in albedo. The mechanism by which an increase of albedo reduces the rainfall during conditions of high evaporation is considered.

  14. Estimation of shortwave hemispherical reflectance (albedo) from bidirectionally reflected radiance data

    NASA Technical Reports Server (NTRS)

    Starks, Patrick J.; Norman, John M.; Blad, Blaine L.; Walter-Shea, Elizabeth A.; Walthall, Charles L.

    1991-01-01

    An equation for estimating albedo from bidirectional reflectance data is proposed. The estimates of albedo are found to be greater than values obtained with simultaneous pyranometer measurements. Particular attention is given to potential sources of systematic errors including extrapolation of bidirectional reflectance data out to a view zenith angle of 90 deg, the use of inappropriate weighting coefficients in the numerator of the albedo equation, surface shadowing caused by the A-frame instrumentation used to measure the incoming and outgoing radiation fluxes, errors in estimates of the denominator of the proposed albedo equation, and a 'hot spot' contribution in bidirectional data measured by a modular multiband radiometer.

  15. Natural versus anthropogenic factors affecting low-level cloud albedo over the North Atlantic

    NASA Technical Reports Server (NTRS)

    Falkowski, Paul G.; Kim, Yongseung; Kolber, Zbigniew; Wilson, Cara; Wirick, Creighton; Cess, Robert

    1992-01-01

    Cloud albedo plays a key role in regulating earth's climate. Cloud albedo depends on column-integrated liquid water content and the density of cloud condensation nuclei, which consists primarily of submicrometer-sized aerosol sulfate particles. A comparison of two independent satellite data sets suggests that, although anthropogenic sulfate emissions may enhance cloud albedo immediately adjacent to the east coast of the United States, over the central North Atlantic Ocean the variability in albedo can be largely accounted for by natural marine and atmospheric processes that probably have remained relatively constant since the beginning of the industrial revolution.

  16. The Effect of Aerosol Deposition on Snow Albedo Reduction in the Sierra Nevada Mountains

    NASA Astrophysics Data System (ADS)

    Lee, W.; Liou, K.

    2008-12-01

    We investigate snow cover and albedo changes in the Sierra Nevada regions due to deposition of black carbon and dust particles from East Asia. We note that coal combustion reaches maximum in the winter, while dust storms originate in the Gobi Desert occur most frequently in April. We selected snow and albedo data from MODIS/Terra to examine albedo reduction in March and April from 2000 to 2008. To eliminate the contamination of albedo by bare land, only the pixels with 100% snow cover in the entire period were used. Analysis using the 8-day average snow cover and 16-day average surface albedo reveals that there is a small increasing trend of albedo reduction. We also show that a large snow albedo reduction in 2001 is possibly due to the strong dust storm event that occurred in April, 2001. Finally, composite time series have been made using daily data to demonstrate decrease in snow albedo after each snowfall event. We illustrate that the rate of albedo reduction increases by 0.01/day per year from 2000 to 2008.

  17. Changes on albedo after a large forest fire in Mediterranean ecosystems

    NASA Astrophysics Data System (ADS)

    Quintano, Carmen; Fernández-Manso, Alfonso; Fernández-García, Victor; Marcos, Elena; Calvo, Leonor

    2015-09-01

    Fires are one of the main causes of environmental alteration in Mediterranean forest ecosystems. Albedo varies and evolves seasonally based on solar illumination. It is greatly influenced by changes on vegetation: vegetation growth, cutting/planting forests or forest fires. This work analyzes albedo variations due to a large forest fire that occurred on 19- 21 September 2012 in northwestern Spain. From this area, albedo post-fire images (immediately and 1-year after fire) were generated from Landsat 7 Enhanced Thematic Mapper (ETM+) data. Specifically we considered total shortwave albedo, total-, direct-, and diffuse-visible, and near-infrared albedo. Nine to twelve weeks after fire, 111 field plots were measured (27 unburned plots, 84 burned plots). The relationship between albedo values and thematic class (burned/unburned) was evaluated by one-way analysis of variance. Our results demonstrate that albedo changes were related to burned/unburned variable with statistical significance, indicating the importance of forestry areas as regulators of land surface energy fluxes and revealing the potential of post-fire albedo for assessing burned areas. Future research, however, is needed to evaluate the persistence of albedo changes.

  18. Natural Versus Anthropogenic Factors Affecting Low-Level Cloud Albedo over the North Atlantic.

    PubMed

    Falkowski, P G; Kim, Y; Kolber, Z; Wilson, C; Wirick, C; Cess, R

    1992-05-29

    Cloud albedo plays a key role in regulating Earth's climate. Cloud albedo depends on column-integrated liquid water content and the density of cloud condensation nuclei, which consists primarily of submicrometer-sized aerosol sulfate particles. A comparison of two independent satellite data sets suggests that, although anthropogenic sulfate emissions may enhance cloud albedo immediately adjacent to the east coast of the United States, over the central North Atlantic Ocean the variability in albedo can be largely accounted for by natural marine and atmospheric processes that probably have remained relatively constant since the beginning of the industrial revolution. PMID:17736762

  19. On the importance of interpolation schemes for albedo data from local to global grid

    NASA Astrophysics Data System (ADS)

    Preuschmann, Swantje; Jacob, Daniela; Löw, Alexander

    2013-04-01

    Surface albedo has a key role in Earth's radiation balance. As vegetation cover is influencing the albedo of solid surfaces, it is clear that land cover changes are leading to changes in the radiation balance and further are influencing the whole Earth's energy budget. It is obvious, that a forested area reflects sunlight differently compared to a sparsely vegetated area of shrubs. Different studies have shown, that certain land cover types (even compounds) have a characteristic annual cycle of the albedo (Moody et al. 2005 and Preuschmann, 2012). An annual cycle for one land cover type might vary in a year about 2%. The difference of the surface albedo of a forested area in summer to an agricultural area at the same time is only about 0.5%. A major question in climate modelling under future conditions is to analyse the impact of land cover changes onto climate. Nevertheless for different reasons it is not easy to describe surface albedo changes due to land cover changes within a climate model. One reason is that differences in the albedo of different surfaces are comparatively small. Another reason is based in the spatial resolution of a climate model. Climate models are operating on grids with horizontal resolutions of 10x10 km² for regional models up to about 200x200 km² for global models with a spectral resolution of T63. This means, that spatial (and also temporal) mean values of surface albedo are taken into account. Therefore one grid box of a climate model is representing a composition of different surface albedos. For model validation, it is of interest to compare the modelled albedo data with observed albedo data, but a comparison is not as trivial as it looks in the first sight. One problematic is the necessity of comparing different data types in the same horizontal and temporal resolution. Commonly used satellite based albedo data are available in 0.05° horizontal resolution, which is about 5 km at the equator, for several-day means and monthly

  20. Systematic approach to personnel neutron monitoring

    SciTech Connect

    Griffith, R.V.; Hankins, D.E.

    1980-01-01

    NTA film and albedo detectors represent the major portion of personnel dosimeters now used for occupational neutron monitoring. However, recent attention to the spectral response of these systems has demonstrated the need for detectors that have a better match to the fields being monitored. Recent developments in direct recoil track etch dosimeters present some intriguing alternatives, and careful use of /sup 237/Np fission fragment detectors offers the advantage of a good dose equivalent spectral match. Work continues on a number of other new detector mechanisms, but problems with sensitivity, energy response, gamma interference, etc., continue to prevent development of most mechanisms into viable personnel dosimeters. Current dosimeter limitations make a systematic approach to personnel neutron monitoring particularly important. Techniques have been developed and tested, using available portable survey instruments, that significantly improve the quality of dosimeter interpretation. Even simple spectrometry can be done with modest effort, significantly improving the health physicists ability to provide accurate neutron monitoring.

  1. Differential neutron energy spectra measured on spacecraft in low Earth orbit

    NASA Technical Reports Server (NTRS)

    Dudkin, V. E.; Akopova, A. B.; Melkumyan, L. V.; Benton, E. V.; Frank, A. L.

    1990-01-01

    Two methods for measuring neutrons in the range from thermal energies to dozens of MeV were used. In the first method, alpha-particles emitted from the 6Li(n,alpha)T reaction are detected with the help of plastic nuclear track detectors, yielding results on thermal and resonance neutrons. Also, fission foils are used to detect fast neutrons. In the second method, fast neutrons are recorded by nuclear photographic emulsions (NPE). The results of measurements on board various satellites are presented. The neutron flux density does not appear to correlate clearly with orbital parameters. Up to 50% of neutrons are due to albedo neutrons from the atmosphere while the fluxes inside the satellites are 15-20% higher than those on the outside. Estimates show that the neutron contribution to the total equivalent radiation dose reaches 20-30%.

  2. Instrument Development for Single-Particle Albedo Measurements

    NASA Astrophysics Data System (ADS)

    Sanford, T. J.; Murphy, D. M.; Fox, R. W.

    2008-12-01

    The ASTER (Aerosol Scattering To Extinction Ratio) instrument simultaneously measures scattering and extinction by single aerosol particles from which the albedo for each particle can be determined. ASTER employs a high-Q laser cavity to amplify loses in the cavity caused by individual particles to produce measurable extinction signals. The instrument collects light in three separate channels representing backward, forward, and wide-angle scattering. The ratio of forward to total scattering provides a proxy measurement for particle size that Mie scattering calculations show to be largely independent of particle refractive index for diameters below about 2 micrometers. Laboratory measurements on particles of known sizes and scattering properties have been used to assess the performance of the instrument and as a guide for ongoing modifications for eventual field deployment. Results from the current version of the instrument will be presented and compared to previous ASTER data to demonstrate improved performance. Data taken from ambient air have shown modes of highly absorbing particles that would not have been evident from bulk measurements. The single-particle nature of the measurements will provide additional information to complement existing methods for measuring aerosol albedos in the atmosphere.

  3. A cavity radiometer for Earth albedo measurement, phase 1

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Radiometric measurements of the directional albedo of the Earth requires a detector with a flat response from 0.2 to 50 microns, a response time of about 2 seconds, a sensitivity of the order of 0.02 mw/sq cm, and a measurement uncertainty of less than 5 percent. Absolute cavity radiometers easily meet the spectral response and accuracy requirements for Earth albedo measurements, but the radiometers available today lack the necessary sensitivity and response time. The specific innovations addressed were the development of a very low thermal mass cavity and printed/deposited thermocouple sensing elements which were incorporated into the radiometer design to produce a sensitive, fast response, absolute radiometer. The cavity is applicable to the measurement of the reflected and radiated fluxes from the Earth surface and lower atmosphere from low Earth orbit satellites. The effort consisted of requirements and thermal analysis; design, construction, and test of prototype elements of the black cavity and sensor elements to show proof-of-concept. The results obtained indicate that a black body cavity sensor that has inherently a flat response from 0.2 to 50 microns can be produced which has a sensitivity of at least 0.02 mw/sq cm per micro volt ouput and with a time constant of less than two seconds. Additional work is required to develop the required thermopile.

  4. Tackling regional climate change by leaf albedo bio-geoengineering.

    PubMed

    Ridgwell, Andy; Singarayer, Joy S; Hetherington, Alistair M; Valdes, Paul J

    2009-01-27

    The likelihood that continuing greenhouse-gas emissions will lead to an unmanageable degree of climate change has stimulated the search for planetary-scale technological solutions for reducing global warming ("geoengineering"), typically characterized by the necessity for costly new infrastructures and industries. We suggest that the existing global infrastructure associated with arable agriculture can help, given that crop plants exert an important influence over the climatic energy budget because of differences in their albedo (solar reflectivity) compared to soils and to natural vegetation. Specifically, we propose a "bio-geoengineering" approach to mitigate surface warming, in which crop varieties having specific leaf glossiness and/or canopy morphological traits are specifically chosen to maximize solar reflectivity. We quantify this by modifying the canopy albedo of vegetation in prescribed cropland areas in a global-climate model, and thereby estimate the near-term potential for bio-geoengineering to be a summertime cooling of more than 1 degrees C throughout much of central North America and midlatitude Eurasia, equivalent to seasonally offsetting approximately one-fifth of regional warming due to doubling of atmospheric CO(2). Ultimately, genetic modification of plant leaf waxes or canopy structure could achieve greater temperature reductions, although better characterization of existing intraspecies variability is needed first. PMID:19147356

  5. Soot climate forcing via snow and ice albedos

    PubMed Central

    Hansen, James; Nazarenko, Larissa

    2004-01-01

    Plausible estimates for the effect of soot on snow and ice albedos (1.5% in the Arctic and 3% in Northern Hemisphere land areas) yield a climate forcing of +0.3 W/m2 in the Northern Hemisphere. The “efficacy” of this forcing is ∼2, i.e., for a given forcing it is twice as effective as CO2 in altering global surface air temperature. This indirect soot forcing may have contributed to global warming of the past century, including the trend toward early springs in the Northern Hemisphere, thinning Arctic sea ice, and melting land ice and permafrost. If, as we suggest, melting ice and sea level rise define the level of dangerous anthropogenic interference with the climate system, then reducing soot emissions, thus restoring snow albedos to pristine high values, would have the double benefit of reducing global warming and raising the global temperature level at which dangerous anthropogenic interference occurs. However, soot contributions to climate change do not alter the conclusion that anthropogenic greenhouse gases have been the main cause of recent global warming and will be the predominant climate forcing in the future. PMID:14699053

  6. Evaluation of the EUMETSAT Meteosat Surface Albedo Climate Data Record

    NASA Astrophysics Data System (ADS)

    Lattanzio, Alessio; Schulz, Joerg; Roebeling, Rob; Fell, Frank; Bennartz, Ralf; Cahill, Brownwyn; Muller, Jan-Peter; Shane, Neville; Trigo, Isabel; Watson, Gill

    2013-04-01

    Understanding the climate system, with its variability and changes, requires a joint long-term international commitment from research and governmental institutions. The Global Climate Observing System (GCOS) formulated scientific requirements for the needed global observations and products including a list of relevant parameters, the so called Essential Climate Variables (ECVs). The Sustained and Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM) activity, is answering to these requirements by establishing an international network of facilities to ensure a continuous and sustained generation of high-quality Climate Data Records (CDR) from satellite data in compliance with the GCOS principles and guidelines. Currently, SCOPE-CM represents a partnership between operational space agencies to coordinate the generation of CDRs. Within the SCOPE-CM framework the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) has generated the Meteosat Surface Albedo (MSA) Climate Data Record that comprises up to 25 years (1982-2010) of continuous surface albedo coverage for large areas of the Earth. As part of the SCOPE-CM activity on land surface albedo, involving the operational meteorological satellite agencies in Europe (EUMETSAT), in Japan (JMA: Japanese Meteorological Agency) and in the USA (NOAA: National Oceanic and Atmospheric Administration), the MSA CDR contributes to the creation of a global harmonised surface albedo record derived from all satellites in geostationary orbit. This presentation discusses the results of an evaluation study for the MSA CDR that has been performed by independent researchers in Europe and the US. The MSA CDR has been evaluated in terms of its internal consistency, its compatibility to other satellite-derived surface albedo products, its validity against in-situ observations of superior quality, and its temporal homogeneity. The evaluation of the MSA data record has revealed a

  7. β -Decay Half-Lives of 110 Neutron-Rich Nuclei across the N=82 Shell Gap: Implications for the Mechanism and Universality of the Astrophysical r Process

    SciTech Connect

    Lorusso, G.; Nishimura, S.; Xu, Z. Y.; Jungclaus, A.; Shimizu, Y.; Simpson, G. S.; Söderström, P. -A.; Watanabe, H.; Browne, F.; Doornenbal, P.; Gey, G.; Jung, H. S.; Meyer, B.; Sumikama, T.; Taprogge, J.; Vajta, Zs.; Wu, J.; Baba, H.; Benzoni, G.; Chae, K. Y.; Crespi, F. C. L.; Fukuda, N.; Gernhäuser, R.; Inabe, N.; Isobe, T.; Kajino, T.; Kameda, D.; Kim, G. D.; Kim, Y. -K.; Kojouharov, I.; Kondev, F. G.; Kubo, T.; Kurz, N.; Kwon, Y. K.; Lane, G. J.; Li, Z.; Montaner-Pizá, A.; Moschner, K.; Naqvi, F.; Niikura, M.; Nishibata, H.; Odahara, A.; Orlandi, R.; Patel, Z.; Podolyák, Zs.; Sakurai, H.; Schaffner, H.; Schury, P.; Shibagaki, S.; Steiger, K.; Suzuki, H.; Takeda, H.; Wendt, A.; Yagi, A.; Yoshinaga, K.

    2015-05-01

    The β -decay half-lives of 110 neutron-rich isotopes of the elements from Rb 37 to Sn 50 were measured at the Radioactive Isotope Beam Factory. The 40 new half-lives follow robust systematics and highlight the persistence of shell effects. The new data have direct implications for r -process calculations and reinforce the notion that the second (A≈130 ) and the rare-earth-element (A≈160 ) abundance peaks may result from the freeze-out of an (n,γ)⇌(γ,n) equilibrium. In such an equilibrium, the new half-lives are important factors determining the abundance of rare-earth elements, and allow for a more reliable discussion of the r process universality. It is anticipated that universality may not extend to the elements Sn, Sb, I, and Cs, making the detection of these elements in metal-poor stars of the utmost importance to determine the exact conditions of individual r -process events.

  8. Spring-summer albedo variations of Antarctic sea ice from 1982 to 2009

    NASA Astrophysics Data System (ADS)

    Shao, Zhu-De; Ke, Chang-Qing

    2015-06-01

    This study examined the spring-summer (November, December, January and February) albedo averages and trends using a dataset consisting of 28 years of homogenized satellite data for the entire Antarctic sea ice region and for five longitudinal sectors around Antarctica: the Weddell Sea (WS), the Indian Ocean sector (IO), the Pacific Ocean sector (PO), the Ross Sea (RS) and the Bellingshausen-Amundsen Sea (BS). Time series data of the sea ice concentrations and sea surface temperatures were used to analyse their relations to the albedo. The results indicated that the sea ice albedo increased slightly during the study period, at a rate of 0.314% per decade, over the Antarctic sea ice region. The sea ice albedos in the PO, the IO and the WS increased at rates of 2.599% per decade (confidence level 99.86%), 0.824% per decade and 0.413% per decade, respectively, and the steepest increase occurred in the PO. However, the sea ice albedo in the BS decreased at a rate of -1.617% per decade (confidence level 95.05%) and was near zero in the RS. The spring-summer average albedo over the Antarctic sea ice region was 50.24%. The highest albedo values were mainly found on the continental coast and in the WS; in contrast, the lowest albedo values were found on the outer edge of the sea ice, the RS and the Amery Ice Shelf. The average albedo in the western Antarctic sea ice region was distinctly higher than that in the east. The albedo was significantly positively correlated with sea ice concentration (SIC) and was significantly negatively correlated with sea surface temperature (SST); these scenarios held true for all five longitudinal sectors. Spatially, the higher surface albedos follow the higher SICs and lower SST patterns. The increasing albedo means that Antarctic sea ice region reflects more solar radiation and absorbs less, leading to a decrease in temperature and much snowfall on sea ice, and further resulted in an increase in albedo. Conversely, the decreasing albedo

  9. Impacts of Satellite-Based Snow Albedo Assimilation on Offline and Coupled Land Surface Model Simulations.

    PubMed

    Wang, Tao; Peng, Shushi; Krinner, Gerhard; Ryder, James; Li, Yue; Dantec-Nédélec, Sarah; Ottlé, Catherine

    2015-01-01

    Seasonal snow cover in the Northern Hemisphere is the largest component of the terrestrial cryosphere and plays a major role in the climate system through strong positive feedbacks related to albedo. The snow-albedo feedback is invoked as an important cause for the polar amplification of ongoing and projected climate change, and its parameterization across models is an important source of uncertainty in climate simulations. Here, instead of developing a physical snow albedo scheme, we use a direct insertion approach to assimilate satellite-based surface albedo during the snow season (hereafter as snow albedo assimilation) into the land surface model ORCHIDEE (ORganizing Carbon and Hydrology In Dynamic EcosystEms) and assess the influences of such assimilation on offline and coupled simulations. Our results have shown that snow albedo assimilation in both ORCHIDEE and ORCHIDEE-LMDZ (a general circulation model of Laboratoire de Météorologie Dynamique) improve the simulation accuracy of mean seasonal (October throughout May) snow water equivalent over the region north of 40 degrees. The sensitivity of snow water equivalent to snow albedo assimilation is more pronounced in the coupled simulation than the offline simulation since the feedback of albedo on air temperature is allowed in ORCHIDEE-LMDZ. We have also shown that simulations of air temperature at 2 meters in ORCHIDEE-LMDZ due to snow albedo assimilation are significantly improved during the spring in particular over the eastern Siberia region. This is a result of the fact that high amounts of shortwave radiation during the spring can maximize its snow albedo feedback, which is also supported by the finding that the spatial sensitivity of temperature change to albedo change is much larger during the spring than during the autumn and winter. In addition, the radiative forcing at the top of the atmosphere induced by snow albedo assimilation during the spring is estimated to be -2.50 W m-2, the magnitude of

  10. Impacts of Satellite-Based Snow Albedo Assimilation on Offline and Coupled Land Surface Model Simulations

    PubMed Central

    Wang, Tao; Peng, Shushi; Krinner, Gerhard; Ryder, James; Li, Yue; Dantec-Nédélec, Sarah; Ottlé, Catherine

    2015-01-01

    Seasonal snow cover in the Northern Hemisphere is the largest component of the terrestrial cryosphere and plays a major role in the climate system through strong positive feedbacks related to albedo. The snow-albedo feedback is invoked as an important cause for the polar amplification of ongoing and projected climate change, and its parameterization across models is an important source of uncertainty in climate simulations. Here, instead of developing a physical snow albedo scheme, we use a direct insertion approach to assimilate satellite-based surface albedo during the snow season (hereafter as snow albedo assimilation) into the land surface model ORCHIDEE (ORganizing Carbon and Hydrology In Dynamic EcosystEms) and assess the influences of such assimilation on offline and coupled simulations. Our results have shown that snow albedo assimilation in both ORCHIDEE and ORCHIDEE-LMDZ (a general circulation model of Laboratoire de Météorologie Dynamique) improve the simulation accuracy of mean seasonal (October throughout May) snow water equivalent over the region north of 40 degrees. The sensitivity of snow water equivalent to snow albedo assimilation is more pronounced in the coupled simulation than the offline simulation since the feedback of albedo on air temperature is allowed in ORCHIDEE-LMDZ. We have also shown that simulations of air temperature at 2 meters in ORCHIDEE-LMDZ due to snow albedo assimilation are significantly improved during the spring in particular over the eastern Siberia region. This is a result of the fact that high amounts of shortwave radiation during the spring can maximize its snow albedo feedback, which is also supported by the finding that the spatial sensitivity of temperature change to albedo change is much larger during the spring than during the autumn and winter. In addition, the radiative forcing at the top of the atmosphere induced by snow albedo assimilation during the spring is estimated to be -2.50 W m-2, the magnitude of

  11. Implications of albedo changes following afforestation on the benefits of forests as carbon sinks

    NASA Astrophysics Data System (ADS)

    Kirschbaum, M. U. F.; Whitehead, D.; Dean, S. M.; Beets, P. N.; Shepherd, J. D.; Ausseil, A.-G. E.

    2011-12-01

    Increased carbon storage with afforestation leads to a decrease in atmospheric carbon dioxide concentration and thus decreases radiative forcing and cools the Earth. However, afforestation also changes the reflective properties of the surface vegetation from more reflective pasture to relatively less reflective forest cover. This increase in radiation absorption by the forest constitutes an increase in radiative forcing, with a warming effect. The net effect of decreased albedo and carbon storage on radiative forcing depends on the relative magnitude of these two opposing processes. We used data from an intensively studied site in New Zealand's Central North Island that has long-term, ground-based measurements of albedo over the full short-wave spectrum from a developing Pinus radiata forest. Data from this site were supplemented with satellite-derived albedo estimates from New Zealand pastures. The albedo of a well-established forest was measured as 13 % and pasture albedo as 20 %. We used these data to calculate the direct radiative forcing effect of changing albedo as the forest grew. We calculated the radiative forcing resulting from the removal of carbon from the atmosphere as a decrease in radiative forcing of -104 GJ tC-1 yr-1. We also showed that the observed change in albedo constituted a direct radiative forcing of 2759 GJ ha-1 yr-1. Thus, following afforestation, 26.5 tC ha-1 needs to be stored in a growing forest to balance the increase in radiative forcing resulting from the observed albedo change. Measurements of tree biomass and albedo were used to estimate the net change in radiative forcing as the newly planted forest grew. Albedo and carbon-storage effects were of similar magnitude for the first four to five years after tree planting, but as the stand grew older, the carbon storage effect increasingly dominated. Averaged over the whole length of the rotation, the changes in albedo negated the benefits from increased carbon storage by 17-24 %.

  12. Mineralogical Variations Among High Albedo E-Type Asteroids: Implications for Asteroid Igneous Processes

    NASA Technical Reports Server (NTRS)

    Gaffey, Michael J.; Kelley, Michael S.

    2004-01-01

    The link between the E-type asteroids and the enstatite achondrites (aubrites) was first proposed for the original E-asteroid, 44 Nysa. The association was based on the high albedos and the featureless spectra shared by the E-asteroids and the aubrites. Among the plausible geologic and meteoritic materials, only enstatite (the magnesium end-member of the pyroxene solid solution series) is sufficiently abundant to comprise asteroid-sized bodies. However, the presence of a weak 0.89 m absorption feature in the spectrum of 44 Nysa indicates that its pyroxene contains a small amount of Fe(2+) but still substantially more than any aubrite present in the meteorite collection. The original E-class was defined based on its high albedo and flat to slightly reddish spectrum. In the absence of albedo data, the E-type was degenerate with the M- and P-types, and together these were designated as X-types. Recently, a taxonomy has been proposed to identify E-types in the absence of albedo data. In this newer classification system three subdivisions of the X-type have been proposed, including Xc, Xe and Xk. Of nine albedo-defined E-types [d], this newer non-albedo based taxonomy produced the following classifications: X-1 asteroid; Xc-2 asteroids; Xe-5 asteroids; and Xk-1 asteroid. Although the Xe subtype includes the largest number of albedo-defined E-types, most of the remaining 24 Xe-types can be excluded based on their low measured IRAS albedos, ranging from 0.116 to 0.329, which are below the lower albedo limit of the E-class (0.34) and substantially below that of the lowest albedo an actual E-type asteroid (0.41). The present discussion will be limited to unambiguous E-type asteroids determined on albedo criteria.

  13. Bimodal albedo distributions in the ablation zone of the southwestern Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Moustafa, S. E.; Rennermalm, A. K.; Smith, L. C.; Miller, M. A.; Mioduszewski, J. R.

    2014-09-01

    Surface albedo is a key variable controlling solar radiation absorbed at the Greenland Ice Sheet (GrIS) surface, and thus, meltwater production. Recent decline in surface albedo over the GrIS has been linked to enhanced snow grain metamorphic rates and amplified ice-albedo feedback from atmospheric warming. However, the importance of distinct surface types on ablation zone albedo and meltwater production is still relatively unknown, and excluded in surface mass balance models. In this study, we analyze albedo and ablation rates using in situ and remotely-sensed data. Observations include: (1) a new high-quality in situ spectral albedo dataset collected with an Analytical Spectral Devices (ASD) spectroradiometer measuring at 325-1075 nm, along a 1.25 km transect during three days in June 2013; (2) broadband albedo at two automatic weather stations; and (3) daily MODerate Resolution Imaging Spectroradiometer (MODIS) albedo (MOD10A1) between 31 May and 30 August. We find that seasonal ablation zone albedos have a bimodal distribution, with two alternate states. This suggests that an abrupt switch from high to low albedo can be triggered by a modest melt event, resulting in amplified surface ablation rates. Our results show that such a shift corresponds to an observed melt rate percent difference increase of 51.6% during peak melt season (between 10-14 and 20-24 July 2013). Furthermore, our findings demonstrate that seasonal changes in GrIS ablation zone albedo are not exclusively a function of a darkening surface from ice crystal growth, but rather are controlled by changes in the fractional coverage of snow, bare ice, and impurity-rich surface types. As the climate continues to warm, regional climate models should consider the seasonal evolution of ice surface types in Greenland's ablation zone to improve projections of mass loss contributions to sea level rise.

  14. Bimodal Albedo Distributions in the Ablation Zone of the Southwestern Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Moustafa, S.; Rennermalm, A. K.; Smith, L. C.; Miller, M. A.; Mioduszewski, J.; Koenig, L.

    2014-12-01

    Surface albedo is a key variable controlling solar radiation absorbed at the Greenland Ice Sheet (GrIS) surface, and thus meltwater production. Recent decline in surface albedo over the GrIS has been linked to enhanced snow grain metamorphic rates and amplified ice-albedo feedback from atmospheric warming. However, the importance of distinct surface types on ablation zone albedo and meltwater production is still relatively unknown, and excluded in surface mass balance models. In this study, we analyze albedo and ablation rates (m d-1) using in situ and remotely-sensed data. Observations include: 1) a new high-quality in situ spectral albedo dataset collected with an Analytical Spectral Devices (ASD) spectroradiometer measuring at 325-1075 nm, along a 1.25 km transect during three days in June 2013; 2) broadband albedo at two automatic weather stations; and 3) daily MODerate Resolution Imaging Spectroradiometer (MODIS) albedo (MOD10A1) between 31 May and 30 August. We find that seasonal ablation zone albedos have a bimodal distribution, with two alternate states. This suggests that an abrupt switch from high to low albedo can be triggered by a modest melt event, resulting in amplified ablation rates. Our results show that such a shift corresponds to an observed melt rate percent difference increase of 51.6% during peak melt season (between 10-14 July and 20-24 July, 2013). Furthermore, our findings demonstrate that seasonal changes in GrIS ablation zone albedo are not exclusively a function of a darkening surface from ice crystal growth, but rather are controlled by changes in the fractional coverage of snow, bare ice, and impurity-rich surface types. As the climate continues to warm, regional climate models should consider the seasonal evolution of ice surface types in Greenland's ablation zone to improve projections of mass loss contributions to sea level rise.

  15. Effects of aerosol and horizontal inhomogeneity on the broadband albedo of marine stratus: Numerical simulations

    SciTech Connect

    Duda, D.P.; Stephens, G.L.; Stevens, B.; Cotton, W.R.

    1996-12-15

    Recent estimates of the effect of increasing of anthropogenic sulfate aerosol on the radiative forcing of the atmosphere have indicated that its impact may be comparable in magnitude to the effect from increases in CO{sub 2}. Much of this impact is expected from the effects of the aerosol on cloud microphysics and the subsequent impact on cloud albedo. A solar broadband version of a 2D radiative transfer model was used to quantify the impact of enhanced aerosol concentrations and horizontal inhomogeneity on the solar broadband albedo of marine stratus. The results of the radiative transfer calculations indicated that in unbroken marine stratus clouds the net horizontal transport of photons over a domain of a few kilometers was nearly zero, and the domain-average broadband albedo computed in a 2D cross section was nearly identical to the domain average calculated from a series of independent pixel approximation (IPA) calculations of the same cross section. However, the horizontal inhomogeneity does affect the cloud albedo compared to plane-parallel approximation (PPA) computations due to the nonlinear relationship between albedo and optical depth. The reduction in cloud albedo could be related to the variability of the distribution of log (cloud optical depth). These results extend the finding of Cahalan et al. to broadband solar albedos in a more realistic cloud model and suggest that accurate computation of domain-averaged broadband albedos in unbroken (or nearly unbroken) marine stratus can be made using IPA calculations with 1D radiative transfer models. Computations of the mean albedo over portions of the 3D RAMS domain show the relative increase in cloud albedo due to a 67% increase in the boundary-layer average CCN concentration was between 6% and 9%. The effects of cloud inhomogeneity on the broadband albedo as measured from the PPA bias ranged from 3% to 5%. 25 refs., 8 figs., 4 tabs.

  16. Physical basis for prompt-neutron activation analysis

    SciTech Connect

    Chrien, R.E.

    1982-01-01

    The technique called prompt ..gamma..-ray neutron activation analysis has been applied to rapid materials analysis. The radiation following the neutron radiation capture is prompt in the sense that the nuclear decay time is on the order of 10/sup -15/ second, and thus the technique is not strictly activation, but should be called radiation neutron capture spectroscopy or neutron capture ..gamma..-ray spectroscopy. This paper reviews the following: sources and detectors, theory of radiative capture, nonstatistical capture, giant dipole resonance, fast neutron capture, and thermal neutron capture ..gamma..-ray spectra. 14 figures.

  17. Neutron Spectra and Dose Equivalent Inside Nuclear Power Reactor Containment

    SciTech Connect

    Aldrich, J. M.

    1981-08-01

    This study was conducted to determine absorbed dose, dose-equivalent rates, and neutron spectra inside containment at nuclear power plants. We gratefully acknowledge funding support by the Nuclear Regulatory Commission. The purpose of this study is: 1) measure dose-equivalent rates with various commercial types of rem meters, such as the Snoopy and Rascal, and neutron absorbed dose rates with a tissue-equivalent proportional counter 2) determine neutron spectra using the multi sphere or Bonner sphere technique and a helium-3 spectrometer 3) compare several types of personnel neutron dosimeter responses such as NTA film, polycarbonates, TLD albedo, and a recently introduced proton recoil track etch dosimeter, and CR-39. These measurements were made inside containments of pressurized water reactors (PWRs) and outside containment penetrations of boiling water reactors (BWRs) operating at full power. The neutron spectral information, absorbed dose. and dose-equivalent measurements are needed for proper interpretation of instrument and personnel dosimeter responses.

  18. Atmospheric neutrons

    NASA Technical Reports Server (NTRS)

    Korff, S. A.; Mendell, R. B.; Merker, M.; Light, E. S.; Verschell, H. J.; Sandie, W. S.

    1979-01-01

    Contributions to fast neutron measurements in the atmosphere are outlined. The results of a calculation to determine the production, distribution and final disappearance of atmospheric neutrons over the entire spectrum are presented. An attempt is made to answer questions that relate to processes such as neutron escape from the atmosphere and C-14 production. In addition, since variations of secondary neutrons can be related to variations in the primary radiation, comment on the modulation of both radiation components is made.

  19. Neutron guide

    DOEpatents

    Greene, Geoffrey L.

    1999-01-01

    A neutron guide in which lengths of cylindrical glass tubing have rectangular glass plates properly dimensioned to allow insertion into the cylindrical glass tubing so that a sealed geometrically precise polygonal cross-section is formed in the cylindrical glass tubing. The neutron guide provides easier alignment between adjacent sections than do the neutron guides of the prior art.

  20. Neutron dosimetry

    DOEpatents

    Quinby, Thomas C.

    1976-07-27

    A method of measuring neutron radiation within a nuclear reactor is provided. A sintered oxide wire is disposed within the reactor and exposed to neutron radiation. The induced radioactivity is measured to provide an indication of the neutron energy and flux within the reactor.