Elastic proton-proton scattering at RHIC
Yip, K.
2011-09-03
Here we describe elastic proton+proton (p+p) scattering measurements at RHIC in p+p collisions with a special optics run of {beta}* {approx} 21 m at STAR, at the center-of-mass energy {radical}s = 200 GeV during the last week of the RHIC 2009 run. We present preliminary results of single and double spin asymmetries.
Relativistic analysis of proton elastic scattering
NASA Astrophysics Data System (ADS)
El Nohy, N. A.; El-Hammamy, M. N.; Yoseph, S. I.; Abdel-Moneim, A. M.
2015-04-01
The Dirac equation as the relevant wave equation, is used in modified DWUCK4 program to calculate the elastic scattering cross section throughout the energy range suitable for relativistic treatment of proton elastic scattering by nuclei 40Ca, 58Ni, 90Zr and 208Pb. A good fit to the experimental data is presented. The real and imaginary potentials are well determined and behave regularly with energy. The behaviour of the real central effective potential shows the development of a "wine-bottle" shape in the transition energy region and the persistence of a small attractive potential in the nuclear surface region, even at 800 MeV.
THE POLARIZATION PARAMETER IN ELASTIC PROTON-PROTON SCATTERING FROM .75 TO 2.84 GEV.
PROTON SCATTERING, POLARIZATION), (*NUCLEAR SPINS, POLARIZATION), PROTON REACTIONS, ELASTIC SCATTERING, MEASUREMENT, PARTICLE ACCELERATOR TARGETS, LIQUEFIED GASES, HELIUM, CARBON, ANTIPARTICLES , PROTON CROSS SECTIONS
Differential Cross Sections for Proton-Proton Elastic Scattering
NASA Technical Reports Server (NTRS)
Norman, Ryan B.; Dick, Frank; Norbury, John W.; Blattnig, Steve R.
2009-01-01
Proton-proton elastic scattering is investigated within the framework of the one pion exchange model in an attempt to model nucleon-nucleon interactions spanning the large range of energies important to cosmic ray shielding. A quantum field theoretic calculation is used to compute both differential and total cross sections. A scalar theory is then presented and compared to the one pion exchange model. The theoretical cross sections are compared to proton-proton scattering data to determine the validity of the models.
Electron- and positron-proton elastic scattering in CLAS
Weinstein, L. B.
2009-09-02
There is a significant disagreement between measurements of the proton electric form factor, G{sup p}{sub E}, using Rosenbluth separations and polarization transfer. This disagreement, if not explained, could pose a fundamental challenge to our understanding of electron scattering or proton structure. Two-photon exchange (TPE) processes, although not fully calculable, are the most likely explanation of this disagreement. We will definitively test this assertion by comparing the electron-proton and positron-proton elastic scattering cross section in the Jefferson Lab CLAS. We will make a mixed identical electron and positron tertiary beam by passing a 5.5 GeV primary electron beam through a radiator to make a photon beam and then passing the photon beam through a converter to make electron-positron pairs. Measuring the elastic cross sections simultaneously using identical lepton beams should significantly reduce systematic uncertainties.
Electron- and positron-proton elastic scattering in CLAS
L.B. Weinstein
2009-08-01
There is a significant disagreement between measurements of the proton electric form factor, G{sup p}{sub E}, using Rosenbluth separations and polarization transfer. This disagreement, if not explained, could pose a fundamental challenge to our understanding of electron scattering or proton structure. Two-photon exchange (TPE) processes, although not fully calculable, are the most likely explanation of this disagreement. We will definitively test this assertion by comparing the electron-proton and positron-proton elastic scattering cross section in the Jefferson Lab CLAS. We will make a mixed identical electron and positron tertiary beam by passing a 5.5 GeV primary electron beam through a radiator to make a photon beam and then passing the photon beam through a converter to make electron-positron pairs. Measuring the elastic cross sections simultaneously using identical lepton beams should significantly reduce systematic uncertainties.
Elastic Lambda-proton Scattering in CLAS
NASA Astrophysics Data System (ADS)
Price, John; CLAS Collaboration
2016-03-01
The Λ-proton reaction is important to our understanding of the structure of the proton and the nature of the strong nuclear force. Most previous measurements used bubble chambers with kaon beams to produce the Λ ``beam'', which then interacted with a second proton inside the chamber. The Λ can also be produced in the process γp -->K+ Λ , which has been studied at Jefferson Lab by the CLAS Collaboration. The long decay length of the Λ allows it to interact with a second proton in the target, leading to the process Λp --> Λp . The large acceptance of CLAS makes it a good choice for the study of this final state. A data-mining project was initiated with the CLAS g12 run, which used a tagged photon beam with 3.6
Low energy analyzing powers in pion-proton elastic scattering
NASA Astrophysics Data System (ADS)
Meier, R.; Cröni, M.; Bilger, R.; van den Brandt, B.; Breitschopf, J.; Clement, H.; Comfort, J. R.; Denz, H.; Erhardt, A.; Föhl, K.; Friedman, E.; Gräter, J.; Hautle, P.; Hofman, G. J.; Konter, J. A.; Mango, S.; Pätzold, J.; Pavan, M. M.; Wagner, G. J.; von Wrochem, F.
2004-05-01
Analyzing powers of pion-proton elastic scattering have been measured at PSI with the Low Energy Pion Spectrometer LEPS and a novel polarized scintillator target. Angular distributions between 40 and 120 deg (c.m.) were taken at 45.2, 51.2, 57.2, 68.5, 77.2, and 87.2 MeV incoming pion kinetic energy for π+p scattering, and at 67.3 and 87.2 MeV for π-p scattering. These new measurements constitute a substantial extension of the polarization data base at low energies. Predictions from phase shift analyses are compared with the experimental results, and deviations are observed at low energies.
The recoil proton polarization in. pi. p elastic scattering
Seftor, C.J.
1988-09-01
The polarization of the recoil proton for ..pi../sup +/p and ..pi../sup -/p elastic scattering has been measured for various angles at 547 MeV/c and 625 MeV/c by a collaboration involving The George Washington University; the University of California, Los Angeles; and Abilene Christian University. The experiment was performed at the P/sup 3/ East experimental area of the Los Alamos Meson Physics Facility. Beam intensities varied from 0.4 to 1.0 x 10/sup 7/ ..pi../sup -/'s/sec and from 3.0 to 10.0 x 10/sup 7/ ..pi../sup +/'s/sec. The beam spot size at the target was 1 cm in the horizontal direction by 2.5 cm in the vertical direction. A liquid-hydrogen target was used in a flask 5.7 cm in diameter and 10 cm high. The scattered pion and recoil proton were detected in coincidence using the Large Acceptance Spectrometer (LAS) to detect and momentum analyze the pions and the JANUS recoil proton polarimeter to detect and measure the polarization of the protons. Results from this experiment are compared with previous measurements of the polarization, with analyzing power data previously taken by this group, and to partial-wave analysis predictions. 12 refs., 53 figs., 18 tabs.
Parity Violation in Forward Angle Elastic Electron-Proton Scattering
Miller, IV, Grady Wilson
2001-01-01
We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton at Jefferson Laboratory. The kinematic point (θ_{lab} = 12.3 deg. and (Q^{2}) = 0.48 (GeV/c)^{2}) is chosen to provide sensitivity to the strange electric form factor G^{s}_{E}. A 3.36 GeV beam of longitudinally polarized electrons was scattered from protons in a liquid hydrogen target. The scattered flux was detected by a pair of spectrometers which focussed the elastically-scattered electrons onto total-absorption detectors. The detector signals were integrated and digitized by a custom data acquisition system. A feedback system reduced systematic errors by controlling helicity-correlated beam intensity differences at the sub-ppm (part per million) level. The experimental result, A = 14.5 +/- 2.0 (stat) ± 1.1 (syst) ppm, is consistent with the electroweak Standard Model with no additional contributions from strange quarks. In particular, the measurement implies G^{S}_{E} + 0.39 G^{s}_{M} = 0.023 ± 0.040 ± 0.026 (ζG^{n}_{E}), where the last uncertainty is due to the estimated uncertainty in the neutron electric form factor G^{n}_{E} . This result represents the first experimental constraint of the strange electric form factor.
Elastic proton-deuteron scattering at intermediate energies
NASA Astrophysics Data System (ADS)
Ramazani-Moghaddam-Arani, A.; Amir-Ahmadi, H. R.; Bacher, A. D.; Bailey, C. D.; Biegun, A.; Eslami-Kalantari, M.; Gašparić, I.; Joulaeizadeh, L.; Kalantar-Nayestanaki, N.; Kistryn, St.; Kozela, A.; Mardanpour, H.; Messchendorp, J. G.; Micherdzinska, A. M.; Moeini, H.; Shende, S. V.; Stephan, E.; Stephenson, E. J.; Sworst, R.
2008-07-01
Observables in elastic proton-deuteron scattering are sensitive probes of the nucleon-nucleon interaction and three-nucleon force effects. The present experimental database for this reaction is large, but contains a large discrepancy between data sets for the differential cross section taken at 135 MeV/nucleon by two experimental research groups. This article reviews the background of this problem and presents new data taken at Kernfysisch Versneller Instituute (KVI). Differential cross sections and analyzing powers for the 2H(p→,d)p and 1H(d→,d)p reactions at 135 MeV/nucleon and 65 MeV/nucleon, respectively, have been measured. The differential cross-section data differ significantly from previous measurements and consistently follow the energy dependence as expected from an interpolation of published data taken over a large range at intermediate energies.
PROTON-4He Elastic Scattering at ~ 1 GeV
NASA Astrophysics Data System (ADS)
Khan, Z. A.; Singh, Minita
Based on the (spin-independent) Sugar-Blanckenbecler eikonal expansion for the T-matrix, we parametrize the (spin-dependent) NN amplitude (SNN) which successfully describes the pp and pn elastic scattering observables at ~ 1 GeV up to the available momentum transfers. Using SNN, we calculate the differential cross-section, polarization, and spin-rotation function of ~ 1 GeV protons on 4He within the framework of the Glauber model. The analysis also includes the phase variation in the NN amplitude. It is found that the use of SNN, in comparision with the usually parametrized one-term amplitude, improves the agreement with the experimental data. The introduction of a global phase variation provides only a slight improvement over the results with a constant phase. However, if we allow different phases in the central- and spin-dependent parts of the NN amplitude, the agreement with the polarization data improves further without affecting the differential cross-section results.
Small angle elastic scattering of protons off of spinless nuclei
Ling, A.G.
1988-07-01
Elastic differential cross sections and analyzing powers for 800 MeV protons incident on /sup 12/C, /sup 40/Ca, and /sup 208/Pb in the momentum transfer range 20 MeV/c < q < 130 MeV/c have been measured. The data was taken with the High Resolution Spectrometer (HRS) at the Los Alamos Meson Physics Facility. Special delay-line drift chambers with dead regions for the beam to pass through them were used to obtain the data. Through the interference of the Coulomb and nuclear contributions to the differential cross section in the small angle region, the ratio of the real to imaginary part of the forward nuclear amplitude ..cap alpha../sub n/(0) = Ref/sub n/(0)/Imf/sub n/(0) is extracted. The importance of knowing this quantity at lower energies in order to study the differences between relativistic and non-relativistic scattering theories is discussed. 130 refs., 60 figs., 12 tabs.
Proton form factors and two-photon exchange in elastic electron-proton scattering
Nikolenko, D. M.; Arrington, J.; Barkov, L. M.; Vries, H. de; Gauzshtein, V. V.; Golovin, R. A.; Gramolin, A. V.; Dmitriev, V. F.; Zhilich, V. N.; Zevakov, S. A.; Kaminsky, V. V.; Lazarenko, B. A.; Mishnev, S. I.; Muchnoi, N. Yu.; Neufeld, V. V.; Rachek, I. A.; Sadykov, R. Sh.; Stibunov, V. N.; Toporkov, D. K.; Holt, R. J.; and others
2015-05-15
Proton electromagnetic form factors are among the most important sources of information about the internal structure of the proton. Two different methods for measuring these form factors, the method proposed by Rosenbluth and the polarization-transfer method, yield contradictory results. It is assumed that this contradiction can be removed upon taking into account the hard part of the contribution of two-photon exchange to the cross section for elastic electron-proton scattering. This contribution can measured experimentally via a precision comparison of the cross sections for the elastic scattering of positrons and electrons on protons. Such a measurement, performed at the VEPP-3 storage ring in Novosibirsk at the beam energies of 1.6 and 1.0 GeV for positron (electron) scattering angles in the ranges of θ{sub e} = 15°–25° and 55°–75° in the first case and in the range of θ{sub e} = 65°–105° in the second case is described in the present article. Preliminary results of this experiment and their comparison with theoretical predictions are described.
E710, Proton, Antiproton Elastic Scattering at Tevatron Energies
NASA Astrophysics Data System (ADS)
Sadr, Sasan
Experiment E710, located at site E0 of the Tevatron collider at Fermilab, was conceived in order to measure pp elastic scattering. The measured parameters were: the total cross section sigma_{t }, the ratio of the real to the imaginary part of the forward scattering amplitude rho, the nuclear slope parameter B, the nuclear curvature parameter C, the total elastic cross section sigma _{el}, and the single diffractive cross section sigma_{sd} . These measurements were taken at center-of-mass energies of sqrt{s}=1.02 and 1.8 TeV.
Measuring the Weak Charge of the Proton via Elastic Electron-Proton Scattering
Jones, Donald C.
2015-10-01
The Qweak experiment which ran in Hall C at Jefferson Lab in Newport News, VA, and completed data taking in May 2012, measured the weak charge of the proton Q^{p}_{W} via elastic electron-proton scattering. Longitudinally polarized electrons were scattered from an unpolarized liquid hydrogen target. The helicity of the electron beam was flipped at approximately 1 kHz between left and right spin states. The Standard Model predicts a small parity-violating asymmetry of scattering rates between right and left helicity states due to the weak interaction. An initial result using 4% of the data was published in October 2013 [1] with a measured parity-violating asymmetry of -279 ± 35(stat) ± 31 (syst) ppb. This asymmetry, along with other data from parity-violating electron scattering experiments, provided the world's first determination of the weak charge of the proton. The weak charge of the proton was found to be ^{p}_{W} = 0.064 ± 0.012, in good agreement with the Standard Model prediction of ^{p}_{W}(SM) = 0.0708 ± 0.0003[2].
Two-photon exchange correction to muon-proton elastic scattering at low momentum transfer
NASA Astrophysics Data System (ADS)
Tomalak, Oleksandr; Vanderhaeghen, Marc
2016-03-01
We evaluate the two-photon exchange (TPE) correction to the muon-proton elastic scattering at small momentum transfer. Besides the elastic (nucleon) intermediate state contribution, which is calculated exactly, we account for the inelastic intermediate states by expressing the TPE process approximately through the forward doubly virtual Compton scattering. The input in our evaluation is given by the unpolarized proton structure functions and by one subtraction function. For the latter, we provide an explicit evaluation based on a Regge fit of high-energy proton structure function data. It is found that, for the kinematics of the forthcoming muon-proton elastic scattering data of the MUSE experiment, the elastic TPE contribution dominates, and the size of the inelastic TPE contributions is within the anticipated error of the forthcoming data.
Spin observables in neutron-proton elastic scattering
Ahmidouch, A.; Arnold, J.; van den Brandt, B.; Daum, M.; Demierre, P.; Drevenak, R.; Finger, M. |; Finger, M. Jr.; Franz, J.; Goujon, N.; Hautle, P.; Janout, Z. Jr.; Hajdas, W.; Heer, E.; Hess, R.; Koger, R.; Konter, J.A.; Lacker, H.; Lechanoine-LeLuc, C.; Lehar, F.; Mango, S.; Mascarini, C.; Rapin, D.; Roessle, E.; Schmelzbach, P.A.; Schmitt, H.; Sereni, P.; Slunecka, M.
1995-07-15
We describe here two experiments presently running at PSI using the NA2 polarized neutron beam. They are devoted to the measurement of 2- and 3-spin observables in {ital np} elastic scattering for kinetic energies from 230 to 590 MeV with a center of mass angular range from 60 to 180 degrees. The goal is to determine the five {ital NN} scattering amplitudes for isospin 0 in a model independent way. Preliminary results for {ital K}{sub {ital OSKO}} and {ital K}{sub {ital OSSO}} spin-transfers are presented.
A coherent analysis of elastic electron-proton scattering data
NASA Astrophysics Data System (ADS)
Bernauer, Jan
2016-09-01
The extraction of form factors and radii from scattering data is a treacherous business, and it is easy to bias the result with the choice of an unsuitable fit function. In the first part of the talk, I will present our analysis of the Mainz and world data sets, and the checks we have made to ensure that the results are accurate and unbiased. Recently, several authors have reanalyzed the Mainz and world data sets on electron-proton scattering, with the aim to extract the proton charge radius. The results fall into two groups: radii around 0.88 fm and around 0.84 fm, respectively. We find that the latter group typically is affected by various problems, discussed in the second part of the talk.
Contribution of σ meson exchange to elastic lepton-proton scattering
NASA Astrophysics Data System (ADS)
Koshchii, Oleksandr; Afanasev, Andrei
2016-12-01
Lepton mass effects play a decisive role in the description of elastic lepton-proton scattering when the beam's energy is comparable to the mass of the lepton. The future Muon Scattering Experiment (MUSE) experiment, which is devised to solve the "Proton Radius Puzzle," is going to cover the corresponding kinematic region for a scattering of muons by a proton target. We anticipate that helicity-flip meson exchanges will make a difference in the comparison of elastic electron-proton vs muon-proton scattering in MUSE. In this article, we estimate the σ meson exchange contribution in the t channel. This contribution, mediated by two-photon coupling of σ , is calculated to be at most ˜0.1 % for muons in the kinematics of MUSE, and it appears to be about 3 orders of magnitude larger than for electrons because of the lepton-mass difference.
Two-photon exchange corrections in elastic lepton-proton scattering at small momentum transfer
NASA Astrophysics Data System (ADS)
Tomalak, Oleksandr; Vanderhaeghen, Marc
2016-03-01
In recent years, elastic electron-proton scattering experiments, with and without polarized protons, gave strikingly different results for the electric over magnetic proton form factor ratio. A mysterious discrepancy (``the proton radius puzzle'') has been observed in the measurement of the proton charge radius in muon spectroscopy experiments versus electron spectroscopy and electron scattering. Two-photon exchange (TPE) contributions are the largest source of the hadronic uncertainty in these experiments. We compare the existing models of the elastic contribution to TPE correction in lepton-proton scattering. A subtracted dispersion relation formalism for the TPE in electron-proton scattering has been developed and tested. Its relative effect on cross section is in the 1 - 2 % range for a low value of the momentum transfer. An alternative dispersive evaluation of the TPE correction to the hydrogen hyperfine splitting was found and applied. For the inelastic TPE contribution, the low momentum transfer expansion was studied. In addition with the elastic TPE it describes the experimental TPE fit to electron data quite well. For a forthcoming muon-proton scattering experiment (MUSE) the resulting TPE was found to be in the 0 . 5 - 1 % range, which is the planned accuracy goal.
A measurement of two-photon exchange in unpolarized elastic electron-proton scattering
NASA Astrophysics Data System (ADS)
Yurov, Mikhail
2016-03-01
Jefferson Lab experiment E05-017 was designed to study 2-photon exchange contributions to elastic electron-proton scattering over a wide kinematic range. By detecting the scattered proton instead of the electron these measurements will be very sensitive to the ɛ dependence of the cross section and consequently the ratio GE/GM. The goals of the experiment, the experimental technique and the kinematic range will be presented. The analysis sequence and results of the early steps will be outlined.
NASA Astrophysics Data System (ADS)
Tomalak, O.; Vanderhaeghen, M.
2016-01-01
We evaluate the two-photon exchange (TPE) correction to the unpolarized elastic electron-proton scattering at small momentum transfer Q2 . We account for the inelastic intermediate states approximating the double virtual Compton scattering by the unpolarized forward virtual Compton scattering. The unpolarized proton structure functions are used as input for the numerical evaluation of the inelastic contribution. Our calculation reproduces the leading terms in the Q2 expansion of the TPE correction and goes beyond this approximation by keeping the full Q2 dependence of the proton structure functions. In the range of small momentum transfer, our result is in good agreement with the empirical TPE fit to existing data.
Single-spin asymmetries from two-photon exchange in elastic electron proton scattering
A.V. Afanasev; N.P. Merenkov
2005-02-01
The parity-conserving single-spin beam asymmetry of elastic electron-proton scattering is induced by an absorptive part of the two-photon exchange amplitude. We demonstrate that this asymmetry has logarithmic and double-logarithmic enhancement due to contributions of hard collinear quasi-real photons. An optical theorem is used to evaluate the asymmetry in terms of the total photoproduction cross section on the proton.
a Technique to Calibrate Neutron-Proton Elastic Scattering Spin Observables Near 183 Mev
NASA Astrophysics Data System (ADS)
Bowyer, Theodore William
Free neutron-proton scattering is one of the most fundamental reactions we can study in the field of nuclear physics, yet the n-p scattering data base is quite sparse. The data that does exist is often plagued by systematic uncertainties associated with the determination of beam and/or target polarizations. In contrast, there is an abundance of high quality, high statistics p-p elastic scattering data. We report on a technique which we have developed which exploits the high quality of the p-p data to calibrate n-p elastic scattering spin observables by simultaneous measurement of vec n-vec p and p-vec p elastic scattering by bombarding a polarized proton target with a mixed beam of polarized neutrons and protons. This technique has allowed us to calibrate the n-p elastic spin observables at 183 MeV: the beam and target analyzing powers A _{n}(theta_{p}),A _{p}(theta p), and the spin correlation coefficient, C_{NN}( theta_{p}). The mixed secondary beam was produced by bombarding a liquid deuterium target with a 200 MeV beam of polarized protons. The experiment was preformed in the Polarized Neutron Facility at the Indiana University Cyclotron Facility utilizing a left-right symmetric detection system, sensitive to both scattered protons and neutrons, and spanned the laboratory angular range of 24^circ to 62^circ. We identified free scattering events through a number of kinematic correlations. We compare our results to various phase shift calculations and potential models and examine the sensitivity of magnitude of various phase shifts results to the inclusion of our data into the n-p data base.
Elastic scattering of polarized protons on deuterium at 800 MeV
Weston, G.S.
1984-07-01
A specific set of spin transfer coefficients has been measured for proton-deuteron elastic scattering at 800 MeV using an unpolarized liquid deuterium target. The experiment was done using the High Resolution Spectrometer (HRS) at the Los Alamos Meson Physics Facility (LAMPF) with a polarized proton beam. The scattered proton spin direction was determined using the Focal Plane Polarimeter (FPP) of the HRS, which employs a carbon analyzer. Some of the spin dependent parameters measured in this experiment are of considerable interest because they provide selective information about the nucleon-nucleon (NN) amplitude. Since the deuteron is the simplest bound nucleus, pd elastic scattering is particularly well suited for testing multiple scattering theories. These measurements will also be used to eventually determine the full pd collision matrix, which contains all possible information about the scattering process. In addition, the experimental setup is described for a polarized proton-polarized deuterium target spin transfer experiment also done at the HRS at 800 MeV incident proton energy. 71 references.
Transverse Beam Spin Asymmetries in Forward-Angle Elastic Electron-Proton Scattering
Armstrong, D. S.; Averett, T.; Bailey, S. L.; Finn, J. M.; Griffioen, K. A.; Moffit, B.; Phillips, S. K.; Secrest, J.; Sulkosky, V.; Arvieux, J.; Bimbot, L.; Guler, H.; Lenoble, J.; Marchand, D.; Morlet, M.; Ong, S.; Van de Wiele, J.
2007-08-31
We have measured the beam-normal single-spin asymmetry in elastic scattering of transversely polarized 3 GeV electrons from unpolarized protons at Q{sup 2}=0.15, 0.25 (GeV/c){sup 2}. The results are inconsistent with calculations solely using the elastic nucleon intermediate state and generally agree with calculations with significant inelastic hadronic intermediate state contributions. A{sub n} provides a direct probe of the imaginary component of the 2{gamma} exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments.
A recoil detector for the measurement of antiproton-proton elastic scattering at angles close to 90°
NASA Astrophysics Data System (ADS)
Hu, Q.; Bechstedt, U.; Gillitzer, A.; Grzonka, D.; Khoukaz, A.; Klehr, F.; Lehrach, A.; Prasuhn, D.; Ritman, J.; Sefzick, T.; Stockmanns, T.; Täschner, A.; Wuestner, P.; Xu, H.
2014-10-01
The design and construction of a recoil detector for the measurement of recoil protons of antiproton-proton elastic scattering at scattering angles close to are described. The performance of the recoil detector has been tested in the laboratory with radioactive sources and at COSY with proton beams by measuring proton-proton elastic scattering. The results of laboratory tests and commissioning with beam are presented. Excellent energy resolution and proper working performance of the recoil detector validate the conceptual design of the KOALA experiment at HESR to provide the cross section data needed to achieve a precise luminosity determination at the PANDA experiment.
A predictive theory for elastic scattering and recoil of protons from 4He
Hupin, Guillaume; Quaglioni, Sofia; Navratil, Petr
2014-12-08
Low-energy cross sections for elastic scattering and recoil of protons from 4He nuclei (also known as α particles) are calculated directly by solving the Schrodinger equation for five nucleons interacting through accurate two- and three-nucleon forces derived within the framework of chiral effective field theory. Precise knowledge of these processes at various proton backscattering/recoil angles and energies is needed for the ion-beam analysis of numerous materials, from the surface layers of solids, to thin films, to fusion-reactor materials. Indeed, the same elastic scattering process, in two different kinematic configurations, can be used to probe the concentrations and depth profiles ofmore » either hydrogen or helium. Furthermore, we compare our results to available experimental data and show that direct calculations with modern nuclear potentials can help to resolve remaining inconsistencies among data sets and can be used to predict these cross sections when measurements are not available.« less
A predictive theory for elastic scattering and recoil of protons from ^{4}He
Hupin, Guillaume; Quaglioni, Sofia; Navratil, Petr
2014-12-08
Low-energy cross sections for elastic scattering and recoil of protons from ^{4}He nuclei (also known as α particles) are calculated directly by solving the Schrodinger equation for five nucleons interacting through accurate two- and three-nucleon forces derived within the framework of chiral effective field theory. Precise knowledge of these processes at various proton backscattering/recoil angles and energies is needed for the ion-beam analysis of numerous materials, from the surface layers of solids, to thin films, to fusion-reactor materials. Indeed, the same elastic scattering process, in two different kinematic configurations, can be used to probe the concentrations and depth profiles of either hydrogen or helium. Furthermore, we compare our results to available experimental data and show that direct calculations with modern nuclear potentials can help to resolve remaining inconsistencies among data sets and can be used to predict these cross sections when measurements are not available.
Two-Photon Exchange in Elastic Electron-Proton Scattering: A QCD Factorization Approach
Kivel, Nikolai; Vanderhaeghen, Marc
2009-08-28
We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer Q{sup 2}. It is shown that the leading two-photon exchange amplitude behaves as 1/Q{sup 4}, and can be expressed in a model independent way in terms of the leading twist nucleon distribution amplitudes. Using several models for the nucleon distribution amplitudes, we provide estimates for existing data and for ongoing experiments.
Elastic proton scattering on tritium below the n-{sup 3}He threshold
Lazauskas, Rimantas
2009-05-15
Elastic proton scattering on the {sup 3}H nucleus is studied between p-{sup 3}H and n-{sup 3}He thresholds, in the energy region where the first excited state of the {alpha} particle is embedded in the continuum. Faddeev-Yakubovski equations are solved in configuration space by fully considering effects from isospin breaking and rigorously treating the Coulomb interaction. Different realistic nuclear Hamiltonians are tested, elucidating open problems in the description of the nuclear interaction.
Large Logarithms in the Beam Normal Spin Asymmetry of Elastic Electron--Proton Scattering
Andrei Afanasev; Mykola Merenkov
2004-06-01
We study a parity-conserving single-spin beam asymmetry of elastic electron-proton scattering induced by an absorptive part of the two-photon exchange amplitude. It is demonstrated that excitation of inelastic hadronic intermediate states by the consecutive exchange of two photons leads to logarithmic and double-logarithmic enhancement due to contributions of hard collinear quasi-real photons. The asymmetry at small electron scattering angles is expressed in terms of the total photoproduction cross section on the proton, and is predicted to reach the magnitude of 20-30 parts per million. At these conditions and fixed 4-momentum transfers, the asymmetry is rising logarithmically with increasing electron beam energy, following the high-energy diffractive behavior of total photoproduction cross section on the proton.
Henderson, B S; Ice, L D; Khaneft, D; O'Connor, C; Russell, R; Schmidt, A; Bernauer, J C; Kohl, M; Akopov, N; Alarcon, R; Ates, O; Avetisyan, A; Beck, R; Belostotski, S; Bessuille, J; Brinker, F; Calarco, J R; Carassiti, V; Cisbani, E; Ciullo, G; Contalbrigo, M; De Leo, R; Diefenbach, J; Donnelly, T W; Dow, K; Elbakian, G; Eversheim, P D; Frullani, S; Funke, Ch; Gavrilov, G; Gläser, B; Görrissen, N; Hasell, D K; Hauschildt, J; Hoffmeister, Ph; Holler, Y; Ihloff, E; Izotov, A; Kaiser, R; Karyan, G; Kelsey, J; Kiselev, A; Klassen, P; Krivshich, A; Lehmann, I; Lenisa, P; Lenz, D; Lumsden, S; Ma, Y; Maas, F; Marukyan, H; Miklukho, O; Milner, R G; Movsisyan, A; Murray, M; Naryshkin, Y; Perez Benito, R; Perrino, R; Redwine, R P; Rodríguez Piñeiro, D; Rosner, G; Schneekloth, U; Seitz, B; Statera, M; Thiel, A; Vardanyan, H; Veretennikov, D; Vidal, C; Winnebeck, A; Yeganov, V
2017-03-03
The OLYMPUS Collaboration reports on a precision measurement of the positron-proton to electron-proton elastic cross section ratio, R_{2γ}, a direct measure of the contribution of hard two-photon exchange to the elastic cross section. In the OLYMPUS measurement, 2.01 GeV electron and positron beams were directed through a hydrogen gas target internal to the DORIS storage ring at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight scintillators detected elastically scattered leptons in coincidence with recoiling protons over a scattering angle range of ≈20° to 80°. The relative luminosity between the two beam species was monitored using tracking telescopes of interleaved gas electron multiplier and multiwire proportional chamber detectors at 12°, as well as symmetric Møller or Bhabha calorimeters at 1.29°. A total integrated luminosity of 4.5 fb^{-1} was collected. In the extraction of R_{2γ}, radiative effects were taken into account using a Monte Carlo generator to simulate the convolutions of internal bremsstrahlung with experiment-specific conditions such as detector acceptance and reconstruction efficiency. The resulting values of R_{2γ}, presented here for a wide range of virtual photon polarization 0.456<ε<0.978, are smaller than some hadronic two-photon exchange calculations predict, but are in reasonable agreement with a subtracted dispersion model and a phenomenological fit to the form factor data.
NASA Astrophysics Data System (ADS)
Henderson, B. S.; Ice, L. D.; Khaneft, D.; O'Connor, C.; Russell, R.; Schmidt, A.; Bernauer, J. C.; Kohl, M.; Akopov, N.; Alarcon, R.; Ates, O.; Avetisyan, A.; Beck, R.; Belostotski, S.; Bessuille, J.; Brinker, F.; Calarco, J. R.; Carassiti, V.; Cisbani, E.; Ciullo, G.; Contalbrigo, M.; de Leo, R.; Diefenbach, J.; Donnelly, T. W.; Dow, K.; Elbakian, G.; Eversheim, P. D.; Frullani, S.; Funke, Ch.; Gavrilov, G.; Gläser, B.; Görrissen, N.; Hasell, D. K.; Hauschildt, J.; Hoffmeister, Ph.; Holler, Y.; Ihloff, E.; Izotov, A.; Kaiser, R.; Karyan, G.; Kelsey, J.; Kiselev, A.; Klassen, P.; Krivshich, A.; Lehmann, I.; Lenisa, P.; Lenz, D.; Lumsden, S.; Ma, Y.; Maas, F.; Marukyan, H.; Miklukho, O.; Milner, R. G.; Movsisyan, A.; Murray, M.; Naryshkin, Y.; Perez Benito, R.; Perrino, R.; Redwine, R. P.; Rodríguez Piñeiro, D.; Rosner, G.; Schneekloth, U.; Seitz, B.; Statera, M.; Thiel, A.; Vardanyan, H.; Veretennikov, D.; Vidal, C.; Winnebeck, A.; Yeganov, V.; Olympus Collaboration
2017-03-01
The OLYMPUS Collaboration reports on a precision measurement of the positron-proton to electron-proton elastic cross section ratio, R2 γ , a direct measure of the contribution of hard two-photon exchange to the elastic cross section. In the OLYMPUS measurement, 2.01 GeV electron and positron beams were directed through a hydrogen gas target internal to the DORIS storage ring at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight scintillators detected elastically scattered leptons in coincidence with recoiling protons over a scattering angle range of ≈20 ° to 80°. The relative luminosity between the two beam species was monitored using tracking telescopes of interleaved gas electron multiplier and multiwire proportional chamber detectors at 12°, as well as symmetric Møller or Bhabha calorimeters at 1.29°. A total integrated luminosity of 4.5 fb-1 was collected. In the extraction of R2 γ, radiative effects were taken into account using a Monte Carlo generator to simulate the convolutions of internal bremsstrahlung with experiment-specific conditions such as detector acceptance and reconstruction efficiency. The resulting values of R2 γ, presented here for a wide range of virtual photon polarization 0.456 <ɛ <0.978 , are smaller than some hadronic two-photon exchange calculations predict, but are in reasonable agreement with a subtracted dispersion model and a phenomenological fit to the form factor data.
Elastic Proton Scattering of Medium Mass Nuclei from Coupled-Cluster Theory
Hagen, G.; MichelN.,
2012-01-01
Using coupled-cluster theory and interactions from chiral effective field theory, we compute overlap functions for transfer and scattering of low-energy protons on the target nucleus 40Ca. Effects of three-nucleon forces are included phenomenologically as in-medium two-nucleon interactions. Using known asymptotic forms for one-nucleon overlap functions we derive a simple and intuitive way of computing scattering observables such as elastic scattering phase shifts and cross sections. As a first application and proof of principle, we compute phase shifts and differential interaction cross sections at energies of 9.6 and 12.44 MeV and compare with experimental data. Our computed diffraction minima are in fair agreement with experimental results, while we tend to overestimate the cross sections at large scattering angles.
Transverse Beam Spin Asymmetries in Forward-Angle Elastic Electron-Proton Scattering
David Armstrong; Francois Arvieux; Razmik Asaturyan; Todd Averett; Stephanie Bailey; Guillaume Batigne; Douglas Beck; Elizabeth Beise; Jay Benesch; Louis Bimbot; James Birchall; Angela Biselli; Peter Bosted; Elodie Boukobza; Herbert Breuer; Roger Carlini; Robert Carr; Nicholas Chant; Yu-Chiu Chao; Swapan Chattopadhyay; Russell Clark; Silviu Covrig; Anthony Cowley; Daniel Dale; Charles Davis; Willie Falk; John Finn; Tony Forest; Gregg Franklin; Christophe Furget; David Gaskell; Joseph Grames; Keith Griffioen; Klaus Grimm; Benoit Guillon; Hayko Guler; Lars Hannelius; Richard HASTY; Alice Hawthorne Allen; Tanja Horn; Kathleen Johnston; Mark Jones; Peter Kammel; Reza Kazimi; Paul King; Ameya Kolarkar; Elie Korkmaz; Wolfgang Korsch; Serge Kox; Joachim Kuhn; Jeff Lachniet; Lawrence Lee; Jason Lenoble; Eric Liatard; Jianglai Liu; Berenice Loupias; Allison Lung; Dominique Marchand; Jeffery Martin; Kenneth McFarlane; David McKee; Robert McKeown; Fernand Merchez; Hamlet Mkrtchyan; Bryan Moffit; M. Morlet; Itaru Nakagawa; Kazutaka Nakahara; Retief Neveling; Silvia Niccolai; S. Ong; Shelley Page; Vassilios Papavassiliou; Stephen Pate; Sarah Phillips; Mark Pitt; Benard Poelker; Tracy Porcelli; Gilles Quemener; Brian Quinn; William Ramsay; Aamer Rauf; Jean-Sebastien Real; Julie Roche; Philip Roos; Gary Rutledge; Jeffery Secrest; Neven Simicevic; Gregory Smith; Damon Spayde; Samuel Stepanyan; Marcy Stutzman; Vince Sulkosky; Vincent Sulkosky; Vince Sulkosky; Vincent Sulkosky; Vardan Tadevosyan; Raphael Tieulent; Jacques Van de Wiele; Willem van Oers; Eric Voutier; William Vulcan; Glen Warren; Steven Wells; Steven Williamson; Stephen Wood; Chen Yan; Junho Yun; Valdis Zeps
2007-08-01
We have measured the beam-normal single-spin asymmetry in elastic scattering of transversely-polarized 3 GeV electrons from unpolarized protons at Q^2 values of 0.15 and 0.25 (GeV/c)^2 with results of A_n = -4.06 +- 0.99(stat) +- 0.63(syst) and A_n = -4.82 +- 1.87(stat) +- 0.98(syst) ppm. These results are inconsistent with calculations solely using the elastic nucleon intermediate state, and generally agree with calculations with significant inelastic hadronic intermediate state contributions. A_n provides a direct probe of the imaginary component of the two-photon exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments.
Svirida, D.
2011-07-15
Elastic scattering of polarized protons at small four momentum transfer squared t is described by interference of Coulomb and nuclear amplitudes. Coulomb amplitude is well calculable by QED and such interference provides a unique opportunity to study the nuclear amplitude. At high energies this amplitude is believed to be dominated by Pomeron exchange. Measurement of asymmetries can provide evidence for contribution of other Reggeons, including hypothetical Odderon. Polarized proton collider at RHIC facility is a perfect place for such experiment.A one-week dedicated run with special beam optics in June 2009 allowed us to collect statistics of more than 30 millions of elastic triggers with transversely polarized beams in the -t range 0.005-0.035 (GeV/c){sup 2} at {radical}(s) = 200 GeV. In this paper we present preliminary results of single and double transverse spin asymmetries.
Fast proton hopping detection in ice I{sub h} by quasi-elastic neutron scattering.
Presiado, I.; Lal, J.; Mamontov, E.; Kolesnikov, A. I.; Huppert, D.
2011-01-01
Quasi-elastic neutron scattering was employed on samples of HCl-doped polycrystalline ice I{sub h}. The analysis of the scattering signal provides the excess proton hopping time, {tau}{sub hop}, in the temperature range of 140-195 K. The hopping time strongly depends on the temperature of the sample, and the activation energy of a hopping step is 17 kJ/mol. The values of {tau}{sub hop} of the current experiment are in good agreement with calculated values derived from previous photochemical experiments, in which we found that the proton hopping time at T > 242 K is on the order of 200 fs, roughly 10 times shorter than in liquid water at room temperature.
Fast Proton Hopping Detection in Ice Ih by Quasi-Elastic Neutron Scattering
Presiado, Itay; Lal, Jyotsana; Mamontov, Eugene; Kolesnikov, Alexander I; Huppert, Dan I
2011-01-01
Quasi-elastic neutron scattering was employed on samples of HCl-doped polycrystalline ice I{sub h}. The analysis of the scattering signal provides the excess proton hopping time, {tau}{sub hop}, in the temperature range of 140-195 K. The hopping time strongly depends on the temperature of the sample, and the activation energy of a hopping step is 17 kJ/mol. The values of {tau}{sub hop} of the current experiment are in good agreement with calculated values derived from previous photochemical experiments,(1) in which we found that the proton hopping time at T > 242 K is on the order of 200 fs, roughly 10 times shorter than in liquid water at room temperature.
Relativistic impulse approximation analysis of elastic proton scattering from He isotopes
NASA Astrophysics Data System (ADS)
Kaki, Kaori
2014-01-01
Recent relativistic mean field (RMF) calculations have provided nuclear distributions of some isotopes whose mass numbers are much larger than atomic numbers. For helium isotopes, the RMF calculation seems to be inappropriate because of the small mass numbers; however, applicable results are obtained for 6,8He nuclei. The author calculates observables of proton elastic scattering from the helium isotopes and discusses relations between observables and nuclear distributions of the isotopes by comparison of the calculated results with experimental data. The calculations are based on relativistic impulse approximation (RIA) at incident proton energy: 71 MeV for 4,6,8He, 300 and 500 MeV for 4He, and 0.7 GeV for 6He. Scattering observables are predicted for 6,8He at 200 MeV.
Y. C. Chen; A. Afanasev; S. J. Brodsky; C. E. Carlson; Marc Vanderhaeghen
2004-03-01
We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer through the scattering off a parton in the proton. We relate the process on the nucleon to the generalized parton distributions which also enter in other wide angle scattering processes. We find that when taking the polarization transfer determinations of the form factors as input, adding in the 2 photon correction, does reproduce the Rosenbluth data.
Elastic scattering of polarized protons on helium three at 800 MeV
Azizi, A.
1985-07-01
A set of spin dependent parameters and cross sections has been measured for polarized p-/sup 3/He elastic scattering over the range of q .7 to 4.2 fm/sup -1/. The experiment was done at the Los Alamos Meson Physics Facility (LAMPF) using the High Resolution Spectrometer (HRS) with a polarized proton beam at .8 GeV. The focal plane polarimeter of the HRS was used to determine the spin direction of the scattered proton. Since /sup 3/He is one of the simplest nuclei, polarized p-/sup 3/He scattering provides a very sensitive test of multiple scattering theories. The theoretical analysis was done by using two different wave functions for /sup 3/He as input to the multiple scattering theory. The theoretical calculations and experimental data together will give us useful information about nucleon-nucleon amplitudes and also help us to obtain a better understanding of the scattering process. 68 refs., 55 figs., 9 tabs.
Lepton mass effects in elastic lepton-proton scattering beyond the leading order of QED
NASA Astrophysics Data System (ADS)
Koshchii, Oleksandr; Afanasev, Andrei
2017-01-01
The future MUSE experiment is devised to solve the ``Proton Radius Puzzle'' by considering simultaneously elastic e+/- p and μ+/- p scattering. This experiment requires a per cent level accuracy in comparison of electron-proton and muon-proton scattering. Our goal is to provide all the relevant radiative corrections calculations for MUSE without using ultrarelativistic (ml -> 0) approximation. This approximation is not applicable for the scattering of muons in kinematics of MUSE. In this talk, we will present our up-to-date results on radiative corrections calculations obtained by using a Monte Carlo generator ELRADGEN modified to treat the lepton mass effects with no ultra-relativistic approximation. Next, we will discuss our estimations of the important helicity-flip contribution represented by a scalar σ meson exchange in the t-channel. This term vanishes in the ultra-relativistic and/or one-photon exchange approximation, and makes a difference in comparison of electron vs muon scattering in MUSE. This work was supported by the NSF under Grants Nos. PHY-1404342, PHY-1309130 and by The George Washington University through the Gus Weiss endowment.
Quark structure of the nucleon and angular asymmetry of proton-neutron hard elastic scattering.
Granados, Carlos G; Sargsian, Misak M
2009-11-20
We investigate an asymmetry in the angular distribution of hard elastic proton-neutron scattering with respect to the 90 degrees center of mass scattering angle and demonstrate that it's magnitude is related to the helicity-isospin symmetry of the quark wave function of the nucleon. Our estimate of the asymmetry within the quark-interchange model of hard scattering demonstrates that the quark wave function of a nucleon based on the exact SU(6) symmetry predicts an angular asymmetry opposite to that of experimental observations. We found that the quark wave function based on the diquark picture of the nucleon produces a correct asymmetry. Comparison with the data allowed us to show that the vector diquarks contribute around 10% in the nucleon wave function and they are in negative phase relative to the scalar diquarks. These observations are essential in constraining QCD models of a nucleon.
Phenomenological optical potential analysis of proton-carbon elastic scattering at 200 MeV
NASA Technical Reports Server (NTRS)
Bidasaria, H. B.; Townsend, L. W.
1982-01-01
Differential cross sections for 200 MeV protons elastically scattered from C-12 were analyzed utilizing a local, complex, spin-dependent optical potential with a harmonic well radial dependence. Analyses were performed using the WKB and eikonal approximations. For the latter, first-order corrections to he phase shifts were incorporated to account for the spin-orbit contribution. Large disagreement between theory and experiment was observed when the usual Thomas form for the spin-orbit potential was utilized. Substantial improvement was obtained by allowing the parameters in the central and spin-orbit potential terms to vary independently.
NASA Astrophysics Data System (ADS)
Alkhazov, G. D.; Vorobyov, A. A.; Dobrovolsky, A. V.; Inglessi, A. G.; Korolev, G. A.; Khanzadeev, A. V.
2015-05-01
In order to study the spatial structure of exotic nuclei, it was proposed at the Petersburg Nuclear Physics Institute (PNPI) to measure the differential cross section for small-angle proton elastic scattering in inverse kinematics. Several experiments in beams of 0.7-GeV/nucleon exotic nuclei were performed at the heavy-ion accelerator facility of GSI (Gesellschaft für Schwerionenforschung, Darmstadt, Germany) by using the IKAR ionization spectrometer developed at PNPI. The IKAR ionization chamber filled with hydrogen at a pressure of 10 bar served simultaneously as a target and as a recoil-proton detector, which measured the recoil-proton energy. The beam-particle scattering angle was also measured. The results obtained for the cross sections in question were analyzed on the basis of the Glauber-Sitenko theory using phenomenological nuclear-density distributions with two free parameters. Nuclear-matter distributions and root-mean-square radii were found for the nuclei under investigation. The size of the halo in the 6He, 8He, 11Li, and 14Be nuclei was determined among other things. Information about neutron distributions in nuclei was deduced by combining the data obtained here with the known values of the radii of proton distributions. A sizable neutron skin was revealed in the 8Li, 9Li, and 12Be nuclei.
Alkhazov, G. D.; Vorobyov, A. A.; Dobrovolsky, A. V. Inglessi, A. G.; Korolev, G. A.; Khanzadeev, A. V.
2015-05-15
In order to study the spatial structure of exotic nuclei, it was proposed at the Petersburg Nuclear Physics Institute (PNPI) to measure the differential cross section for small-angle proton elastic scattering in inverse kinematics. Several experiments in beams of 0.7-GeV/nucleon exotic nuclei were performed at the heavy-ion accelerator facility of GSI (Gesellschaft für Schwerionenforschung, Darmstadt, Germany) by using the IKAR ionization spectrometer developed at PNPI. The IKAR ionization chamber filled with hydrogen at a pressure of 10 bar served simultaneously as a target and as a recoil-proton detector, which measured the recoil-proton energy. The beam-particle scattering angle was also measured. The results obtained for the cross sections in question were analyzed on the basis of the Glauber-Sitenko theory using phenomenological nuclear-density distributions with two free parameters. Nuclear-matter distributions and root-mean-square radii were found for the nuclei under investigation. The size of the halo in the {sup 6}He, {sup 8}He, {sup 11}Li, and {sup 14}Be nuclei was determined among other things. Information about neutron distributions in nuclei was deduced by combining the data obtained here with the known values of the radii of proton distributions. A sizable neutron skin was revealed in the {sup 8}Li, {sup 9}Li, and {sup 12}Be nuclei.
NASA Astrophysics Data System (ADS)
Ramazani-Moghaddam-Arani, A.; Amir-Ahmadi, H. R.; Bacher, A. D.; Bailey, C. D.; Biegun, A.; Eslami-Kalantari, M.; Gašparić, I.; Joulaeizadeh, L.; Kalantar-Nayestanaki, N.; Kistryn, St.; Kozela, A.; Mardanpour, H.; Messchendorp, J. G.; Micherdzinska, A. M.; Moeini, H.; Shende, S. V.; Stephan, E.; Stephenson, E. J.; Sworst, R.
2011-05-01
This paper discusses some of the recent results obtained in a deuteron-deuteron scattering experiment using a polarized beam of deuterons with an incident energy of 130 MeV. A 4π detection system allowed to measure cross sections and spin observables for various final-state configurations. Here, we discuss the quasi-free elastic deuteron-proton scattering process in deuteron-deuteron scattering which has been observed by analyzing kinematical configurations for which the target neutron acts as a spectator particle. This part of the data can be compared directly to three-nucleon calculations and with existing data for the elastic deuteron-proton scattering process. The results for the polarization observables iT11 and T22 agree well with elastic scattering data published so-far and measured concurrently using a proton target. Surprisingly, the tensor observable T20 shows significant discrepancies with data taken using a proton target.
Polarization observables in the elastic scattering of protons from {sup 4,6,8}He
Crespo, R.; Moro, A. M.
2007-11-15
We have calculated the p-{sup 4,6,8}He elastic scattering differential cross section and polarizations at 297 MeV using the Multiple Scattering expansion of the Optical potential (MSO) reaction scattering framework. The role of the core and valence neutrons contribution to the interaction in the description of the elastic scattering observables is analyzed.
Two-photon exchange contribution to elastic electron-proton scattering
NASA Astrophysics Data System (ADS)
Yurov, Mikhail
2015-04-01
Two experimental techniques, Rosenbluth separation and recoil polarization transfer, used to extract proton's electromagnetic form factors ratio GE/GM yield markedly different results. Modern theoretical calculations suggest that two-photon exchange might be responsible for the observed discrepancy and that it is epsilon dependent. Jefferson Lab Experiment E05-017 was designed to measure the two-photon exchange contribution over a wide range of ɛ and Q2. In contrast with the conventional Rosenbluth method, E05-017 detected the elastically scattered proton rather than the electron. This approach returns a much more precise extraction of the form factor ratios. After a brief description of the experimental goals and techniques, the current status of the analysis will be presented.
Mchedlishvili, D.; Chiladze, D.; Dymov, S.; ...
2016-02-03
The differential cross section for proton-proton elastic scattering has been measured at a beam kinetic energy of 1.0 GeV and in 200 MeV steps from 1.6 to 2.8 GeV for centre-of-mass angles in the range from 12°-16° to 25°-30°, depending on the energy. A precision in the overall normalisation of typically 3% was achieved by studying the energy losses of the circulating beam of the COSY storage ring as it passed repeatedly through the windowless hydrogen target of the ANKE magnetic spectrometer. It is shown that the data have a significant impact upon the results of a partial wave analysis.more » Furthermore, after extrapolating the differential cross sections to the forward direction, the results are broadly compatible with the predictions of forward dispersion relations.« less
Mchedlishvili, D.; Chiladze, D.; Dymov, S.; Bagdasarian, Z.; Barsov, S.; Gebel, R.; Gou, B.; Hartmann, M.; Kacharava, A.; Keshelashvili, I.; Khoukaz, A.; Kulessa, P.; Kulikov, A.; Lehrach, A.; Lomidze, N.; Lorentz, B.; Maier, R.; Macharashvili, G.; Merzliakov, S.; Mikirtychyants, S.; Nioradze, M.; Ohm, H.; Prasuhn, D.; Rathmann, F.; Serdyuk, V.; Schroer, D.; Shmakova, V.; Stassen, R.; Stein, H. J.; Stockhorst, H.; Strakovsky, I. I.; Stroher, H.; Tabidze, M.; Taschner, A.; Trusov, S.; Tsirkov, D.; Uzikov, Yu.; Valdau, Yu.; Wilkin, C.; Workman, R. L.; Wustner, P.
2016-02-03
The differential cross section for proton-proton elastic scattering has been measured at a beam kinetic energy of 1.0 GeV and in 200 MeV steps from 1.6 to 2.8 GeV for centre-of-mass angles in the range from 12°-16° to 25°-30°, depending on the energy. A precision in the overall normalisation of typically 3% was achieved by studying the energy losses of the circulating beam of the COSY storage ring as it passed repeatedly through the windowless hydrogen target of the ANKE magnetic spectrometer. It is shown that the data have a significant impact upon the results of a partial wave analysis. Furthermore, after extrapolating the differential cross sections to the forward direction, the results are broadly compatible with the predictions of forward dispersion relations.
Proton-Nucleus Elastic Cross Sections Using Two-Body In-Medium Scattering Amplitudes
NASA Technical Reports Server (NTRS)
Tripathi, R. K.; Wilson, John W.; Cucinotta, Francis A.
2001-01-01
Recently, a method was developed of extracting nucleon-nucleon (NN) cross sections in the medium directly from experiment. The in-medium NN cross sections form the basic ingredients of several heavy-ion scattering approaches including the coupled-channel approach developed at the Langley Research Center. The ratio of the real to the imaginary part of the two-body scattering amplitude in the medium was investigated. These ratios are used in combination with the in-medium NN cross sections to calculate elastic proton-nucleus cross sections. The agreement is excellent with the available experimental data. These cross sections are needed for the radiation risk assessment of space missions.
Elastic scattering of 1-GeV protons and the distribution of matter in 1p-shell nuclei
Alkhazov, G.D.; Belostotskii, S.L.; Vorob'ev, A.A.; Domchenkov, O.A.; Dotsenko, Y.V.; Kuropatkin, N.P.; Nikulin, V.N.
1985-07-01
We report measurements of the differential cross sections for elastic scattering of 1-GeV protons by the nuclei /sup 9/Be, /sup 11/B, /sup 12/C, /sup 13/C, /sup 14/N, and /sup 16/O. In scattering by /sup 9/Be and /sup 11/B a strong effect of quadrupole filling of the diffraction minima was observed. The cross sections are analyzed in the framework of the Glauber-Sitenko theory and information is obtained on the parameters of both the spherical and nonspherical components of the density. Data on scattering of protons by /sup 6/Li nuclei are also analyzed.
Contribution of Δ(1232) to real photon radiative corrections for elastic electron-proton scattering
NASA Astrophysics Data System (ADS)
Gerasimov, R. E.; Fadin, V. S.
2016-12-01
Here we consider the contribution of the Δ(1232) resonance to the real photon radiative corrections for elastic ep-scattering. The effect is found to be small for past experiments studying the unpolarized cross section, as well as for the recent VEPP-3 experiment investigating two-photon exchange effects by the precision measurement of the {e}+/- p-scattering cross section ratio.
Two-photon exchange corrections in elastic lepton-proton scattering
NASA Astrophysics Data System (ADS)
Tomalak, Oleksandr; Vanderhaeghen, Marc
2016-09-01
In recent years, two experimental approaches, with and without polarized protons, gave strikingly different results for the ratio of the electric to magnetic proton form factors. Even more recently, a mysterious discrepancy (``the proton radius puzzle'') has been observed in the extraction of the proton charge radius from the muonic hydrogen versus regular hydrogen and electron-proton scattering. Two-photon exchange (TPE) contributions are the largest source of the hadronic uncertainty in these experiments. To determine TPE corrections to the S level in muonic hydrogen, the forward virtual Compton scattering is calculated within dispersion relation (DR) formalism. Comparing a box graph model with the DRs at fixed low momentum transfer, we develop and test the subtracted DR formalism for TPE in electron-proton scattering. Its relative effect on the cross section is in the 1 - 2 % range. We include the inelastic states both in the approximation of the near-forward unpolarized virtual Compton scattering as well as using the empirical information on the πN states contribution. We compare the resulting TPE with MAMI, VEPP-3 and CLAS data, and make predictions for the OLYMPUS and the forthcoming MUSE experiments.
Elastic Scattering of Neutron-Rich Helium Isotopes from Polarized Protons at 71 MeV/A
NASA Astrophysics Data System (ADS)
Sakaguchi, S.; Uesaka, T.; Kawabata, T.; Wakui, T.; Aoi, N.; Hashimoto, Y.; Ichikawa, Y.; Itoh, K.; Itoh, M.; Iwasaki, H.; Kawahara, T.; Kondo, Y.; Kuboki, H.; Maeda, Y.; Nakamura, T.; Nakao, T.; Nakayama, Y.; Okamura, H.; Sakai, H.; Sasamoto, Y.; Sasano, M.; Satou, Y.; Sekiguchi, K.; Shimamura, T.; Shimizu, Y.; Shinohara, M.; Suda, K.; Suzuki, D.; Takahashi, Y.; Tamii, A.; Yako, K.; Yamaguchi, M.
2011-09-01
The vector analyzing power has been measured for the elastic scattering of neutron-rich 6He and 8He from polarized protons at 71 MeV/A making use of a newly constructed solid polarized proton target operated in a low magnetic field of 0.1 T and at a relatively high temperature of 100 K. An optical model analysis revealed that the spin-orbit potentials for 6He and 8He are characterized by shallow and long-ranged shape compared with the global systematics of stable nuclei. Such a characteristics reflect a diffused density distribution of the neutron-rich isotopes.
The Intermediate Energy Elastic Scattering of Protons by α-CLUSTER 20Ne and 24Mg Nuclei
NASA Astrophysics Data System (ADS)
Berezhnoy, Yu. A.; Mikhailyuk, V. P.; Pilipenko, V. V.
The multiple diffraction scattering theory and the α-cluster model with dispersion have been applied for calculations of the observables for the elastic scattering of intermediate energy protons by 20Ne and 24Mg nuclei. The target nuclei are considered as composed of the core (16O nucleus) and additional α-clusters (one α-cluster for 20Ne nucleus and a dumb-bell α-cluster configuration for 24Mg nucleus). Taking into account the α-cluster configuration of the core, it was supposed that the additional α-cluster or center of mass of the dumb-bell are arranged with the most probability inside or outside of the core. The calculated observables for the elastic p-20Ne and p-24Mg scattering are in agreement with the existing experimental data. The influence of the deformed core contribution on the behavior of the calculated observables also is tested.
NASA Astrophysics Data System (ADS)
Chen, Hong-Yu; Zhou, Hai-Qing
2014-10-01
A new form of two-photon exchange (TPE) effect is studied to explain the discrepancy between unpolarized and polarized experimental data in elastic ep scattering. The mechanism is based on a simple idea that apart from the usual TPE effects from box and crossed-box diagrams, the mesons may also be exchanged in elastic ep scattering by two-photon coupling at loop level. The detailed study shows such contributions to reduced unpolarized cross section (σun) and polarized observables (Pt,Pl) at fixed Q2 are only dependent on proton's electromagnetic form factors GE ,M and a new unknown universal parameter g. After combining this contribution with the usual TPE contributions from box and crossed-box diagrams, the ratio μpGE/GM extracted from the recent precise unpolarized and polarized experimental data can be described consistently.
NASA Astrophysics Data System (ADS)
Spasova, K.; Lukyanov, V. K.; Kadrev, D. N.; Antonov, A. N.; Zemlyanaya, E. V.; Lukyanov, K. V.; Gaidarov, M. K.
2014-09-01
Theoretical analysis of the elastic scattering and breakup in interactions of the 11Li nucleus with protons are presented. The hybrid model of the microscopic optical potential (OP) is applied. The OP includes the single-folding real part, while its imaginary part is derived within the high-energy approximation (HEA) theory. The spin-orbit contribution to the OP is also included. The differential cross sections of 11Li+p elastic scattering and the total reaction cross sections are calculated at energies of 62, 68.4, and 75 MeV/nucleon and are compared with the available experimental data. The breakup cross sections at 62 MeV/nucleon and the momentum distributions of the fragments using a two cluster model of the 11 Li nucleus are obtained. An analysis of the single-particle density of 11Li is performed.
Proton-proton elastic scattering analyzing power in the 2.16 to 2.28 GeV energy region.
Arvieux, J.; Ball, J.; Bystricky, J.; Fontaine, J. M.; Gaillard, G.; Goudour, J. P.; Hess, R.; Kunne, R.; Lehar, F.; de Lesquen, A.; Lopiano, D.; de Mali, M.; Perrot-Kunne, F.; Rapin, D.; van Rossum, L.; Sans, J. L.; Spinka, H. M.; High Energy Physics; Lab. National Saturne; CEA; Univ. of Geneva; CENB; Lab. National Saturne; Univ. of Geneva
1997-11-01
The angular dependence of the pp elastic scattering analyzing power was measured at SATURNE II with an unpolarized proton beam and the Saclay polarized proton target. The energy region in the vicinity of the accelerator depolarizing resonance G g = 6 at Tkin = 2.202 GeV was studied. Measurements were carried out at seven energies between 2.16 and 2.28 GeV from 17 to 55 CM. No significant anomaly was observed in the angular and energy dependence of the results presented, whereas the existing data sets differ in this energy range.
Zhou Haiqing; Kao Chungwen; Yang Shinnan
2007-12-31
Leading electroweak corrections play an important role in precision measurements of the strange form factors. We calculate the two-photon-exchange (TPE) and {gamma}Z-exchange corrections to the parity-violating asymmetry of the elastic electron-proton scattering in a simple hadronic model including the finite size of the proton. We find both can reach a few percent and are comparable in size with the current experimental measurements of strange-quark effects in the proton neutral weak current. The effect of {gamma}Z exchange is in general larger than that of TPE, especially at low momentum transfer Q{sup 2}{<=}1 GeV{sup 2}. Their combined effects on the values of G{sub E}{sup s}+G{sub M}{sup s} extracted in recent experiments can be as large as -40% in certain kinematics.
Li, Z. P.; Hillhouse, G. C.; Meng, J.
2008-07-15
We present the first study to examine the validity of the relativistic impulse approximation (RIA) for describing elastic proton-nucleus scattering at incident laboratory kinetic energies lower than 200 MeV. For simplicity we choose a {sup 208}Pb target, which is a spin-saturated spherical nucleus for which reliable nuclear structure models exist. Microscopic scalar and vector optical potentials are generated by folding invariant scalar and vector scattering nucleon-nucleon (NN) amplitudes, based on our recently developed relativistic meson-exchange model, with Lorentz scalar and vector densities resulting from the accurately calibrated PK1 relativistic mean field model of nuclear structure. It is seen that phenomenological Pauli blocking (PB) effects and density-dependent corrections to {sigma}N and {omega}N meson-nucleon coupling constants modify the RIA microscopic scalar and vector optical potentials so as to provide a consistent and quantitative description of all elastic scattering observables, namely, total reaction cross sections, differential cross sections, analyzing powers and spin rotation functions. In particular, the effect of PB becomes more significant at energies lower than 200 MeV, whereas phenomenological density-dependent corrections to the NN interaction also play an increasingly important role at energies lower than 100 MeV.
NASA Astrophysics Data System (ADS)
Adikaram, Dasuni Kalhari
The electric (GE) and magnetic ( GM) form factors of the proton are fundamental observables which characterize its charge and magnetization distributions. There are two methods to measure the proton form factors: the Rosenbluth separation method and the polarization transfer technique. However, the ratio of the electric and magnetic form factors measured by those methods significantly disagree at momentum transfer Q2 > 1 GeV2. The most likely explanation of this discrepancy is the inclusion of two-photon exchange (TPE) amplitude contributions to the elastic electron-proton cross section which significantly changes the extraction of GE from the Rosenbluth separation measurement. The Jefferson Lab CLAS TPE experiment determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections. The primary electron beam was used to create an intense bremsstrahlung photon beam. Some of the photons were then converted to a mixed e+/ e- beam which then interacted with a liquid hydrogen target. The e+p and e-p events were detected by the CLAS (CEBAF Large Acceptance Spectrometer). The elastic cross section ratios ((sigma( e+p)/(sigma(e -p)) were measured over a wide range of virtual photon polarization epsilon and Q2. The cross section ratios displayed a strong epsilon dependence at Q2 = 1.45 GeV2. There is no significant Q2 dependence observed at epsilon = 0.45. The results are consistent with a recent measurement at the VEPP-3 lepton storage ring in Novosibirsk and with the hadronic calculation by Blunders, Melnitchouk and Tjon. The hadronic calculation resolves the disagreement between the Rosenbluth separation and polarization transfer extractions of GE/GM at Q2 up to 2 -- 3 GeV2. Applying the GLAS TPE correction to the Rosenbluth cross section measurements significantly decreases the extracted value of GE and brings it into good agreement with the polarization transfer measurement at Q2˜1.75 GeV2. Thus, these
Konrad Aniol; David Armstrong; Todd Averett; Maud Baylac; Etienne Burtin; John Calarco; Gordon Cates; Christian Cavata; Zhengwei Chai; C. Chang; Jian-Ping Chen; Eugene Chudakov; Evaristo Cisbani; Marius Coman; Daniel Dale; Alexandre Deur; Pibero Djawotho; Martin Epstein; Stephanie Escoffier; Lars Ewell; Nicolas Falletto; John Finn; A. Fleck; Bernard Frois; Salvatore Frullani; Juncai Gao; Franco Garibaldi; Ashot Gasparian; G. M. Gerstner; Ronald Gilman; Oleksandr Glamazdin; Javier Gomez; Viktor Gorbenko; Jens-ole Hansen; F. Hersman; Douglas Higinbotham; Richard Holmes; Maurik Holtrop; Thomas Humensky; Sebastien Incerti; Mauro Iodice; Cornelis De Jager; Johann Jardillier; Xiaodong Jiang; Mark Jones; J. Jorda; Christophe Jutier; W. Kahl; James Kelly; Donghee Kim; M. -J. Kim; Minsuk Kim; Ioannis Kominis; Edgar Kooijman; Kevin Kramer; Krishna Kumar; Michael Kuss; John LeRose; Raffaele De Leo; M. Leuschner; David Lhuillier; Meihua Liang; Nilanga Liyanage; R. Lourie; Richard Madey; Sergey Malov; Demetrius Margaziotis; Frederic Marie; Pete Markowitz; Jacques Martino; Peter Mastromarino; Kathy McCormick; Justin McIntyre; Zein-Eddine Meziani; Robert Michaels; Brian Milbrath; Gerald Miller; Joseph Mitchell; Ludyvine Morand; Damien Neyret; Gerassimos Petratos; Roman Pomatsalyuk; John Price; David Prout; Thierry Pussieux; Gilles Quemener; Ronald Ransome; David Relyea; Yves Roblin; Julie Roche; Gary Rutledge; Paul Rutt; Marat Rvachev; Franck Sabatie; Arunava Saha; Paul Souder; Marcus Spradlin; Steffen Strauch; Riad Suleiman; Jeffrey Templon; T. Teresawa; James Thompson; Raphael Tieulent; Luminita Todor; Baris Tonguc; Paul Ulmer; Guido Urciuoli; Branislav Vlahovic; Krishni Wijesooriya; R. Wilson; Bogdan Wojtsekhowski; Rhett Woo; Wang Xu; Imran Younus; C. Zhang
2001-06-01
We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The result is A = -15.05 +- 0.98(stat) {+-} 0.56(syst) ppm at the kinematic point theta{sub lab} = 12.3 degrees and Q{sup 2} = 0.477 (GeV/c){sup 2}. The measurement implies that the value for the strange form factor (G{sub E}{sup s} + 0.392 G{sub M}{sup s})/(G{sub M}{sup p} {mu}{sub p}) = 0.069 +- 0.056 +- 0.039, where the first error is experimental and the second arises from the uncertainties in electromagnetic form factors. This measurement is the first fixed-target parity violation experiment that used either a ''strained'' GaAs photocathode to produce highly polarized electrons or a Compton polarimeter to continuously monitor the electron beam polarization.
NASA Astrophysics Data System (ADS)
Csörgő, T.; Nemes, F.
2014-01-01
The Bialas-Bzdak model of elastic proton-proton scattering is generalized to the case when the real part of the parton-parton level forward scattering amplitude is nonvanishing. Such a generalization enables the model to describe well the dip region of the differential cross-section of elastic scattering at the intersecting storage rings (ISR) energies, and improves significantly the ability of the model to describe also the recent TOTEM data at √ {s} = 7 TeV LHC energy. Within this framework, both the increase of the total cross-section, as well as the decrease of the location of the dip with increasing colliding energies, is related to the increase of the quark-diquark distance and to the increase of the "fragility" of the protons with increasing energies. In addition, we present and test the validity of two new phenomenological relations: one of them relates the total p+p cross-section to an effective, model-independent proton radius, while the other relates the position of the dip in the differential elastic cross-section to the measured value of the total cross-section.
Nagata, Keitaro; Kao, C. W.; Zhou Haiqing; Yang Shinnan
2009-06-15
We study the leading electroweak corrections in the precision measurement of the strange form factors. Specifically, we calculate the two-boson exchange (TBE), two-photon exchange (TPE) plus {gamma}Z exchange ({gamma}ZE), and corrections with {delta}(1232) excitation to the parity-violating asymmetry of the elastic electron-proton scattering. The interplay between nucleon and {delta} contributions is found to depend strongly on the kinematics, as {delta}{sub {delta}} begins as negligible at backward angles but becomes very large and negative and dominant at forward angles, while {delta}{sub N} always stays positive and decreases monotonically with increasing {epsilon}. The total TBE corrections to the extracted values of G{sub E}{sup s}+{beta}G{sub M}{sup s} in recent experiments of HAPPEX and G0 are, depending on kinematics, found to be large and range between 13% and -75%, but are found to be small in the case of A4 experiments.
Study of proton resonance structure in {sup 27}P via resonant elastic scattering of {sup 26}Si+p
Jung, H. S.; Lee, C. S.; Kwon, Y. K.; Moon, J. Y.; Lee, J. H.; Yun, C. C.; Kubono, S.; Yamaguchi, H.; Hashimoto, T.; Kahl, D.; Hayakawa, S.; Choi, Seonho; Kim, M. J.; Kim, Y. H.; Kim, Y. K.; Park, J. S.; Kim, E. J.; Moon, C.-B.; Teranishi, T.; Wakabayashi, Y.; and others
2012-11-12
A measurement of resonant elastic scattering of {sup 26}Si+p was performed with a thick target using a {sup 26}Si radioactive ion beam at the CRIB (CNS Radioactive Ion Beam separator) of the Center for Nuclear Study (CNS), the University of Tokyo. The excitation function of {sup 27}P was measured successfully with the inverse kinematics method through a covered the range of excitation energies from E{sub x}{approx} 2.3 to 3.8 MeV, providing information about the resonance structure of this nucleus. The properties of these resonances are important to better determine the production rates of {sup 26}Si(p,g){sup 27}P reaction, which is one of the astrophysically important nuclear reactions to understand the production of the {sup 26}Al. Some new resonant states have been investigated, and determined their resonance parameters, such as excitation energies, proton partial widths, and spin-parities by R-matrix calculation.
NASA Astrophysics Data System (ADS)
Yang, Y. Y.; Liu, X.; Pang, D. Y.
2016-09-01
Experimental data show that the elastic scattering cross sections of the neutron-rich nucleus 11Be are greatly reduced by the coupling effects from the breakup channels, while those of the proton-rich nucleus 8B are not. Such difference is found to persist in results of systematic calculations of 8B elastic scattering from 208Pb at 60 and 170.3 MeV and from 64Zn at 32 and 86 MeV, and 11Be elastic scattering from 208Pb at 55 and 143 MeV and from 64Zn at 29 and 66 MeV with the continuum-discretized coupled channel (CDCC) method. The Coulomb and centrifugal barriers experienced by the valence proton in the ground state of 8B, which do not exist for the valence neutron in the ground state of 11Be, are found to be the reason for such differences in the angular distributions of elastic scattering cross sections of these two weakly bound nuclei.
Parity violation in the elastic scattering from the proton in Hall A
Souder, Paul
1992-06-01
We are planning to measure the parity-violating electroweak asymmetry in the scattering of polarized electrons from hydrogen. We expect to obtain unique information about the weak form factors of the nucleon emphasizing the possible contributions of strange quarks to the weak vector matrix elements involved. Helium and deuterium and other possible targets of interest.
NASA Astrophysics Data System (ADS)
Farag, M. Y. H.; Esmael, E. H.; Maridi, H. M.
2014-03-01
The proton elastic scattering data on 4,6,8 He and 6,7,9,11Li nuclei at energies below 160 MeV/nucleon are analyzed using the optical model. The optical potential (OP) is taken microscopically, with few and limited fitting parameters, using the single folding model for the real part and high-energy approximation (HEA) for the imaginary one. Clear dependencies of the volume integrals on energy and rms radii are obtained from the results. The calculated differential and the reaction cross sections are in good agreement with the available experimental data. In general, this OP with few and limited fitting parameters, which have a systematic behavior with incident energy and matter radii, successfully describes the proton elastic scattering data with stable and exotic light nuclei at energies up to 160 MeV/nucleon.
Two-Photon Exchange Effects in Elastic Electron-Proton Scattering
Johnson, Myriam James
2013-08-01
Two methods, Rosenbluth separation and polarization transfer, can be used to extract the proton form factor ratio μp G_{Ep}/G_{Mp}, but they do not yield the same results. It is thought that the disagreement is due to two photon exchange corrections to the differential cross sections. High precision proton Rosenbluth extractions were carried out at 102 kinematics points spanning 16 values of momentum transfer Q^{2}, from 0.40 to 5.76 GeV^{2}. Reduced cross sections were found to 1.1% or better for Q^{2} less than 3 GeV^{2} increasing to 4% at 5.76 GeV^{2} The form factor ratios were determined to 1:5-3% for Q^{2} < 1.5 GeV^{2}, increasing to 9% by 3 GeV^{2} and rapidly above. Our data agrees with prior Rosenbluth, improving upon it the 1.0 - 2.0 GeV^{2} range to conclusively show a separation from polarization transfer where it had not been certain before. In addition, reduced cross sections at each Q^{2} were tested for nonlinearity in the angular variable. Such a departure from linearity would be a signature of two photon exchange effects, and prior data had not been sufficiently precise to show nonzero curvature. Our data begins to hint at negative curvature but does not yet show a significant departure from zero.
Waidyawansa, Dinayadura Buddhini
2013-08-01
The beam normal single spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable of the imaginary part of the two-photon exchange process. Moreover, it is a potential source of false asymmetry in parity violating electron scattering experiments. The Q{sub weak} experiment uses parity violating electron scattering to make a direct measurement of the weak charge of the proton. The targeted 4% measurement of the weak charge of the proton probes for parity violating new physics beyond the Standard Model. The beam normal single spin asymmetry at Q{sub weak} kinematics is at least three orders of magnitude larger than 5 ppb precision of the parity violating asymmetry. To better understand this parity conserving background, the Q{sub weak} Collaboration has performed elastic scattering measurements with fully transversely polarized electron beam on the proton and aluminum. This dissertation presents the analysis of the 3% measurement (1.3% statistical and 2.6% systematic) of beam normal single spin asymmetry in electronproton scattering at a Q2 of 0.025 (GeV/c)2. It is the most precise existing measurement of beam normal single spin asymmetry available at the time. A measurement of this precision helps to improve the theoretical models on beam normal single spin asymmetry and thereby our understanding of the doubly virtual Compton scattering process.
Qattan, I. A.; Alsaad, A.
2011-05-15
The most recent electron-proton elastic scattering data were re-analyzed using an empirical parametrization of the two-photon-exchange (TPE) effect contributions to {sigma}{sub R}. The TPE effect contribution F(Q{sup 2},{epsilon}) was double Taylor series expanded as a polynomial of order n keeping only terms linear in {epsilon} to account for the experimentally observed and verified linearity of the Rosenbluth plots. We fix the ratio R=G{sub Ep}/G{sub Mp} to be that obtained from a fit to the recoil-polarization data and parametrize {sigma}{sub R} first by a three-parameter formula (fit I) and then by a two-parameter formula (fit III). In contrast to previous analyses, the fit parameter G{sub Mp}{sup 2} as obtained from these fits is either smaller or equal to the values obtained from our conventional Rosenbluth fit (fit II) but never larger. The ratio g(Q{sup 2})/G{sub Mp}{sup 2} which represents the ratio of the TPE and one-photon-exchange (OPE) effect contributions to the intercept of {sigma}{sub R} is large and it ranges 3%-88%. The ratio R{sub 1{gamma}x2{gamma}={tau}}f(Q{sup 2})/G{sub Ep}{sup 2} which represents the ratio of the TPE and OPE effect contributions to the slope of {sigma}{sub R} is also large, reaching a value of 12.0-14.4 at Q{sup 2}= 5.25 (GeV/c){sup 2}. The ratio R{sub 1{gamma}x2{gamma}} as obtained from fits I and III is consistent, within error, with those obtained from previous analyses. Our formulas seem to explain the linearity of {sigma}{sub R}. Moreover, our analysis shows that the extracted G{sub Ep}{sup 2} and G{sub Mp}{sup 2} using the conventional Rosenbluth separation method can in fact be broken into the usual OPE and TPE contributions. Therefore, {sigma}{sub R} can in fact be derived under weaker conditions than those imposed by the Born approximation. Our results show that the TPE amplitudes, g(Q{sup 2})/G{sub Mp}{sup 2} and f(Q{sup 2})/G{sub Mp}{sup 2}, are sizable and grow with Q{sup 2} value up to Q{sup 2}{approx}6 (Ge
Measurement of the analyzing power for pion-proton elastic scattering between 471 and 687 MeV/c
Mokhtari-Amirmajdi, A.
1984-01-01
The analyzing power, A/sub N/, has been measured for ..pi../sup +/-/p ..-->.. ..pi../sup +/-/p at 471, 547, 625, and 687 MeV/c in an angular range corresponding to -0.9 less than or equal to cos(theta)/sub cm/ less than or equal to 0.8. A polarized proton target with polarization axis normal to the scattering plane was used. The scattered pion and recoil proton were detected in coincidence, using a magnetic spectrometer and a wire chamber/scintillator array, except in cases where one of the particles was kinematically inaccessible. Statistical uncertainties in the data are as low as 0.02; systematic uncertainties are estimated to be less than 5%. The ..pi../sup -/p data are characterized by large values of analyzing power, and rapid variations in the angular distribution with incident momentum. The measurements are compared with the results of existing partical wave analysis.
Adams, D.L.
1986-10-01
Analyzing powers and spin transfer coefficients which describe the elastic scattering of polarized protons from a polarized deuteron target have been measured. The energy of the proton beam was 800 MeV and data were taken at laboratory scattering angles of 7, 11, 14, and 16.5 degrees. One analyzing power was also measured at 180 degrees. Three linearly independent orientations of the beam polarization were used and the target was polarized parallel and antiparallel to the direction of the beam momentum. The data were taken with the high resolution spectrometer at the Los Alamos Meson Physics Facility (experiment 685). The results are compared with multiple scattering predictions based on Dirac representations of the nucleon-nucleon scattering matrices. 27 refs., 28 figs., 4 tabs.
Subedi, Adesh
2014-12-01
The Qweak experiment has taken data to make a 2.5% measurement of parity violating elastic e+p asymmetry in the four momentum transfer region of 0.0250 (GeV/c)^{2}. This asymmetry is proportional to the weak charge of the proton, which is related to the weak mixing angle, sin^{2}(theta_W). The final Qweak measurement will provide the most precise measurement of the weak mixing angle below the Z^{0} pole to test the Standard Model prediction. A description of the experimental apparatus is provided in this dissertation. The experiment was carried out using a longitudinally polarized electron beam of up to 180 microampere on a 34.5 cm long unpolarized liquid hydrogen target. The Qweak target is not only the world's highest cryogenic target ever built for a parity experiment but also is the least noisy target. This dissertation provides a detailed description of this target and presents a thorough analysis of the target performance. Statistical analysis of Run 1 data, collected between Feb - May 2011, is done to extract a blinded parity violating asymmetry of size -299.7 ± 13.4 (stat.) ± 17.2 (syst.) ± 68 (blinding) parts-per-billion. This resulted in a preliminary proton's weak charge of value 0.0865 ± 0.0085, a 9% measurement. Based on this blinded asymmetry, the weak mixing angle was determined to be sin^{2}(theta_W) = 0.23429 ± 0.00211.
Elastic and diffractive scattering at D0
Edwards, Tamsin; /Manchester U.
2004-04-01
The first search for diffractively produced Z bosons in the muon decay channel is presented, using a data set collected by the D0 detector at the Fermilab Tevatron at {radical}s = 1.96 TeV between April and September 2003, corresponding to an integrated luminosity of approximately 110 pb{sup -1}. The first dN/d|t| distribution for proton-antiproton elastic scattering at this c.o.m. energy is also presented, using data collected by the D0 Forward Proton Detector between January and May 2002. The measured slope is reproduced by theoretical predictions.
Proton resonance scattering of 7Be
Yamaguchi, H.; Saito, A.; He, J. J.; Wakabayashi, Y.; Amadio, G.; Fujikawa, H.; Kubono, S.; Khiem, L. H.; Niikura, M.; Kwon, Y. K.; Teranishi, T.; Nishimura, S.; Togano, Y.; Iwasa, N.; Inafuku, K.
2006-07-12
We have studied the proton resonance scattering of 7Be by using a pure 7Be beam produced at CRIB (CNS Radioactive Ion Beam separator; CNS stands for Center of Nuclear Study, University of Tokyo). The excitation function of 8B was measured up to the excitation energy of 6.8 MeV, with the thick-target method. The excited states of 8B higher than 3.5 MeV were not known by the past experiments. This proton elastic scattering is also of importance in relation with the 7Be(p,{gamma})8B reaction, which is a key reaction in the standard solar model.
NASA Astrophysics Data System (ADS)
Brack, Jeffrey Thomas
Differential cross sections for elastic pi^{+/-}p scattering have been measured at TRIUMF for 10 incident pion energies in three separate experiments at 66.8 <= T_{pi} <= 138.8 MeV, Tpi = 66.8 MeV (pi^+p only), and 30 <= T_{pi} <= 66.8 MeV, using three independent techniques. Typical statistical accuracies are 1-3% and normalization uncertainties are 1.2-3.0%. Extensive experimental checks were employed to minimize systematic errors. Incident pion beam rates were varied by a factor of 5, target thickness was varied by a factor of 10, different target compositions were used (CH_2 and CH_{1.1 }), and derangements of the detector geometry tested the reproducibility of the cross sections under widely varying conditions. Three separate Monte Carlo routines were used. All measurements used solid targets. Thin scintillators and time-of-flight (TOF) techniques were used to count and identify particles incident on the targets and to detect the scattered pions. Recoil protons were detected in coincidence with the scattered pions in two of the three experiments. At the upper range of incident pion energies (66.8 to 138 MeV), a two-arm coincidence technique was used in which proton detection was similar to pion detection (TOF). At the three lowest incident pion energies, an active target technique was used in which the recoil particles were detected by means of the light generated within the CH_ {1.1} scintillator-target. These are the only elastic pip coincidence measurements by any experimental group below 140 MeV incident pion energy. At 66.8 MeV, a third technique was used in which no recoil particles were detected. At incident pion energies of 100 MeV and above, all pi^{+/-}p results from these three measurements are in good agreement with previous measurements, as are the pi ^-p results at all energies. However, while the pi^{+/-}p results of these three experiments are consistent within experimental error at the overlapping energy of 66.8 MeV, they are 10-25% lower than
NASA Astrophysics Data System (ADS)
Spasova, K.; Lukyanov, V. K.; Kadrev, D. N.; Antonov, A. N.; Zemlyanaya, E. V.; Lukyanov, K. V.; Gaidarov, M. K.
2016-06-01
The elastic scattering cross-sections of 10,11Be on protons and 12C at energy E < 100 MeV/nucleon using microscopically calculated optical potentials (OP) are presented. The real OP is obtained by a folding procedure with effective NN interactions, while the imaginary OP is estimated within the high energy approximation (HEA). The spin-orbit part of the OP is also included. The characteristics of the breakup processes of 11Be on different nuclear targets are also considered. The cross-sections of diffractive breakup and stripping reactions of 11Be on 9Be, 93Nb, 181Ta and 238U at energy E = 63 MeV/nucleon and the longitudinal momentum distributions of 10Be fragments produced in the breakup of 11Be on these nuclei are presented. The results are in a good agreement with the available experimental data, in particular the obtained widths of about 50 MeV/c are closed to the empirical ones.
Two-photon exchange in electron-trinucleon elastic scattering
NASA Astrophysics Data System (ADS)
Kobushkin, A. P.; Timoshenko, Ju. V.
2013-10-01
We discuss two-photon exchange (TPE) in elastic electron scattering off the trinucleon systems, 3He and 3H. The calculations are done in the semirelativistic approximation with the trinucleon wave functions obtained with the Paris and CD-Bonn nucleon-nucleon potentials. An applicability area of the model is wide enough and includes the main part of kinematical domain where experimental data exist. All three TPE amplitudes (generalized form factors) for electron 3He elastic scattering are calculated. We find that the TPE amplitudes are a few times more significant in the scattering of electrons off 3He then in the electron-proton scattering.
Electron-Hydrogen Elastic Scattering
NASA Technical Reports Server (NTRS)
Bhatia, A. K.
2004-01-01
Scattering by single-electron systems is always of interest because the wave function of the target is known exactly. Various approximations have been employed to take into account distortion produced in the target. Among them are the method of polarized orbitals and the close coupling approximation. Recently, e-H and e-He+ S-wave scattering in the elastic region has been studied using the Feshbach projection operator formalism. In this approach, the usual Hartree-Fock and exchange potentials are augmented by an optical potential and the resulting phase shifts have rigorous lower bounds. Now this method is being applied to the e-H P-wave scattering in the elastic region. The number of terms in the Hylleraas-type wave function for the 1,3 P phase shifts is 84 and the resulting phase shifts (preliminary) are given. The results have been given up to five digits because to that accuracy they are rigorous lower bounds. They are in general agreement with the variational (VAR) results of Armstead, and those obtained from the intermediate energy R-matrix method (RM) of Scholz et al., and the finite element method (FEM) of Botero and Shertzer. The later two methods do not provide any bounds on phase shifts.
Proton radius from electron-proton scattering and chiral perturbation theory
NASA Astrophysics Data System (ADS)
Horbatsch, Marko; Hessels, Eric A.; Pineda, Antonio
2017-03-01
We determine the root-mean-square proton charge radius, Rp, from a fit to low-Q2 electron-proton elastic-scattering cross-section data with the higher moments fixed (within uncertainties) to the values predicted by chiral perturbation theory. We obtain Rp=0.855 (11 ) fm. This number falls between the value obtained from muonic hydrogen analyses and the CODATA value (based upon atomic hydrogen spectroscopy and electron-proton scattering determinations).
Johnson, K S; Laskin, A; Jimenez, J L; Shutthanandan, V; Molina, L T; Salcedo, D; Dzepina, K; Molina, M J
2008-09-01
A multifaceted approach to atmospheric aerosol analysis is often desirable in field studies where an understanding of technical comparability among different measurement techniques is essential. Herein, we report quantitative intercomparisons of particle-induced X-ray emission (PIXE) and proton elastic scattering analysis (PESA), performed of fline under a vacuum, with analysis by aerosol mass spectrometry (AMS) carried out in real-time during the MCMA-2003 Field Campaign in the Mexico City Metropolitan Area. Good agreement was observed for mass concentrations of PIXE-measured sulfur (assuming it was dominated by SO4(2-)) and AMS-measured sulfate during most of the campaign. PESA-measured hydrogen mass was separated into sulfate H and organic H mass fractions, assuming the only major contributions were (NH4)2SO4 and organic compounds. Comparison of the organic H mass with AMS organic aerosol measurements indicates that about 75% of the mass of these species evaporated under a vacuum. However approximately 25% of the organics does remain under a vacuum, which is only possible with low-vapor-pressure compounds, and which supports the presence of high-molecular-weight or highly oxidized organics consistent with atmospheric aging. Approximately 10% of the chloride detected by AMS was measured by PIXE, possibly in the form of metal-chloride complexes, while the majority of Cl was likely present as more volatile species including NH4Cl. This is the first comparison of PIXE/PESA and AMS and, to our knowledge, also the first report of PESA hydrogen measurements for urban organic aerosols.
Evaluation of the Proton Charge Radius from Electron–Proton Scattering
Arrington, John; Sick, Ingo
2015-09-15
In light of the proton radius puzzle, the discrepancy between measurements of the proton charge radius from muonic hydrogen and those from electronic hydrogen and electron–proton (e–p) scattering measurements, we re-examine the charge radius extractions from electron scattering measurements. We provide a recommended value for the proton root-mean-square charge radius, r{sub E} = 0.879 ± 0.011 fm, based on a global examination of elastic e–p scattering data. The uncertainties include contributions to account for tension between different data sets and inconsistencies between radii using different extraction procedures.
Elastic scattering with weakly bound projectiles
Figueira, J. M.; Abriola, D.; Arazi, A.; Capurro, O. A.; Marti, G. V.; Martinez Heinmann, D.; Pacheco, A. J.; Testoni, J. E.; Barbara, E. de; Fernandez Niello, J. O.; Padron, I.; Gomes, P. R. S.; Lubian, J.
2007-02-12
Possible effects of the break-up channel on the elastic scattering threshold anomaly has been investigated. We used the weakly bound 6,7Li nuclei, which is known to undergo break-up, as projectiles in order to study the elastic scattering on a 27Al target. In this contribution we present preliminary results of these experiments, which were analyzed in terms of the Optical Model and compared with other elastic scattering data using weakly bound nuclei as projectile.
Polarized e-p elastic scattering in the collider frame
Sofiatti, C.; Donnelly, T. W.
2011-07-15
Double polarization elastic e-vector-p-vector cross sections and asymmetries are considered in collider kinematics. Covariant expressions are derived for the general situation involving crossed beams; these are checked against the well-known results obtained when the proton is at rest. Results are given using modern models for the proton electromagnetic form factors for kinematics of interest in e-p colliders such as the Electron-Ion Collider facility which is in its planning stage. In context, parity-violating elastic e-vector-p scattering is compared and contrasted with these double-polarization (parity-conserving) results.
Lukyanov, V. K. Zemlyanaya, E. V.; Lukyanov, K. V.
2015-01-15
The {sup 11}Li scattering and breakup on protons is considered under the assumption that the {sup 11}Li nucleus consists of two interacting clusters, which are a c = {sup 9}Li core and a h = 2n dineutron halo. The single-particle density of the {sup 11}Li nucleus, amicroscopic optical potential, and the cross section for {sup 11}Li+p scattering for various choices of cluster shape are obtained and analyzed by folding the density distribution for either cluster with the probability density for the relative motion of two clusters. A comparison with experimental data of the scattering cross section at low, 60–75 MeV, and intermediate, 700 MeV, energies is performed. The momentum distribution of c fragments upon {sup 11}Li breakup is calculated and studied with a help of the obtained p + c and p + h microscopic optical potentials.
Proton Elastic Form Factor Ratio: the JLab Polarization Experiments
Charles Perdrisat; Vina Punjabi
2003-07-30
The ratio of the electric and magnetic proton form factors, G{sub Ep}/G{sub Mp}, has been obtained in two Hall A experiments, from measurements of the longitudinal and transverse polarization of the recoil proton, P{sub l} and P{sub t}, respectively, in the elastic scattering of polarized electrons, {rvec e}p {yields} e{rvec p}. Together these experiments cover the Q{sup 2}-range 0.5 to 5.6 GeV{sup 2}. A new experiment is currently being prepared, to extend the Q{sup 2}-range to 9 GeV{sup 2} in Hall C.
Elastic Compton Scattering from 3He
NASA Astrophysics Data System (ADS)
Margaryan, Arman; Griesshammer, Harald W.; Phillips, Daniel R.; Strandberg, Bruno; McGovern, Judith A.; Shukla, Deepshikha
2017-01-01
We study elastic Compton scattering on 3He using chiral effective field theory (χEFT) at photon energies from 60 MeV to approximately 120 MeV. Experiments to measure this process have been proposed for both MAMI at Mainz and the HI γS facility at TUNL. I will present the revised results of a full calculation at third order in the expansion (O (Q3)). The amplitude involves a sum of both one- and two-nucleon Compton-scattering mechanisms. We have recently computed the fourth-order two-nucleon diagrams. The numerical impact they have on the cross-section results will be discussed. I will also present results in which amplitudes used so far are augmented by the leading effects from Δ (1232) degrees of freedom, a step which has already been performed for the proton and deuteron processes. Both cross sections and doubly-polarized asymmetries will be presented, and the sensitivity of these observables to the values of neutron scalar and spin polarizabilities will be assessed. This material is based upon work supported in part by DOE and George Washington University.
Proton-Proton Scattering at 105 Mev and 75 Mev
DOE R&D Accomplishments Database
Birge, R. W.; Kruse, U. E.; Ramsey, N. F.
1951-01-31
The scattering of protons by protons provides an important method for studying the nature of nuclear forces. Recent proton-proton scattering experiments at energies as high as thirty Mev{sup 1} have failed to show any appreciable contribution to the cross section from higher angular momentum states, but it is necessary to bring in tensor forces to explain the magnitude of the observed cross section.
NASA Astrophysics Data System (ADS)
He, J. J.; Kubono, S.; Teranishi, T.; Notani, M.; Baba, H.; Nishimura, S.; Moon, J. Y.; Nishimura, M.; Michimasa, S.; Iwasaki, H.; Yanagisawa, Y.; Hokoiwa, N.; Kibe, M.; Lee, J. H.; Kato, S.; Gono, Y.; Lee, C. S.
2008-04-01
Proton resonances in 22Mg have been investigated by the resonant elastic scattering of 21 Na + p . The 21Na beam with a mean energy of 4.00 MeV/nucleon was separated by the CNS radioactive-ion-beam separator (CRIB) and bombarded a thick ( CH2 n target. The energy spectra of recoiled protons were measured at scattering angles of θc.m. ≈ 172° , 146° , respectively. Several excited states observed before have been confirmed including two states (at 6.616, 6.796 MeV) observed at TRIUMF. A new state at 7.06 MeV has been observed, and another new one at 7.28 MeV is tentatively identified due to its low statistics. The proton resonant parameters were deduced from an R -matrix analysis of the differential cross-section data with a SAMMY-M6-BETA code. The astrophysical implication for the 18 Ne(α, p)21 Na reaction has been briefly discussed.
Positron-inert gas differential elastic scattering
NASA Technical Reports Server (NTRS)
Kauppila, W. E.; Smith, Steven J.; Kwan, C. K.; Stein, T. S.
1990-01-01
Measurements are being made in a crossed beam experiment of the relative elastic differential cross section (DCS) for 5 to 300 eV positrons scattering from inert gas atoms (He, Ne, Ar, Kr, and Xe) in the angular range from 30 to 134 deg. Results obtained at energies around the positronium (Ps) formation threshold provide evidence that Ps formation and possibly other inelastic channels have an effect on the elastic scattering channel.
Elastic scattering, polarization and absorption of relativistic antiprotons on nuclei
NASA Astrophysics Data System (ADS)
Larionov, A. B.; Lenske, H.
2017-01-01
We perform Glauber model calculations of the antiproton-nucleus elastic and quasielastic scattering and absorption in the beam momentum range ∼ 0.5 ÷ 10 GeV / c. A good agreement of our calculations with available LEAR data and with earlier Glauber model studies of the p bar A elastic scattering allows us to make predictions at the beam momenta of ∼10 GeV/c, i.e. at the regime of the PANDA experiment at FAIR. The comparison with the proton-nucleus elastic scattering cross sections shows that the diffractive minima are much deeper in the p bar A case due to smaller absolute value of the ratio of the real-to-imaginary part of the elementary elastic amplitude. Significant polarization signal for p bar A elastic scattering at 10 GeV/c is expected. We have also revealed a strong dependence of the p bar A absorption cross section on the slope parameter of the transverse momentum dependence of the elementary p bar N amplitude. The p bar A optical potential is discussed.
Hadronic uncertainties in the elastic scattering of supersymmetric dark matter
Ellis, John; Olive, Keith A.; Savage, Christopher
2008-03-15
We review the uncertainties in the spin-independent and spin-dependent elastic scattering cross sections of supersymmetric dark matter particles on protons and neutrons. We propagate the uncertainties in quark masses and hadronic matrix elements that are related to the {pi}-nucleon {sigma} term and the spin content of the nucleon. By far the largest single uncertainty is that in spin-independent scattering induced by our ignorance of the
Dark matter elastic scattering through Higgs loops
NASA Astrophysics Data System (ADS)
Berlin, Asher; Hooper, Dan; McDermott, Samuel D.
2015-12-01
We consider a complete list of simplified models in which Majorana dark matter particles annihilate at tree level to h h or h Z final states and calculate the loop-induced elastic scattering cross section with nuclei in each case. Expressions for these annihilation and elastic scattering cross sections are provided and can be easily applied to a variety of UV-complete models. We identify several phenomenologically viable scenarios, including dark matter that annihilates through the s -channel exchange of a spin-zero mediator or through the t -channel exchange of a fermion. Although the elastic scattering cross sections predicted in this class of models are generally quite small, XENON1T and LZ should be sensitive to significant regions of this parameter space. Models in which the dark matter annihilates to h h or h Z can also generate a gamma-ray signal that is compatible with the excess observed from the Galactic center.
Full Elasticity Tensor from Thermal Diffuse Scattering
NASA Astrophysics Data System (ADS)
Wehinger, Björn; Mirone, Alessandro; Krisch, Michael; Bosak, Alexeï
2017-01-01
We present a method for the precise determination of the full elasticity tensor from a single crystal diffraction experiment using monochromatic x rays. For the two benchmark systems calcite and magnesium oxide, we show that the measurement of thermal diffuse scattering in the proximity of Bragg reflections provides accurate values of the complete set of elastic constants. This approach allows for a reliable and model-free determination of the elastic properties and can be performed together with crystal structure investigation in the same experiment.
NASA Astrophysics Data System (ADS)
Kłusek-Gawenda, Mariola; Schäfer, Wolfgang; Szczurek, Antoni
2016-10-01
We discuss the two-gluon exchange contribution (formally three-loops) to elastic photon-photon scattering in the high-energy approximation. The elastic γγ → γγ amplitude is given in the impact-factor representation for all helicity configurations and finite quark masses. We discuss the importance of including the charm quark, which contribution, due to interference, can enhance the cross section considerably. We investigate the contribution to the γγ → γγ amplitude from the soft region, by studying its dependence on nonperturbative gluon mass. Helicity-flip contributions are shown to be much smaller than helicity-conserving ones. We identify region(s) of phase space where the two-gluon exchange contribution becomes important ingredient compared to box and nonperturbative VDM-Regge mechanisms considered in the literature. Consequences for the AA → AAγγ reaction are discussed. Several differential distributions are shown. A feasibility study to observe the effect of two-gluon exchange is presented. We perform a similar analysis for the pp → ppγγ reaction. Only by imposing severe cuts on Mγγ and a narrow window on photon transverse momenta the two gluon contribution becomes comparable to the box contribution but the corresponding cross section is rather small.
Hydrogen analysis for granite using proton-proton elastic recoil coincidence spectrometry.
Komatsubara, T; Sasa, K; Ohshima, H; Kimura, H; Tajima, Y; Takahashi, T; Ishii, S; Yamato, Y; Kurosawa, M
2008-07-01
In an effort to develop DS02, a new radiation dosimetry system for the atomic bomb survivors of Hiroshima and Nagasaki, measurements of neutron-induced activities have provided valuable information to reconstruct the radiation situation at the time of the bombings. In Hiroshima, the depth profile of (152)Eu activity measured in a granite pillar of the Motoyasu Bridge (128 m from the hypocenter) was compared with that calculated using the DS02 methodology. For calculation of the (152)Eu production due to the thermal-neutron activation reaction, (151)Eu(n,gamma)(152)Eu, information on the hydrogen content in granite is important because the transport and slowing-down process of neutrons penetrating into the pillar is strongly affected by collisions with the protons of hydrogen. In this study, proton-proton elastic recoil coincidence spectrometry has been used to deduce the proton density in the Motoyasu pillar granite. Slices of granite samples were irradiated by a 20 MeV proton beam, and the energies of scattered and recoil protons were measured with a coincidence method. The water concentration in the pillar granite was evaluated to be 0.30 +/- 0.07%wt. This result is consistent with earlier data on adsorptive water (II) and bound water obtained by the Karl Fisher method.
Radiative corrections to polarization observables in electron-proton scattering
NASA Astrophysics Data System (ADS)
Borisyuk, Dmitry; Kobushkin, Alexander
2014-08-01
We consider radiative corrections to polarization observables in elastic electron-proton scattering, in particular, for the polarization transfer measurements of the proton form factor ratio μGE/GM. The corrections are of two types: two-photon exchange (TPE) and bremsstrahlung (BS); in the present work we pay special attention to the latter. Assuming small missing energy or missing mass cutoff, the correction can be represented in a model-independent form, with both electron and proton radiation taken into account. Numerical calculations show that the contribution of the proton radiation is not negligible. Overall, at high Q2 and energies, the total correction to μGE/GM grows, but is dominated by TPE. At low energies both TPE and BS may be significant; the latter amounts to ˜0.01 for some reasonable cut-off choices.
Positron elastic scattering from alkaline earth targets
NASA Astrophysics Data System (ADS)
Poveda, Luis A.; Assafrão, Denise; Mohallem, José R.
2016-07-01
A previously reported model potential approach [Poveda et al., Phys. Rev. A 87, 052702 (2013)] was extended to study low energy positron elastic scattering from beryllium and magnesium. The cross sections were computed for energies ranging from 10-5 eV up to well above the positronium formation threshold. The present results are in good agreement with previous reports, including the prediction of a p-wave resonance in the cross section for magnesium. The emergence of this shape resonance is connected to a trend observed in the evolution of the partial wave cross section in going from Be to Mg target. This trend lead us to speculate that a sharp d-wave resonance should be observed in positron elastic scattering from calcium. The positron-target binding energies are investigated in detail, both using the scattering information and by direct computation of the bound state energies using the model potentials. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.Supplementary material in the form of one pdf file available from the Journal web page at http://dx.doi.org/10.1140/epjd/e2016-70120-y
Exploring central opacity and asymptotic scenarios in elastic hadron scattering
NASA Astrophysics Data System (ADS)
Fagundes, D. A.; Menon, M. J.; Silva, P. V. R. G.
2016-02-01
In the absence of a global description of the experimental data on elastic and soft diffractive scattering from the first principles of QCD, model-independent analyses may provide useful phenomenological insights for the development of the theory in the soft sector. With that in mind, we present an empirical study on the energy dependence of the ratio X between the elastic and total cross sections; a quantity related to the evolution of the hadronic central opacity. The dataset comprises all the experimental information available on proton-proton and antiproton-proton scattering in the c.m. energy interval 5 GeV-8 TeV. Generalizing previous works, we discuss four model-independent analytical parameterizations for X, consisting of sigmoid functions composed with elementary functions of the energy and three distinct asymptotic scenarios: either the standard black disk limit or scenarios above or below that limit. Our two main conclusions are the following: (1) although consistent with the experimental data, the black disk does not represent an unique solution; (2) the data reductions favor a semi-transparent scenario, with asymptotic average value for the ratio X bar = 0.30 ± 0.12. In this case, within the uncertainty, the asymptotic regime may already be reached around 1000 TeV. We present a comparative study of the two scenarios, including predictions for the inelastic channel (diffraction dissociation) and the ratio associated with the total cross-section and the elastic slope. Details on the selection of our empirical ansatz for X and physical aspects related to a change of curvature in this quantity at 80-100 GeV, indicating the beginning of a saturation effect, are also presented and discussed.
The energy dependence of the diffraction minimum in the elastic scattering and new LHC data
NASA Astrophysics Data System (ADS)
Selyugin, O. V.
2017-03-01
The soft diffraction phenomena in the elastic proton-proton scattering are reviewed from the viewpoint of experiments at the LHC (TOTEM and ATLAS collaboration). In the framework of the High Energy Generalized Structure (HEGS) model the form of the diffraction minimum in the nucleon-nucleon elastic scattering in a wide energy region is analyzed. The energy dependencies of the main characteristics of the diffraction dip are obtained. The numerical predictions at LHC energies are presented. The comparison of the model predictions with the new LHC data at √{ s} = 13 TeV is made.
The Muon Scattering Experiment (MUSE) at PSI and the proton radius puzzle
NASA Astrophysics Data System (ADS)
Kohl, Michael
2014-11-01
The unexplained large discrepancy of the proton charge radius measurements with muonic hydrogen Lamb shift and determinations from elastic electron scattering and Lamb shift in regular hydrogen of seven standard deviations is known as the proton radius puzzle. Suggested solutions of the puzzle range from possible errors in the experiments through unexpectedly large hadronic physics effects to new physics beyond the Standard Model. A new approach to verify the radius discrepancy in a systematic manner will be pursued with the Muon Scattering Experiment (MUSE) at PSI. The experiment aims to compare elastic cross sections, the proton elastic form factors, and the extracted proton charge radius with scattering of electrons and muons of either charge and under identical conditions. The difference in the observed radius will be probed with a high precision to verify the discrepancy. An overview of the experiment and the current status will be presented.
Elastic Electron Scattering from Tritium and Helium-3
DOE R&D Accomplishments Database
Collard, H.; Hofstadter, R.; Hughes, E. B.; Johansson, A.; Yearian, M. R.; Day, R. B.; Wagner, R. T.
1964-10-01
The mirror nuclei of tritium and helium-3 have been studied by the method of elastic electron scattering. Absolute cross sections have been measured for incident electron energies in the range 110 - 690 MeV at scattering angles lying between 40 degrees and 135 degrees in this energy range. The data have been interpreted in a straightforward manner and form factors are given for the distributions of charge and magnetic moment in the two nuclei over a range of four-momentum transfer squared 1.0 - 8.0 F{sup -2}. Model-independent radii of the charge and magnetic moment distributions are given and an attempt is made to deduce form factors describing the spatial distribution of the protons in tritium and helium-3.
Quasi-Elastic Light Scattering in Ophthalmology
NASA Astrophysics Data System (ADS)
Ansari, Rafat R.
The eye is not just a "window to the soul"; it can also be a "window to the human body." The eye is built like a camera. Light which travels from the cornea to the retina traverses through tissues that are representative of nearly every tissue type and fluid type in the human body. Therefore, it is possible to diagnose ocular and systemic diseases through the eye. Quasi-elastic light scattering (QELS) also known as dynamic light scattering (DLS) is a laboratory technique routinely used in the characterization of macromolecular dispersions. QELS instrumentation has now become more compact, sensitive, flexible, and easy to use. These developments have made QELS/DLS an important tool in ophthalmic research where disease can be detected early and noninvasively before the clinical symptoms appear.
Inverse obstacle scattering for elastic waves
NASA Astrophysics Data System (ADS)
Li, Peijun; Wang, Yuliang; Wang, Zewen; Zhao, Yue
2016-11-01
Consider the scattering of a time-harmonic plane wave by a rigid obstacle which is embedded in an open space filled with a homogeneous and isotropic elastic medium. An exact transparent boundary condition is introduced to reduce the scattering problem into a boundary value problem in a bounded domain. Given the incident field, the direct problem is to determine the displacement of the wave field from the known obstacle; the inverse problem is to determine the obstacle’s surface from the measurement of the displacement on an artificial boundary enclosing the obstacle. In this paper, we consider both the direct and inverse problems. The direct problem is shown to have a unique weak solution by examining its variational formulation. The domain derivative is derived for the displacement with respect to the variation of the surface. A continuation method with respect to the frequency is developed for the inverse problem. Numerical experiments are presented to demonstrate the effectiveness of the proposed method.
Proton Scattering on Liquid Argon
NASA Astrophysics Data System (ADS)
Bouabid, Ryan; LArIAT Collaboration
2017-01-01
LArIAT (Liquid Argon In A Test-beam) is a liquid argon time projection chamber (LArTPC) positioned in a charged particle beamline whose primary purpose is to study the response of LArTPC's to charged particle interactions. This previously unmeasured experimental data will allow for improvement of Monte Carlo simulations and development of identification techniques, important for future planned LArTPC neutrino experiments. LArIAT's beamline is instrumented to allow for the identification of specific particles as well as measurement of those particles' incoming momenta. Among the particles present in the beamline, the analysis presented here focuses on proton-Argon interactions. This study uses particle trajectories and calorimetric information to identify proton-Argon interaction candidates. We present preliminary data results on the measurement of the proton-Argon cross-section. Liquid Argon In A Test Beam. The work is my analysis made possible through the efforts of LArIAT detector, data, and software.
Electron Elastic-Scattering Cross-Section Database
National Institute of Standards and Technology Data Gateway
SRD 64 NIST Electron Elastic-Scattering Cross-Section Database (PC database, no charge) This database provides values of differential elastic-scattering cross sections, corresponding total elastic-scattering cross sections, phase shifts, and transport cross sections for elements with atomic numbers from 1 to 96 and for electron energies between 50 eV and 20,000 eV (in steps of 1 eV).
Generalizations of Karp's theorem to elastic scattering theory
NASA Astrophysics Data System (ADS)
Tuong, Ha-Duong
Karp's theorem states that if the far field pattern corresponding to the scattering of a time-harmonic acoustic plane wave by a sound-soft obstacle in R2 is invariant under the group of rotations, then the scatterer is a circle. The theorem is generalized to the elastic scattering problems and the axisymmetric scatterers in R3.
Phonon coupling effects in proton scattering from Ca40
NASA Astrophysics Data System (ADS)
Mackintosh, R. S.; Keeley, N.
2014-10-01
Background: Formal optical model theory shows that coupling to vibrational nuclear states generates a nonlocal and l-dependent dynamical polarization potential (DPP). Little is established concerning the DPP, yet its properties are crucial for explaining the departures of optical model potentials (OMPs) from global behavior and for the rigorous extraction of spectroscopic information from direct reactions. Purpose: To appraise the application of channel coupling followed by S-matrix inversion for the systematic exploration of the contribution of the coupling of collective states to the nucleon OMP and to identify properties of nuclear potentials indicative of l-dependence. Methods: S-matrix to potential, Slj→V(r )+l .sVSO(r), inversion provides local potentials that precisely reproduce the elastic channel S-matrix from coupled channel (CC) calculations. Subtracting the elastic channel uncoupled (bare) potential yields a local and l-independent representation of the DPP. The dependence of this local DPP upon the nature of the coupled states and upon other parameters can be studied. Results: All components of the DPP arising from coupling to vibrational states are substantially undulatory with a point-by-point magnitude therefore disproportionate to their contribution to volume integrals. Information relating to dynamical nonlocality is found. The proton charge leads to a substantial difference between DPPs for protons and neutrons. Conclusions: Undulatory features in potentials found in precision fits to elastic scattering data are significant, are a consequence of coupling to inelastic channels and must be allowed for in phenomenology; they are indirect evidence of l-dependence. Within the model, coupling to excited states magnifies the effect of the proton charge on the difference between proton-nucleus and neutron-nucleus interactions. Coupled channel plus inversion is a procedure of wide applicability, complementary to evaluation of the Feshbach formalism.
Positron-proton to electron-proton elastic cross section ratios from CLAS
NASA Astrophysics Data System (ADS)
Adikaram, Dasuni; Rimal, Dipak; Weinstein, Larry; Raue, Brian
2014-03-01
There is a significant discrepancy between the ratio of the electromagnetic form factors of the proton measured by the Rosenbluth and the polarization transfer technique. The most likely explanation of this discrepancy is the inclusion of two-photon exchange (TPE) amplitude contributions to the elastic electron-proton cross section. The CLAS TPE experiment measured the TPE contribution in the wide range of Q2 and ɛ range using a comparison of positron-proton to electron-proton elastic cross sections (R = σ (e+ p) / σ (e- p)). Preliminary results will be presented, along with the estimations of systematic uncertainties. A detailed comparison of new results with previous R measurements and theoretical calculations will be presented. Implications of the CLAS TPE measurements on the elastic electron-proton cross section will be also discussed.
Cancellation of acoustic scattering from an elastic sphere.
Guild, Matthew D; Alù, Andrea; Haberman, Michael R
2011-03-01
Recent research has suggested the possibility of creating acoustic cloaks using metamaterial layers to eliminate the acoustic field scattered from an elastic object. This paper explores the possibility of applying the scattering cancellation cloaking technique to acoustic waves and the use of this method to investigate its effectiveness in cloaking elastic and fluid spheres using only a single isotropic elastic layer. Parametric studies showing the influence of cloak stiffness and geometry on the frequency dependent scattering cross-section of spheres have been developed to explore the design space of the cloaking layer. This analysis shows that an appropriately designed single isotropic elastic cloaking layer can provide up to 30 dB of scattering reduction for ka values up to 1.6. This work also illustrates the importance of accounting for the elasticity of the object and the relevant limitations of simplistic quasi-static analyses proposed in recent papers.
Improved Optics For Quasi-Elastic Light Scattering
NASA Technical Reports Server (NTRS)
Cheung, Harry Michael
1995-01-01
Improved optical train devised for use in light-scattering measurements of quasi-elastic light scattering (QELS) and laser spectroscopy. Measurements performed on solutions, microemulsions, micellular solutions, and colloidal dispersions. Simultaneous measurements of total intensity and fluctuations in total intensity of light scattered from sample at various angles provides data used, in conjunction with diffusion coefficients, to compute sizes of particles in sample.
An Examination of Proton Charge Radius Extractions from e–p Scattering Data
Arrington, John
2015-09-15
A detailed examination of issues associated with proton radius extractions from elastic electron–proton scattering experiments is presented. Sources of systematic uncertainty and model dependence in the extractions are discussed, with an emphasis on how these may impact the proton charge and magnetic radii. A comparison of recent Mainz data to previous world data is presented, highlighting the difference in treatment of systematic uncertainties as well as tension between different data sets. We find several issues that suggest that larger uncertainties than previously quoted may be appropriate, but do not find any corrections which would resolve the proton radius puzzle.
Few-body multiple scattering calculations for {sup 6}He on protons
Al-Khalili, J. S.; Johnson, R. C.; Thompson, I. J.; Crespo, R.; Moro, A. M.
2007-02-15
The elastic scattering of the halo nucleus {sup 6}He from a proton target at 717 MeV/nucleon is investigated within three different multiple-scattering formulations of the total transition amplitude. The factorized impulse approximation (FIA) and the fixed scatterer approximation (FSA) of the multiple-scattering expansion are used to evaluate accurately the single-scattering terms and to test the validity of a few-body Glauber approach. The latter also includes terms beyond single scattering and the importance of these terms is investigated. The differential cross section is calculated for proton scattering from {sup 6}He at 717 MeV in inverse kinematics and compared with recent data.
Proton radius from electron scattering data
NASA Astrophysics Data System (ADS)
Higinbotham, Douglas W.; Kabir, Al Amin; Lin, Vincent; Meekins, David; Norum, Blaine; Sawatzky, Brad
2016-05-01
Background: The proton charge radius extracted from recent muonic hydrogen Lamb shift measurements is significantly smaller than that extracted from atomic hydrogen and electron scattering measurements. The discrepancy has become known as the proton radius puzzle. Purpose: In an attempt to understand the discrepancy, we review high-precision electron scattering results from Mainz, Jefferson Lab, Saskatoon, and Stanford. Methods: We make use of stepwise regression techniques using the F test as well as the Akaike information criterion to systematically determine the predictive variables to use for a given set and range of electron scattering data as well as to provide multivariate error estimates. Results: Starting with the precision, low four-momentum transfer (Q2) data from Mainz (1980) and Saskatoon (1974), we find that a stepwise regression of the Maclaurin series using the F test as well as the Akaike information criterion justify using a linear extrapolation which yields a value for the proton radius that is consistent with the result obtained from muonic hydrogen measurements. Applying the same Maclaurin series and statistical criteria to the 2014 Rosenbluth results on GE from Mainz, we again find that the stepwise regression tends to favor a radius consistent with the muonic hydrogen radius but produces results that are extremely sensitive to the range of data included in the fit. Making use of the high-Q2 data on GE to select functions which extrapolate to high Q2, we find that a Padé (N =M =1 ) statistical model works remarkably well, as does a dipole function with a 0.84 fm radius, GE(Q2) =(1+Q2/0.66 GeV2) -2 . Conclusions: Rigorous applications of stepwise regression techniques and multivariate error estimates result in the extraction of a proton charge radius that is consistent with the muonic hydrogen result of 0.84 fm; either from linear extrapolation of the extremely-low-Q2 data or by use of the Padé approximant for extrapolation using a larger
Proton radius from electron scattering data
Higinbotham, Douglas W.; Kabir, Al Amin; Lin, Vincent; Meekins, David; Norum, Blaine; Sawatzky, Brad
2016-05-01
Background: The proton charge radius extracted from recent muonic hydrogen Lamb shift measurements is significantly smaller than that extracted from atomic hydrogen and electron scattering measurements. The discrepancy has become known as the proton radius puzzle. Purpose: In an attempt to understand the discrepancy, we review high-precision electron scattering results from Mainz, Jefferson Lab, Saskatoon, and Stanford. Methods: We make use of stepwise regression techniques using the F test as well as the Akaike information criterion to systematically determine the predictive variables to use for a given set and range of electron scattering data as well as to provide multivariate error estimates. Results: Starting with the precision, low four-momentum transfer (Q2) data from Mainz (1980) and Saskatoon (1974), we find that a stepwise regression of the Maclaurin series using the F test as well as the Akaike information criterion justify using a linear extrapolation which yields a value for the proton radius that is consistent with the result obtained from muonic hydrogen measurements. Applying the same Maclaurin series and statistical criteria to the 2014 Rosenbluth results on GE from Mainz, we again find that the stepwise regression tends to favor a radius consistent with the muonic hydrogen radius but produces results that are extremely sensitive to the range of data included in the fit. Making use of the high-Q2 data on GE to select functions which extrapolate to high Q2, we find that a Padé (N=M=1) statistical model works remarkably well, as does a dipole function with a 0.84 fm radius, GE(Q2)=(1+Q2/0.66GeV2)−2. Conclusions: Rigorous applications of stepwise regression techniques and multivariate error estimates result in the extraction of a proton charge radius that is consistent with the muonic hydrogen result of 0.84 fm; either from linear extrapolation of the extremely-low-Q2 data or by use of the Padé approximant for extrapolation using a larger range of
Global analysis of proton elastic form factor data with two-photon exchange corrections
J. Arrington; W. Melnitchouk; J. A. Tjon
2007-09-01
We use the world's data on elastic electron-proton scattering and calculations of two-photon exchange effects to extract corrected values of the proton's electric and magnetic form factors over the full Q^2 range of the existing data. Our analysis combines the corrected Rosenbluth cross section and polarization transfer data, and is the first extraction of G_Ep and G_Mp including explicit two-photon exchange corrections and their associated uncertainties. In addition, we examine the angular dependence of the corrected cross sections, and discuss the possible nonlinearities of the cross section as a function of epsilon.
Emission of neutron-proton and proton-proton pairs in neutrino scattering
NASA Astrophysics Data System (ADS)
Ruiz Simo, I.; Amaro, J. E.; Barbaro, M. B.; De Pace, A.; Caballero, J. A.; Megias, G. D.; Donnelly, T. W.
2016-11-01
We use a recently developed model of relativistic meson-exchange currents to compute the neutron-proton and proton-proton yields in (νμ ,μ-) scattering from 12C in the 2p-2h channel. We compute the response functions and cross sections with the relativistic Fermi gas model for different kinematics from intermediate to high momentum transfers. We find a large contribution of neutron-proton configurations in the initial state, as compared to proton-proton pairs. In the case of charge-changing neutrino scattering the 2p-2h cross section of proton-proton emission (i.e., np in the initial state) is much larger than for neutron-proton emission (i.e., two neutrons in the initial state) by a (ω , q)-dependent factor. The different emission probabilities of distinct species of nucleon pairs are produced in our model only by meson-exchange currents, mainly by the Δ isobar current. We also analyze other effects including exchange contributions and the effect of the axial and vector currents.
Numerical solution of acoustic scattering by finite perforated elastic plates
NASA Astrophysics Data System (ADS)
Cavalieri, A. V. G.; Wolf, W. R.; Jaworski, J. W.
2016-04-01
We present a numerical method to compute the acoustic field scattered by finite perforated elastic plates. A boundary element method is developed to solve the Helmholtz equation subjected to boundary conditions related to the plate vibration. These boundary conditions are recast in terms of the vibration modes of the plate and its porosity, which enables a direct solution procedure. A parametric study is performed for a two-dimensional problem whereby a cantilevered perforated elastic plate scatters sound from a point quadrupole near the free edge. Both elasticity and porosity tend to diminish the scattered sound, in agreement with previous work considering semi-infinite plates. Finite elastic plates are shown to reduce acoustic scattering when excited at high Helmholtz numbers k0 based on the plate length. However, at low k0, finite elastic plates produce only modest reductions or, in cases related to structural resonance, an increase to the scattered sound level relative to the rigid case. Porosity, on the other hand, is shown to be more effective in reducing the radiated sound for low k0. The combined beneficial effects of elasticity and porosity are shown to be effective in reducing the scattered sound for a broader range of k0 for perforated elastic plates.
Inelastic Scattering Of Electrons By Protons
DOE R&D Accomplishments Database
Cone, A. A.; Chen, K. W.; Dunning, J. R. Jr.; Hartwig, G.; Ramsey, N. F.; Walker, J. K.; Wilson, R.
1966-12-01
The inelastic scattering of electrons by protons has been measured at incident electron energies up to 5 BeV/c and momentum transfers q{sup 2}=4(BeV/c){sup 2}. Excitation of known nucleon resonances at M=1238, 1512, 1688 and possibly 1920 MeV have been observed. The calculations for the resonance at M=1238 MeV have been compared with calculations by Adler based on the dispersion theory of Chew, Goldberger, Low and Nambu. The agreement is good. Qualitative models are discussed for the other resonances.
Andrei V. Afanasev; Stanley J. Brodsky; Carl E. Carlson; Yu-Chun Chen; Marc Vanderhaeghen
2005-01-01
We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer by using a quark-parton representation of virtual Compton scattering. We thus can relate the two-photon exchange amplitude to the generalized parton distributions which also enter in other wide angle scattering processes. We find that the interference of one- and two-photon exchange contribution is able to substantially resolve the difference between electric form factor measurements from Rosenbluth and polarization transfer experiments.
Measurement of proton inelastic scattering cross sections on fluorine
NASA Astrophysics Data System (ADS)
Chiari, M.; Caciolli, A.; Calzolai, G.; Climent-Font, A.; Lucarelli, F.; Nava, S.
2016-10-01
Differential cross-sections for proton inelastic scattering on fluorine, 19F(p,p')19F, from the first five excited levels of 19F at 110, 197, 1346, 1459 and 1554 keV were measured for beam energies from 3 to 7 MeV at a scattering angle of 150° using a LiF thin target (50 μg/cm2) evaporated on a self-supporting C thin film (30 μg/cm2). Absolute differential cross-sections were calculated with a method not dependent on the absolute values of collected beam charge and detector solid angle. The validity of the measured inelastic scattering cross sections was then tested by successfully reproducing EBS spectra collected from a thick Teflon (CF2) target. As a practical application of these measured inelastic scattering cross sections in elastic backscattering spectroscopy (EBS), the feasibility of quantitative light element (C, N and O) analysis in aerosol particulate matter samples collected on Teflon by EBS measurements and spectra simulation is demonstrated.
Transformational Acoustics Applied to Scattering from a Thin Elastic Shell
2011-06-01
invariant form.” New Journal of Physics, 8 (248), 2006. [6] H. Chen and C. T. Chan. “ Acoustic cloaking in three dimensions using acoustic metamaterials ...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS TRANSFORMATIONAL ACOUSTICS APPLIED TO SCATTERING FROM A THIN ELASTIC SHELL by Ana Margarida R...Prescribed by ANSI Std. Z39.18 22–6–2011 Master’s Thesis 2102-06-01—2104-10-31 Transformational Acoustics Applied to Scattering From a Thin Elastic
Measuring the 2{gamma} Exchange Effect in Electron-Proton Scattering at CLAS
Bennett, Robert Paul
2011-10-24
Recent results from experiments at Jefferson Laboratory, Newport News VA, which measure the ratio of the electric to magnetic form factors of the proton, G{sub E}/G{sub M}, have forced us to reexamine the single photon exchange approximation in lepton-proton elastic scattering. Discrepancies between the ratio obtained via the time-tested Rosenbluth separation method and new polarization transfer measurements, which differ by as much as a factor of three, may be resolved by considering the effect of two photon exchange (TPE). Theoretical corrections for the TPE effect are difficult due to the large number of excited nucleon states that can contribute to the process. The TPE effect can, however, be determined directly by measuring the ratio of the positron-proton to electron-proton elastic scattering cross sections, R = {sigma}(e{sup +})/{sigma}(e{sup -}), since the TPE effect changes sign with the charge of the incident particle. The CLAS TPE experiment at Jefferson Laboratory, will determine the effect of two-photon exchange in elastic lepton-proton scattering by precisely measuring the ratio of positron-proton to electron-proton elastic cross sections over a large kinematic range (0.1<{epsilon}<0.96, 0.02{<=}Q{sup 2}{<=}2.0). We will accomplish this by directing the 5.5 GeV primary electron beam, provided by the Continuous Electron Beam Accelerator Facility (CEBAF), onto a set of radiators and converters to produce simultaneous and identical beams of electron and positrons. Acceptance and efficiency concerns are minimized by only considering the ratios of the elastic cross sections and switching polarity of magnets in the beam line and the spectrometer. Guided by the results of a short 2006 test run and extensive GEANT based modeling, new shielding and beam line components were designed to maximize luminosity. The unique experimental design and challenges of the TPE experiment and the projected luminosities will be presented.
12C+p resonant elastic scattering in the Maya active target
NASA Astrophysics Data System (ADS)
Sambi, S.; Raabe, R.; Borge, M. J. G.; Caamano, M.; Damoy, S.; Fernández-Domínguez, B.; Flavigny, F.; Fynbo, H.; Gibelin, J.; Grinyer, G. F.; Heinz, A.; Jonson, B.; Khodery, M.; Nilsson, T.; Orlandi, R.; Pancin, J.; Perez-Loureiro, D.; Randisi, G.; Ribeiro, G.; Roger, T.; Suzuki, D.; Tengblad, O.; Thies, R.; Datta, U.
2015-03-01
In a proof-of-principle measurement, the Maya active target detector was employed for a 12C( p, p) resonant elastic scattering experiment in inverse kinematics. The excitation energy region from 0 to 3MeV above the proton breakup threshold in 13N was investigated in a single measurement. By using the capability of the detector to localize the reaction vertex and record the tracks of the recoiling protons, data covering a large solid angle could be utilized, at the same time keeping an energy resolution comparable with that of direct-kinematics measurements. The excitation spectrum in 13N was fitted using the R-matrix formalism. The level parameters extracted are in good agreement with previous studies. The active target proved its potential for the study of resonant elastic scattering in inverse kinematics with radioactive beams, when detection efficiency is of primary importance.
Test of 600 and 750 MeV NN matrix on elastic scattering Glauber model calculations
NASA Astrophysics Data System (ADS)
Brissaud, I.
1980-09-01
The 600 and 750 MeV proton nucleus elastic scattering cross section and polarization calculations have been performed in the framework of the Glauber model to test the pp and pn scattering amplitudes deduced from a phase shift analysis by Bystricky, Lechanoine and Lehar. It is well known that up to now we do not possess a non-phenomenological NN scattering matrix at intermediate energies. However proton-nucleus scattering analyses are used to extract information about short range correlations1), Δ resonance2) or pion condensation presences)... etc. Most scattering calculations made at these energies have been done with phenomenological NN amplitudes having a gaussian q-dependence 10050_2005_Article_BF01438168_TeX2GIFE1.gif A(q) = {kσ }/{4π }(α + i) e^{ - β ^2 q^2 /2} and 10050_2005_Article_BF01438168_TeX2GIFE2.gif C(q) = {kσ }/{4π }iq(α + i) D_e - β ^2 q^2 /2 K and σ being respectively the projectile momentum and the total pN total cross section. The parameters α, β and D are badly known and are adjusted by fitting some specific reactions as p+4He elastic scattering4). Even when these amplitudes provide good fits to the data, our understanding of the dynamics of the scattering remains obscure.
Quasi-elastic neutron scattering studies of protein dynamics
Rorschach, H.E.
1993-05-25
Results that shed new light on the study of protein dynamics were obtained by quasi-elastic neutron scattering. The triple axis instrument H-9 supplied by the cold source was used to perform a detailed study of the quasi-elastic spectrum and the Debye-Waller factor for trypsin in powder form, in solution, and in crystals. A preliminary study of myoglobin crystals was also done. A new way to view the results of quasi-elastic scattering experiments is sketched, and the data on trypsin are presented and analyze according to this new picture.
Elastic pd scattering at 316, 364, 470, and 590 MeV in the backward hemisphere.
NASA Technical Reports Server (NTRS)
Alder, J. C.; Dollhoff, W.; Lunke, C.; Perdrisat, C. F.; Roberts, W. K.; Kitching, P.; Moss, G.; Olsen, W. C.; Priest, J. R.
1972-01-01
The elastic pd differential cross section at center-of-mass angles between 91 and 164 deg was determined for 316, 364, 470, and 590 MeV proton scattering in a backward hemisphere. For the three largest energies, the cross sections were within 10% of each other at any given angle larger than 130 deg. The extrapolated 180 deg differential cross section remained nearly constant from 316 to 590 MeV.
Quasi-elastic nuclear scattering at high energies
NASA Technical Reports Server (NTRS)
Cucinotta, Francis A.; Townsend, Lawrence W.; Wilson, John W.
1992-01-01
The quasi-elastic scattering of two nuclei is considered in the high-energy optical model. Energy loss and momentum transfer spectra for projectile ions are evaluated in terms of an inelastic multiple-scattering series corresponding to multiple knockout of target nucleons. The leading-order correction to the coherent projectile approximation is evaluated. Calculations are compared with experiments.
Scattering of antiplane shear waves by layered circular elastic cylinder.
Cai, Liang-Wu
2004-02-01
An exact analytical solution for the scattering of antiplane elastic waves by a layered elastic circular cylinder is obtained. The solution and its degenerate cases are compared with other simpler models of circular cylindrical scatterers. The effects of the geometrical and physical properties of the interphase are studied. Numerical results confirm the existence of a resonance mode in which the scatterer's core undergoes a rigid-body motion when the outer layer of the scatterer is very compliant. This resonance mode has been attributed [Liu et al., Science 289, 1734 (2000)] to a new mechanism for the band gap formed in the extremely low frequency range for phononic crystals made of layered spherical scatterers. Numerical results also show the existence of a similar resonance mode when the outer layer of the scatterer has very high mass density.
Dissipation induced by phonon elastic scattering in crystals
Li, Guolong; Ren, Zhongzhou; Zhang, Xin
2016-01-01
We demonstrate that the phonon elastic scattering leads to a dominant dissipation in crystals at low temperature. The two-level systems (TLSs) should be responsible for the elastic scattering, whereas the dissipation induced by static-point defects (SPDs) can not be neglected. One purpose of this work is to show how the energy splitting distribution of the TLS ensemble affects the dissipation. Besides, this article displays the proportion of phonon-TLS elastic scattering to total phonon dissipation. The coupling coefficient of phonon-SPD scattering and the constant P0 of the TLS distribution are important that we estimate their magnitudes in this paper. Our results is useful to understand the phonon dissipation mechanism, and give some clues to improve the performance of mechanical resonators, apply the desired defects, or reveal the atom configuration in lattice structure of disordered crystals. PMID:27669517
Diffraction phenomena in elastic scattering of heavy ions
Kotlyar, V.V.; Shebeko, A.V.
1981-08-01
Nuclear diffraction phenomena in elastic scattering of heavy ions are studied in the intermediate energy range. Examination is carried out using the strong absorption models for the S-matrix in the angular momentum representation. New asymptotic expressions for the diffraction scattering amplitudes are obtained. The main attention is paid to the study of the relation between the Fresnel and the Fraunhofer parts of the amplitudes obtained in different regions of scattering angles.
Weak charge of the proton: loop corrections to parity-violating electron scattering
Wally Melnitchouk
2011-05-01
I review the role of two-boson exchange corrections to parity-violating elastic electron–proton scattering. Direct calculations of contributions from nucleon and Delta intermediate states show generally small, [script O](1–2%), effects over the range of kinematics relevant for proton strangeness form factor measurements. For the forward angle Qweak experiment at Jefferson Lab, which aims to measure the weak charge of the proton, corrections from the gammaZ box diagram are computed within a dispersive approach and found to be sizable at the E~1 GeV energy scale of the experiment.
NASA Astrophysics Data System (ADS)
Deur, Alexandre
1999-10-01
The Jefferson Lab beam energy measurement in Hall A using the elastic ep scattering will be described. This new, non-magnetic, energy measurement method allows a ( triangle E/E=10-4 ) precision. First-order corrections are canceled by the measurements of the electron and proton scattering angles for two symmetric kinematics. The measurement principle will be presented as well as the device and measurement results. Comparison with independent magnetic energy measurements of the same accuracy will be shown. This project is the result of a collaboration between the LPC: université Blaise Pascal/in2p3), Saclay and Jefferson Lab.
Measurement of the Wolfenstein parameters for proton-proton and proton-neutron scattering at 500 MeV
Marshall, J.A.
1984-07-01
Using liquid hydrogen and liquid deuterium targets respectively, forward angle (ten degrees to sixty degrees in the center of Mass) free proton-proton and quasielastic proton-proton and proton-neutron triple scattering data at 500 MeV have been obtained using the high resolution spectrometer at the Los Alamos Meson Physics Facility. The data are in reasonable agreement with recent predictions from phase shift analyses, indicating that the proton-nucleon scattering amplitudes are fairly well determined at 500 MeV. 32 references.
Elastic np → np( pn) scattering at intermediate energies
NASA Astrophysics Data System (ADS)
Troyan, Yu. A.; Anikina, M. Kh.; Belyaev, A. V.; Ierusalimov, A. P.; Troyan, A. Yu.
2014-03-01
The study of the elastic np → np( pn) scattering was carried out at the momenta of incident quasimonochromatic neutrons P 0 = 1.43, 2.23 and 5.20 GeV/ c. The differential cross sections of the processes of elastic np scattering, both without (cos Φ* p < 0) and with charge exchange (cos Φ* p >0) of nucleons, are analyzed. The results are compared with the data of other experiments. The suggested pole model takes into account exchange by π meson, ρ meson, and includes the peripheral exchange mechanism. This model permits one to get a good description of the data of elastic np scattering at the energy region 1-10 GeV.
Effective field theory for large logarithms in radiative corrections to electron proton scattering
NASA Astrophysics Data System (ADS)
Hill, Richard J.
2017-01-01
Radiative corrections to elastic electron proton scattering are analyzed in effective field theory. A new factorization formula identifies all sources of large logarithms in the limit of large momentum transfer, Q2≫me2. Explicit matching calculations are performed through two-loop order. A renormalization analysis in soft-collinear effective theory is performed to systematically compute and resum large logarithms. Implications for the extraction of charge radii and other observables from scattering data are discussed. The formalism may be applied to other lepton-nucleon scattering and e+e- annihilation processes.
Elastic electron scattering from formic acid
Trevisan, Cynthia S.; Orel, Ann E.; Rescigno, Thomas N.
2006-07-31
Following our earlier study on the dynamics of low energy electron attachment to formic acid, we report the results of elastic low-energy electron collisions with formic acid. Momentum transfer and angular differential cross sections were obtained by performing fixed-nuclei calculations employing the complex Kohn variational method. We make a brief description of the technique used to account for the polar nature of this polyatomic target and compare our results with available experimental data.
Study of 11Li and 10,11Be nuclei through elastic scattering and breakup reactions
NASA Astrophysics Data System (ADS)
Gaidarov, M. K.; Lukyanov, V. K.; Kadrev, D. N.; Zemlyanaya, E. V.; Antonov, A. N.; Lukyanov, K. V.; Spasova, K.
2016-01-01
The hybrid model of the microscopic optical potential (OP) is applied to calculate the 11Li+p, 10,11Be+p, and 10,11Be+12C elastic scattering cross sections at energies E < 100 MeV/nucleon. The OP's contain the folding-model real part (ReOP) with the direct and exchange terms included, while its imaginary part (ImOP) is derived within the high-energy approximation (HEA) theory. For the 11Li+p elastic scattering, the microscopic large-scale shell model (LSSM) density of 11Li is used, while the density distributions of 10,11Be nuclei obtained within the quantum Monte Carlo (QMC) model and the generator coordinate method (GCM) are utilized to calculate the microscopic OPs and cross sections of elastic scattering of these nuclei on protons and 12C. The depths of the real and imaginary parts of OP are fitted to the elastic scattering data, being simultaneously adjusted to reproduce the true energy dependence of the corresponding volume integrals. Also, the cluster models, in which 11Li consists of 2n-halo and the 9Li core having its own LSSM form of density and 11Be consists of a n-halo and the 10Be core, are adopted. Within the latter, we give predictions for the longitudinal momentum distributions of 9Li fragments produced in the breakup of 11Li at 62 MeV/nucleon on a proton target. It is shown that our results for the diffraction and stripping reaction cross sections in 11Be scattering on 9Be, 93Nb, 181Ta, and 238U targets at 63 MeV/nucleon are in a good agreement with the available experimental data.
Elastic scattering of electrons from Rb, Cs and Fr atoms
NASA Astrophysics Data System (ADS)
Gangwar, R. K.; Tripathi, A. N.; Sharma, L.; Srivastava, R.
2010-04-01
Differential, integrated elastic, momentum-transfer and total cross sections as well as differential S, T and U spin parameters for scattering of electrons from rubidium, caesium and francium atoms in the incident energy range up to 300 eV are calculated using a relativistic Dirac equation. The projectile electron-target atom interaction is represented by both real and complex parameter-free optical potentials for obtaining the solution of a Dirac equation for scattered electrons. The Dirac-Fock wavefunctions have been used to represent the Rb, Cs and Fr target atoms. The results of differential cross sections and spin asymmetry parameter S for e-Rb and e-Cs have been compared with the available experimental and theoretical results. Detailed results are reported for the elastic scattering of electrons from the ground states of a francium atom for the first time in the wide range of incident electron energies. The results of electron-Fr elastic scattering show the similar features to those obtained in the case of e-Rb and e-Cs elastic scattering.
Elastic and Viscoelastic Wave Scattering and Diffraction.
1981-01-01
scattering and diffration at various discon- tinuities is dicsussed by Keller(1958, 1962), Keller and Karal(1964) and Kouyoumjian (1975). Excellent...and the receiver are kept far enough from each end of the cylinder so that diffrations from the ends do not interfere with the arrivals of pri- mary
Differential cross sections for positron-xenon elastic scattering
Marler, J. P.; Surko, C. M.; McEachran, R. P.; Stauffer, A. D.
2006-06-15
Absolute measurements of differential cross sections for the elastic scattering of positrons from xenon are made at 2, 5 and 8 eV using a trap-based beam and the technique of measuring scattering cross sections in a strong magnetic field. Calculations are carried out using the relativistic Dirac equations with a static plus polarization potential. Generally good absolute agreement is found between experiment and theory.
Beam normal spin asymmetry in elastic lepton-nucleon scattering
M. Gorchtein; P.A.M. Guichon; M. Vanderhaeghen
2004-04-01
We discuss the two-photon exchange contribution to observables which involve lepton helicity flip in elastic lepton-nucleon scattering. This contribution is accessed through the spin asymmetry for a lepton beam polarized normal to the scattering plane. We estimate this beam normal spin asymmetry at large momentum transfer using a parton model and we express the corresponding amplitude in terms of generalized parton distributions.
Energy distribution of elastically scattered electrons from double layer samples
NASA Astrophysics Data System (ADS)
Tőkési, K.; Varga, D.
2016-02-01
We present a theoretical description of the spectra of electrons elastically scattered from thin double layered Au-C samples. The analysis is based on the Monte Carlo simulation of the recoil and Doppler effects in reflection and transmission geometries of the scattering at a fixed angle of 44.3 ° and a primary energy of 40 keV. The relativistic correction is taken into account. Besides the experimentally measurable energy distributions the simulations give many partial distributions separately, depending on the number of elastic scatterings (single, and multiple scatterings of different types). Furthermore, we present detailed analytical calculations for the main parameters of the single scattering, taking into account both the ideal scattering geometry, i.e. infinitesimally small angular range, and the effect of the real, finite angular range used in the measurements. We show our results for intensity ratios, peak shifts and broadenings for four cases of measurement geometries and layer thicknesses. While in the peak intensity ratios of gold and carbon for transmission geometries were found to be in good agreement with the results of the single scattering model, especially large deviations were obtained in reflection geometries. The separation of the peaks, depending on the geometry and the thickness, generally smaller, and the peak width generally larger than it can be expected from the nominal values of the primary energy, scattering angle, and mean kinetic energy of the atoms. We also show that the peaks are asymmetric even for the case of the single scattering due to the finite solid angle. Finally, we present a qualitative comparison with the experimental data. We find our resulting energy distribution of elastically scattered electrons to be in good agreement with recent measurements.
Contraband detection via neutron elastic scattering
Gomberg, H.J.; Charatis, G.; Brundage, J.
1993-04-01
Reliable detection of explosives and narcotics depends on generating signatures of compounds which characterize them. Major explosives and also alkaloid narcotics contain unique concentrations of Carbon (C), Nitrogen (N), and Oxygen (O). The kinematic energy shifts of neutrons scattered through angles larger than 140{degrees} allows separate determinations of C, N, and O; ratios of N/C and O/C together give clear signatures of the presence of plastic explosives or narcotics. The ability to detect these signatures under conditions similar to those that would obtain for airport screening has been demonstrated for neutrons for energies less {le} 3 MeV. Strong N resonances and a deep window for scattering from O enhance the confidence of element quantification. Detection of contraband in large cargo containers presents a much more difficult problem. Use of higher energy neutrons is now being tested for shielding penetration, so narcotic signatures could be identified behind the shielding of cargo containers. Scattered neutron spectra, or {open_quotes}signatures{close_quotes} of different organic compounds will be presented.
Microscopic cluster model analysis of 14O+p elastic scattering
NASA Astrophysics Data System (ADS)
Baye, D.; Descouvemont, P.; Leo, F.
2005-08-01
The 14O+p elastic scattering is discussed in detail in a fully microscopic cluster model. The 14O cluster is described by a closed p shell for protons and a closed p3/2 subshell for neutrons in the translation-invariant harmonic-oscillator model. The exchange and spin-orbit parameters of the effective forces are tuned on the energy levels of the 15C mirror system. With the generator-coordinate and microscopic R-matrix methods, phase shifts and cross sections are calculated for the 14O+p elastic scattering. An excellent agreement is found with recent experimental data. A comparison is performed with phenomenological R-matrix fits. Resonances properties in 15F are discussed.
Microscopic cluster model analysis of {sup 14}O+p elastic scattering
Baye, D.; Descouvemont, P.; Leo, F.
2005-08-01
The {sup 14}O+p elastic scattering is discussed in detail in a fully microscopic cluster model. The {sup 14}O cluster is described by a closed p shell for protons and a closed p3/2 subshell for neutrons in the translation-invariant harmonic-oscillator model. The exchange and spin-orbit parameters of the effective forces are tuned on the energy levels of the {sup 15}C mirror system. With the generator-coordinate and microscopic R-matrix methods, phase shifts and cross sections are calculated for the {sup 14}O+p elastic scattering. An excellent agreement is found with recent experimental data. A comparison is performed with phenomenological R-matrix fits. Resonances properties in {sup 15}F are discussed.
Elastic and inelastic scattering of 50-MeV pions from 28Si and 30Si
NASA Astrophysics Data System (ADS)
Wienands, U.; Hessey, N.; Barnett, B. M.; Rozon, F. M.; Roser, H. W.; Altman, A.; Johnson, R. R.; Gill, D. R.; Smith, G. R.; Wiedner, C. A.; Manley, D. M.; Berman, B. L.; Crawford, H. J.; Grion, N.
1987-02-01
Angular distributions of the differential cross section for elastic and inelastic scattering of 50-MeV π+ and π- on 28Si and 30Si have been measured to a relative accuracy of 5-10 We fitted the cross section of elastic π+ and π- scattering from 28Si simultaneously with an optical model using a second-order potential of the Michigan State University form. Our best-fit parameters differ from those given previously. The ratio of the neutron and proton transition-matrix elements for the first Jπ=2+ state in 28Si is found from the inelastic cross section to be 1.13+/-0.09. For 30Si, the ratio is found to be 0.93+/-0.09, which differs significantly from the value derived from lifetime measurements on mirror nuclei.
Precision Measurements of the Proton Elastic Form Factor Ratio
Douglas Higinbotham
2010-08-01
New high precision polarization measurements of the proton elastic form factor ratio in the Q^2 from 0.3 to 0.7 [GeV/c]^2 have been made. These elastic H(e,e'p) measurementswere done in Jefferson Lab's Hall A using 80% longitudinally polarized electrons and recoil polarimetry. For Q^2 greater than 1 [GeV/c]^2, previous polarization data indicated a strong deviation of the form factor ratio from unity which sparked renewed theoretical and experimental interest in how two-photon diagrams have been taken into account. The new high precision data indicate that the deviation from unity, while small, persists even at Q^2 less than 1 [GeV/c]^2.
High energy parton-parton elastic scattering in QCD
Tang, W.K.
1993-08-01
We show that the high energy limit of quark-quark, or gluon-gluon, elastic scattering is calculable in terms of the BFKL pomeron when {minus}t {much_gt} {Lambda}{sub QCD}{sup 2}. Surprisingly, this on-shell amplitudes does not have infrared divergences in the high energy limit.
Rayleigh scattering and nonlinear inversion of elastic waves
Gritto, Roland
1995-12-01
Rayleigh scattering of elastic waves by an inclusion is investigated and the limitations determined. In the near field of the inhomogeneity, the scattered waves are up to a factor of 300 stronger than in the far field, excluding the application of the far field Rayleigh approximation for this range. The investigation of the relative error as a function of parameter perturbation shows a range of applicability broader than previously assumed, with errors of 37% and 17% for perturbations of -100% and +100%, respectively. The validity range for the Rayleigh limit is controlled by large inequalities, and therefore, the exact limit is determined as a function of various parameter configurations, resulting in surprisingly high values of up to k_{p}R = 0.9. The nonlinear scattering problem can be solved by inverting for equivalent source terms (moments) of the scatterer, before the elastic parameters are determined. The nonlinear dependence between the moments and the elastic parameters reveals a strong asymmetry around the origin, which will produce different results for weak scattering approximations depending on the sign of the anomaly. Numerical modeling of cross hole situations shows that near field terms are important to yield correct estimates of the inhomogeneities in the vicinity of the receivers, while a few well positioned sources and receivers considerably increase the angular coverage, and thus the model resolution of the inversion parameters. The pattern of scattered energy by an inhomogeneity is complicated and varies depending on the object, the wavelength of the incident wave, and the elastic parameters involved. Therefore, it is necessary to investigate the direction of scattered amplitudes to determine the best survey geometry.
Acoustic scattering reduction using layers of elastic materials
NASA Astrophysics Data System (ADS)
Dutrion, Cécile; Simon, Frank
2017-02-01
Making an object invisible to acoustic waves could prove useful for military applications or measurements in confined space. Different passive methods have been proposed in recent years to avoid acoustic scattering from rigid obstacles. These techniques are exclusively based on acoustic phenomena, and use for instance multiple resonators or scatterers. This paper examines the possibility of designing an acoustic cloak using a bi-layer elastic cylindrical shell to eliminate the acoustic field scattered from a rigid cylinder hit by plane waves. This field depends on the dimensional and mechanical characteristics of the elastic layers. It is computed by a semi-analytical code modelling the vibrations of the coating under plane wave excitation. Optimization by genetic algorithm is performed to determine the characteristics of a bi-layer material minimizing the scattering. Considering an external fluid consisting of air, realistic configurations of elastic coatings emerge, composed of a thick internal orthotopic layer and a thin external isotropic layer. These coatings are shown to enable scattering reduction at a precise frequency or over a larger frequency band.
Nuclear rainbow in elastic scattering of {sup 9}Be nuclei
Glukhov, Yu. A. Ogloblin, A. A.; Artemov, K. P.; Rudakov, V. P.
2010-01-15
A systematic investigation of the elastic scattering of the {sup 9}Be nucleus, which is among themost loosely bound stable nuclei was performed.Differential cross sections for elastic {sup 9}Be + {sup 16}O scattering were measured at a c.m. energy of 47.5 MeV (beam of 132-MeV {sup 16}O nuclei). Available data at different energy values and data for neighboring nuclei were included in our analysis. As a result, the very fact of rainbow scattering was reliably established for the first time in systems involving {sup 9}Be. In addition, the analysis in question made it possible to identify Airy minima and to determine unambiguously the nucleus-nucleus potential with a high probability.
Elastic positron-cadmium scattering at low energies
Bromley, M. W. J.; Mitroy, J.
2010-05-15
The elastic and annihilation cross sections for positron-cadmium scattering are reported up to the positronium-formation threshold (at 2.2 eV). The low-energy phase shifts for the elastic scattering of positrons from cadmium were derived from the bound and pseudostate energies of a very large basis configuration-interaction calculation of the e{sup +}-Cd system. The s-wave binding energy is estimated to be 126{+-}42 meV, with a scattering length of A{sub scat}=(14.2{+-}2.1)a{sub 0}, while the threshold annihilation parameter, Z{sub eff}, was 93.9{+-}26.5. The p-wave phase shift exhibits a weak shape resonance that results in a peak Z{sub eff} of 91{+-}17 at a collision energy of about 490{+-}50 meV.
Precision Measurement of the Proton Elastic Cross Section at High Q2
NASA Astrophysics Data System (ADS)
Ou, Longwu; E12-07-108 Collaboration
2017-01-01
The measurement of proton electromagnetic form factors (FF) is a powerful way to understand the internal structure of proton and gain insight into the nature of the strong interaction. Current data of FF at high Q2 have large statistical and systematic uncertainties, which translate into large uncertainties in the extracted cross section in this kinematic range. The GMp experiment in Hall A at Jefferson Lab, starting from 2014, performed precision measurements of elastic ep scattering cross section in the Q2 range from 7 to 14 (GeV / c) 2. These measurements will improve the precision on the cross section in the covered Q2 range to about 2 % . They represent a great complement to the world's cross section data set and will be key inputs for future electromagnetic form factor experiments at similar kinematics. In this talk, the instrumentation and techniques used in the experiment will be described, and the current status of the analysis will be presented.
Low-Energy Elastic Electron Scattering by Atomic Oxygen
NASA Technical Reports Server (NTRS)
Zatsarinny O.; Bartschat, K.; Tayal, S. S.
2006-01-01
The B-spline R-matrix method is employed to investigate the low-energy elastic electron scattering by atomic oxygen. Flexible non-orthogonal sets of radial functions are used to construct the target description and to represent the scattering functions. A detailed investigation regarding the dependence of the predicted partial and total cross sections on the scattering model and the accuracy of the target description is presented. The predicted angle-integrated elastic cross sections are in good agreement with experiment, whereas significant discrepancies are found in the angle-differential elastic cross sections near the forward direction. .The near-threshold results are found to strongly depend on the treatment of inner-core short-range correlation effects in the target description, as well as on a proper account of the target polarizability. A sharp increase in the elastic cross sections below 1 eV found in some earlier calculations is judged to be an artifact of an unbalanced description of correlation in the N-electron target structure and the (N+l)-electron-collision problems.
Strange Quark Contribution to the Proton Spin, from Elastic $\\vecep$ and $\
Stephen Pate
2006-10-02
The strangeness contribution to the vector and axial form factors of the proton is presented for momentum transfers in the range 0.45 < Q{sup 2} < 1.0 GeV{sup 2}. The results are obtained via a combined analysis of forward-scattering parity-violating elastic {rvec e}p asymmetry data from the G0 and HAPPEx experiments at Jefferson Lab, and elastic {nu}p and {bar {nu}}p scattering data from Experiment 734 at Brookhaven National Laboratory. The combination of the two data sets allows for the simultaneous extraction of G{sub E}{sup s}, G{sub M}{sup s}, and G{sub A}{sup s} over a significant range of Q{sup 2} for the very first time. Determination of the strange axial form factor G{sub A}{sup s} is vital to an understanding of the strange quark contribution to the proton spin.
The Proton Coulomb Form Factor from Polarized Inclusive e-p Scattering
Harris, Christopher Matthew
2001-05-01
The proton form factors provide information on the fundamental properties of the proton and provide a test for models based on QCD. In 1998 at Jefferson Lab (JLAB) in Newport News, VA, experiment E93026 measured the inclusive e-p scattering cross section from a polarized ammonia (^{15}NH_{3}) target at a four momentum transfer squared of Q^{2} = 0.5 (GeV/c)^{2}. Longitudinally polarized electrons were scattered from the polarized target and the scattered electron was detected. Data has been analyzed to obtain the asymmetry from elastically scattered electrons from hydrogen in ^{15}NH_{3}. The asymmetry, A_{p}, has been used to determine the proton elastic form factor G_{Ep}. The result is consistent with the dipole model and data from previous experiments. However, due to the choice of kinematics, the uncertainty in the measurement is large.
Tensor polarization in pion-deuteron elastic scattering
Holt, R.J.
1983-01-01
The angular dependence of the tensor polarization t/sub 20//sup lab/ of recoiling deuterons in ..pi..-d elastic scattering was measured as a function of incident pion energy in the range 134 to 256 MeV. No evidence was found for rapid energy or angular dependences in t/sub 20//sup lab/. The results agree most favorably with theoretical calculations in which the P/sub 11/ ..pi..-N amplitude has been removed altogether. This agreement is consistent with a small effect of pion absorption on the elastic channel. 14 references.
Scattering of time-harmonic elastic waves by an elastic inclusion with quadratic nonlinearity.
Tang, Guangxin; Jacobs, Laurence J; Qu, Jianmin
2012-04-01
This paper considers the scattering of a plane, time-harmonic wave by an inclusion with heterogeneous nonlinear elastic properties embedded in an otherwise homogeneous linear elastic solid. When the inclusion and the surrounding matrix are both isotropic, the scattered second harmonic fields are obtained in terms of the Green's function of the surrounding medium. It is found that the second harmonic fields depend on two independent acoustic nonlinearity parameters related to the third order elastic constants. Solutions are also obtained when these two acoustic nonlinearity parameters are given as spatially random functions. An inverse procedure is developed to obtain the statistics of these two random functions from the measured forward and backscattered second harmonic fields.
Precision Rosenbluth measurement of the proton elastic form factors
I. A. Qattan; J. Arrington; R. E. Segel; X. Zheng; K. Aniol; O. K. Baker; R. Beams; E. J. Brash; J. Calarco; A. Camsonne; J.-P. Chen; M. E. Christy; D. Dutta; R. Ent; S. Frullani; D. Gaskell; O. Gayou; R. Gilman; C. Glashausser; K. Hafidi; J.-O. Hansen; D. W. Higinbotham; W. Hinton; R. J. Holt; G. M. Huber; H. Ibrahim; L. Jisonna; M. K. Jones; C. E. Keppel; E. Kinney; G. J. Kumbartzki; A. Lung; D. J. Margaziotis; K. McCormick; D. Meekins; R. Michaels; P. Monaghan; P. Moussiegt; L. Pentchev; C. Perdrisat; V. Punjabi; R. Ransome; J. Reinhold; B. Reitz; A. Saha; A. Sarty; E. C. Schulte; K. Slifer; P. Solvignon; V. Sulkosky; K. Wijesooriya; B. Zeidman
2004-10-01
We report the results of a new Rosenbluth measurement of the proton form factors at Q{sup 2} values of 2.64, 3.20 and 4.10 GeV{sup 2}. Cross sections were determined by detecting the recoiling proton in contrast to previous measurements in which the scattered electron was detected. At each Q{sup 2}, relative cross sections were determined to better than 1%. The measurement focused on the extraction of G{sub E}/G{sub M} which was determined to 4-8% and found to approximate form factor scaling, i.e. {mu}{sub p}G{sub E} {approx} G{sub M}. These results are consistent with and much more precise than previous Rosenbluth extractions. However, they are inconsistent with recent polarization transfer measurements of comparable precision, implying a systematic difference between the two techniques.
Three-body calculation of elastic and inelastic scattering of deuterons on 24Mg
NASA Astrophysics Data System (ADS)
Deltuva, A.
2016-03-01
Deuteron-nucleus scattering is described using exact three-particle equations. The theory is formulated in an extended Hilbert space allowing the excitation of the target nucleus. Alt, Grassberger, and Sandhas equations for transition operators are solved in the momentum-space framework including the Coulomb interaction via the screening and renormalization method. The calculations are performed for elastic and inelastic scattering of deuterons on 24Mg using the rotational model for the excitation potential. A reasonable agreement with the experimental data for the first excited state 2+ of 24Mg is achieved when the quadrupole deformation parameter β2 = 0.47 is used. This new value is more consistent with the inelastic proton scattering data requiring β2 ≈ 0.5 than previous determinations β2 ≈ 0.4 based on two-body deuteron-nucleus models.
Measuring the 2-gamma Exchange Effect in Electron-Proton Scattering at CLAS
Bennett, Robert
2011-10-01
Recent results from experiments at Jefferson Laboratory, Newport News VA, which measure the ratio of the electric to magnetic form factors of the proton, G{sub E}/G{sub M}, have forced us to reexamine the single photon exchange approximation in lepton-proton elastic scattering. Discrepancies between the ratio obtained via the time-tested Rosenbluth separation method and new polarization transfer measurements, which differ by as much as a factor of three, may be resolved by considering the effect of two photon exchange (TPE). Theoretical corrections for the TPE effect are difficult due to the large number of excited nucleon states that can contribute to the process. The TPE effect can, however, be determined directly by measuring the ratio of the positron-proton to electron-proton elastic scattering cross sections, R = {sigma}(e{sup +})/{sigma}(e{sup -}), since the TPE effect changes sign with the charge of the incident particle. The CLAS TPE experiment at Jefferson Laboratory, will determine the effect of two-photon exchange in elastic lepton-proton scattering by precisely measuring the ratio of positron-proton to electron-proton elastic cross sections over a large kinematic range (0.1 < {var_epsilon} < 0.96, 0.02 {le} Q{sup 2} {le} 2.0). We will accomplish this by directing the 5.5 GeV primary electron beam, provided by the Continuous Electron Beam Accelerator Facility (CEBAF), onto a set of radiators and converters to produce simultaneous and identical beams of electron and positrons. Acceptance and efficiency concerns are minimized by only considering the ratios of the elastic cross sections and switching polarity of magnets in the beam line and the spectrometer. Guided by the results of a short 2006 test run and extensive GEANT based modeling, new shielding and beam line components were designed to maximize luminosity. The unique experimental design and challenges of the TPE experiment and the projected luminosities will be presented.
Measurement of Neutrino-Nucleon Neutral-Current Elastic Scattering Cross-section at SciBooNE
Takei, Hideyuki
2009-02-01
In this thesis, results of neutrino-nucleon neutral current (NC) elastic scattering analysis are presented. Neutrinos interact with other particles only with weak force. Measurement of cross-section for neutrino-nucleon reactions at various neutrino energy are important for the study of nucleon structure. It also provides data to be used for beam flux monitor in neutrino oscillation experiments. The cross-section for neutrino-nucleon NC elastic scattering contains the axial vector form factor G_{A}(Q^{2}) as well as electromagnetic form factors unlike electromagnetic interaction. G_{A} is propotional to strange part of nucleon spin (Δs) in Q^{2} → 0 limit. Measurement of NC elastic cross-section with smaller Q^{2} enables us to access Δs. NC elastic cross-sections of neutrino-nucleon and antineutrino-nucleon were measured earlier by E734 experiment at Brookheaven National Laboratory (BNL) in 1987. In this experiment, cross-sections were measured in Q^{2} > 0.4 GeV^{2} region. Result from this experiment was the only published data for NC elastic scattering cross-section published before our experiment. SciBooNE is an experiment for the measurement of neutrino-nucleon scattering cross-secitons using Booster Neutrino Beam (BNB) at FNAL. BNB has energy peak at 0.7 GeV. In this energy region, NC elastic scattering, charged current elastic scattering, charged current pion production, and neutral current pion production are the major reaction branches. SciBar, electromagnetic calorimeter, and Muon Range Detector are the detectors for SciBooNE. The SciBar consists of finely segmented scintillators and 14336 channels of PMTs. It has a capability to reconstruct particle track longer than 8 cm and separate proton from muons and pions using energy deposit information. Signal of NC elastic scattering is a single proton track. In vp → vp process, the recoil proton is detected. On the other hand, most of vn → vn is
Relativistic effects in elastic scattering of electrons in TEM.
Rother, Axel; Scheerschmidt, Kurt
2009-01-01
Transmission electron microscopy typically works with highly accelerated thus relativistic electrons. Consequently the scattering process is described within a relativistic formalism. In the following, we will examine three different relativistic formalisms for elastic electron scattering: Dirac, Klein-Gordon and approximated Klein-Gordon, the standard approach. This corresponds to a different consideration of spin effects and a different coupling to electromagnetic potentials. A detailed comparison is conducted by means of explicit numerical calculations. For this purpose two different formalisms have been applied to the approaches above: a numerical integration with predefined boundary conditions and the multislice algorithm, a standard procedure for such simulations. The results show a negligibly small difference between the different relativistic equations in the vicinity of electromagnetic potentials, prevailing in the electron microscope. The differences between the two numeric approaches are found to be small for small-angle scattering but eventually grow large for large-angle scattering, recorded for instance in high-angle annular dark field.
Dual-ring scattering method for proton beam spreading
NASA Astrophysics Data System (ADS)
Takada, Yoshihisa
1994-01-01
A dual-ring double scattering method has been proposed to obtain a large uniform beam field in the proton rotating gantry used for cancer treatment. This method makes it possible to reduce the distance for beam field formation and to use the larger part of the beam. A flat beam field can be formed at a position on the patient by scattering the beam more strongly at the inner part of the dual-ring second scatterer than the outer part.
Proton-proton Scattering Above 3 GeV/c
A. Sibirtsev, J. Haidenbauer, H.-W. Hammer S. Krewald ,Ulf-G. Meissner
2010-01-01
A large set of data on proton-proton differential cross sections, analyzing powers and the double-polarization parameter A{sub NN} is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3 GeV/c to 50 GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the {rho}, {omega}, f{sub 2}, and a{sub 2} trajectories and single-Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model.
Elastic scattering and breakup of 11Be on deuterons at 26.9 A MeV
NASA Astrophysics Data System (ADS)
Chen, J.; Lou, J. L.; Ye, Y. L.; Rangel, J.; Moro, A. M.; Pang, D. Y.; Li, Z. H.; Ge, Y. C.; Li, Q. T.; Li, J.; Jiang, W.; Sun, Y. L.; Zang, H. L.; Zhang, Y.; Aoi, N.; Ideguchi, E.; Ong, H. J.; Lee, J.; Wu, J.; Liu, H. N.; Wen, C.; Ayyad, Y.; Hatanaka, K.; Tran, T. D.; Yamamoto, T.; Tanaka, M.; Suzuki, T.; Nguyen, T. T.
2016-12-01
The elastic scattering and breakup reactions of the halo nucleus 11Be on deuterons at an incident energy of 26.9 A MeV are reported for the first time. Special attention has been paid to the determination and subtraction of the proton contaminations in the deuterated polyethylene (CD2)n target (where D2 denotes H22 ). The cross sections for elastic scattering are analyzed with the systematic optical potentials of Daehnick et al. and DA1p, as well as with single-folding potentials, derived from the Jeukenne-Lejeune-Mahaux effective nucleon-nucleon interaction. An extended version of the continuum-discretized coupled-channels (XCDCC) formalism, including dynamic core excitation (DCX) effects, is applied to analyze the elastic scattering and breakup data. Comparisons of the full XCDCC calculation with that omitting DCX effects indicate that the core excitation plays a remarkable role in reproducing breakup reactions of 11Be+d .
Low-energy elastic differential scattering of He/++/ by He.
NASA Technical Reports Server (NTRS)
Lam, S. K.; Doverspike, L. D.; Champion, R. L.
1973-01-01
Experimental results are developed for the relative elastic differential scattering of He(++) by He for collision energies in the range 4 equal to or less than E equal to or less than 75 eV. In the analysis of the data, semiclassical considerations are utilized, assuming that the dynamics of the scattering is governed solely by the B and E states of He2(++). It is shown that existing ab initio calculations for the intermolecular potentials predict differential cross sections which are not in particularly good agreement with the experimental data.
Ultracold elastic H(bar sign)-He scattering
Sinha, Prabal K.; Ghosh, A. S.
2003-08-01
In view of the current interest in trapping antihydrogen H(bar sign) atoms below 1 K, the s-wave elastic-scattering parameters for the antihydrogen scattering off atomic helium target are calculated in the energy range 1x10{sup -16}-1x10{sup -2} a.u. using close-coupling models. The predicted cross section will help to simulate the evolution of a realistic mixture of He and H{sub 2} through the process involving ejection of H(bar sign) from the trap. The trend of the present results with different basis sets conclusively indicates the reliability of the predicted results.
Measurement of neutrino flux from neutrino-electron elastic scattering
Park, J.; Aliaga, L.; Altinok, O.; Bellantoni, L.; Bercellie, A.; Betancourt, M.; Bodek, A.; Bravar, A.; Budd, H.; Cai, T.; Carneiro, M. F.; Christy, M. E.; Chvojka, J.; da Motta, H.; Dytman, S. A.; Díaz, G. A.; Eberly, B.; Felix, J.; Fields, L.; Fine, R.; Gago, A. M.; Galindo, R.; Ghosh, A.; Golan, T.; Gran, R.; Harris, D. A.; Higuera, A.; Kleykamp, J.; Kordosky, M.; Le, T.; Maher, E.; Manly, S.; Mann, W. A.; Marshall, C. M.; Martinez Caicedo, D. A.; McFarland, K. S.; McGivern, C. L.; McGowan, A. M.; Messerly, B.; Miller, J.; Mislivec, A.; Morfín, J. G.; Mousseau, J.; Naples, D.; Nelson, J. K.; Norrick, A.; Nuruzzaman,; Osta, J.; Paolone, V.; Patrick, C. E.; Perdue, G. N.; Rakotondravohitra, L.; Ramirez, M. A.; Ray, H.; Ren, L.; Rimal, D.; Rodrigues, P. A.; Ruterbories, D.; Schellman, H.; Solano Salinas, C. J.; Tagg, N.; Tice, B. G.; Valencia, E.; Walton, T.; Wolcott, J.; Wospakrik, M.; Zavala, G.; Zhang, D.
2016-06-10
Muon-neutrino elastic scattering on electrons is an observable neutrino process whose cross section is precisely known. Consequently, a measurement of this process in an accelerator-based ν_{μ} beam can improve the knowledge of the absolute neutrino flux impinging upon the detector; typically this knowledge is limited to ~10% due to uncertainties in hadron production and focusing. We also isolated a sample of 135±17 neutrino-electron elastic scattering candidates in the segmented scintillator detector of MINERvA, after subtracting backgrounds and correcting for efficiency. We show how this sample can be used to reduce the total uncertainty on the NuMI ν_{μ} flux from 9% to 6%. Finally, our measurement provides a flux constraint that is useful to other experiments using the NuMI beam, and this technique is applicable to future neutrino beams operating at multi-GeV energies.
Phenomenological models of elastic nucleon scattering and predictions for LHC
NASA Astrophysics Data System (ADS)
Kašpar, Jan; Kundrát, Vojtěch; Lokajíček, Miloš; Procházka, Jiří
2011-02-01
The hitherto analyses of elastic collisions of charged nucleons involving common influence of Coulomb and hadronic scattering have been based practically on West and Yennie formula. However, this approach has been shown recently to be inadequate from experimental as well as theoretical points of view. The eikonal model enabling to determine physical characteristics in impact parameter space seems to be more pertinent. The contemporary phenomenological models admit, of course, different distributions of collision processes in the impact parameter space and cannot give any definite answer. Nevertheless, some predictions for the planned LHC energy that have been given on their basis may be useful, as well as the possibility of determining the luminosity from elastic scattering.
Measurement of neutrino flux from neutrino-electron elastic scattering
Park, J.; Aliaga, L.; Altinok, O.; ...
2016-06-10
Muon-neutrino elastic scattering on electrons is an observable neutrino process whose cross section is precisely known. Consequently, a measurement of this process in an accelerator-based νμ beam can improve the knowledge of the absolute neutrino flux impinging upon the detector; typically this knowledge is limited to ~10% due to uncertainties in hadron production and focusing. We also isolated a sample of 135±17 neutrino-electron elastic scattering candidates in the segmented scintillator detector of MINERvA, after subtracting backgrounds and correcting for efficiency. We show how this sample can be used to reduce the total uncertainty on the NuMI νμ flux from 9%more » to 6%. Finally, our measurement provides a flux constraint that is useful to other experiments using the NuMI beam, and this technique is applicable to future neutrino beams operating at multi-GeV energies.« less
Measurement of neutrino flux from neutrino-electron elastic scattering
NASA Astrophysics Data System (ADS)
Park, J.; Aliaga, L.; Altinok, O.; Bellantoni, L.; Bercellie, A.; Betancourt, M.; Bodek, A.; Bravar, A.; Budd, H.; Cai, T.; Carneiro, M. F.; Christy, M. E.; Chvojka, J.; da Motta, H.; Dytman, S. A.; Díaz, G. A.; Eberly, B.; Felix, J.; Fields, L.; Fine, R.; Gago, A. M.; Galindo, R.; Ghosh, A.; Golan, T.; Gran, R.; Harris, D. A.; Higuera, A.; Kleykamp, J.; Kordosky, M.; Le, T.; Maher, E.; Manly, S.; Mann, W. A.; Marshall, C. M.; Martinez Caicedo, D. A.; McFarland, K. S.; McGivern, C. L.; McGowan, A. M.; Messerly, B.; Miller, J.; Mislivec, A.; Morfín, J. G.; Mousseau, J.; Naples, D.; Nelson, J. K.; Norrick, A.; Nuruzzaman; Osta, J.; Paolone, V.; Patrick, C. E.; Perdue, G. N.; Rakotondravohitra, L.; Ramirez, M. A.; Ray, H.; Ren, L.; Rimal, D.; Rodrigues, P. A.; Ruterbories, D.; Schellman, H.; Solano Salinas, C. J.; Tagg, N.; Tice, B. G.; Valencia, E.; Walton, T.; Wolcott, J.; Wospakrik, M.; Zavala, G.; Zhang, D.; Miner ν A Collaboration
2016-06-01
Muon-neutrino elastic scattering on electrons is an observable neutrino process whose cross section is precisely known. Consequently a measurement of this process in an accelerator-based νμ beam can improve the knowledge of the absolute neutrino flux impinging upon the detector; typically this knowledge is limited to ˜10 % due to uncertainties in hadron production and focusing. We have isolated a sample of 135 ±17 neutrino-electron elastic scattering candidates in the segmented scintillator detector of MINERvA, after subtracting backgrounds and correcting for efficiency. We show how this sample can be used to reduce the total uncertainty on the NuMI νμ flux from 9% to 6%. Our measurement provides a flux constraint that is useful to other experiments using the NuMI beam, and this technique is applicable to future neutrino beams operating at multi-GeV energies.
NASA Astrophysics Data System (ADS)
Biegun, A. K.; Takatsu, J.; Nakaji, T.; van Goethem, M. J.; van der Graaf, E. R.; Koffeman, E. N.; Visser, J.; Brandenburg, S.
2016-12-01
The novel proton radiography imaging technique has a large potential to be used in direct measurement of the proton energy loss (proton stopping power, PSP) in various tissues in the patient. The uncertainty of PSPs, currently obtained from translation of X-ray Computed Tomography (xCT) images, should be minimized from 3-5% or higher to less than 1%, to make the treatment plan with proton beams more accurate, and thereby better treatment for the patient. With Geant4 we simulated a proton radiography detection system with two position-sensitive and residual energy detectors. A complex phantom filled with various materials (including tissue surrogates), was placed between the position sensitive detectors. The phantom was irradiated with 150 MeV protons and the energy loss radiograph and scattering angles were studied. Protons passing through different materials in the phantom lose energy, which was used to create a radiography image of the phantom. The multiple Coulomb scattering of a proton traversing different materials causes blurring of the image. To improve image quality and material identification in the phantom, we selected protons with small scattering angles. A good quality proton radiography image, in which various materials can be recognized accurately, and in combination with xCT can lead to more accurate relative stopping powers predictions.
Guryn, W.
1998-02-01
The authors are describing an experiment to study proton-proton (pp) elastic scattering experiment at the Relativistic Heavy Ion Collider (RHIC). Using both polarized and unpolarized beams, the experiment will study pp elastic scattering from {radical}s = 50 GeV to {radical}s = 500 GeV in two kinematical regions. In the Coulomb Nuclear Interference (CNI) region, 0.0005 < {vert_bar}t{vert_bar} < 0.12 (GeV/c){sup 2}, they will measure and study the s dependence of the total and elastic cross sections, {sigma}{sub tot} and {sigma}{sub el}; the ratio of the real to the imaginary part of the forward elastic scattering amplitude, {rho}; and the nuclear slope parameter of the pp elastic scattering, b. In the medium {vert_bar}t{vert_bar}-region, {vert_bar}t{vert_bar} < 1.5 (GeV/c){sup 2}, they plan to study the evolution of the dip structure with s, as observed at ISR in the differential elastic cross section, d{sigma}{sub el}/dt, and the s and {vert_bar}t{vert_bar} dependence of b. With the polarized beams the following can be measured: the difference in the total cross sections as function of initial transverse spin states {Delta}{sigma}{sub T}, the analyzing power, A{sub N}, and the transverse spin correlation parameter A{sub NN}. The behavior of the analyzing power A{sub N} at RHIC energies in the dip region of d{sigma}{sub el}/dt, where a pronounced structure was found at fixed-target experiments will be studied. The relation of pp elastic scattering to the beam polarization measurement at RHIC is also discussed.
Deconstruction and elastic {pi}{pi} scattering in Higgsless models
Chivukula, R. Sekhar; Simmons, Elizabeth H.; He, Hong-Jian; Kurachi, Masafumi; Tanabashi, Masaharu
2007-02-01
We study elastic pion-pion scattering in global linear moose models and apply the results to a variety of Higgsless models in flat and anti-de Sitter (AdS) space using the equivalence theorem. In order to connect the global moose to Higgsless models, we first introduce a block-spin transformation which corresponds, in the continuum, to the freedom to perform coordinate transformations in the Higgsless model. We show that it is possible to make an 'f-flat' deconstruction in which all of the f-constants f{sub j} of the linear moose model are identical; the phenomenologically relevant f-flat models are those in which the coupling constants of the groups at either end of the moose are small--corresponding to the global linear moose. In studying pion-pion scattering, we derive various sum rules, including one analogous to the Kawarabayashi-Suzuki-Riazuddin-Fayyazuddin (KSRF) relation, and use them in evaluating the low-energy and high-energy forms of the leading elastic partial-wave scattering amplitudes. We obtain elastic unitarity bounds as a function of the mass of the lightest KK mode and discuss their physical significance.
Deconstruction and elastic ππ scattering in Higgsless models
NASA Astrophysics Data System (ADS)
Chivukula, R. Sekhar; Simmons, Elizabeth H.; He, Hong-Jian; Kurachi, Masafumi; Tanabashi, Masaharu
2007-02-01
We study elastic pion-pion scattering in global linear moose models and apply the results to a variety of Higgsless models in flat and anti-de Sitter (AdS) space using the equivalence theorem. In order to connect the global moose to Higgsless models, we first introduce a block-spin transformation which corresponds, in the continuum, to the freedom to perform coordinate transformations in the Higgsless model. We show that it is possible to make an “f-flat” deconstruction in which all of the f-constants fj of the linear moose model are identical; the phenomenologically relevant f-flat models are those in which the coupling constants of the groups at either end of the moose are small—corresponding to the global linear moose. In studying pion-pion scattering, we derive various sum rules, including one analogous to the Kawarabayashi-Suzuki-Riazuddin-Fayyazuddin (KSRF) relation, and use them in evaluating the low-energy and high-energy forms of the leading elastic partial-wave scattering amplitudes. We obtain elastic unitarity bounds as a function of the mass of the lightest KK mode and discuss their physical significance.
Elastic scattering measurements for {sup 7}Be+{sup 27}Al system at RIBRAS facility
Morcelle, V.; Lichtenthaeler, R.; Morais, M. C.; Lepine-Szily, A.; Guimaraes, V.; Faria, P. N. de; Gasques, L.; Pires, K. C. C.; Condori, R. P.; Gomes, P. R. S.; Lubian, J.; Mendes, D. R. Jr.; Barioni, A.; Shorto, J. M. B.; Zamora, J. C.
2013-05-06
Elastic scattering angular distribution measurements of {sup 7}Be+{sup 27}Al system were performed at the laboratory energy of 15.6 MeV. The {sup 7}Be secondary beam was produced by the proton transfer reaction {sup 3}He({sup 6}Li,{sup 7}Be) and impinged on {sup 27}Al and {sup 197}Au targets, using the Radioactive Ion Beam (RIB) facility, RIBRAS. The elastic angular distribution was obtained within the angular range of 15{sup 0} - 80{sup 0} at the center of mass frame. Optical model calculations have been performed using the Woods- Saxon form factors and the Sao Paulo potential to fit the experimental data. The total reaction cross section was derived.
NASA Astrophysics Data System (ADS)
Liu, Jianglai
2003-10-01
G^0 (JLab experiment E00-006, D.H. Beck, spokesperson.) is an experiment to study parity-violating (PV) elastic electron-proton scattering. The PV asymmetry of the scattering cross-section is sensitive to the contribution of strange quarks to the proton's electromagnetic structure. The first commissioning of the G0 hardware took place in late 2002/early 2003 in Hall C at Jefferson Lab, during which several days of asymmetry data were acquired. In this talk, a summary of the data analysis will be presented, as well as preliminary results from the two days of asymmetry running. The report will include a discussion of the statistical properties of the data and of the dominant systematic effects, including electronic deadtime, target density fluctuations, beam induced false asymmetry and background due to inelastic scattering.
A Double Scattering Analytical Model For Elastic Recoil Detection Analysis
Barradas, N. P.; Lorenz, K.; Alves, E.; Darakchieva, V.
2011-06-01
We present an analytical model for calculation of double scattering in elastic recoil detection measurements. Only events involving the beam particle and the recoil are considered, i.e. 1) an ion scatters off a target element and then produces a recoil, and 2) an ion produces a recoil which then scatters off a target element. Events involving intermediate recoils are not considered, i.e. when the primary ion produces a recoil which then produces a second recoil. If the recoil element is also present in the stopping foil, recoil events in the stopping foil are also calculated. We included the model in the standard code for IBA data analysis NDF, and applied it to the measurement of hydrogen in Si.
Quasi-elastic X-ray scattering divergence analysis calculation
NASA Astrophysics Data System (ADS)
Reid, John S.; Milne, Gordon J.
1989-08-01
A FORTRAN 77 program is described that enables a numerical investigation to be made of the variation of instrumental resolution corrections with apparatus configuration for quasi-elastic X-ray scattering. The program is useful for scattering from phonons, defects, low angle Comptom processes and all instances where the energy change on scattering is at most a small fraction of the incident energy. Account can be taken of an irregular incident beam distribution (in angle and in space), a sample crystal mosaic spread and a finite area detector. The numerical convolutions for each smearing effect are performed separately but cumulatively, allowing the effects of individual processes to be investigated or treated in variant fashion. The program provides a shell of organisation that could be adapted to related problems.
Contributions From yZ Box Diagrams to Parity Violating Elastic e-p Scattering
Benjamin Rislow, Carl Carlson
2011-06-01
Parity-violating (PV) elastic electron-proton scattering measures Q-weak for the proton, Q{sub W}{sup p}. To extract Q{sub W}{sup p} from data, all radiative corrections must be well-known. Recently, disagreement on the {gamma}Z box contribution to Q{sub W}{sup p} has prompted the need for further analysis of this term. Here, we support one choice of a debated factor, go beyond the previously assumed equality of electromagnetic and {gamma}Z structure functions, and find an analytic result for one of the {gamma}Z box integrals. Our numerical evaluation of the {gamma}Z box is in agreement within errors with previous reports, albeit somewhat larger in central value, and is within the uncertainty requirements of current experiments.
Constraining Proton-Dark Matter Scattering Using Cosmic Ray Measurements
NASA Astrophysics Data System (ADS)
Cappiello, Christopher; Ng, Kenny; Beacom, John
2017-01-01
Dark matter scattering cross sections with protons and electrons are largely unconstrained below a dark matter mass of 1 GeV. By considering propagation of cosmic rays through a region with the dark matter density of the Milky Way, we demonstrate that if electrons and protons scatter with dark matter, this interaction adds an energy loss term to the cosmic ray propagation equation. This energy loss term distorts the calculated cosmic ray spectra from the observed spectra. By fitting the calculated spectra to data, we can set limits on the proton and electron scattering cross sections for dark matter. Chris Cappiello was supported by both The Ohio State University and the Ohio State University Department of Physics. Kenny Ng and John Beacom were supported by NSF Grant PHY-1404311 to John Beacom.
A Microscopic Optical Potential Approach to {sup 6,8}He+p Elastic Scattering
Lukyanov, V. K.; Zemlyanaya, E. V.; Lukyanov, K. V.; Kadrev, D. N.; Antonov, A. N.; Gaidarov, M. K.; Massen, S. E.
2009-08-26
A microscopic approach to calculate the optical potential (OP) with the real part obtained by a folding procedure and with the imaginary part inherent in the high-energy approximation (HEA) is applied to study the {sup 6,8}He+p elastic scattering data at energies of tens of MeV/N. The OP's and the cross sections are calculated using different models for the neutron and proton densities of {sup 6,8}He. The role of the spin-orbit (SO) potential and effects of the energy and density dependence of the effective NN forces are studied. Comparison of the calculations with the available experimental data on the elastic scattering differential cross sections at beam energies <100 MeV/N is performed and conclusions on the role of the aforesaid effects are made. It is shown that the present approach, which uses only parameters that renormalize the depths of the OP, can be applied along with other methods like that from the microscopic g-matrix description of the complex proton optical potential.
Deep-Elastic pp Scattering at Lhc from LOW-x Gluons
NASA Astrophysics Data System (ADS)
Islam, M. M.; Kašpar, J.; Luddy, R. J.
Deep-elastic pp scattering at c.m. energy 14 TeV at LHC in the momentum transfer range 4 GeV2 ≲ |t| ≲ 10 GeV2 is planned to be measured by the TOTEM group. We study this process in a model where the deep-elastic scattering is due to a single hard collision of a valence quark from one proton with a valence quark from the other proton. The hard collision originates from the low-x gluon cloud around one valence quark interacting with that of the other. The low-x gluon cloud can be identified as color glass condensate and has size ≃0.3 F. Our prediction is that pp dσ/dt in the large |t| region decreases smoothly as momentum transfer increases. This is in contrast to the prediction of pp dσ/dt with visible oscillations and smaller cross sections by a large number of other models.
Measuring Quasi-Elastic e-n and e-p Scattering from Deuterium
NASA Astrophysics Data System (ADS)
Balsamo, Alexander; Sherman, Keegan; Gilfoyle, Gerard
2016-09-01
The main physics goal of Jefferson Lab is to understand how quarks and gluons form nuclei. We are developing algorithms to extract the relative amounts of electron-neutron (e-n) to electron-proton (e-p) scattering events from deuterium in quasi-elastic (QE) kinematics for an approved experiment with the CLAS12 detector. Our analysis focuses on neutrons detected in the CLAS12 calorimeters and protons measured with the CLAS12 toroidal magnetic field. Events were generated with the Quasi-Elastic Event Generator (QUEEG) and passed through the Monte Carlo code gemc to simulate the CLAS12 response. These simulated events were then reconstructed using CLAS12 Common Tools. We first match the solid angle for e-n and e-p events. The electron information is used to predict the trajectory of both a neutron and proton through CLAS12. If both particles would interact in the CLAS12 volume, we know the sample has the same solid angle for e-n and e-p events. We then select QE events by searching for a nucleon near the predicted position. The angle between the predicted 3-momentum of the nucleon and the measured value, θpq, reaches a peak near zero for QE events, but not for other inelastic events. A cut on θpq separates QE events from inelastic ones. Work supported by the University of Richmond and the US Department of Energy.
Polarisation Transfer in Proton Compton Scattering at High Momentum Transfer
Hamilton, David Jonathan
2004-01-01
The Jefferson Lab Hall A experiment E99-114 comprised a series of measurements to explore proton Compton scattering at high momentum transfer. For the first time, the polarisation transfer observables in the p ($\\vec{γ}$, γ' \\vec{p}$) reaction were measured in the GeV energy range, where it is believed that quark-gluon degrees of freedom begin to dominate. The experiment utilised a circularly polarised photon beam incident on a liquid hydrogen target, with the scattered photon and recoil proton detected in a lead-glass calorimeter and a magnetic spectrometer, respectively.
Polarization Transfer in Proton Compton Scattering at High Momentum Transfer
Hamilton, D.J.; Annand, J.R.M.; Mamyan, V.H.; Aniol, K.A.; Margaziotis, D.J.; Bertin, P.Y.; Camsonne, A.; Laveissiere, G.; Bosted, P.; Paschke, K.; Calarco, J.R.; Chang, G.C.; Horn, T.; Savvinov, N.; Chang, T.-H.; Danagoulian, A.; Nathan, A.M.; Roedelbronn, M.; Chen, J.-P.
2005-06-24
Compton scattering from the proton was investigated at s=6.9 GeV{sup 2} and t=-4.0 GeV{sup 2} via polarization transfer from circularly polarized incident photons. The longitudinal and transverse components of the recoil proton polarization were measured. The results are in disagreement with a prediction of perturbative QCD based on a two-gluon exchange mechanism, but agree well with a prediction based on a reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton.
NASA Astrophysics Data System (ADS)
Sekiguchi, K.; Wada, Y.; Watanabe, A.; Eto, D.; Akieda, T.; Kon, H.; Miki, K.; Sakamoto, N.; Sakai, H.; Sasano, M.; Shimizu, Y.; Suzuki, H.; Uesaka, T.; Yanagisawa, Y.; Dozono, M.; Kawase, S.; Kubota, Y.; Lee, C. S.; Yako, K.; Maeda, Y.; Kawakami, S.; Yamamoto, T.; Sakaguchi, S.; Wakasa, T.; Yasuda, J.; Ohkura, A.; Shindo, Y.; Tabata, M.; Milman, E.; Chebotaryov, S.; Okamura, H.; Tang, T. L.
2017-03-01
We have measured a complete set of deuteron analyzing powers in deuteron-proton elastic scattering at 190, 250, and 294 MeV/nucleon. The obtained data are compared with the Faddeev calculations based on the modern nucleon-nucleon forces together with the Tucson-Melbourne'99, and UrbanaIX three nucleon forces. The data are also presented with the calculations based on the N4LO NN potentials of the chiral effective field theory.
Towards a Resolution of the Proton Form Factor Problem: New Electron and Positron Scattering Data
Adikaram, D.; Rimal, D.; Weinstein, L. B.; Raue, B.; Khetarpal, P.; Bennett, R.; Arrington, J.; Brooks, W.; Adhikari, K.; Afanasev, A.; Amaryan, M.; Anderson, M.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Battaglieri, M.; Bedlinskiy, I.; Biselli, A.; Bono, J.; Boiarinov, S.; Briscoe, W.; Burkert, V.; Carman, D.; Careccia, S.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P.; Contalbrigo, M.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dodge, G.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J.; Fradi, A.; Garillon, B.; Gilfoyle, G.; Giovanetti, K.; Girod, F.; Goetz, J.; Gohn, W.; Golovatch, E.; Gothe, R.; Griffioen, K.; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hicks, K.; Holtrop, M.; Hughes, S.; Hyde, C. E.; Ilieva, Y.; Ireland, D.; Ishkhanov, B.; Jenkins, D.; Jiang, H.; Jo, H.; Joo, K.; Joosten, S.; Kalantarians, N.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F.; Koirala, S.; Kubarovsky, V.; Kuhn, S.; Livingston, K.; Lu, H.; MacGregor, I.; Markov, N.; Mattione, P.; Mayer, M.; McKinnon, B.; Mestayer, M.; Meyer, C.; Mirazita, M.; Mokeev, V.; Montgomery, R.; Moody, C.; Moutarde, H.; Movsisyan, A.; Camacho, C. Munoz; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Ostrovidov, A.; Park, K.; Pasyuk, E.; Pisano, S.; Pogorelko, O.; Price, J.; Procureur, S.; Prok, Y.; Protopopescu, D.; Puckett, A.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabati, F.; Salgado, C.; Schott, D.; Schumacher, R.; Seder, E.; Sharabian, Y.; Simonyan, A.; Skorodumina, I.; Smith, E.; Smith, G.; Sober, D.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tian, Ye; Trivedi, A.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N.; Watts, D.; Wei, X.; Wood, M.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z.; Zonta, I.
2015-02-10
There is a significant discrepancy between the values of the proton electric form factor, GpE, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GpE from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (epsilon) and momentum transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ε at Q2=1.45 GeV2. This measurement is consistent with the size of the form factor discrepancy at Q2≈1.75 GeV2 and with hadronic calculations including nucleon and Delta intermediate states, which have been shown to resolve the discrepancy up to 2-3 GeV2.
Towards a Resolution of the Proton Form Factor Problem: New Electron and Positron Scattering Data
NASA Astrophysics Data System (ADS)
Adikaram, D.; Rimal, D.; Weinstein, L. B.; Raue, B.; Khetarpal, P.; Bennett, R. P.; Arrington, J.; Brooks, W. K.; Adhikari, K. P.; Afanasev, A. V.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Battaglieri, M.; Bedlinskiy, I.; Biselli, A. S.; Bono, J.; Boiarinov, S.; Briscoe, W. J.; Burkert, V. D.; Carman, D. S.; Careccia, S.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dodge, G. E.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J. A.; Fradi, A.; Garillon, B.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hicks, K.; Holtrop, M.; Hughes, S. M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Jiang, H.; Jo, H. S.; Joo, K.; Joosten, S.; Kalantarians, N.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Markov, N.; Mattione, P.; Mayer, M.; McKinnon, B.; Mestayer, M. D.; Meyer, C. A.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moody, C. I.; Moutarde, H.; Movsisyan, A.; Camacho, C. Munoz; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Pasyuk, E.; Peña, C.; Pisano, S.; Pogorelko, O.; Price, J. W.; Procureur, S.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Sharabian, Y. G.; Simonyan, A.; Skorodumina, I.; Smith, E. S.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tian, Ye; Trivedi, A.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.; CLAS Collaboration
2015-02-01
There is a significant discrepancy between the values of the proton electric form factor, GEp, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GEp from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (ɛ ) and momentum transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ɛ at Q2=1.45 GeV2 . This measurement is consistent with the size of the form factor discrepancy at Q2≈1.75 GeV2 and with hadronic calculations including nucleon and Δ intermediate states, which have been shown to resolve the discrepancy up to 2 - 3 GeV2 .
Towards a Resolution of the Proton Form Factor Problem: New Electron and Positron Scattering Data
Adikaram, D.; Rimal, D.; Weinstein, L. B.; ...
2015-02-10
There is a significant discrepancy between the values of the proton electric form factor, GpE, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GpE from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (epsilon) and momentummore » transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ε at Q2=1.45 GeV2. This measurement is consistent with the size of the form factor discrepancy at Q2≈1.75 GeV2 and with hadronic calculations including nucleon and Delta intermediate states, which have been shown to resolve the discrepancy up to 2-3 GeV2.« less
Towards a resolution of the proton form factor problem: new electron and positron scattering data.
Adikaram, D; Rimal, D; Weinstein, L B; Raue, B; Khetarpal, P; Bennett, R P; Arrington, J; Brooks, W K; Adhikari, K P; Afanasev, A V; Amaryan, M J; Anderson, M D; Anefalos Pereira, S; Avakian, H; Ball, J; Battaglieri, M; Bedlinskiy, I; Biselli, A S; Bono, J; Boiarinov, S; Briscoe, W J; Burkert, V D; Carman, D S; Careccia, S; Celentano, A; Chandavar, S; Charles, G; Colaneri, L; Cole, P L; Contalbrigo, M; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Dodge, G E; Dupre, R; Egiyan, H; El Alaoui, A; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fegan, S; Filippi, A; Fleming, J A; Fradi, A; Garillon, B; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Gohn, W; Golovatch, E; Gothe, R W; Griffioen, K A; Guegan, B; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Harrison, N; Hattawy, M; Hicks, K; Holtrop, M; Hughes, S M; Hyde, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Jenkins, D; Jiang, H; Jo, H S; Joo, K; Joosten, S; Kalantarians, N; Keller, D; Khandaker, M; Kim, A; Kim, W; Klein, A; Klein, F J; Koirala, S; Kubarovsky, V; Kuhn, S E; Livingston, K; Lu, H Y; MacGregor, I J D; Markov, N; Mattione, P; Mayer, M; McKinnon, B; Mestayer, M D; Meyer, C A; Mirazita, M; Mokeev, V; Montgomery, R A; Moody, C I; Moutarde, H; Movsisyan, A; Camacho, C Munoz; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Peña, C; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Puckett, A J R; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Sabatié, F; Salgado, C; Schott, D; Schumacher, R A; Seder, E; Sharabian, Y G; Simonyan, A; Skorodumina, I; Smith, E S; Smith, G D; Sober, D I; Sokhan, D; Sparveris, N; Stepanyan, S; Stoler, P; Strauch, S; Sytnik, V; Taiuti, M; Tian, Ye; Trivedi, A; Ungaro, M; Voskanyan, H; Voutier, E; Walford, N K; Watts, D P; Wei, X; Wood, M H; Zachariou, N; Zana, L; Zhang, J; Zhao, Z W; Zonta, I
2015-02-13
There is a significant discrepancy between the values of the proton electric form factor, G(E)(p), extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of G(E)(p) from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (ϵ) and momentum transfer (Q(2)) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ϵ at Q(2)=1.45 GeV(2). This measurement is consistent with the size of the form factor discrepancy at Q(2)≈1.75 GeV(2) and with hadronic calculations including nucleon and Δ intermediate states, which have been shown to resolve the discrepancy up to 2-3 GeV(2).
Elastic and inelastic scattering of neutrons on 238U nucleus
NASA Astrophysics Data System (ADS)
Capote, R.; Trkov, A.; Sin, M.; Herman, M. W.; Soukhovitskiĩ, E. Sh.
2014-04-01
Advanced modelling of neutron induced reactions on the 238U nucleus is aimed at improving our knowledge of neutron scattering. Capture and fission channels are well constrained by available experimental data and neutron standard evaluation. A focus of this contribution is on elastic and inelastic scattering cross sections. The employed nuclear reaction model includes - a new rotational-vibrational dispersive optical model potential coupling the low-lying collective bands of vibrational character observed in even-even actinides; - the Engelbrecht-Weidenmüller transformation allowing for inclusion of compound-direct interference effects; - and a multi-humped fission barrier with absorption in the secondary well described within the optical model for fission. Impact of the advanced modelling on elastic and inelastic scattering cross sections including angular distributions and emission spectra is assessed both by comparison with selected microscopic experimental data and integral criticality benchmarks including measured reaction rates (e.g. JEMIMA, FLAPTOP and BIG TEN). Benchmark calculations provided feedback to improve the reaction modelling. Improvement of existing libraries will be discussed.
A method for calculating proton-nucleus elastic cross-sections
NASA Technical Reports Server (NTRS)
Tripathi, R. K.; Wilson, J. W.; Cucinotta, F. A.
2002-01-01
Recently [Nucl. Instr. and Meth. B 145 (1998) 277; Extraction of in-medium nucleon-nucleon amplitude from experiment, NASA-TP, 1998], we developed a method of extracting nucleon-nucleon (N-N) cross-sections in the medium directly from experiment. The in-medium N-N cross-sections form the basic ingredients of several heavy-ion scattering approaches including the coupled-channel approach developed at the NASA Langley Research Center. We investigated [Proton-nucleus total cross-sections in coupled-channel approach, NASA/TP, 2000; Nucl. Instr. and Meth. B 173-174 (2001) 391] the ratio of real to imaginary part of the two body scattering amplitude in the medium. These ratios are used in combination with the in-medium N-N cross-sections to calculate proton-nucleus elastic cross-sections. The agreement is excellent with the available experimental data. These cross-sections are needed for the radiation risk assessment of space missions. c2002 Elsevier Science B.V. All rights reserved.
David Armstrong; Francois Arvieux; Razmik Asaturyan; Todd Averett; Stephanie Bailey; Guillaume Batigne; Douglas Beck; Elizabeth Beise; Jay Benesch; Louis Bimbot; James Birchall; Angela Biselli; Peter Bosted; Elodie Boukobza; Herbert Breuer; Roger Carlini; R. Carr; Nicholas Chant; Yu-Chiu Chao; Swapan Chattopadhyay; Russell Clark; Silviu Covrig; Anthony Cowley; Daniel Dale; C. Davis; Willie Falk; John Finn; Tony Forest; Gregg Franklin; Christophe Furget; David Gaskell; Joseph Grames; Keith Griffioen; Klaus Grimm; Benoit Guillon; Hayko Guler; Lars Hannelius; R. Hasty; A. Hawthorne Allen; Tanja Horn; Kathleen Johnston; Mark Jones; Peter Kammel; Reza Kazimi; Paul King; Ameya Kolarkar; Elie Korkmaz; Wolfgang Korsch; Serge Kox; Joachim Kuhn; Jeff Lachniet; Lawrence Lee; Jason Lenoble; Eric Liatard; J. Liu; Berenice Loupias; A. Lung; Glen MacLachlan; Dominique Marchand; J.W. Martin; Kenneth McFarlane; Daniella Mckee; Robert McKeown; Fernand Merchez; Hamlet Mkrtchyan; Bryan Moffit; M. Morlet; Itaru Nakagawa; Kazutaka Nakahara; Melissa Nakos; Retief Neveling; Silvia Niccolai; S. Ong; Shelley Page; Vassilios Papavassiliou; Stephen Pate; Sarah Phillips; Mark Pitt; Benard Poelker; Tracy Porcelli; Gilles Quemener; Brian Quinn; William Ramsay; Aamer Rauf; Jean-Sebastien Real; Julie Roche; Philip Roos; Gary Rutledge; Jeffery Secrest; Neven Simicevic; G.R. Smith; Damon Spayde; Samuel Stepanyan; Marcy Stutzman; Vincent Sulkosky; Vardan Tadevosyan; Raphael Tieulent; Jacques Van de Wiele; Willem van Oers; Eric Voutier; William Vulcan; G. Warren; S.P. Wells; Steven Williamson; S.A. Wood; Chen Yan; Junho Yun; Valdis Zeps
2005-06-01
We have measured parity-violating asymmetries in elastic electron-proton scattering over the range of momentum transfers 0.12 < Q{sup 2} < 1.0 GeV{sup 2}. These asymmetries, arising from interference of the electromagnetic and neutral weak interactions, are sensitive to strange quark contributions to the currents of the proton. The measurements were made at JLab using a toroidal spectrometer to detect the recoiling protons from a liquid hydrogen target. The results indicate non-zero, Q{sup 2} dependent, strange quark contributions and provide new information beyond that obtained in previous experiments.
Angular distribution of electrons elastically scattered from hydrogen atoms
Shyn, T. W.; Cho, S. Y.
1989-08-01
Absolute elastic differential cross sections of atomic hydrogen have been measured by a modulated crossed-beam method. The energy and angular range covered were from 5 to 30 eV and from 12/degree/ to 156/degree/, respectively. The present results agree with the previous measurements within the experimental uncertainty below 15 eV, but it is found that the present results show stronger backward scattering (/gt/120/degree/) than the previous measurement and theoretical results by more than a factor of 2 above 20 eV.
Tensor analyzing power in πd elastic scattering
NASA Astrophysics Data System (ADS)
Smith, G. R.; Altman, A.; Delheij, P.; Gill, D. R.; Healey, D.; Johnson, R. R.; Jones, G.; Ottewell, D.; Rozon, F. M.; Sevior, M. E.; Tervisidis, F.; Trelle, R. P.; Wait, G. D.; Walden, P.; Mathie, E. L.; Lolos, G. J.; Naqvi, S. I.; Boschitz, E. T.; Ottermann, C. R.; Kyle, G. S.; Amaudruz, P. A.
1986-08-01
A tensor-polarized deuteron target has been employed for the first measurements of the tensor analyzing power, T20, in πd elastic scattering. Data at six angles were measured at pion bombarding energies of 133.8 and 150.9 MeV. The results settle a long-standing controversy over conflicting measurements of the tensor polarization t20, and dispute evidence for dibaryon resonances predicated on one of these t20 measurements. The data are shown to be in reasonable agreement with recent Faddeev calculations which have reduced contributions from pion absorption.
Quasi-elastic electron scattering from polarized 3He
H. J. Bulten; Ricardo Alarcon; Th. Bauer; D. Boersma; T. Botto; J. F. J. van den Brand; L. van Buuren; Rolf Ent; M. Ferro-Luzzi; D. Geurts; M. Harvey; Peter Heimberg; D. Highinbotham; Kees de Jager; Blaine Norum; I. Passchier; H. R. Poolman; M. van den Putte; E. Six; J. Steijger; D. Szczerba; H. de Vries
1997-08-01
Quasi-elastic electron scattering may provide precise information on the S and the D-wave parts of the {sup 3}He ground-state wave function, the neutron form factors, and the role of spin-dependent reaction mechanism effects. An experiment is being performed at the AmPS storage ring at NIKHEF (Amsterdam, the Netherlands), where polarized electrons (up to 900 MeV) are used in combination with large acceptance electron and hadron detectors. Preliminary results from data at four-momentum transfer squared Q{sup 2} = 0.15 GeV{sup 2} are presented.
High Precision Measurement of the Proton Elastic Form Factor Ratio at Low Q^{2}
Zhan, Xiaohui
2010-01-01
Experiment E08-007 measured the proton elastic form factor ratio μ_{p}G_{E}/G_{M} in the range of Q^{2} = 0.3-0.7(GeV/c)^{2} by recoil polarimetry. Data were taken in 2008 at the Thomas Jefferson National Accelerator Facility in Virginia, USA. A 1.2 GeV polarized electron beam was scattered off a cryogenic hydrogen target. The recoil proton was detected in the left HRS in coincidence with the elasticly scattered electrons tagged by the BigBite spectrometer. The proton polarization was measured by the focal plane polarimeter (FPP). In this low Q^{2} region, previous measurement from Jefferson Lab Hall A (LEDEX) along with various fits and calculations indicate substantial deviations of the ratio from unity. For this new measurement, the proposed statistical uncertainty (< 1%) was achieved. These new results are a few percent lower than expected from previous world data and fits, which indicate a smaller G_{Ep} at this region. Beyond the intrinsic interest in nucleon structure, the new results also have implications in determining the proton Zemach radius and the strangeness form factors from parity violation experiments.
Radiative corrections to the elastic e-p and mu-p scattering in Monte Carlo simulation approach
NASA Astrophysics Data System (ADS)
Koshchii, Oleksandr; Afanasev, Andrei; MUSE Collaboration
2015-04-01
In this paper, we calculated exactly lepton mass corrections for the elastic e-p and mu-p scatterings using the ELRADGEN 2.1 Monte Carlo generator. These estimations are essential to be used in the MUSE experiment that is designed to solve the proton radius puzzle. This puzzle is due to the fact that two methods of measuring proton radius (the spectroscopy method, which measures proton energy levels in hydrogen, and the electron scattering experiment) predicted the radius to be 0.8768 +/-0.0069 fm, whereas the experiment that used muonic hydrogen provided the value that is 5% smaller. Since the radiative corrections are different for electrons and muons due to their mass difference, these corrections are extremely important for analysis and interpretation of upcoming MUSE data.
Angular distribution of electrons elastically scattered from water vapor
NASA Astrophysics Data System (ADS)
Shyn, T. W.; Grafe, Alan
1992-10-01
The angular distributions of electrons elastically scattered from H2O have been measured by electron impact using a modulated crossed-beam method. The energy and angular range measured were from 30 to 200 eV and 12° to 156°, respectively. The present results show a high backward scattering for low incident energies, but this falls off for high incident energies. The present results are in qualitative agreement with the measurements of Danjo and Nishimura [J. Phys. Soc. Jpn. 54, 1224 (1985)] and in quantitative agreement with the measurements of Katase et al. [J. Phys. B 19, 2715 (1986)]. Agreement between the present results and the calculation of Jain, Tripathi, and Jain [Phys. Rev. A 37, 2893 (1988)] is good except at 200-eV impact.
Elastic scattering of Beryllium isotopes near the Coulomb barrier
Di Pietro, A.; Figuera, P.; Amorini, F.; Fisichella, M.; Lattuada, M.; Musumarra, A.; Pellegriti, M. G.; Randisi, G.; Rizzo, F.; Santonocito, D.; Scalia, G.; Scuderi, V.; Strano, E.; Torresi, D.; Papa, M.; Acosta, L.; Martel, I.; Perez-Bernal, F.; Borge, M. J. G.; Tengblad, O.
2011-10-28
In this contribution, results of experiments performed with the three Beryllium isotopes {sup 9,10,11}Be on a medium mass {sup 64}Zn target, at a center of mass energy of {approx_equal}1.4 the Coulomb barrier, will be discussed. Elastic scattering angular distributions have been measured for the {sup 9,10}Be reactions. In the {sup 11}Be case the quasielastic scattering angular distribution was obtained. In the halo nucleus case, the angular distribution exhibit a non-Fresnel-type pattern with a strong damping of the Coulomb-nuclear interference peak. Moreover, it is found that the total reaction cross-section for the halo nucleus induced collision is more than double the ones extracted in the collisions induced by the non-halo Beryllium isotopes. A large contribution to the total-reaction cross-section in the {sup 11}Be case could be attributed to transfer and/or break-up events.
Desmin filaments studied by quasi-elastic light scattering.
Hohenadl, M; Storz, T; Kirpal, H; Kroy, K; Merkel, R
1999-01-01
We studied polymers of desmin, a muscle-specific type III intermediate filament protein, using quasi-elastic light scattering. Desmin was purified from chicken gizzard. Polymerization was induced either by 2 mM MgCl(2) or 150 mM NaCl. The polymer solutions were in the semidilute regime. We concluded that the persistence length of the filaments is between 0.1 and 1 microm. In all cases, we found a hydrodynamic diameter of desmin filaments of 16-18 nm. The filament dynamics exhibits a characteristic frequency in the sense that correlation functions measured on one sample but at different scattering vectors collapse onto a single master curve when time is normalized by the experimentally determined initial decay rate. PMID:10512839
Quasi-Elastic Scattering with Neutrinos in MINERvA
NASA Astrophysics Data System (ADS)
Osta, Jyotsna; Hurtado, Kenyi; Minerva Collaboration
2014-09-01
MINERvA is a few GeV neutrino-nucleus scattering experiment designed to study low energy neutrino interactions both in support of neutrino oscillation experiments as well as a pure weak probe of the nuclear medium. The experiment uses a fine-grained, high resolution detector. The active region is composed of plastic scintillator with additional targets of helium, carbon, iron, lead and water placed upstream of the active region. We present preliminary results from the double differential cross section analysis that aims to study quasi-elastic scattering of neutrinos in the phase space of the muon transverse and longitudinal momenta. This analysis uses the low energy neutrino dataset recorded from November 2009 to April 2012.
NASA Astrophysics Data System (ADS)
Simo, I. Ruiz; Amaro, J. E.; Barbaro, M. B.; De Pace, A.; Caballero, J. A.; Megias, G. D.; Donnelly, T. W.
2016-11-01
We use a relativistic model of meson-exchange currents to compute the proton-neutron and proton-proton yields in (e ,e') scattering from 12C in the 2p-2h channel. We compute the response functions and cross section with the relativistic Fermi gas model for a range of kinematics from intermediate- to high-momentum transfers. We find a large contribution of neutron-proton configurations in the initial state, as compared to proton-proton pairs. The different emission probabilities of distinct species of nucleon pairs are produced in our model only by meson-exchange currents, mainly by the Δ isobar current. We also analyze the effect of the exchange contribution and show that the direct-exchange interference strongly affects the determination of the n p /p p ratio.
Elastic scattering of slow electrons by n-pentanol alcohol
NASA Astrophysics Data System (ADS)
de Oliveira, Eliane M.; Varella, Márcio T. do N.; Bettega, Márcio H. F.; Lima, Marco A. P.
2014-03-01
We report elastic integral (ICS), differential (DCS) and momentum transfer cross sections (MTCS) for low-energy electron scattering by n-pentanol alcohol in the gas phase. The Schwinger multichannel method implemented with pseudopotentials was employed in the calculations. The DCSs were computed for energies from 1 to 50 eV and the ICS and MTCS from 1 to 100 eV. Due to the significant value of the electric dipole moment, the DCSs are dominated by strong forward scattering. Despite this fact, the DCS around 10 eV displays a behavior related to a f-wave scattering pattern at intermediate angles which may be associated with shape resonances. This result is consistent with the ICS and the MTCS since they show a pronounced peak near this energy. For energies below 1 eV, the MTCS obtained in the static-exchange plus polarization approximation does not increase, as expected for polar molecules, suggesting that a Ramsauer-Townsend minimum could be present. This finding motivated us to revisit the previously studied methanol, ethanol, n-propanol and n-butanol molecules and to perform new calculations for impact energies below 1 eV (not addressed before). With the inclusion of polarization effects, the MTCS for the five alcohols suggest a Ramsauer-Townsend minimum coming from the negative to the positive scattering energies. To the best of our knowledge, there are neither experimental nor calculated cross sections for comparison with the present results.
Extracting the hexadecapole deformation from backward quasi-elastic scattering
NASA Astrophysics Data System (ADS)
Jia, H. M.; Lin, C. J.; Yang, F.; Xu, X. X.; Zhang, H. Q.; Liu, Z. H.; Wu, Z. D.; Yang, L.; Ma, N. R.; Bao, P. F.; Sun, L. J.
2014-09-01
Background: The hexadecapole deformation β4 is usually difficult to determine experimentally, especially its sign. The rapidly accumulated knowledge of β2 inspires the desire of β4 for radioactive nuclei, but the current low-quality beam is a severe experimental challenge. Therefore, a simple but sensitive method to extract β4 in such a condition is urgently called for. Purpose: To study the feasibility of extracting β4 from the lower-energy backward quasi-elastic (QEL) scattering. Methods: The QEL scattering at sub-barrier energy region is sensitive to the coupled-channels (CC) effect and consequently may be used to extract β4. The QEL scattering excitation functions for O16+Sm152,Er170, and Yb174 were measured at a backward angle with small energy intervals at energies near the Coulomb barrier. Experimental fusion barrier distributions were also derived. The lower-energy data were analyzed to extract β4 with the help of the CC calculations. Results: The obtained β4 agrees with the available results reasonably well. Conclusions: We have demonstrated that the QEL scattering at sub-barrier energies provides a feasible and sensitive method to extract the value of β4, which is essentially meaningful for the radioactive nucleus because of its low beam intensity.
NASA Astrophysics Data System (ADS)
Luppov, V. G.; Alexeeva, L. V.; Anferov, V. A.; Courant, E. D.; Derbenev, Ya. S.; Fidecaro, G.; Fidecaro, M.; Khiari, F. Z.; Koutin, S. V.; Krisch, A. D.; Leonova, M. A.; Lin, A. M. T.; Lorenzon, W.; Morozov, V. S.; Peaslee, D. C.; Peters, C. C.; Raymond, R. S.; Sivers, D. W.; Stewart, J. A.; Varzar, S. M.; Wong, V. K.; Yonehara, K.; Crabb, D. G.; Ado, Yu. M.; Afonin, A. G.; Belousov, V. I.; Chujko, B. V.; Davidenko, A. N.; Galyaev, N. A.; Garkusha, V. I.; Grishin, V. N.; Kachanov, V. A.; Kharlov, Yu. V.; Kotov, V. I.; Kusnetsov, A. V.; Medvedev, V. A.; Melnik, Yu. M.; Mochalov, V. V.; Mysnik, A. I.; Nurushev, S. B.; Prudkoglyad, A. F.; Semenov, P. A.; Solovianov, V. L.; Stepanov, V. P.; Teplyakov, V. A.; Troshin, S. M.; Ufimtsev, A. G.; Ukhanov, M. N.; Yakutin, A. E.; Zapolsky, V. N.; Zarucheisky, V. G.; Borisov, N. S.; Fimushkin, V. V.; Nikitin, V. A.; Nomokonov, P. V.; Rufanov, I. A.; Pilipenko, Yu. K.; Delheij, P. P. J.; van Oers, W. T. H.; Zelenski, A. N.
2003-07-01
The SPIN@U-70 experiment plans to measure the one-spin analyzing power An for 70 GeV proton-proton elastic scattering at large P⊥2 values of 1 to 12 (GeV/c)2. The Michigan frozen NH3 polarized proton target (Solid PPT) should later be installed in the Channel 8 extracted beam-line of the 70 GeV U-70 accelerator in IHEP, Protvino. The forward-scattered protons are detected by small scintillation counters placed at about 9 m from the PPT, while the recoil-scattered protons are detected by a 35-m-long focusing magnetic spectrometer, with a 12 degree vertical bend, placed at 30 degrees to the beam. A tune-up run for testing the beam and the spectrometer, using a polyethylene target, was carried out in April 2002 at IHEP. The layout and the results of the test run are presented.
Limits on dark matter proton scattering from neutrino telescopes using micrOMEGAs
Bélanger, G.; Silva, J. Da; Perrillat-Bottonet, T.; Pukhov, A.
2015-12-17
Limits on dark matter spin dependent elastic scattering cross section on protons derived from IceCube data are obtained for different dark matter annihilation channels using micrOMEGAs. The uncertainty on the derived limits, estimated by using different neutrino spectra, can reach a factor two. For all dark matter annihilation channels except for quarks, the limits on the spin dependent cross section are more stringent than those obtained in direct detection experiments. The new functions that allow to derive those limits are described.
Limits on dark matter proton scattering from neutrino telescopes using micrOMEGAs
Bélanger, G.; Perrillat-Bottonet, T.; Silva, J. Da; Pukhov, A. E-mail: dasilva@lapth.cnrs.fr E-mail: pukhov@lapth.cnrs.fr
2015-12-01
Limits on dark matter spin dependent elastic scattering cross section on protons derived from IceCube data are obtained for different dark matter annihilation channels using micrOMEGAs. The uncertainty on the derived limits, estimated by using different neutrino spectra, can reach a factor two. For all dark matter annihilation channels except for quarks, the limits on the spin dependent cross section are more stringent than those obtained in direct detection experiments. The new functions that allow to derive those limits are described.
Triple Parton Scatterings in High-Energy Proton-Proton Collisions
NASA Astrophysics Data System (ADS)
d'Enterria, David; Snigirev, Alexander M.
2017-03-01
A generic expression to compute triple parton scattering cross sections in high-energy proton-proton (p p ) collisions is presented as a function of the corresponding single parton cross sections and the transverse parton profile of the proton encoded in an effective parameter σeff,TPS . The value of σeff,TPS is closely related to the similar effective cross section that characterizes double parton scatterings, and amounts to σeff,TPS=12.5 ±4.5 mb . Estimates for triple charm (c c ¯) and bottom (b b ¯) production in p p collisions at LHC and FCC energies are presented based on next-to-next-to-leading-order perturbative calculations for single c c ¯ , b b ¯ cross sections. At √{s }≈100 TeV , about 15% of the p p collisions produce three c c ¯ pairs from three different parton-parton scatterings.
Geometry Survey of the Time-of-Flight Neutron-Elastic Scattering (Antonella) Experiment
Oshinowo, Babatunde O.; Izraelevitch, Federico
2016-10-17
The Antonella experiment is a measurement of the ionization efficiency of nuclear recoils in silicon at low energies [1]. It is a neutron elastic scattering experiment motivated by the search for dark matter particles. In this experiment, a proton beam hits a lithium target and neutrons are produced. The neutron shower passes through a collimator that produces a neutron beam. The beam illuminates a silicon detector. With a certain probability, a neutron interacts with a silicon nucleus of the detector producing elastic scattering. After the interaction, a fraction of the neutron energy is transferred to the silicon nucleus which acquires kinetic energy and recoils. This kinetic energy is then dissipated in the detector producing ionization and thermal energy. The ionization produced is measured with the silicon detector electronics. On the other hand, the neutron is scattered out of the beam. A neutron-detector array (made of scintillator bars) registers the neutron arrival time and the scattering angle to reconstruct the kinematics of the neutron-nucleus interaction with the time-of-flight technique [2]. In the reconstruction equations, the energy of the nuclear recoil is a function of the scattering angle with respect to the beam direction, the time-of-flight of the neutron and the geometric distances between components of the setup (neutron-production target, silicon detector, scintillator bars). This paper summarizes the survey of the different components of the experiment that made possible the off-line analysis of the collected data. Measurements were made with the API Radian Laser Tracker and I-360 Probe Wireless. The survey was completed at the University of Notre Dame, Indiana, USA in February 2015.
A covariant multiple scattering series for elastic projectile-target scattering
NASA Technical Reports Server (NTRS)
Gross, Franz; Maung-Maung, Khin
1989-01-01
A covariant formulation of the multiple scattering series for the optical potential is presented. The case of a scalar nucleon interacting with a spin zero isospin zero A-body target through meson exchange, is considered. It is shown that a covariant equation for the projectile-target t-matrix can be obtained which sums the ladder and crossed ladder diagrams efficiently. From this equation, a multiple scattering series for the optical potential is derived, and it is shown that in the impulse approximation, the two-body t-matrix associated with the first order optical potential is the one in which one particle is kept on mass-shell. The meaning of various terms in the multiple scattering series is given. The construction of the first-order optical potential for elastic scattering calculations is described.
Fast-neutron elastic scattering from elemental vanadium
Smith, A.B.; Guenther, P.T.; Lawson, R.D.
1988-03-01
Differential neutron elastic- and inelastic-scattering cross sections of vanadium were measured from 4.5 to 10 MeV. These results were combined with previous 1.5 to 4.0 MeV data from this laboratory, the 11.1 MeV elastic-scattering results obtained at Ohio University, and the reported neutron total cross sections to energies of approx.20.0 MeV, to form a data base which was interpreted in terms of the spherical optical-statistical model. A fit to the data was achieved by making both the strengths and geometries of the optical-model potential energy dependent. This energy dependence was large below approx.6.0 MeV. Above approx.6.0 MeV the energy dependencies are smaller, and similar to those characteristic of global models. Using the dispersion relationship and the method of moments, the optical-model potential energy deduced from 0.0 to 11.1 MeV neutron-scattering data was extrapolated to higher energies and to the bound-state regime. This extrapolation leads to predicted neutron total cross sections that are within 3% of the experimental values throughout the energy range 0.0 to 20.0 MeV. Furthermore, the values of the volume-integral-per-nucleon of the real potential are in excellent agreement with those needed to reproduce the observed binding energies of particle- and hole-states. The latter gives clear evidence of the Fermi surface anomaly. Using only the 0.0 to 11.1 MeV data, the predicted E < O behavior of the strength and radius of the real shell-model Woods-Saxon potential are somewhat different from those obtained by Mahaux and Sartor in their analysis of nuclei near closed shells. 61 refs., 9 figs., 2 tabs.
Quasi-elastic pn scattering in 6LiD and 6LiH targets from 1.1 to 2.4 GeV
NASA Astrophysics Data System (ADS)
de Lesquen, A.; Allgower, C. E.; Ball, J.; Beddo, M.; Bystrický, J.; Combet, M.; Demierre, Ph.; Durand, G.; Fontaine, J.-M.; Grosnick, D.; Hess, R.; Janout, Z.; Janout, Z. F.; Kalinnikov, V. A.; Kasprzyk, T. E.; Khachaturov, B. A.; Kunne, R.; Lehar, F.; Lopiano, D.; Matafonov, V. N.; Pisarev, I. L.; Popov, A. A.; Prokofiev, A. N.; Rapin, D.; Sans, J.-L.; Spinka, H. M.; Usov, Yu. A.; Vikhrov, V. V.; Vuaridel, B.; Zhdanov, A. A.
1999-11-01
A polarized proton beam from SATURNE II, the Saclay polarized targets with ^6Li compounds, and an unpolarized CH_2 target were used to measure spin-dependent observables for protons scattered on bound nucleons. The beam and target polarizations were oriented vertically. The analyzing power A_{oono} and the depolarization D_{nono} were determined at seven energies between 1.1 and 2.4 GeV. The spin correlation parameter A_{oonn} was measured at only 1.1 and 1.6 GeV. Measurements with the CH_2 target at 1.1 GeV provided A_{oono} data for scattering of polarized protons on neutrons in carbon. The quasi-elastic observables are compared with previous elastic scattering measurements and at 1.1 GeV with predictions of phase shift analyses.
Determination of the cervical transformation zone using elastic-scattering spectroscopy
Bigio, I.J.; Johnson, T.M.; Mourant, J.R.
1996-04-01
Optical measurements of the cervical transformation zone (sometimes referred to as the transition zone) using elastic-scattering spectroscopy, demonstrate sensitivity to the epithelial cell-type differences.
NASA Astrophysics Data System (ADS)
Cao, Xing; Ni, Binbin; Liang, Jun; Xiang, Zheng; Wang, Qi; Shi, Run; Gu, Xudong; Zhou, Chen; Zhao, Zhengyu; Fu, Song; Liu, Jiang
2016-02-01
This is a companion study to Liang et al. (2014) which reported a "reversed" energy-latitude dispersion pattern of ion precipitation in that the lower energy ion precipitation extends to lower latitudes than the higher-energy ion precipitation. Electromagnetic ion cyclotron (EMIC) waves in the central plasma sheet (CPS) have been suggested to account for this reversed-type ion precipitation. To further investigate the association, we perform a comprehensive study of pitch angle diffusion rates induced by EMIC wave and the resultant proton loss timescales at L = 8-12 around the midnight. Comparing the proton scattering rates in the Earth's dipole field and a more realistic quiet time geomagnetic field constructed from the Tsyganenko 2001 (T01) model, we find that use of a realistic, nondipolar magnetic field model not only decreases the minimum resonant energies of CPS protons but also considerably decreases the limit of strong diffusion and changes the proton pitch angle diffusion rates. Adoption of the T01 model increases EMIC wave diffusion rates at > ~ 60° equatorial pitch angles but decreases them at small equatorial pitch angles. Pitch angle scattering coefficients of 1-10 keV protons due to H+ band EMIC waves can exceed the strong diffusion rate for both geomagnetic field models. While He+ and O+ band EMIC waves can only scatter tens of keV protons efficiently to cause a fully filled loss cone at L > 10, in the T01 magnetic field they can also cause efficient scattering of ~ keV protons in the strong diffusion limit at L > 10. The resultant proton loss timescales by EMIC waves with a nominal amplitude of 0.2 nT vary from a few hours to several days, depending on the wave band and L shell. Overall, the results demonstrate that H+ band EMIC waves, once present, can act as a major contributor to the scattering loss of a few keV protons at lower L shells in the CPS, accounting for the reversed energy-latitude dispersion pattern of proton precipitation at low
Proton radiography, nuclear cross sections and multiple Coulomb scattering
Sjue, Sky K.
2015-11-04
The principles behind proton radiography including multiple Coulomb scattering are discussed for a purely imaginary square well nucleus in the eikonal approximation. It is found that a very crude model can reproduce the angular dependence of the cross sections measured at 24 GeV/c. The largest differences are ~3% for the 4.56 mrad data, and ~4% for the 6.68 mrad data. The prospect of understanding how to model deterministically high-energy proton radiography over a very large range of energies is promising, but it should be tested more thoroughly.
Park, Yang-Kyun; Sharp, Gregory C.; Phillips, Justin; Winey, Brian A.
2015-01-01
Purpose: To demonstrate the feasibility of proton dose calculation on scatter-corrected cone-beam computed tomographic (CBCT) images for the purpose of adaptive proton therapy. Methods: CBCT projection images were acquired from anthropomorphic phantoms and a prostate patient using an on-board imaging system of an Elekta infinity linear accelerator. Two previously introduced techniques were used to correct the scattered x-rays in the raw projection images: uniform scatter correction (CBCTus) and a priori CT-based scatter correction (CBCTap). CBCT images were reconstructed using a standard FDK algorithm and GPU-based reconstruction toolkit. Soft tissue ROI-based HU shifting was used to improve HU accuracy of the uncorrected CBCT images and CBCTus, while no HU change was applied to the CBCTap. The degree of equivalence of the corrected CBCT images with respect to the reference CT image (CTref) was evaluated by using angular profiles of water equivalent path length (WEPL) and passively scattered proton treatment plans. The CBCTap was further evaluated in more realistic scenarios such as rectal filling and weight loss to assess the effect of mismatched prior information on the corrected images. Results: The uncorrected CBCT and CBCTus images demonstrated substantial WEPL discrepancies (7.3 ± 5.3 mm and 11.1 ± 6.6 mm, respectively) with respect to the CTref, while the CBCTap images showed substantially reduced WEPL errors (2.4 ± 2.0 mm). Similarly, the CBCTap-based treatment plans demonstrated a high pass rate (96.0% ± 2.5% in 2 mm/2% criteria) in a 3D gamma analysis. Conclusions: A priori CT-based scatter correction technique was shown to be promising for adaptive proton therapy, as it achieved equivalent proton dose distributions and water equivalent path lengths compared to those of a reference CT in a selection of anthropomorphic phantoms. PMID:26233175
Intermediate Energy Proton Nucleus Scattering from CALCIUM-40, ZIRCONIUM-90 and LEAD-208.
NASA Astrophysics Data System (ADS)
Lee, Lawrence
In recent years, there has been much interest in studying proton-nucleus scattering at intermediate bombarding energies. We focus on two main themes in this thesis. Firstly, we examine the importance of measuring scattering observables out to high momentum transfers where they become sensitive to the matter distribution in the interior of the nucleus. Here, we find that nuclear medium and exchange effects are needed, especially at lower proton kinetic energies (~ 200 MeV). Secondly, we focus on the remarkable and systematic agreement between experimental data and theory when a consistent microscopic approach is used. As part of our study, we have made high momentum transfer measurements at TRIUMF for proton elastic and inelastic scattering from ^{40} Ca, ^{90}Zr and ^{208}Pb. Differential cross sections and analyzing powers are presented for proton kinetic energies of 200, 362 and 400 MeV out to a maximum momentum transfer of q~ 4.8 fm^{-1}, well above the typical limit of ~2.5 fm ^{-1}. Our elastic data are analyzed with a nonrelativistic microscopic optical model based on the Hamburg density -dependent two-body interaction (Ge83a) and on the Decharge and Gogny (De87) theoretical ground states, and involve no adjustable parameters. The calculations show surprisingly good agreement with data as it follows the cross section through typically 9 orders of magnitude and reproduces the oscillations in the analyzing power out to high q for a number of target nuclei and at various bombarding energies. The success of the elastic calculations also suggests that the theoretical model(s) are sufficiently well understood that nuclear structure problems can now be investigated. We study this aspect mainly through the low-lying natural -parity 3^- and 5^ - transitions. The inelastic data are analyzed with distorted-wave Born approximation calculations using the same nonrelativistic density-dependent interaction to drive the transition, the same optical model potential to distort
Determination of the Proton's Weak Charge via Parity Violating Electron Scattering
Hoskins, Joshua Russell
2015-08-01
The Qweak experiment, which completed running in May of 2012 at Jefferson Laboratory, has measured the parity-violating asymmetry in elastic electron-proton scattering at four-momentum transfer Q^{2}=0.025 (GeV/c)^{2} in order to provide the first direct measurement of the proton's weak charge, Qpw. The Standard Model makes firm predictions for the weak charge; deviations from the predicted value would provide strong evidence of new physics beyond the Standard Model. Using an 89% polarized electron beam at 145 microA scattering from a 34.4 cm long liquid hydrogen target, scattered electrons were detected using an array of eight fused-silica detectors placed symmetric about the beam axis. The parity-violating asymmetry was then measured by reversing the helicity of the incoming electrons and measuring the normalized difference in rate seen in the detectors. The low Q^{2} enables a theoretically clean measurement; the higher order hadronic corrections are constrained using previous parity-violating electron scattering world data. The experimental method will be discussed, with recent results constituting 4% of our total data and projections of our proposed uncertainties on the full data set.
Proton Magnetic Form Factor from Existing Elastic e-p Cross Section Data
NASA Astrophysics Data System (ADS)
Ou, Longwu; Christy, Eric; Gilad, Shalev; Keppel, Cynthia; Schmookler, Barak; Wojtsekhowski, Bogdan
2015-04-01
The proton magnetic form factor GMp, in addition to being an important benchmark for all cross section measurements in hadron physics, provides critical information on proton structure. Extraction of GMp from e-p cross section data is complicated by two-photon exchange (TPE) effects, where available calculations still have large theoretical uncertainties. Studies of TPE contributions to e-p scattering have observed no nonlinear effects in Rosenbluth separations. Recent theoretical investigations show that the TPE correction goes to 0 when ɛ approaches 1, where ɛ is the virtual photon polarization parameter. In this talk, existing e-p elastic cross section data are reanalyzed by extrapolating the reduced cross section for ɛ approaching 1. Existing polarization transfer data, which is supposed to be relatively immune to TPE effects, are used to produce a ratio of electric and magnetic form factors. The extrapolated reduced cross section and polarization transfer ratio are then used to calculate GEp and GMp at different Q2 values.
Extracting the Proton Backward Spin Polarizability using Compton Scattering
NASA Astrophysics Data System (ADS)
Lefcochilos-Fogelquist, Heraclitos
2016-09-01
The proton spin-polarizabilities (SPs) are properties that quantify the response of the proton spin to electromagnetic waves. The SPs can be expressed in a linear combination called the backward spin polarizability (γπ) which arises in the cross-section of a Compton scattering event in which the incident photon is scattered at 180 degrees. As the cross-section at this angle cannot be experimentally determined, measurements of γπ are fitted using data with scattering angles close to 180 degrees. However, as the scattering angle is reduced the cross-section rapidly becomes determined by the values of the individual SPs, not γπ . This project investigated the viability of using cross-section data from different energy and angle bins to extract the γπ in order to optimize future experiments for γπ extraction. A Dispersion Relation was used to generate theory points based on randomly specified values of γπ and SPs for data sets of different energy and scattering angle. This was repeated 2000 times and the χ2 of each iteration was measured to determine if fits to a data set were dependent on the individual SPs values or γπ . This material is based upon work supported by the National Science Foundation under Grant No. IIA-1358175.
Folding model calculations for 6He+12C elastic scattering
NASA Astrophysics Data System (ADS)
Awad, A. Ibraheem
2016-03-01
In the framework of the double folding model, we used the α+2n and di-triton configurations for the nuclear matter density of the 6He nucleus to generate the real part of the optical potential for the system 6He+12C. As an alternative, we also use the high energy approximation to generate the optical potential for the same system. The derived potentials are employed to analyze the elastic scattering differential cross section at energies of 38.3, 41.6 and 82.3 MeV/u. For the imaginary part of the potential we adopt the squared Woods-Saxon form. The obtained results are compared with the corresponding measured data as well as with available results in the literature. The calculated total reaction cross sections are investigated and compared with the optical limit Glauber model description.
Low-energy elastic electron scattering from furan
Khakoo, M. A.; Muse, J.; Ralphs, K.; Costa, R. F.; Bettega, M. H. F.; Lima, M. A. P.
2010-06-15
We report normalized experimental and theoretical differential cross sections for elastic electron scattering by C{sub 4}H{sub 4}O (furan) molecules from a collaborative project between several Brazilian theoretical groups and an experimental group at California State Fullerton, USA. The measurements are obtained by using the relative flow method with helium as the standard gas and a thin aperture target gas collimating source. The relative flow method is applied without the restriction imposed by the relative flow pressure condition on helium and the unknown gas. The experimental data were taken at incident electron energies of 1, 1.5, 1.73, 2, 2.7, 3, 5, 7, 10, 20, 30, and 50 eV and covered the angular range between 10 deg. and 130 deg. The measurements verify observed {pi}* shape resonances at 1.65{+-}0.05eV and 3.10{+-}0.05 eV scattering energies, in good agreement with the transmission electron data of Modelli and Burrow [J. Phys. Chem. A 108, 5721 (2004)]. Furthermore, the present results also indicated both resonances dominantly in the d-wave channel. The differential cross sections are integrated in the standard way to obtain integral elastic cross sections and momentum transfer cross sections. The calculations employed the Schwinger multichannel method with pseudopotentials and were performed in the static-exchange and in the static-exchange plus polarization approximations. The calculated integral and momentum transfer cross sections clearly revealed the presence of two shape resonances located at 1.95 and 3.56 eV and ascribed to the B{sub 1} and A{sub 2} symmetries of the C{sub 2v} point group, respectively, in very good agreement with the experimental findings. Overall agreement between theory and experiment regarding the differential, momentum transfer, and integral cross sections is very good, especially for energies below 10 eV.
Weakly interacting massive particle-nucleus elastic scattering response
NASA Astrophysics Data System (ADS)
Anand, Nikhil; Fitzpatrick, A. Liam; Haxton, W. C.
2014-06-01
Background: A model-independent formulation of weakly interacting massive particle (WIMP)-nucleon scattering was recently developed in Galilean-invariant effective field theory. Purpose: Here we complete the embedding of this effective interaction in the nucleus, constructing the most general elastic nuclear cross section as a factorized product of WIMP and nuclear response functions. This form explicitly defines what can and cannot be learned about the low-energy constants of the effective theory—and consequently about candidate ultraviolet theories of dark matter—from elastic scattering experiments. Results: We identify those interactions that cannot be reliably treated in a spin-independent/spin-dependent (SI/SD) formulation: For derivative- or velocity-dependent couplings, the SI/SD formulation generally mischaracterizes the relevant nuclear operator and its multipolarity (e.g., scalar or vector) and greatly underestimates experimental sensitivities. This can lead to apparent conflicts between experiments when, in fact, none may exist. The new nuclear responses appearing in the factorized cross section are related to familiar electroweak nuclear operators such as angular momentum l⃗(i) and the spin-orbit coupling σ⃗(i).l⃗(i). Conclusions: To unambiguously interpret experiments and to extract all of the available information on the particle physics of dark matter, experimentalists will need to (1) do a sufficient number of experiments with nuclear targets having the requisite sensitivities to the various operators and (2) analyze the results in a formalism that does not arbitrarily limit the candidate operators. In an appendix we describe a code that is available to help interested readers implement such an analysis.
NASA Technical Reports Server (NTRS)
Berger, Pascal; Sayir, Ali; Berger, Marie-Helene
2004-01-01
The interaction between hydrogen and various high temperature protonic conductors (HTPC) has not been clearly understood due to poor densification and unreacted secondary phases. the melt-processing technique is used in producing fully dense simple SrCe(0.9)Y (0.10) O(3-delta) and complex Sr3Ca(1+x)Nb(2+x)O(9-delta) perovskites that can not be achieved by solid-state sintering. the possibilities of ion beam analysis have been investigated to quantify hydrogen distribution in HTPC perovskites subjected to water heat treatment. Nuclear microprobe technique is based on the interactions of a focused ion beam of MeV light ions (H-1, H-2, He-3, He-4,.) with the sample to be analyzed to determine local elemental concentrations at the cubic micrometer scale, the elastic recoil detection analysis technique (ERDA) has been carried out using He-4(+) microbeams and detecting the resulting recoil protons. Mappings of longitudinal sections of water treated SrCeO3 and Sr(Ca(1/3)Nb(2/3))O3 perovskites have been achieved, the water treatment strongly alters the surface of simple SrCe(0.9)Y(0.10)O(3-delta) perovskite. From Rutherford Back Scattering measurements (RBS), both Ce depletion and surface re-deposition is evidenced. the ERDA investigations on water treated Sr3Ca(1+x)Nb(2+x)O(9-delta) perovskite did not exhibit any spatial difference for the hydrogen incorporation from the surface to the centre. the amount of hydrogen incorporation for Sr3Ca(1+x)Nb(2+x)O(9-delta) was low and required further development of two less conventional techniques, ERDA in forward geometry and forward elastic diffusion H-1(p,p) H-1 with coincidence detection.
Global analysis of parity-violating asymmetry data for elastic electron scattering
NASA Astrophysics Data System (ADS)
González-Jiménez, R.; Caballero, J. A.; Donnelly, T. W.
2014-08-01
We perform a statistical analysis of the full set of parity-violating asymmetry data for elastic electron scattering including the most recent high precision measurement from Q-weak. Given the basis of the present analysis, our estimates appear to favor nonzero vector strangeness, specifically, positive (negative) values for the electric (magnetic) strange form factors. We also provide an accurate estimate of the axial-vector nucleon form factor at zero momentum transfer, GAep(0). Our study shows GAep(0) to be importantly reduced with respect to the currently accepted value. We also find our analysis of data to be compatible with the Standard Model values for the weak charges of the proton and neutron.
Ma, Guo -Liang; Bzdak, Adam
2014-11-04
In this study, we show that the incoherent elastic scattering of partons, as present in a multi-phase transport model (AMPT), with a modest parton–parton cross-section of σ = 1.5 – 3 mb, naturally explains the long-range two-particle azimuthal correlation as observed in proton–proton and proton–nucleus collisions at the Large Hadron Collider.
Kiss, G. G.; Gyuerky, Gy.; Elekes, Z.; Fueloep, Zs.; Somorjai, E.; Galaviz, D.; Sonnabend, K.; Zilges, A.; Mohr, P.; Goerres, J.; Wiescher, M.; Oezkan, N.; Gueray, T.; Yalcin, C.; Avrigeanu, M.
2008-05-21
To improve the reliability of statistical model calculations in the region of heavy proton rich isotopes alpha elastic scattering experiments have been performed at ATOMKI, Debrecen, Hungary. The experiments were carried out at several energies above and below the Coulomb barrier with high precision. The measured angular distributions can be used for testing the predictions of the global and regional optical potential parameter sets. Moreover, we derived the variation of the elastic alpha scattering cross section along the Z = 50 ({sup 112}Sn-{sup 124}Sn) isotopic and N = 50 ({sup 89}Y-{sup 92}Mo) isotonic chains. In this paper we summarize the efforts to provide high precision experimental angular distributions for several A{approx_equal}100 nuclei to test the global optical potential parameterizations applied to p-process network calculations.
High-Accuracy Analysis of Compton Scattering in Chiral EFT: Proton and Neutron Polarisabilities
NASA Astrophysics Data System (ADS)
Griesshammer, Harald W.; Phillips, Daniel R.; McGovern, Judith A.
2013-10-01
Compton scattering from protons and neutrons provides important insight into the structure of the nucleon. A new extraction of the static electric and magnetic dipole polarisabilities αE 1 and βM 1 of the proton and neutron from all published elastic data below 300 MeV in Chiral Effective Field Theory shows that within the statistics-dominated errors, the proton and neutron polarisabilities are identical, i.e. no iso-spin breaking effects of the pion cloud are seen. Particular attention is paid to the precision and accuracy of each data set, and to an estimate of residual theoretical uncertainties. ChiEFT is ideal for that purpose since it provides a model-independent estimate of higher-order corrections and encodes the correct low-energy dynamics of QCD, including, for few-nucleon systems used to extract neutron polarisabilities, consistent nuclear currents, rescattering effects and wave functions. It therefore automatically respects the low-energy theorems for photon-nucleus scattering. The Δ (1232) as active degree of freedom is essential to realise the full power of the world's Compton data.Its parameters are constrained in the resonance region. A brief outlook is provided on what kind of future experiments can improve the database. Supported in part by UK STFC, DOE, NSF, and the Sino-German CRC 110.
Rhodopsin photoactivation dynamics revealed by quasi-elastic neutron scattering
Bhowmik, Debsindhu; Shrestha, Utsab; Perera, Suchithranga M.d.c.; ...
2015-01-27
Rhodopsin is a G-protein-coupled receptor (GPCR) responsible for vision under dim light conditions. During rhodopsin photoactivation, the chromophore retinal undergoes cis-trans isomerization, and subsequently dissociates from the protein yielding the opsin apoprotein [1]. What are the changes in protein dynamics that occur during the rhodopsin photoactivation process? Here, we studied the microscopic dynamics of the dark-state rhodopsin and the ligand-free opsin using quasi-elastic neutron scattering (QENS). The QENS technique tracks the individual hydrogen atom motions in the protein molecules, because the neutron scattering cross-section of hydrogen is much higher than other atoms [2-4]. We used protein (rhodopsin/opsin) samples with CHAPSmore » detergent hydrated with heavy water. The solvent signal is suppressed due to the heavy water, so that only the signals from proteins and detergents are detected. The activation of proteins is confirmed at low temperatures up to 300 K by the mean-square displacement (MSD) analysis. Our QENS experiments conducted at temperatures ranging from 220 K to 300 K clearly indicate that the protein dynamic behavior increases with temperature. The relaxation time for the ligand-bound protein rhodopsin was longer compared to opsin, which can be correlated with the photoactivation. Moreover, the protein dynamics are orders of magnitude slower than the accompanying CHAPS detergent, which forms a band around the protein molecule in the micelle. Unlike the protein, the CHAPS detergent manifests localized motions that are the same as in the bulk empty micelles. Furthermore QENS provides unique understanding of the key dynamics involved in the activation of the GPCR involved in the visual process.« less
Rhodopsin photoactivation dynamics revealed by quasi-elastic neutron scattering
Bhowmik, Debsindhu; Shrestha, Utsab; Perera, Suchithranga M.d.c.; Chawla, Udeep; Mamontov, Eugene; Brown, Michael F.; Chu, Xiang -Qiang
2015-01-27
Rhodopsin is a G-protein-coupled receptor (GPCR) responsible for vision under dim light conditions. During rhodopsin photoactivation, the chromophore retinal undergoes cis-trans isomerization, and subsequently dissociates from the protein yielding the opsin apoprotein [1]. What are the changes in protein dynamics that occur during the rhodopsin photoactivation process? Here, we studied the microscopic dynamics of the dark-state rhodopsin and the ligand-free opsin using quasi-elastic neutron scattering (QENS). The QENS technique tracks the individual hydrogen atom motions in the protein molecules, because the neutron scattering cross-section of hydrogen is much higher than other atoms [2-4]. We used protein (rhodopsin/opsin) samples with CHAPS detergent hydrated with heavy water. The solvent signal is suppressed due to the heavy water, so that only the signals from proteins and detergents are detected. The activation of proteins is confirmed at low temperatures up to 300 K by the mean-square displacement (MSD) analysis. Our QENS experiments conducted at temperatures ranging from 220 K to 300 K clearly indicate that the protein dynamic behavior increases with temperature. The relaxation time for the ligand-bound protein rhodopsin was longer compared to opsin, which can be correlated with the photoactivation. Moreover, the protein dynamics are orders of magnitude slower than the accompanying CHAPS detergent, which forms a band around the protein molecule in the micelle. Unlike the protein, the CHAPS detergent manifests localized motions that are the same as in the bulk empty micelles. Furthermore QENS provides unique understanding of the key dynamics involved in the activation of the GPCR involved in the visual process.
Detecting skin malignancy using elastic light scattering spectroscopy
NASA Astrophysics Data System (ADS)
Canpolat, Murat; Akman, Ayşe; Çiftçioğlu, M. Akif; Alpsoy, Erkan
2007-07-01
We have used elastic light scattering spectroscopy to differentiate between malign and benign skin lesions. The system consists of a UV spectrometer, a single optical fiber probe and a laptop. The single optical fiber probe was used for both delivery and detection of white light to tissue and from the tissue. The single optical fiber probe received singly scattered photons rather than diffused photons in tissue. Therefore, the spectra are correlated with morphological differences of the cells. It has been shown that spectra of malign skin lesions are different than spectra of benign skin lesions. While slopes of the spectra taken on benign lesions or normal skin tissues were positive, slopes of the spectra taken on malign skin lesions tissues were negative. In vivo experiments were conducted on 20 lesions from 18 patients (11 men with mean age of 68 +/- 9 years and 7 women with mean age of 52 +/- 20 years) applied to the Department of Dermatology and Venerology. Before the biopsy, spectra were taken on the lesion and adjacent (approximately 1 cm distant) normal-appearing skin. Spectra of the normal skin were used as a control group. The spectra were correlated to the pathology results with sensitivity and specificity of 82% and 89%, respectively. Due to small diameter of fiber probe and limited number of sampling (15), some positive cases are missed, which is lowered the sensitivity of the system. The results are promising and could suggest that the system may be able to detect malignant skin lesion non-invasively and in real time.
Park, Yang-Kyun Sharp, Gregory C.; Phillips, Justin; Winey, Brian A.
2015-08-15
Purpose: To demonstrate the feasibility of proton dose calculation on scatter-corrected cone-beam computed tomographic (CBCT) images for the purpose of adaptive proton therapy. Methods: CBCT projection images were acquired from anthropomorphic phantoms and a prostate patient using an on-board imaging system of an Elekta infinity linear accelerator. Two previously introduced techniques were used to correct the scattered x-rays in the raw projection images: uniform scatter correction (CBCT{sub us}) and a priori CT-based scatter correction (CBCT{sub ap}). CBCT images were reconstructed using a standard FDK algorithm and GPU-based reconstruction toolkit. Soft tissue ROI-based HU shifting was used to improve HU accuracy of the uncorrected CBCT images and CBCT{sub us}, while no HU change was applied to the CBCT{sub ap}. The degree of equivalence of the corrected CBCT images with respect to the reference CT image (CT{sub ref}) was evaluated by using angular profiles of water equivalent path length (WEPL) and passively scattered proton treatment plans. The CBCT{sub ap} was further evaluated in more realistic scenarios such as rectal filling and weight loss to assess the effect of mismatched prior information on the corrected images. Results: The uncorrected CBCT and CBCT{sub us} images demonstrated substantial WEPL discrepancies (7.3 ± 5.3 mm and 11.1 ± 6.6 mm, respectively) with respect to the CT{sub ref}, while the CBCT{sub ap} images showed substantially reduced WEPL errors (2.4 ± 2.0 mm). Similarly, the CBCT{sub ap}-based treatment plans demonstrated a high pass rate (96.0% ± 2.5% in 2 mm/2% criteria) in a 3D gamma analysis. Conclusions: A priori CT-based scatter correction technique was shown to be promising for adaptive proton therapy, as it achieved equivalent proton dose distributions and water equivalent path lengths compared to those of a reference CT in a selection of anthropomorphic phantoms.
Maximum likelihood techniques applied to quasi-elastic light scattering
NASA Technical Reports Server (NTRS)
Edwards, Robert V.
1992-01-01
There is a necessity of having an automatic procedure for reliable estimation of the quality of the measurement of particle size from QELS (Quasi-Elastic Light Scattering). Getting the measurement itself, before any error estimates can be made, is a problem because it is obtained by a very indirect measurement of a signal derived from the motion of particles in the system and requires the solution of an inverse problem. The eigenvalue structure of the transform that generates the signal is such that an arbitrarily small amount of noise can obliterate parts of any practical inversion spectrum. This project uses the Maximum Likelihood Estimation (MLE) as a framework to generate a theory and a functioning set of software to oversee the measurement process and extract the particle size information, while at the same time providing error estimates for those measurements. The theory involved verifying a correct form of the covariance matrix for the noise on the measurement and then estimating particle size parameters using a modified histogram approach.
NASA Astrophysics Data System (ADS)
Khalil, Abdullah; Horowitz, W. A.
2017-01-01
We calculate the elastic scattering cross section for an electron off of a classical point source in weak-coupling perturbative quantum electrodynamics at next-to-leading order accuracy in the renormalization scheme. Since we use the \\overline {MS} renormalization scheme, our result is valid up to arbitrary large momentum transfers between the source and the scattered electron.
Total elastic cross section for H-bar-H scattering at thermal energies
Sinha, Prabal K.; Chaudhuri, Puspitapallab; Ghosh, A. S.
2004-01-01
This paper reports the elastic scattering cross sections for a few low-lying partial waves and also the converged elastic cross sections with added partial waves in the energy range 10{sup -10}-10{sup -2} a.u. for the H-bar-H system using atomic orbital techniques. The present s-wave predictions are in good agreement with the other existing theoretical estimates. Nonzero low-order partial-wave elastic cross sections show dips like for s-wave scattering. The converged elastic cross section shows structurelike behavior in the energy range 4.2x10{sup -4}-10{sup -2} a.u.
Covariance Matrix of a Double-Differential Doppler-broadened Elastic Scattering Cross Section
Arbanas, Goran; Becker, B.; Dagan, R; Dunn, Michael E; Larson, Nancy M; Leal, Luiz C; Williams, Mark L
2012-01-01
Legendre moments of a double-differential Doppler-broadened elastic neutron scattering cross section on {sup 238}U are computed near the 6.67 eV resonance at temperature T = 10{sup 3} K up to angular order 14. A covariance matrix of these Legendre moments is computed as a functional of the covariance matrix of the elastic scattering cross section. A variance of double-differential Doppler-broadened elastic scattering cross section is computed from the covariance of Legendre moments.
Strong intrabeam scattering in heavy ion and proton beams
Parzen, G.
1985-01-01
Intrabeam scattering is the scattering of the particles in the beam from each other through the Coulomb forces that act between each pair of particles. This causes the beam dimensions to grow both longitudinally and transversely. In strong intrabeam scattering, the beam dimensions may grow by several fold, and the accelerator aperture is large enough to contain the beam as it grows. The growth rates may be very large initially, but they quickly decrease as the beam increases in size. The growth of a beam of particles has been studied over long periods of time of the order of many hours, for a beam of gold ions and for a beam of protons, and as function of the beam energy. These studies revealed certain features of strong intrabeam scattering which are likely to have a general validity. Some simple general results were found to hold in the high energy limit which hold for ..gamma.. sufficiently above the transition energy, ..gamma..t. One result is the time invariant. (X/sub p/sigma/sub p/)/sup 2/ - sigma/sub x//sup 2/ = constant, where sigma/sub x/ is the rms betatron oscillation amplitude, sigma/sub p/ is the rms relative momentum, ..delta..p/p, and X/sub p/ is the horizontal dispersion. 6 refs., 6 figs.
Inelastic scattering of 65 MeV protons from /sup 12/C, /sup 24/Mg, /sup 28/Si, and /sup 32/S
Kato, S.; Okada, K.; Kondo, M.; Hosono, K.; Saito, T.; Matsuoka, N.; Hatanaka, K.; Noro, T.; Nagamachi, S.; Shimizu, H.; Ogino, K.; Kadota, Y.; Matsuki, S.; Wakai, M.
1985-05-01
Measurements of angular distributions of the cross sections and analyzing powers for the elastic and inelastic scatterings of 65 MeV polarized protons from /sup 12/C, /sup 24/Mg, /sup 28/Si, and /sup 32/S are reported. Coupled channels analyses of the scattering data are presented assuming the 0/sub 1//sup +/, 2/sub 1//sup +/, and 4/sub 1//sup +/ states to be members of the ground band, the 0/sub 2//sup +/ state to begin the
Inelastic proton scattering of Sn isotopes studied with GRETINA
NASA Astrophysics Data System (ADS)
Campbell, Christopher
2014-03-01
The chain of semi-magic Sn nuclei, with many stable isotopes, has been a fertile ground for experimental and theoretical studies. Encompassing a major neutron shell from N = 50 to 82, the properties and structure of these nuclei provided important data for the development of the pairing-plus-quadrupole model. Recent experimental information on B(E2) for 106,108,110,112Sn came as a surprise as it indicated a larger collectivity than the predicted parabolic trend of quadrupole collectivity. These data, instead, show an unexpectedly flat trend even as the number of valence particles is reduced from 12 to 6. To fully understand how collectivity is evolving in these isotopes, 108,110,112Sn have been studied using thick-target, inelastic proton scattering with GRETINA tagging inelastic scattering events by detecting gamma-rays from the prompt decay of states excited in the reaction. We will present the trend of 2 + excitation cross-sections, the deduced quadrupole deformation parameters, and observations of other low-lying collective states. Comparison of these (p,p') quadrupole deformation parameters with B(E2) data will provide new insights into the relative importance of proton and neutron contributions to collectivity in these nuclei. GRETINA was funded by the US DOE - Office of Science. Operation of the array at NSCL is supported by NSF under Cooperative Agreement PHY-1102511(NSCL) and DOE under grant DE-AC02-05CH11231(LBNL).
Proton Spin Polarizabilities with Polarized Compton Scattering at MAMI
NASA Astrophysics Data System (ADS)
Paudyal, Dilli; A2 Collaboration
2015-10-01
The nucleon polarizabilities are fundamental structure observables, which describe its response to an applied electric or magnetic field. While the electric and magnetic scalar polarizabilities of the nucleon have been measured, little effort has been made to extract the spin dependent polarizabilities. These leading order spin dependent terms of the nucleon polarizabilities, γE1E1 ,γM1M1 ,γM1E2 and γE1M2 describe the spin response of a proton to electric and magnetic dipole and quadrupole interactions. We plan to extract these spin polarizabilities of the proton using real polarised Compton scattering off the proton at the MAMI tagged photon facility in Mainz, Germany. This requires precise measurement of the single and double polarization observables which are sensitive to these polarizabilities. The double polarization observables ∑2 x, ∑2 z are measured via a circulary polarized photon beam and a transversely and a linearly polarized butanol target in the resonance region (E = 250 - 310 MeV). This presentation will be focused on the status and analyis of an experiment completed at MAMI in 2014 and 2015 for the measurement of ∑2 z at different energies and angles. Supported by the Natural Sciences and Engineering Research Council of Canada (NSERC).
Measurements of electron-proton elastic cross sections for 0.4 < Q{sup 2} < 5.5 (GeV/c){sup 2}
M.E. Christy; Abdellah Ahmidouch; Christopher Armstrong; John Arrington; Razmik Asaturyan; Steven Avery; O. Baker; Douglas Beck; Henk Blok; C.W.Bochna; Werner Boeglin; Peter Bosted; Maurice Bouwhuis; Herbert Breuer; D.S.Brown; Antje Bruell; Roger Carlini; Nicholas Chant; Anthony Cochran; Leon Cole; Samuel Danagoulian; Donal Day; James Dunne; Dipangkar Dutta; Rolf Ent; Howard Fenker; B.Fox; Liping Gan; Haiyan Gao; Kenneth Garrow; David Gaskell; Ashot Gasparian; Don Geesaman; Paul Gueye; Mark Harvey; Roy Holt; Xiaodong Jiang; Cynthia Keppel; Edward Kinney; Yongguang Liang; Wolfgang Lorenzon; Allison Lung; Pete Markowitz; J.W.Martin; Kevin McIlhany; Daniella Mckee; David Meekins; M.A.Miller; Richard Milner; Joseph Mitchell; Hamlet Mkrtchyan; Robert Mueller; Alan Nathan; Gabriel Niculescu; Maria-Ioana Niculescu; Thomas O'neill; Vassilios Papavassiliou; Stephen Pate; Buz Piercey; David Potterveld; Ronald Ransome; Joerg Reinhold; E.Rollinde; Philip Roos; Adam Sarty; Reyad Sawafta; Elaine Schulte; Edwin Segbefia; C.Smith; Stepan Stepanyan; Steffen Strauch; Vardan Tadevosyan; Liguang Tang; Raphael Tieulent; Alicia Uzzle; William Vulcan; Stephen Wood; Feng Xiong; Lulin Yuan; Markus Zeier; Benedikt Zihlmann; Vitaliy Ziskin
2004-01-01
We report on precision measurements of the elastic cross section for electron-proton scattering performed in Hall C at Jefferson Lab. The measurements were made at 28 unique kinematic settings covering a range in momentum transfer of 0.4 < Q{sup 2} < 5.5 (/rm GeV/c){sup 2}. These measurements represent a significant contribution to the world's cross section data set in the Q{sup 2} range where a large discrepancy currently exists between the ratio of electric to magnetic proton form factors extracted from previous cross section measurements and that recently measured via polarization transfer in Hall A at Jefferson Lab.
Cancer detection using NIR elastic light scattering and tissue fluorescence imaging
Demos, S G; Staggs, M; Radousky, H B; Gandour-Edwards, R; deVere White, R
2000-12-04
Near infrared imaging using elastic light scattering and tissue fluorescence under long-wavelength laser excitation are explored for cancer detection. Various types of normal and malignant human tissue samples were utilized in this investigation.
P(P bar)P elastic scattering and cosmic ray data
NASA Technical Reports Server (NTRS)
FAZAL-E-ALEEM; Saleem, M.
1985-01-01
It is shown that the total cross section for pp elastic scattering at cosmic ray energies, as well as the total cross section, the slope parameter b(s,t) and the differential cross section for small momentum transfer at ISR and collider energies for p(p)p elastic scattering can be simultaneously fitted by using a simple Regge pole model. The results of this theory is discussed in detail.
14O+p elastic scattering in a microscopic cluster model
Descouvemont, P.; Baye, D.; Leo, F.
2006-04-26
The 14O+p elastic scattering is analyzed in a fully microscopic cluster model. With the Resonating Group Method associated with the microscopic R-matrix theory, phase shifts and cross sections are calculated. Data on 16O+p are used to test the precision of the model. For the 14O+p elastic scattering, an excellent agreement is found with recent experimental data. Resonances properties in 15F are discussed.
The elastic constants of rubrene determined by Brillouin scattering and density functional theory
NASA Astrophysics Data System (ADS)
Zhang, Yaqi; Manke, David R.; Sharifzadeh, Sahar; Briseno, Alejandro L.; Ramasubramaniam, Ashwin; Koski, Kristie J.
2017-02-01
The linear elastic stiffness tensor of the crystalline organic semiconductor, rubrene, is measured using Brillouin light scattering spectroscopy and computed from first-principles van der Waals density functional theory calculations. Results are compared with recent measurements of in-plane reduced elastic constants c¯ 22, c¯ 33 , and c¯ 23 determined through anisotropic buckling experiments.
Parity Nonconservation in Proton-Proton and Proton-Water Scattering at 1.5 GeV/c
DOE R&D Accomplishments Database
Mischke, R. E.; Bowman, J. D.; Carlini, R.; MacArthur, D.; Nagle, D. E.; Frauenfelder, H.; Harper, R. W.; Yuan, V.; McDonald, A. B.; Talaga, R. L.
1984-07-01
Experiments searching for parity nonconservation in the scattering of 1.5 GeV/c (800 MeV) polarized protons from an unpolarized water target and a liquid hydrogen target are described. The intensity of the incident proton beam was measured upstream and downstream of the target by a pair of ionization detectors. The beam helicity was reversed at a 30-Hz rate. Auxiliary detectors monitored beam properties that could give rise to false effects. The result for the longitudinal asymmetry from the water is A{sub L} = (1.7 +- 3.3 +- 1.4) x 10{sup -7}, where the first error is statistical and the second is an estimate of systematic effects. The hydrogen data yield a preliminary result of A{sub L} = (1.0 +- 1.6) x 10{sup -7}. The systematic errors for p-p are expected to be < 1 x 10{sup -7}.
Leakage and scatter radiation from a double scattering based proton beamline
Moyers, M. F.; Benton, E. R.; Ghebremedhin, A.; Coutrakon, G.
2008-01-15
Proton beams offer several advantages over conventional radiation techniques for treating cancer and other diseases. These advantages might be negated if the leakage and scatter radiation from the beamline and patient are too large. Although the leakage and scatter radiation for the double scattering proton beamlines at the Loma Linda University Proton Treatment Facility were measured during the acceptance testing that occurred in the early 1990s, recent discussions in the radiotherapy community have prompted a reinvestigation of this contribution to the dose equivalent a patient receives. The dose and dose equivalent delivered to a large phantom patient outside a primary proton field were determined using five methods: simulations using Monte Carlo calculations, measurements with silver halide film, measurements with ionization chambers, measurements with rem meters, and measurements with CR-39 plastic nuclear track detectors. The Monte Carlo dose distribution was calculated in a coronal plane through the simulated patient that coincided with the central axis of the beam. Measurements with the ionization chambers, rem meters, and plastic nuclear track detectors were made at multiple locations within the same coronal plane. Measurements with the film were done in a plane perpendicular to the central axis of the beam and coincident with the surface of the phantom patient. In general, agreement between the five methods was good, but there were some differences. Measurements and simulations also tended to be in agreement with the original acceptance testing measurements and results from similar facilities published in the literature. Simulations illustrated that most of the neutrons entering the patient are produced in the final patient-specific aperture and precollimator just upstream of the aperture, not in the scattering system. These new results confirm that the dose equivalents received by patients outside the primary proton field from primary particles that leak
Measurements of Compton Scattering on the Proton at 2 - 6 GeV
Danagoulian, Areg
2006-01-01
Similar to elastic electron scattering, Compton Scattering on the proton at high momentum transfers(and high p⊥) can be an effective method to study its short-distance structure. An experiment has been carried out to measure the cross sections for Real Compton Scattering (RCS) on the proton for 2.3-5.7 GeV electron beam energies and a wide distribution of large scattering angles. The 25 kinematic settings sampled a domain of s = 5-11(GeV/c)^{2},-t = -7(GeV/c)^{2} and -u = 0.5-6.5(GeV/c)^{2}. In addition, a measurement of longitudinal and transverse polarization transfer asymmetries was made at a 3.48 GeV beam energy and a scattering angle of θ_{cm }= 120°. These measurements were performed to test the existing theoretical mechanisms for this process as well as to determine RCS form factors. At the heart of the scientific motivation is the desire to understand the manner in which a nucleon interacts with external excitations at the above listed energies, by comparing and contrasting the two existing models – Leading Twist Mechanism and Soft Overlap “Handbag” Mechanism – and identify the dominant mechanism. Furthermore, the Handbag Mechanism allows one to calculate reaction observables in the framework of Generalized Parton Distributions (GPD), which have the function of bridging the wide gap between the exclusive(form factors) and inclusive(parton distribution functions) description of the proton. The experiment was conducted in Hall A of Thomas Jefferson National Accelerator Facility(Jefferson Lab). It used a polarized and unpolarized electron beam, a 6% copper radiator with the thickness of 6.1% radiation lengths (to produce a bremsstrahlung photon beam), the Hall A liquid hydrogen target, a high resolution spectrometer with a focal plane polarimeter, and a photon hodoscope calorimeter. Results of the differential cross sections are presented, and discussed in the general context of the scientific motivation.
Dirac Calculations for Proton Inelastic Scattering at Intermediate Energies
NASA Astrophysics Data System (ADS)
El-Nohy, N. A.; El-Hammamy, M. N.; Aly, N. E.; Abdel-Moneim, A. M.; Hamza, A. F.
2016-12-01
Relativistic proton inelastic scattering from different targets (16O, 24Mg, 28Si, 40Ca, 54Fe, 58Ni, 90Zr, 154Sm, 176Yb, and 208Pb) at intermediate energies is analyzed in the framework of phenomenological optical potentials based on the Dirac formalism. Parameters of the Dirac phenomenological potential with Woods Saxon (WS) shape are obtained. The first order vibrational collective model with one phonon is used to calculate the transition optical potentials to the first low-lying excited state (2+) of the investigated target nuclei. Also, the variation of deformation length ( δ) with energy and mass number is studied. It is noticed that the deformation length increases slightly with energy at intermediate range.
The proton-deuteron scattering length in pionless EFT
NASA Astrophysics Data System (ADS)
König, Sebastian; Hammer, Hans-Werner
2015-10-01
We present a fully perturbative calculation of the quartet-channel proton-deuteron scattering length up to next-to-next-to-leading order (NNLO) in pionless effective field theory. In particular, we use a framework that consistently extracts the Coulomb-modified effective range function for a screened Coulomb potential in momentum space and allows for a clear linear extrapolation back to the physical limit without screening. We find a natural convergence pattern as we go to higher orders in the EFT expansion. Our NNLO result of (10 . 9 +/- 0 . 4) fm agrees with older experimental determinations but deviates from more recent results around 14 fm. As a resolution of this discrepancy, we discuss the scheme dependence of Coulomb subtractions in a three-body system. Supported in part by the NSF, DOE (NUCLEI SciDAC), as well as by the DFG and BMBF.
The proton-deuteron scattering length in pionless EFT
NASA Astrophysics Data System (ADS)
König, Sebastian; Hammer, Hans-Werner
2016-03-01
We present a fully perturbative calculation of the quartet-channel proton-deuteron scattering length (4ap-d) up to next-to-next-to-leading order (NNLO) in pionless effective field theory. In particular, we use a framework that consistently extracts the Coulomb-modified effective range function for a screened Coulomb potential in momentum space. We find a natural convergence pattern as we go to higher orders in the EFT expansion. Our NNLO result of (10.9 ± 0.4) fm agrees with older experimental determinations but deviates from more recent calculations, which find values around 14 fm. To resolve this discrepancy, we discuss the scheme dependence of Coulomb subtractions in a three-body system.
Liu, Haitao
2013-10-07
We propose a coherent-form energy conservation relation (ECR) that is generally valid for the elastic transmission and reflection of a guided mode in a symmetric scattering system. In contrast with the classical incoherent-form ECR, |τ|2 + |ρ|2≤1 with τ and ρ denoting the elastic transmission and reflection coefficients of a guided mode, the coherent-form ECR is expressed as |τ + ρ|≤1, which imposes a constraint on a coherent superposition of the transmitted and reflected modes. The coherent-form ECR is rigorously demonstrated and is numerically tested by considering different types of modes in various scattering systems. Further discussions with the scattering matrix formalism indicate that two coherent-form ECRs, |τ + ρ|≤1 and |τ-ρ|≤1, along with the classical ECR |τ|2 + |ρ|2≤1 constitute a complete description of the energy conservation for the elastic scattering of a guided mode in a symmetric scattering system. The coherent-form ECR provides a common tool in terms of energy transfer for understanding and analyzing the scattering dynamics in currently interested scattering systems.
Multiple-scattering model for inclusive proton production in heavy ion collisions
NASA Technical Reports Server (NTRS)
Cucinotta, Francis A.
1994-01-01
A formalism is developed for evaluating the momentum distribution for proton production in nuclear abrasion during heavy ion collisions using the Glauber multiple-scattering series. Several models for the one-body density matrix of nuclei are considered for performing numerical calculations. Calculations for the momentum distribution of protons in abrasion are compared with experimental data for inclusive proton production.
Measurement of quasi-elastic 12C(p,2p) scattering at high momentum transfer
NASA Astrophysics Data System (ADS)
Mardor, Y.; Aclander, J.; Alster, J.; Barton, D.; Bunce, G.; Carroll, A.; Christensen, N.; Courant, H.; Durrant, S.; Gushue, S.; Heppelmann, S.; Kosonovsky, E.; Mardor, I.; Marshak, M.; Makdisi, Y.; Minor, E. D.; Navon, I.; Nicholson, H.; Piasetzky, E.; Roser, T.; Russell, J.; Sutton, C. S.; Tanaka, M.; White, C.; Wu, J.-Y.
1998-10-01
We measured the high-momentum transfer [Q2=4.8 and 6.2 (GeV/c)2] quasi-elastic 12C(p,2p) reaction at θcm~=90 deg for 6 and 7.5 GeV/c incident protons. The momentum components of both outgoing protons and the missing energy and momentum of the proton in the nucleus were measured. We verified the validity of the quasi-elastic picture for ground state momenta up to about 0.5 GeV/c. Transverse and longitudinal momentum distributions of the target proton were measured. They have the same shape with a large momentum tail which is not consistent with independent particle models. We observed that the transverse distribution gets wider as the longitudinal component increases in the beam direction.
Partial-wave analysis of nucleon-nucleon elastic scattering data
NASA Astrophysics Data System (ADS)
Workman, Ron L.; Briscoe, William J.; Strakovsky, Igor I.
2016-12-01
Energy-dependent and single-energy fits to the existing nucleon-nucleon database have been updated to incorporate recent measurements. The fits cover a region from threshold to 3 GeV, in the laboratory kinetic energy, for proton-proton scattering, with an upper limit of 1.3 GeV for neutron-proton scattering. Experiments carried out at the COSY-WASA and COSY-ANKE facilities have had a significant impact on the partial-wave solutions. Results are discussed in terms of both partial-wave and direct reconstruction amplitudes.
Proton-Nucleus Scattering Approximations and Implications for LHC Crystal Collimation
Noble, Robert; /SLAC
2010-06-07
In particle accelerators, scattered protons with energies close to the incident particles may travel considerable distances with the beam before impacting on accelerator components downstream. To analyze such problems, angular deflection and energy loss of scattered particles are the main quantities to be simulated since these lead to changes in the beam's phase space distribution and particle loss. Simple approximations for nuclear scattering processes causing limited energy loss to high-energy protons traversing matter are developed which are suitable for rapid estimates and reduced-description Monte Carlo simulations. The implications for proton loss in the Large Hadron Collider due to nuclear scattering on collimation crystals are discussed.
Trantham, E C; Rorschach, H E; Clegg, J S; Hazlewood, C F; Nicklow, R M; Wakabayashi, N
1984-01-01
Results have been obtained on the quasi-elastic spectra of neutrons scattered from pure water, a 20% agarose gel (hydration four grams H2O per gram of dry solid) and cysts of the brine shrimp Artemia for hydrations between 0.10 and 1.2 grams H2O per gram of dry solids. The spectra were interpreted using a two-component model that included contributions from the covalently bonded protons and the hydration water, and a mobile water fraction. The mobile fraction was described by a jump-diffusion correlation function for the translation motion and a simple diffusive orientational correlation function. The results for the line widths gamma (Q2) for pure water were in good agreement with previous measurements. The agarose results were consistent with NMR measurements that show a slightly reduced translational diffusion for the mobile water fraction. The Artemia results show that the translational diffusion coefficient of the mobile water fraction was greatly reduced from that of pure water. The line width was determined mainly by the rotational motion, which was also substantially reduced from the pure water value as determined from dielectric relaxation studies. The translational and rotational diffusion parameters were consistent with the NMR measurements of diffusion and relaxation. Values for the hydration fraction and the mean square thermal displacement [u2] as determined from the Q-dependence of the line areas were also obtained. PMID:6733243
NASA Astrophysics Data System (ADS)
Schultz, D. R.; Ovchinnikov, S. Yu; Stancil, P. C.; Zaman, T.
2016-04-01
Updating and extending previous work (Krstić and Schultz 1999 J. Phys. B: At. Mol. Opt. Phys. 32 3458 and other references) comprehensive calculations were performed for elastic scattering and charge transfer in proton—atomic hydrogen collisions. The results, obtained for 1301 collision energies in the center-of-mass energy range of 10-4-104 eV, are provided for integral and differential cross sections relevant to transport modeling in astrophysical and other plasma environments, and are made available through a website. Use of the data is demonstrated through a Monte Carlo transport simulation of solar wind proton propagation through atomic hydrogen gas representing a simple model of the solar wind interaction with heliospheric neutrals.
Finite-element modelling of elastic wave propagation and scattering within heterogeneous media
NASA Astrophysics Data System (ADS)
Van Pamel, A.; Sha, G.; Rokhlin, S. I.; Lowe, M. J. S.
2017-01-01
The scattering treated here arises when elastic waves propagate within a heterogeneous medium defined by random spatial fluctuation of its elastic properties. Whereas classical analytical studies are based on lower-order scattering assumptions, numerical methods conversely present no such limitations by inherently incorporating multiple scattering. Until now, studies have typically been limited to two or one dimension, however, owing to computational constraints. This article seizes recent advances to realize a finite-element formulation that solves the three-dimensional elastodynamic scattering problem. The developed methodology enables the fundamental behaviour of scattering in terms of attenuation and dispersion to be studied. In particular, the example of elastic waves propagating within polycrystalline materials is adopted, using Voronoi tessellations to randomly generate representative models. The numerically observed scattering is compared against entirely independent but well-established analytical scattering theory. The quantitative agreement is found to be excellent across previously unvisited scattering regimes; it is believed that this is the first quantitative validation of its kind which provides significant support towards the existence of the transitional scattering regime and facilitates future deployment of numerical methods for these problems.
Finite-element modelling of elastic wave propagation and scattering within heterogeneous media
Sha, G.; Rokhlin, S. I.; Lowe, M. J. S.
2017-01-01
The scattering treated here arises when elastic waves propagate within a heterogeneous medium defined by random spatial fluctuation of its elastic properties. Whereas classical analytical studies are based on lower-order scattering assumptions, numerical methods conversely present no such limitations by inherently incorporating multiple scattering. Until now, studies have typically been limited to two or one dimension, however, owing to computational constraints. This article seizes recent advances to realize a finite-element formulation that solves the three-dimensional elastodynamic scattering problem. The developed methodology enables the fundamental behaviour of scattering in terms of attenuation and dispersion to be studied. In particular, the example of elastic waves propagating within polycrystalline materials is adopted, using Voronoi tessellations to randomly generate representative models. The numerically observed scattering is compared against entirely independent but well-established analytical scattering theory. The quantitative agreement is found to be excellent across previously unvisited scattering regimes; it is believed that this is the first quantitative validation of its kind which provides significant support towards the existence of the transitional scattering regime and facilitates future deployment of numerical methods for these problems. PMID:28265198
Hulthén potential models for α-α and α-He 3 elastic scattering
NASA Astrophysics Data System (ADS)
BHOI, J.; LAHA, U.
2017-03-01
Simple Hulthén-type potential models are proposed to treat the α- α and α {-} {He}3 elastic scattering. The merit of our approach is examined by computing elastic scattering phases through the judicious use of the phase function method. Reasonable agreements in scattering phase shifts are obtained with the standard data.
Anisotropic Elastic Resonance Scattering model for the Neutron Transport equation
Mohamed Ouisloumen; Abderrafi M. Ougouag; Shadi Z. Ghrayeb
2014-11-24
The resonance scattering transfer cross-section has been reformulated to account for anisotropic scattering in the center-of-mass of the neutron-nucleus system. The main innovation over previous implementations is the relaxation of the ubiquitous assumption of isotropic scattering in the center-of-mass and the actual effective use of scattering angle distributions from evaluated nuclear data files in the computation of the angular moments of the resonant scattering kernels. The formulas for the high order anisotropic moments in the laboratory system are also derived. A multi-group numerical formulation is derived and implemented into a module incorporated within the NJOY nuclear data processing code. An ultra-fine energy mesh cross section library was generated using these new theoretical models and then was used for fuel assembly calculations with the PARAGON lattice physics code. The results obtained indicate a strong effect of this new model on reactivity, multi-group fluxes and isotopic inventory during depletion.
NASA Technical Reports Server (NTRS)
Wilson, J. W.
1972-01-01
The exact nucleon-deuteron elastic single scattering integral was calculated numerically in order to evaluate errors in sticking factor approximations. A similar analysis made by using S wave separable potentials concluded that errors for these approximations were negligible except near backward angles where they were found to be about 10 percent.
Backward elastic light scattering of malaria infected red blood cells
NASA Astrophysics Data System (ADS)
Lee, Seungjun; Lu, Wei
2011-08-01
We investigated the backward light scattering pattern of healthy and malaria (Plasmodium falciparum) parasitized red blood cells. The spectrum could clearly distinguish between predominant ring stage infected blood cells and healthy blood cells. Further, we found that infected samples mixed with different stages of P. falciparum showed different signals, suggesting that even variance in parasite stages could also be detected by the spectrum. These results together with the backward scattering technique suggest the potential of non-invasive diagnosis of malaria through light scattering of blood cells near the surface of human body, such as using eyes or skin surface.
Nonlinear coda wave analysis of hysteretic elastic behavior in strongly scattering media
NASA Astrophysics Data System (ADS)
Ouarabi, M. Ait; Boubenider, F.; Gliozzi, A. S.; Scalerandi, M.
2016-10-01
Strongly scattering elastic media, such as consolidated granular materials, respond to ultrasonic pulse excitations with a long response signal with peculiar properties. The portion of the signal at late times, termed coda, is due to multiple scattering. It contains information about the elastic properties of the material, and it has been proven to be very sensitive to small variations in the modulus. Here we propose a technique based on a nonlinear analysis of the coda of a signal, which might be applied to quantify the nonlinear elastic response in consolidated granular media exhibiting a hysteretic elastic behavior. The method proposed allows for an intrinsic definition of the reference signal which is normally needed for applying coda-based methods.
Coupled channel effect in elastic scattering and fusion for 6,7Li+28Si
NASA Astrophysics Data System (ADS)
Sinha, Mandira; Roy, Subinit; Basu, P.; Majumdar, H.; Santra, S.; Parkar, V. V.; Golda, K. S.; Kailas, S.
2011-10-01
The fusion excitation and elastic angular distribution were measured for 6,7Li+28Si from below to above Coulomb barrier (≤ 3Vb) energies. The barrier distribution derived from the fusion data was found to be broad and asymmetric at the sub-barrier region, compared to 1D BPM estimation. Effect of rotational coupling on fusion was found to be not so dominant. Phenomenological optical potential parameters, with surface and volume type imaginary potentials, were obtained from f tting of elastic scattering data and energy dependence of real and imaginary surface strengths were investigated around the barrier. CDCC calculations considering only breakup of projectile were performed for 6,7Li+28Si with the elastic scattering data, using the code FRESCO. The effects of breakup of projectile on elastic cross section do not agree with the energy dependence of real and imaginary strength with volume type imaginary potential around the barrier.
NASA Technical Reports Server (NTRS)
Bhatia, A. K.; Temkin, A.; Fisher, Richard R. (Technical Monitor)
2001-01-01
We report on the first part of a study of electron-hydrogen scattering, using a method which allows for the ab initio calculation of total and elastic cross sections at higher energies. In its general form the method uses complex 'radial' correlation functions, in a (Kohn) T-matrix formalism. The titled method, abbreviated Complex Correlation Kohn T (CCKT) method, is reviewed, in the context of electron-hydrogen scattering, including the derivation of the equation for the (complex) scattering function, and the extraction of the scattering information from the latter. The calculation reported here is restricted to S-waves in the elastic region, where the correlation functions can be taken, without loss of generality, to be real. Phase shifts are calculated using Hylleraas-type correlation functions with up to 95 terms. Results are rigorous lower bounds; they are in general agreement with those of Schwartz, but they are more accurate and outside his error bounds at a couple of energies,
Elastic scattering and total reaction cross section of {sup 6}He+{sup 120}Sn
Faria, P. N. de; Lichtenthaeler, R.; Pires, K. C. C.; Lepine-Szily, A.; Guimaraes, V.; Mendes, D. R. Jr.; Barioni, A.; Morcelle, V.; Morais, M. C.; Camargo, O. Jr.; Alcantara Nunez, J.; Moro, A. M.; Arazi, A.; Rodriguez-Gallardo, M.; Assuncao, M.
2010-04-15
The elastic scattering of {sup 6}He on {sup 120}Sn has been measured at four energies above the Coulomb barrier using the {sup 6}He beam produced at the RIBRAS (Radioactive Ion Beams in Brasil) facility. The elastic angular distributions have been analyzed with the optical model and three- and four-body continuum-discretized coupled-channels calculations. The total reaction cross sections have been derived and compared with other systems of similar masses.
Park, Y; Winey, B; Sharp, G
2014-06-01
Purpose: To demonstrate feasibility of proton dose calculation on scattercorrected CBCT images for the purpose of adaptive proton therapy. Methods: Two CBCT image sets were acquired from a prostate cancer patient and a thorax phantom using an on-board imaging system of an Elekta infinity linear accelerator. 2-D scatter maps were estimated using a previously introduced CT-based technique, and were subtracted from each raw projection image. A CBCT image set was then reconstructed with an open source reconstruction toolkit (RTK). Conversion from the CBCT number to HU was performed by soft tissue-based shifting with reference to the plan CT. Passively scattered proton plans were simulated on the plan CT and corrected/uncorrected CBCT images using the XiO treatment planning system. For quantitative evaluation, water equivalent path length (WEPL) was compared in those treatment plans. Results: The scatter correction method significantly improved image quality and HU accuracy in the prostate case where large scatter artifacts were obvious. However, the correction technique showed limited effects on the thorax case that was associated with fewer scatter artifacts. Mean absolute WEPL errors from the plans with the uncorrected and corrected images were 1.3 mm and 5.1 mm in the thorax case and 13.5 mm and 3.1 mm in the prostate case. The prostate plan dose distribution of the corrected image demonstrated better agreement with the reference one than that of the uncorrected image. Conclusion: A priori CT-based CBCT scatter correction can reduce the proton dose calculation error when large scatter artifacts are involved. If scatter artifacts are low, an uncorrected CBCT image is also promising for proton dose calculation when it is calibrated with the soft-tissue based shifting.
Single-crystal elasticity of hydrous wadsleyite by Brillouin scattering
NASA Astrophysics Data System (ADS)
Mao, Z.; Jiang, F.; Jacobsen, S. D.; Smyth, J. R.; Holl, C.; Duffy, T. S.; Frost, D. J.
2006-12-01
Wadsleyite (β-Mg2SiO4) is the high-pressure polymorph of olivine that is expected to be a dominant mineral in the transition zone from 410 km to 520 km depth in the mantle. The elasticity of wadsleyite is crucial to constrain the mineralogy of the transition zone. Previous studies show wadsleyite can incorporate variable amounts of water up to 3.3 wt% of water (Kohlstedt et al. 1996; Inoue et al. 1995; Smyth et al. 1987, 1994). The effect of water on the bulk modulus of wadsleyite was studied by x-ray diffraction (Yusa and Inoue, 1997; Smyth et al. 2005) but no constraints on the shear modulus exist. We have measured the single-crystal elastic constants of hydrous wadsleyite with varying water content using Brillouin spectroscopy at ambient conditions. We carried out measurements for samples containing 0.3 wt%, 0.6 wt% and 1.6 wt% water using at least 2 crystal planes for each sample. By computing the aggregate elastic properties, we find that the bulk (K0S) and shear modulus (G0) of hydrous wadsleyite decrease linearly with water content according to the following relations: K0S=169.0-11.8X_W; G0=115.1-12.5X_W; where X_W is the water H2O weight percent. Compared with anhydrous wadsleyite, 1 wt% of water will lead to 7.0% decrease in bulk modulus, 10.9% decrease in shear modulus. Water has a greater effect on the elastic moduli of wadsleyite than that of olivine or ringwoodite. The olivine to wadsleyite phase transition is believed to be the origin of the seismic discontinuity near 410 km. Using these new results, the possible effect of water content on the velocity contrast across the 410-km discontinuity will be examined.
NASA Astrophysics Data System (ADS)
Li, Xiao-Hua; Guo, Wen-Jun; Li, Bao-An; Chen, Lie-Wen; Fattoyev, Farrukh J.; Newton, William G.
2015-04-01
The neutron-proton effective mass splitting in asymmetric nucleonic matter of isospin asymmetry δ and normal density is found to be mn-p* ≡ (mn* - mp*) / m = (0.41 ± 0.15) δ from analyzing globally 1088 sets of reaction and angular differential cross sections of proton elastic scattering on 130 targets with beam energies from 0.783 MeV to 200 MeV, and 1161 sets of data of neutron elastic scattering on 104 targets with beam energies from 0.05 MeV to 200 MeV within an isospin dependent non-relativistic optical potential model. It sets a useful reference for testing model predictions on the momentum dependence of the nucleon isovector potential necessary for understanding novel structures and reactions of rare isotopes.
Evolution of Elastic X-ray Scattering in Laser-Shocked Warm Dense Li
Kugland, N L; Gregori, G; Bandyopadhyay, S; Brenner, C; Brown, C; Constantin, C; Glenzer, S H; Khattak, F; Kritcher, A L; Niemann, C; Otten, A; Pasley, J; Pelka, A; Roth, M; Spindloe, C; Riley, D
2009-06-02
We have studied the dynamics of warm dense Li with near-elastic x-ray scattering. Li foils were heated and compressed using shock waves driven by 4 ns long laser pulses. Separate 1 ns long laser pulses were used to generate a bright source of 2.96 keV Cl Ly-{alpha} photons for x-ray scattering, and the spectrum of scattered photons was recorded at a scattering angle of 120{sup o} using a HOPG crystal operated in the von Hamos geometry. A variable delay between the heater and backlighter laser beams measured the scattering time evolution. Comparison with radiation hydrodynamics simulations shows that the plasma is highly coupled during the first several nanoseconds, then relaxes to a moderate coupling state at later times. Near-elastic scattering amplitudes have been successfully simulated using the screened one-component plasma model. Our main finding is that the near-elastic scattering amplitudes are quite sensitive to the mean ionization state {bar Z}, and by extension to the choice of ionization model in the radiation-hydrodynamics simulations used to predict plasma properties within the shocked Li.
Elastic scattering of 17O ions from 58Ni at near-barrier energies
NASA Astrophysics Data System (ADS)
Torresi, D.; Strano, E.; Mazzocco, M.; Boiano, A.; Boiano, C.; Di Meo, P.; Guglielmetti, A.; La Commara, M.; Manea, C.; Nicoletto, M.; Parascandolo, C.; Parascandolo, L.; Pierroutsakou, D.; Sandoli, M.; Signorini, C.; Soramel, F.; Toniolo, N.; Grebosz, J.; Filipescu, D.; Gheorghe, A.; Glodariu, T.; Stroe, L.; Miyatake, H.; Watanabe, Y.; Jeong, S.; Kim, Y. H.; Pakou, A.; Sgouros, O.; Soukeras, V.; Zerva, K.
2014-03-01
Elastic scattering has been studied for the collisions induced by 17O on 58Ni target at energies around and above the Coulomb barrier. The elastic scattering angular distributions were measured for several energies and were analyzed within the framework of the optical model to obtain total reaction cross sections. The reaction cross-sections of the tightly bound 17O were compared with those of weakly bound 17F on the same targets in order to investigate the effects of the low binding energy in the reaction dynamics.
New measurements and phase shift analysis of p16O elastic scattering at astrophysical energies
NASA Astrophysics Data System (ADS)
Dubovichenko, Sergey; Burtebayev, Nassurlla; Dzhazairov-Kakhramanov, Albert; Zazulin, Denis; Kerimkulov, Zhambul; Nassurlla, Marzhan; Omarov, Chingis; Tkachenko, Alesya; Shmygaleva, Tatyana; Kliczewski, Stanislaw; Sadykov, Turlan
2017-01-01
The results of new experimental measurements of p16O elastic scattering in the energy range of 0.6-1.0 MeV at angles of 40°-160° are given. Phase shift analysis of p16O elastic scattering was made using these and other experimental data on differential cross sections in excitation functions and angular distributions at energies of up to 2.5 MeV. Supported by the Ministry of Education and Science of the Republic of Kazakhstan (0073/PCF-IS-MES)
Fluorescence and Elastic Scattering from Laser Dye-Filled Capillaries
1989-08-23
learning. I also thank John Pattison f *s electronic expertise; Tom Wentzel and Dave Abromson for their assistance with the computer; Ka Chun Yu and Jim...34 M.S. Thesis. University of Arizona, 1981. 4. H. C. Van De Hulst, Light Scattering by Small Particles ( John Wiley & Sons. Inc., N.Y., 1957). 5. R. E...Scattering by Molecules Embedded in Concentric Spheres." Journal of the Optical Society of America, 66, 440 (1976). 12. H. Chew, M. Sculley , M. Kerker, P. J
Elastic and inelastic scattering of positrons in gases and solids
NASA Technical Reports Server (NTRS)
Mcgowan, J. W.
1972-01-01
Three apparatuses were designed and built: The first, which is now operative, was designed to study the details of positron thermalization in solids and the subsequent emission of the low energy positrons from moderating foils; The second apparatus now under test is a positron bottle similar in design to an electron trap. It was built to store positrons at a fixed energy and to look at the number of stored positrons (storage time) as a function of a scattering gas in the vacuum chamber. The third apparatus is a crossed beam apparatus where positron-, alkali scattering will be studied. Much of the apparatus is now under test with electrons.
Hybrid Theory of Electron-Hydrogenic Systems Elastic Scattering
NASA Technical Reports Server (NTRS)
Bhatia, A. K.
2007-01-01
Accurate electron-hydrogen and electron-hydrogenic cross sections are required to interpret fusion experiments, laboratory plasma physics and properties of the solar and astrophysical plasmas. We have developed a method in which the short-range and long-range correlations can be included at the same time in the scattering equations. The phase shifts have rigorous lower bounds and the scattering lengths have rigorous upper bounds. The phase shifts in the resonance region can be used to calculate very accurately the resonance parameters.
Bigio, I.J.; Boyer, J.; Johnson, T.M.; Lacey, J.; Mourant, J.R.; Conn, R.; Bohorfoush, A.
1994-10-01
The Los Alamos National Laboratory has continued the development of the Optical Biopsy System (OBS) for noninvasive, real-time in situ diagnosis of tissue pathologies. Our clinical studies have expanded since the last Biomedical Optics Europe conference (Budapest, September 1993), and we report here on the latest results of clinical tests in gastrointestinal tract. The OBS invokes a unique approach to optical diagnosis of tissue pathologies based on the elastic scattering properties, over a wide range of wavelengths, of the tissue. The use of elastic scattering as the key to optical tissue diagnostics in the OBS is based on the fact that many tissue pathologies, including a majority of cancer forms, manifest significant architectural changes at the cellular and sub-cellular level. Since the cellular components that cause elastic scattering have dimensions typically on the order of visible to near-IR wavelengths, the elastic (Mie) scattering properties will be wavelength dependent. Thus, morphology and size changes can be expected to cause significant changes in an optical signature that is derived from the wavelength-dependence of elastic scattering. The OBS employs a small fiberoptic probe that is amenable to use with any endoscope or catheter, or to direct surface examination. The probe is designed to be used in optical contact with the tissue under examination and has separate illuminating and collecting fibers. Thus, the light that is collected and transmitted to the analyzing spectrometer must first scatter through a small volume of the tissue before entering the collection fiber(s). Consequently, the system is also sensitive to the optical absorption spectrum of the tissue, over an effective operating range of <300 to 950 nm, and such absorption adds valuable complexity to the scattering spectral signature.
Scattering of waves by three-dimensional obstacles in elastic metamaterials with zero index
NASA Astrophysics Data System (ADS)
Liu, Fengming; Zhang, Feng; Wei, Wei; Hu, Ni; Deng, Gang; Wang, Ziyu
2016-12-01
The scattering of elastic waves by three-dimensional obstacles in isotropic elastic zero-index-metamaterials (ZIM) is theoretically investigated. We show that the zero values of each single effective parameter and their various combinations of the elastic ZIM can produce different types of wave propagation. Particularly, there is no mode conversion when either longitudinal (P ) wave or transverse (S ) wave is scattered by the obstacles in a specific type of double-ZIM (DZIM), possessing near zero reciprocal of shear modulus and near zero mass density. When the obstacle is off resonance, elastic waves are scarcely scattered; nevertheless, the scattering cross section of the obstacle can be drastically enhanced by orders of magnitude when it is on resonance. While in another type of DZIM possessing near zero reciprocal of bulk modulus and near zero mass density, mode conversion occurs during the scattering process and many other transmission characteristics are also different to the former. Moreover, enhanced transmission can be realized for various types of single-ZIM (SZIM) by introducing obstacles, and numerical analysis shows that the enhanced transmission is due to resonant modes arisen in the embedded obstacles. We expect that our findings could have potential practical application, such as seismic protection and on-chip phononic devices.
Some inverse problems arising from elastic scattering by rigid obstacles
NASA Astrophysics Data System (ADS)
Hu, Guanghui; Kirsch, Andreas; Sini, Mourad
2013-01-01
In the first part of this paper, it is proved that a C2-regular rigid scatterer in { {R}}^3 can be uniquely identified by the shear part (i.e. S-part) of the far-field pattern corresponding to all incident shear waves at any fixed frequency. The proof is short and it is based on a kind of decoupling of the S-part of scattered wave from its pressure part (i.e. P-part) on the boundary of the scatterer. Moreover, uniqueness using the S-part of the far-field pattern corresponding to only one incident plane shear wave holds for a ball or a convex Lipschitz polyhedron. In the second part, we adapt the factorization method to recover the shape of a rigid body from the scattered S-waves (resp. P-waves) corresponding to all incident plane shear (resp. pressure) waves. Numerical examples illustrate the accuracy of our reconstruction in { {R}}^2. In particular, the factorization method also leads to some uniqueness results for all frequencies excluding possibly a discrete set.
NASA Astrophysics Data System (ADS)
Hashimoto, Hiroshi; Kim, Min-Geun; Abe, Kazuhisa; Cho, Seonho
2013-10-01
This paper presents a level set-based topology optimization method for noise barriers formed from an assembly of scatterers. The scattering obstacles are modeled by elastic bodies arranged periodically along the wall. Due to the periodicity, the problem can be reduced to that in a unit cell. The interaction between the elastic scatterers and the acoustic field is described in the context of the level set analysis. The semi-infinite acoustic wave regions located on the both sides of the barrier are represented by impedance matrices. The objective function is defined by the energy transmission passing the barrier. The design sensitivity is evaluated analytically by the aid of adjoint equations. The dependency of the optimal profile on the stiffness of scatterers and on the target frequency band is examined. The feasibility of the developed optimization method is proved through numerical examples.
Resonance estimates for single spin asymmetries in elastic electron-nucleon scattering
Barbara Pasquini; Marc Vanderhaeghen
2004-07-01
We discuss the target and beam normal spin asymmetries in elastic electron-nucleon scattering which depend on the imaginary part of two-photon exchange processes between electron and nucleon. We express this imaginary part as a phase space integral over the doubly virtual Compton scattering tensor on the nucleon. We use unitarity to model the doubly virtual Compton scattering tensor in the resonance region in terms of {gamma}* N {yields} {pi} N electroabsorption amplitudes. Taking those amplitudes from a phenomenological analysis of pion electroproduction observables, we present results for beam and target normal single spin asymmetries for elastic electron-nucleon scattering for beam energies below 1 GeV and in the 1-3 GeV region, where several experiments are performed or are in progress.
Elastic electron scattering in krypton in the energy range from 5 to 10 eV
Linert, Ireneusz; Mielewska, Brygida; Zubek, Mariusz; King, George C.
2010-01-15
Differential cross sections for elastic electron scattering in krypton have been measured at the energies of 5,7.5, and 10 eV over the scattering angle range from 30 deg. to 180 deg. The measurements for backward scattering employed the magnetic angle-changing technique. These differential cross sections have been integrated to yield the elastic integral and momentum transfer cross sections at the above energies. These new results are compared with the most recent measurements and calculations of the respective cross sections in krypton. The dependence of the differential cross sections on atomic polarizability of the heavier rare gas atoms argon, krypton, and xenon has also been investigated over the electron energy range 5-30 eV and for forward, backward, and intermediate scattering angles.
Alkhazov, G. D.; Sarantsev, V. V.
2012-12-15
In order to clear up the sensitivity of the nucleus-nucleus scattering to the nuclear matter distributions in exotic halo nuclei, we have calculated differential cross sections for elastic scattering of the {sup 6}He and {sup 11}Li nuclei on several nuclear targets at the energy of 0.8 GeV/nucleon with different assumed nuclear density distributions in {sup 6}He and {sup 11}Li.
NASA Astrophysics Data System (ADS)
Doster, W.; Nakagawa, H.; Appavou, M. S.
2013-07-01
Numerous neutron scattering studies of bio-molecular dynamics employ a qualitative analysis of elastic scattering data and atomic mean square displacements. We provide a new quantitative approach showing that the intensity at zero energy exchange can be a rich source of information of bio-structural fluctuations on a pico- to nano-second time scale. Elastic intensity scans performed either as a function of the temperature (back-scattering) and/or by varying the instrumental resolution (time of flight spectroscopy) yield the activation parameters of molecular motions and the approximate structural correlation function in the time domain. The two methods are unified by a scaling function, which depends on the ratio of correlation time and instrumental resolution time. The elastic scattering concept is illustrated with a dynamic characterization of alanine-dipeptide, protein hydration water, and water-coupled protein motions of lysozyme, per-deuterated c-phycocyanin (CPC) and hydrated myoglobin. The complete elastic scattering function versus temperature, momentum exchange, and instrumental resolution is analyzed instead of focusing on a single cross-over temperature of mean square displacements at the apparent onset temperature of an-harmonic motions. Our method predicts the protein dynamical transition (PDT) at Td from the collective (α) structural relaxation rates of the solvation shell as input. By contrast, the secondary (β) relaxation enhances the amplitude of fast local motions in the vicinity of the glass temperature Tg. The PDT is specified by step function in the elastic intensity leading from elastic to viscoelastic dynamic behavior at a transition temperature Td.
Doster, W.; Nakagawa, H.; Appavou, M. S.
2013-07-28
Numerous neutron scattering studies of bio-molecular dynamics employ a qualitative analysis of elastic scattering data and atomic mean square displacements. We provide a new quantitative approach showing that the intensity at zero energy exchange can be a rich source of information of bio-structural fluctuations on a pico- to nano-second time scale. Elastic intensity scans performed either as a function of the temperature (back-scattering) and/or by varying the instrumental resolution (time of flight spectroscopy) yield the activation parameters of molecular motions and the approximate structural correlation function in the time domain. The two methods are unified by a scaling function, which depends on the ratio of correlation time and instrumental resolution time. The elastic scattering concept is illustrated with a dynamic characterization of alanine-dipeptide, protein hydration water, and water-coupled protein motions of lysozyme, per-deuterated c-phycocyanin (CPC) and hydrated myoglobin. The complete elastic scattering function versus temperature, momentum exchange, and instrumental resolution is analyzed instead of focusing on a single cross-over temperature of mean square displacements at the apparent onset temperature of an-harmonic motions. Our method predicts the protein dynamical transition (PDT) at T{sub d} from the collective (α) structural relaxation rates of the solvation shell as input. By contrast, the secondary (β) relaxation enhances the amplitude of fast local motions in the vicinity of the glass temperature T{sub g}. The PDT is specified by step function in the elastic intensity leading from elastic to viscoelastic dynamic behavior at a transition temperature T{sub d}.
NASA Astrophysics Data System (ADS)
Gorchtein, Mikhail
2014-11-01
Two-photon-exchange (TPE) contributions to elastic electron-proton scattering in the forward regime in leading logarithmic ˜t ln|t | approximation in the momentum transfer t are considered. The imaginary part of the TPE amplitude in the forward kinematics is related to the total photoabsorption cross section. The real part of the TPE amplitude is obtained from an unsubtracted fixed-t dispersion relation. This allows a clean prediction of the real part of the TPE amplitude at forward angles with the leading term ˜t ln|t | . Numerical estimates are comparable with or exceed the experimental precision in extracting the charge radius from the experimental data.
NASA Astrophysics Data System (ADS)
Tanifuji, M.; Ishikawa, S.; Iseri, Y.; Uesaka, T.; Sakamoto, N.; Satou, Y.; Itoh, K.; Sakai, H.; Tamii, A.; Ohnishi, T.; Sekiguchi, K.; Yako, K.; Sakoda, S.; Okamura, H.; Suda, K.; Wakasa, T.
2000-02-01
For backward elastic scattering of deuterons by 3He, cross sections σ, and tensor analyzing power T20 are measured at Ed=140-270 MeV. The data are analyzed by the plane wave impluse approximation (PWIA) and by the general formula which includes virtual excitations of other channels, with the assumption of the proton transfer from 3He to the deuteron. Using 3He wave functions calculated by the Faddeev equation, the PWIA describes global features of the experimental data, while the virtual excitation effects are important for quantitative fits to the T20 data. Theoretical predictions on T20, Kyy (polarization transfer coefficient), and Cyy (spin correlation coefficient) are provided up to GeV energies.
NASA Astrophysics Data System (ADS)
Fanelli, C.; Cisbani, E.; Hamilton, D. J.; Salmé, G.; Wojtsekhowski, B.; Ahmidouch, A.; Annand, J. R. M.; Baghdasaryan, H.; Beaufait, J.; Bosted, P.; Brash, E. J.; Butuceanu, C.; Carter, P.; Christy, E.; Chudakov, E.; Danagoulian, S.; Day, D.; Degtyarenko, P.; Ent, R.; Fenker, H.; Fowler, M.; Frlez, E.; Gaskell, D.; Gilman, R.; Horn, T.; Huber, G. M.; de Jager, C. W.; Jensen, E.; Jones, M. K.; Kelleher, A.; Keppel, C.; Khandaker, M.; Kohl, M.; Kumbartzki, G.; Lassiter, S.; Li, Y.; Lindgren, R.; Lovelace, H.; Luo, W.; Mack, D.; Mamyan, V.; Margaziotis, D. J.; Markowitz, P.; Maxwell, J.; Mbianda, G.; Meekins, D.; Meziane, M.; Miller, J.; Mkrtchyan, A.; Mkrtchyan, H.; Mulholland, J.; Nelyubin, V.; Pentchev, L.; Perdrisat, C. F.; Piasetzky, E.; Prok, Y.; Puckett, A. J. R.; Punjabi, V.; Shabestari, M.; Shahinyan, A.; Slifer, K.; Smith, G.; Solvignon, P.; Subedi, R.; Wesselmann, F. R.; Wood, S.; Ye, Z.; Zheng, X.
2015-10-01
Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θcmp=70 ° . The longitudinal transfer KLL, measured to be 0.645 ±0.059 ±0.048 , where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ˜3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.
Fanelli, C; Cisbani, E; Hamilton, D J; Salmé, G; Wojtsekhowski, B; Ahmidouch, A; Annand, J R M; Baghdasaryan, H; Beaufait, J; Bosted, P; Brash, E J; Butuceanu, C; Carter, P; Christy, E; Chudakov, E; Danagoulian, S; Day, D; Degtyarenko, P; Ent, R; Fenker, H; Fowler, M; Frlez, E; Gaskell, D; Gilman, R; Horn, T; Huber, G M; de Jager, C W; Jensen, E; Jones, M K; Kelleher, A; Keppel, C; Khandaker, M; Kohl, M; Kumbartzki, G; Lassiter, S; Li, Y; Lindgren, R; Lovelace, H; Luo, W; Mack, D; Mamyan, V; Margaziotis, D J; Markowitz, P; Maxwell, J; Mbianda, G; Meekins, D; Meziane, M; Miller, J; Mkrtchyan, A; Mkrtchyan, H; Mulholland, J; Nelyubin, V; Pentchev, L; Perdrisat, C F; Piasetzky, E; Prok, Y; Puckett, A J R; Punjabi, V; Shabestari, M; Shahinyan, A; Slifer, K; Smith, G; Solvignon, P; Subedi, R; Wesselmann, F R; Wood, S; Ye, Z; Zheng, X
2015-10-09
Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θ_{cm}^{p}=70°. The longitudinal transfer K_{LL}, measured to be 0.645±0.059±0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.
Elastic and Inelastic Scattering of Positrons by Potassium Atoms
NASA Astrophysics Data System (ADS)
El-Bakry, Salah Yaseen
The investigations of the elastic and inelastic collisions of positrons with potassium atoms, K (1s2, 2s2, 2p6, 3s2, 3p6, 4s), are presented. The potassium target atoms are described using Clementi-Roetti wavefunctions within the framework of the one-valence-electron model. The total cross-sections which correspond to eight partial cross-sections are calculated at 34 values of the incident energy k21 (2.5 eV <= k12<= 100 eV) using the coupled-static approximation. The resulting total elastic, ground- and excited-positronium formation cross-sections are compared with experimental results and those calculated by other authors. In the vicinity of 6 eV, and consistent with the measurements of Parikh et al.,2 our total cross-section displays a pronounced peak. We support the conclusion of McAlinden et al.15 and Hewitt et al.14 that above about 4 eV, positronium formation is mainly into excited states. Good agreement is obtained with the total cross-section measurements of Kwan et al.1 and Parikh et al.2 Positronium formation is not important above about 50 eV.
Extraction of structure functions for lepton-nucleus scattering in the quasi-elastic region
NASA Astrophysics Data System (ADS)
Kim, K. S.; Kim, Hungchong; Cheoun, Myung-Ki; So, W. Y.
2016-12-01
Within the framework of a relativistic single-particle model, we calculate inclusive electron-nucleus scattering by electromagnetic current, and neutrino-nucleus scattering by neutral and charged current in the quasi-elastic region. The longitudinal, the transverse, and the transverse-interference structure functions are extracted from the theoretical cross section by using the Rosenbluth separation method at fixed momentum transfer and scattering angle and then compared with each other from the viewpoint of these current interactions. The position of peak for the electron scattering shifts to higher energy transfer than that for the neutrino scattering. The axial and pseudoscalar terms turn out to play an important role in the neutrino-nucleus scattering.
Correlation effects in elastic e-N2 scattering
NASA Technical Reports Server (NTRS)
Huo, Winifred M.; Lima, Marco A. P.; Gibson, Thomas L.; Mckoy, Vincent
1987-01-01
The Schwinger multichannel formulation has been applied to study the role of electron correlation in low-energy e-N2 scattering. For the five nonresonant partial-wave channels studied here, angular correlation is found to be much more important than radial correlation. The calculated total and differential cross sections agree well with experiment except for the differential cross sections at 1.5 eV.
NASA Astrophysics Data System (ADS)
Gerasimov, R. E.; Fadin, V. S.
2015-01-01
An analysis of approximations used in calculations of radiative corrections to electron-proton scattering cross section is presented. We investigate the difference between the relatively recent Maximon and Tjon result and the Mo and Tsai result, which was used in the analysis of experimental data. We also discuss the proton form factors ratio dependence on the way we take into account radiative corrections.
Gerasimov, R. E. Fadin, V. S.
2015-01-15
An analysis of approximations used in calculations of radiative corrections to electron-proton scattering cross section is presented. We investigate the difference between the relatively recent Maximon and Tjon result and the Mo and Tsai result, which was used in the analysis of experimental data. We also discuss the proton form factors ratio dependence on the way we take into account radiative corrections.
Profumo, Stefano; Ubaldi, Lorenzo; Gorchtein, Mikhail E-mail: ubaldi@th.physik.uni-bonn.de
2013-04-01
Active Galactic Nuclei (AGN) host powerful jets containing high-energy electrons and protons. The astrophysical environment where AGNs and their jets are found is characterized by large concentrations of both dark matter (DM) and intra-cluster medium (ICM) gas. As the high-energy jet particles transverse the DM and the ICM, elastic and inelastic scattering processes generically lead to the production of final-state photons. As first envisioned by Bloom and Wells (1998), and as more recently pointed out by us and others, the scattering of electrons off of DM could lead to a potentially detectable gamma-ray signal, with the parton-level contribution from protons offering dimmer perspectives. Recently, Chang et al. argued that taking into account photons from hadronization and showering, the actual photon flux is substantially increased. Here, we point out that the proton-jets have to be highly collimated, contrary to what predicted by simple blob-geometry jet-models sometimes employed in these studies, otherwise they would produce a very large flux of photons from inelaystic collisions with ICM nucleons, which would outshine by many orders of magnitude the signal from DM, for almost any reasonable ICM and DM density profiles.
Anderson, E. K.; Boadle, R. A.; Machacek, J. R.; Makochekanwa, C.; Sullivan, J. P.; Chiari, L.; Buckman, S. J.; Brunger, M. J.; Garcia, G.; Blanco, F.; Ingolfsson, O.
2014-07-21
Measurements of the grand total and total positronium formation cross sections for positron scattering from uracil have been performed for energies between 1 and 180 eV, using a trap-based beam apparatus. Angular, quasi-elastic differential cross section measurements at 1, 3, 5, 10, and 20 eV are also presented and discussed. These measurements are compared to existing experimental results and theoretical calculations, including our own calculations using a variant of the independent atom approach.
Selective Observation of Elastic-Body Resonances via Their Ringing in Transient Acoustic Scattering.
1984-09-12
evident but have not been discussed by him. Subsequent studies of pulse scattering from rigid spheres by Rudgers 3 , or from elastic 4 cylinders by Veksler...Lucite 1.182 2680 1380 1. J. J. Faran, J "" - -’,:. Amer. 23, 405 (1951) 2. R. Hicklinc, J. ,w.L t. Soc. Amer. 34, 1582 (1962). 3. A. J. Rudgers , J
X-Ray Elastic and Inelastic Scattering Factors for Neutral Atoms Z = 2-92
NASA Astrophysics Data System (ADS)
Wang, J. H.; Sagar, R. P.; Schmider, H.; Smith, V. H.
1993-03-01
X-ray elastic and inelastic scattering factors are calculated for the ground states of the neutral atoms, helium to uranium, from the Roothaan-Hartree-Fock nonrelativistic self-consistent-field wave functions of Clementi and Roetti, (Atomic Data and Nuclear Data Tables 14, 177, 1974) and McLean and McLean (Atomic Data and Nuclear Data Tables 26, 197, 1981).
Measurement of the tensor polarization in electron-deuteron elastic scattering
Schulze, M.E.; Beck, D.; Farkhondeh, M.; Gilad, S.; Goloskie, R.; Holt, R.J.; Kowalski, S.; Laszewski, R.M.; Leitch, M.J.; Moses, J.D.
1984-02-20
This paper reports the first measurement of the tensor polarization t/sub 20/ in e-d elastic scattering. The polarization of the recoil deuterons was measured for two values of momentum transfer, q = 1.74 and 2.03 fm/sup -1/, with a high-efficiency polarimeter. The results are in good agreement with reasonable models for the deuteron.
Elastic electron scattering from ortho-, meta-, and paraxylenes, C8H10
NASA Astrophysics Data System (ADS)
Sakaamini, A.; Khakoo, S. M.; Hargreaves, L.; Khakoo, M. A.; Pastega, D. F.; Bettega, M. H. F.
2017-02-01
Ab initio calculations and normalized experimental measurements of the differential, momentum transfer and integral cross sections for vibrationally elastic scattering of low-energy electrons from orthoxylene, metaxylene, and paraxylene are presented. The calculated cross sections are obtained using the Schwinger multichannel method implemented with norm-conserving pseudopotentials. The differential cross sections are measured at incident energies from 1 to 30 eV and scattering angles from 10∘ to 130∘. These cross sections are compared to experimental results for toluene. The comparisons illuminate the role of molecular structure in determining the integral cross sections and the angular distributions of resonantly scattered electrons.
Nanoscale structure in AgSbTe2 determined by diffuse elastic neutron scattering
Specht, Eliot D; Ma, Jie; Delaire, Olivier A; Budai, John D; May, Andrew F; Karapetrova, Evguenia A.
2015-01-01
Diffuse elastic neutron scattering measurements confirm that AgSbTe2 has a hierarchical structure, with defects on length scales from nanometers to microns. While scattering from mesoscale structure is consistent with previously-proposed structures in which Ag and Sb order on a NaCl lattice, more diffuse scattering from nanoscale structure suggests a structural rearrangement in which hexagonal layers form a combination of (ABC), (ABA), and (AAB) stacking sequences. The AgCrSe2 structure is the best-fitting model for the local atomic arrangements.
Elastic Scattering of Low-Energy Electrons byTetrahydrofuran
Trevisan, Cynthia S.; Orel, Ann E.; Rescigno, Thomas N.
2006-05-09
We present the results of ab initio calculations for elasticelectron scattering by tetrahydrofuran (THF) using the complex Kohnvariational method. We carried out fixed-nuclei calculations at theequilibrium geometry of the target molecule for incident electronenergies up to 20 eV. The calculated momentum transfer cross sectionsclearly reveal the presence of broad shape resonance behavior in the 8-10eV energy range, in agreement with recent experiments. The calculateddifferential cross sections at 20 eV, which include the effects of thelong-range electron-dipole interaction, are alsofound to be in agreementwith the most recent experimental findings.
Pion elastic and inelastic 2+1 scattering on 58,60,62,64Ni at Tπ=180 MeV
NASA Astrophysics Data System (ADS)
Laymon, C. M.; Amos, W.; Burlein, M. G.; Fortune, H. T.; Ekenberg, T.; Kotwal, A.; O'donnell, J. M.; Silk, J. D.; Zumbro, J. D.; Morris, C. L.; Seestrom, S. J.; Dhuga, K. S.; Garnett, R.; Rawool-Sullivan, M. W.; Moore, C. F.; Morris, S. L.; Watson, D. L.
1996-03-01
Angular distributions for π+ and π- elastic and inelastic scattering from the Z=28 closed-proton-shell nuclei 58,60,62,64Ni have been measured at an incident pion kinetic energy of 180 MeV. Values for the neutron and proton matrix elements for the transition to the Jπ=2+1 state have been extracted using the distorted wave impulse approximation in which the π+ and π- data were fitted simultaneously and the neutron and proton vibrational transition strengths were treated as free parameters. While all transitions are predominantly collective, extracted values of Mn/Mp indicate increasing collectivity as a function of neutron number and are consistent with the collective limit of N/Z for 64Ni.
Rhodopsin Photoactivation Dynamics Revealed by Quasi-Elastic Neutron Scattering
NASA Astrophysics Data System (ADS)
Bhowmik, Debsindhu; Shrestha, Utsab; Perera, Suchhithranga M. C. D.; Chawla, Udeep; Mamontov, Eugene; Brown, Michael; Chu, Xiang-Qiang
2015-03-01
Rhodopsin is a G-protein-coupled receptor (GPCR) responsible for vision. During photoactivation, the chromophore retinal dissociates from protein yielding the opsin apoprotein. What are the changes in protein dynamics that occur during the photoactivation process? Here, we studied the microscopic dynamics of dark-state rhodopsin and the ligand-free opsin using quasielastic neutron scattering (QENS). The QENS technique tracks individual hydrogen atom motion because of the much higher neutron scattering cross-section of hydrogen than other atoms. We used protein with CHAPS detergent hydrated with heavy water. The activation of proteins is confirmed at low temperatures up to 300 K by mean-square displacement (MSD) analysis. The QENS experiments at temperatures ranging from 220 K to 300 K clearly indicate an increase in protein dynamic behavior with temperature. The relaxation time for the ligand-bound protein rhodopsin is faster compared to opsin, which can be correlated with the photoactivation. Moreover, the protein dynamics are orders of magnitude slower than the accompanying CHAPS detergent, which unlike protein, manifests localized motions.
Bigio, I.J.; Loree, T.R.; Mourant, J.; Shimada, T.; Story-Held, K.; Glickman, R.D.; Conn, R.
1993-08-01
A non-invasive diagnostic tool that could identify malignancy in situ and in real time would have a major impact on the detection and treatment of cancer. We have developed and are testing early prototypes of an optical biopsy system (OBS) for detection of cancer and other tissue pathologies. The OBS invokes a unique approach to optical diagnosis of tissue pathologies based on the elastic scattering properties, over a wide range of wavelengths, of the microscopic structure of the tissue. The use of elastic scattering as the key to optical tissue diagnostics in the OBS is based on the fact that many tissue pathologies, including a majority of cancer forms, manifest significant architectural changes at the cellular and sub-cellular level. Since the cellular components that cause elastic scattering have dimensions typically on the order of visible to near-IR wavelengths, the elastic (Mie) scattering properties will be strongly wavelength dependent. Thus, morphology and size changes can be expected to cause significant changes in an optical signature that is derived from the wavelength dependence of elastic scattering. The data acquisition and storage/display time with the OBS instrument is {approximately}1 second. Thus, in addition to the reduced invasiveness of this technique compared with current state-of-the-art methods (surgical biopsy and pathology analysis), the OBS offers the possibility of impressively faster diagnostic assessment. The OBS employs a small fiber-optic probe that is amenable to use with any endoscope, catheter or hypodermic, or to direct surface examination (e.g. as in skin cancer or cervical cancer). It has been tested in vitro on animal and human tissue samples, and clinical testing in vivo is currently in progress.
Modelling of nonlinear wave scattering in a delaminated elastic bar
Khusnutdinova, K. R.; Tranter, M. R.
2015-01-01
Integrity of layered structures, extensively used in modern industry, strongly depends on the quality of their interfaces; poor adhesion or delamination can lead to a failure of the structure. Can nonlinear waves help us to control the quality of layered structures? In this paper, we numerically model the dynamics of a long longitudinal strain solitary wave in a split, symmetric layered bar. The recently developed analytical approach, based on matching two asymptotic multiple-scales expansions and the integrability theory of the Korteweg–de Vries equation by the inverse scattering transform, is used to develop an effective semi-analytical numerical approach for these types of problems. We also employ a direct finite-difference method and compare the numerical results with each other, and with the analytical predictions. The numerical modelling confirms that delamination causes fission of an incident solitary wave and, thus, can be used to detect the defect. PMID:26730218
High Precision Measurement of the Proton Elastic Form Factor Ratio at Low Q2
Xiaohui Zhan
2009-12-01
A high precision measurement of the proton elastic form factor ratio µpGEp/GMp in the range Q2 = 0.3–0.7 GeV2/c2 was performed using recoil polarimetry in Jefferson Lab Hall A. In this low Q2 range, previous data from LEDEX [5] along with many fits and calculations [2, 3, 4] indicate substantial deviations of the ratio from unity. In this new measurement, with 80% polarized electron beam for 24 days, we are able to achieve <1% statistical uncertainty. Preliminary results are a few percent lower than expected from previous world data and fits, indicating a smaller GEp at this region. Beyond the intrinsic interest in nucleon structure, the improved form factor measurements also have implications for DVCS, determinations of the proton Zemach radius and strangeness form factors through parity violation experiments.
Fanelli, Cristiano V.
2015-10-06
Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The WACS polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θ^{P}_{cm} = 70°. The longitudinal transfer K_{LL}, measured to be 0.645 ± 0.059 ± 0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the GPD-based calculations, which indicates a significant unknown contribution to the scattering amplitude.
Fanelli, Cristiano V.
2015-10-06
Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The WACS polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θPcm = 70°. The longitudinal transfer KLL, measured to be 0.645 ± 0.059 ± 0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton.more » However, the observed value is ~3 times larger than predicted by the GPD-based calculations, which indicates a significant unknown contribution to the scattering amplitude.« less
Towards a Precision Measurement of Parity-Violating e-p Elastic Scattering at Low Momentum Transfer
Pan, Jie
2012-01-01
The goal of the Q-weak experiment is to make a measurement of the proton's weak charge Q_{W}^{p} = 1 - 4 sin^{2}(θ_{W2(θW2(θWWp by measuring the parity violating asymmetry in elastic electron-proton scattering at low momentum transfer Q2 = 0.026 (GeV/c)2 and forward angles (8 degrees). The anticipated size of the asymmetry, based on the SM, is about 230 parts per billion (ppb). With the proposed accuracy, the experiment may probe new physics beyond Standard Model at the TeV scale. This thesis focuses on my contributions to the experiment, including track reconstruction for momentum transfer determination of the scattering process, and the focal plane scanner, a detector I designed and built to measure the flux profile of scattered electrons on the focal plane of the Q-weak spectrometer to assist in the extrapolation of low beam current tracking results to high beam current. Preliminary results from the commissioning and the first run period of the Q-weak experiment are reported and discussed.}
Coupling effects in the elastic scattering of 6He on 12C
NASA Astrophysics Data System (ADS)
Lapoux, V.; Alamanos, N.; Auger, F.; Fékou-Youmbi, V.; Gillibert, A.; Marie, F.; Ottini-Hustache, S.; Sida, J.-L.; Khoa, D. T.; Blumenfeld, Y.; Maréchal, F.; Scarpaci, J.-A.; Suomijärvi, T.; Kelley, J. H.; Casandjian, J.-M.; Chartier, M.; Cortina-Gil, M. D.; Mac Cormick, M.; Mittig, W.; de Oliveira Santos, F.; Ostrowski, A. N.; Roussel-Chomaz, P.; Kemper, K. W.; Orr, N.; Winfield, J. S.
2002-09-01
To study the effect of the weak binding energy on the interaction potential between a light exotic nucleus and a target, elastic scattering of 6He at 38.3 MeV/nucleon on a 12C target was measured at Grand Accélérateur National d'Ions Lourds (GANIL). The 6He beam was produced by fragmentation. The detection of the scattered particles was performed by the GANIL spectrometer. The energy resolution was good enough to separate elastic from inelastic scattering contributions. The measured elastic data have been analyzed within the optical model, with the real part of the optical potential calculated in the double-folding model using a realistic density-dependent nucleon-nucleon interaction and the imaginary part taken in the conventional Woods-Saxon (WS) form. A failure of the ``bare'' real folded potential to reproduce the measured angular distribution over the whole angular range suggests quite a strong coupling of the higher-order breakup channels to the elastic channel. To estimate the strength of the breakup effects, a complex surface potential with a repulsive real part (designed to simulate the polarization effects caused by the projectile breakup) was added to the real folded and imaginary WS potentials. A realistic estimate of the polarization potential caused by the breakup of the weakly bound 6He was made based on a parallel study of 6He+12C and 6Li+12C optical potentials at about the same energies.
Ultracold Three-body Elastic Scattering in the Adiabatic Hyperspherical Representation
NASA Astrophysics Data System (ADS)
Colussi, Victor; D'Incao, Jose; Greene, Chris; Holland, Murray
2016-05-01
In the past few years, advances in ultracold quantum gases together with the ability to control interatomic interactions have opened up important questions related to three-body contributions to collective phenomena observables. In order to theoretically understand such contributions one needs to explore the three-body elastic scattering problem, which is fundamentally different than its two-body counterpart. The main difficulty is in the necessity to determine contributions to three-body scattering that originate from multiple scattering events where two atoms interact while the third spectates. These contributions must be subtracted out in order to determine scattering events that are truly of a three-body nature, i.e., collision events in which all three atoms participate. Here, we study this problem in the adiabatic hyperspherical representation and identify how unwanted two-body scattering events manifest in this picture. This opens up ways to develop a simple procedure capable of extracting truly three-body contributions to elastic scattering. This work was supported by the U. S. National Science Foundation.
Prompt gamma timing range verification for scattered proton beams
Kormoll, T.; Golnik, C.; Hueso Gonzalez, F.; Petzoldt, J.; Tiele, J.; Werner, T.; Enghardt, W.; Pausich, G.; Fiedler, F.; Enghardt, W.; Weinberger, D.; Duplicy, A.; Swanson, R.
2015-07-01
Range verification is a very important point in order to fully exploit the physical advantages of protons compared to photons in cancer irradiation. Recently, a simple method has been proposed which makes use of the time of fight of protons in tissue and the promptly emitted secondary photons along the proton path (Prompt Gamma Timing, PGT). This has been considered so far for monoenergetic pencil beams only. In this work, it has been studied whether this technique can also be applied in passively formed irradiation fields with a so called spread out Bragg peak. Time correlated profiles could be recorded, which show a trend that is consistent with theoretical predictions. (authors)
Velocity-dependent optical potential for neutron elastic scattering from 1 p -shell nuclei
NASA Astrophysics Data System (ADS)
Ghabar, I. N.; Jaghoub, M. I.
2015-06-01
Background: The conventional optical model is quite successful in describing the nucleon elastic scattering data from medium and heavy nuclei. However, its success in describing the light 1 p -shell nuclei is somewhat limited. The velocity-dependent optical potential resulted in a significant improvement in describing the elastic angular distributions for light nuclei in the low energy region. Purpose: To extend the formalism of the velocity-dependent potential to higher energies, and to assess its importance in describing neutron elastic scattering data from light 1 p -shell nuclei at high energies. Method: We fit the angular distribution data for neutron elastic scattering from 12C and 16O using (i) the velocity-dependent optical potential and (ii) the conventional optical potential. The results of the two models are then compared. At low energies, we compare our angular distribution fits with the fits of other works that exist in the literature. Furthermore, the total integrated cross sections in addition to the analyzing power are calculated using the velocity-dependent optical potential and compared to the experimental data. Results: The velocity-dependent potential resulted in significant improvements in describing the angular distributions particularly in the large-angle scattering region and for certain energy ranges. This model is important where the experimental data show structural effects from nuclear surface deformations, which are important in light nuclei. Furthermore, the calculated total elastic cross sections and analyzing power are in good agreement with the experimental data. Conclusions: The velocity-dependent potential gives rise to surface-peaked real terms in the optical model. Such terms account, at least partly, for the structural effects seen in the angular distribution data. The energy range over which the surface terms are needed is found to depend on the target nucleus. Other works that have introduced real surface terms in the optical
NASA Astrophysics Data System (ADS)
Jakubassa-Amundsen, D. H.
2012-04-01
In the scattering of relativistic spin-polarized electrons from point nuclei, two types of polarization correlations are compared: those of a left- or right-circular bremsstrahlung photon at the short-wavelength limit (when the outgoing electron is not observed) and those of an elastically scattered, left- or right-handed electron. Bremsstrahlung is calculated from the Dirac-Sommerfeld-Maue model, and elastic electron scattering is obtained from a partial-wave analysis. By considering a gold target and electron energies Ei up to 20 MeV, a striking similarity of the respective polarization correlations is found to develop when the collision energy is increased beyond 5 MeV. From analytical Born results for light targets it is shown that only for a longitudinally spin-polarized electron do the respective polarization correlations agree in the limit Ei→∞. In the general case, a very high nuclear charge is needed in addition, leading to a sum rule for bremsstrahlung well known from elastic electron scattering.
Revisiting Elastic Scattering of D(n, n)D reaction
Stanoiu, M.; Canton, L.; Kozier, K. S.; Rao, R.; Roubtsov, D.; Nankov, N.; Plompen, A.; Rouki, C.; Svenne, J. P.
2010-04-30
Interest has risen recently concerning the angular distribution of neutron elastic scattering on deuterium at low incident energies. The main subject is the amount of backscattering at energies below 3.2 MeV observed in differential cross-section measurements and represented in various evaluations. These various angles of approach encompass fundamental nuclear-data measurements, three-body nuclear-theory calculations, evaluated nuclear -data libraries and associated data processing, and the simulation of critical experiments involving heav y water. A new theoretical approach on the basis of three -nucleon theory was made that resulted in new angular distributions. At the GELINA neutron time-of-flight facility a new experimental setup was developed to measure elastic scattering of neutrons on deuterium in the energy range of interest. The technique proposed is complementary to the earlier works by detecting the scattered neutron instead of the recoiling deuterium. The setup is an array of two HPGe detectors, each with a {sup 10}B neutron-gamma converter. Preliminary GELINA findings using a C6D6 target indicate less backscatter than predicted by ENDF/B -VII.0, in contrast to the nuclear-theory results. It is expected that completion of the planned work will reduce the uncertainty of the energy-angle distributions for deuterium elastic scattering and contribute to an improved deuterium evaluation in a future release of ENDF/B -VII.
Effects of target polarization in electron elastic scattering off endohedral A @C60
NASA Astrophysics Data System (ADS)
Dolmatov, V. K.; Amusia, M. Ya.; Chernysheva, L. V.
2017-01-01
We have developed an efficient approximation to describe the low-energy electron elastic scattering off an endohedral fullerene A @CN . It accounts for polarization of A @CN by incoming electrons without reference to complicated details of the electronic structure of CN itself. The developed approach has permitted us to unravel spectacular A @CN polarization effects in low-energy e-+A @CN elastic scattering, particularly the effects due to interelectron interaction between the electrons of both CN and A . We show that contribution of a single atom A remains unscreened by the multiatomic CN despite the fact that the projectile's wavelength is bigger than the size of the target. Inclusion of A and CN polarizability interference leads to violation of the previously predicted phase additivity rule. The partial scattering cross sections acquire prominent Ramsauer-type minima which, however, disappear in the total cross section. The study reveals notable trends in e-+A @CN elastic scattering versus the polarizability of an encapsulated atom. We also predict the existence of certain negative ions A @CN- . We chose Ne, Xe, and Ba as atoms A , and C60 as the endohedral CN, as the case study. The work focuses on a reasonable compromise between the qualitative and quantitative aspects of the problem in general rather than on carrying out detailed calculations for one particular system.
H-He elastic scattering at low energies: Contribution of nonzero partial waves
Sinha, Prabal K.; Ghosh, A.S.
2005-01-01
The present study reports the nonzero partial wave elastic cross sections together with s-wave results for the scattering of an antihydrogen atom off a gaseous helium target at thermal energies (up to 10{sup -2} a.u.). We have used a nonadiabatic atomic orbital method having different basis sets to investigate the system. The consideration of all the significant partial waves (up to J=24) reduces the oscillatory nature present in the individual partial wave cross section. The added elastic cross section is almost constant up to 10{sup -7} a.u. and then decreases steadily and very slowly with increasing energy.
Demonstration of a novel technique to measure two-photon exchange effects in elastic e±p scattering
Moteabbed, Maryam; Niroula, Megh; Raue, Brian A.; Weinstein, Lawrence B.
2013-08-30
The discrepancy between proton electromagnetic form factors extracted using unpolarized and polarized scattering data is believed to be a consequence of two-photon exchange (TPE) effects. However, the calculations of TPE corrections have significant model dependence, and there is limited direct experimental evidence for such corrections. The TPE contributions depend on the sign of the lepton charge in e±p scattering, but the luminosities of secondary positron beams limited past measurement at large scattering angles, where the TPE effects are believe to be most significant. We present the results of a new experimental technique for making direct e±p comparisons, which has the potential to make precise measurements over a broad range in Q^{2} and scattering angles. We use the Jefferson Laboratory electron beam and the Hall B photon tagger to generate a clean but untagged photon beam. The photon beam impinges on a converter foil to generate a mixed beam of electrons, positrons, and photons. A chicane is used to separate and recombine the electron and positron beams while the photon beam is stopped by a photon blocker. This provides a combined electron and positron beam, with energies from 0.5 to 3.2 GeV, which impinges on a liquid hydrogen target. The large acceptance CLAS detector is used to identify and reconstruct elastic scattering events, determining both the initial lepton energy and the sign of the scattered lepton. The data were collected in two days with a primary electron beam energy of only 3.3 GeV, limiting the data from this run to smaller values of Q^{2} and scattering angle. Nonetheless, this measurement yields a data sample for e±p with statistics comparable to those of the best previous measurements. We have shown that we can cleanly identify elastic scattering events and correct for the difference in acceptance for electron and positron scattering. Because we ran with only one polarity for the chicane, we are unable to study the
Demonstration of a novel technique to measure two-photon exchange effects in elastic e±p scattering
Moteabbed, Maryam; Niroula, Megh; Raue, Brian A.; ...
2013-08-30
The discrepancy between proton electromagnetic form factors extracted using unpolarized and polarized scattering data is believed to be a consequence of two-photon exchange (TPE) effects. However, the calculations of TPE corrections have significant model dependence, and there is limited direct experimental evidence for such corrections. The TPE contributions depend on the sign of the lepton charge in e±p scattering, but the luminosities of secondary positron beams limited past measurement at large scattering angles, where the TPE effects are believe to be most significant. We present the results of a new experimental technique for making direct e±p comparisons, which has themore » potential to make precise measurements over a broad range in Q2 and scattering angles. We use the Jefferson Laboratory electron beam and the Hall B photon tagger to generate a clean but untagged photon beam. The photon beam impinges on a converter foil to generate a mixed beam of electrons, positrons, and photons. A chicane is used to separate and recombine the electron and positron beams while the photon beam is stopped by a photon blocker. This provides a combined electron and positron beam, with energies from 0.5 to 3.2 GeV, which impinges on a liquid hydrogen target. The large acceptance CLAS detector is used to identify and reconstruct elastic scattering events, determining both the initial lepton energy and the sign of the scattered lepton. The data were collected in two days with a primary electron beam energy of only 3.3 GeV, limiting the data from this run to smaller values of Q2 and scattering angle. Nonetheless, this measurement yields a data sample for e±p with statistics comparable to those of the best previous measurements. We have shown that we can cleanly identify elastic scattering events and correct for the difference in acceptance for electron and positron scattering. Because we ran with only one polarity for the chicane, we are unable to study the difference
NASA Astrophysics Data System (ADS)
Benedetto, Antonio; Kearley, Gordon J.
2016-10-01
A new type of neutron-scattering spectroscopy is presented that is designed specifically to measure dynamics in bio-systems that are difficult to obtain in any other way. The temporal information is largely model-free and is analogous to relaxation processes measured with dielectric spectroscopy, but provides additional spacial and geometric aspects of the underlying dynamics. Numerical simulations of the basic instrument design show the neutron beam can be highly focussed, giving efficiency gains that enable the use of small samples. Although we concentrate on continuous neutron sources, the extension to pulsed neutron sources is proposed, both requiring minimal data-treatment and being broadly analogous with dielectric spectroscopy, they will open the study of dynamics to new areas of biophysics.
Benedetto, Antonio; Kearley, Gordon J
2016-10-05
A new type of neutron-scattering spectroscopy is presented that is designed specifically to measure dynamics in bio-systems that are difficult to obtain in any other way. The temporal information is largely model-free and is analogous to relaxation processes measured with dielectric spectroscopy, but provides additional spacial and geometric aspects of the underlying dynamics. Numerical simulations of the basic instrument design show the neutron beam can be highly focussed, giving efficiency gains that enable the use of small samples. Although we concentrate on continuous neutron sources, the extension to pulsed neutron sources is proposed, both requiring minimal data-treatment and being broadly analogous with dielectric spectroscopy, they will open the study of dynamics to new areas of biophysics.
Benedetto, Antonio; Kearley, Gordon J.
2016-01-01
A new type of neutron-scattering spectroscopy is presented that is designed specifically to measure dynamics in bio-systems that are difficult to obtain in any other way. The temporal information is largely model-free and is analogous to relaxation processes measured with dielectric spectroscopy, but provides additional spacial and geometric aspects of the underlying dynamics. Numerical simulations of the basic instrument design show the neutron beam can be highly focussed, giving efficiency gains that enable the use of small samples. Although we concentrate on continuous neutron sources, the extension to pulsed neutron sources is proposed, both requiring minimal data-treatment and being broadly analogous with dielectric spectroscopy, they will open the study of dynamics to new areas of biophysics. PMID:27703184
NASA Astrophysics Data System (ADS)
Fagundes, D. A.; Pancheri, G.; Grau, A.; Pacetti, S.; Srivastava, Y. N.
2013-11-01
We describe the main features of recent LHC data on elastic pp scattering through a simple parametrization to the amplitude, inspired by a model proposed by Barger and Phillips in 1973, comprised of two exponentials with a relative phase. Despite its simplicity, this parametrization reproduces two essential aspects of the elastic differential cross section: the well-known precipitous descent in the forward direction and a sharp “dip” structure. To include a complete description of data sets near -t=0, we correct the original parametrization. We examine two possibilities: the presence of the two-pion threshold singularity or a multiplicative factor reflecting the proton form factor. We find good descriptions of LHC7 and ISR data in either case. The form-factor model allows simple predictions for higher energies through asymptotic theorems and asymptotic sum rules in impact parameter space. We present predictions for this model at higher LHC energies, which can be used to test whether asymptotia is reached. The black-disk limit in this model is seen to be reached only for s˜106TeV.
Elastic /ital p//sub /up arrow//p/sub /up arrow// scattering between 240 and 470 MeV
Onel, Y.; Hausammann, R.; Heer, E.; Hess, R.; Lechanoine-Leluc, C.; Leo, W. R.; Rapin, D.; Jaccard, S.; Mango, S.
1989-07-01
The polarization parameter /ital P//sub /ital n/000/, the two-spin parameters/ital D//sub /ital n/0/ital n/0/, /ital K//sub /ital n/00/ital n//, /ital D//sub /ital s//prime/0/ital s/0/,/ital D//sub /ital s//prime/0/ital k/0/ and the three-spin parameters /ital M//sub /ital s//prime/0/ital sn//and /ital M//sub /ital s//prime/0/ital kn// have been measured for /ital pp/ elastic scatteringangles between 60/degree/ and 88/degree/ center of mass at 241 and 314 MeV incidentkinetic energies, and between 38/degree/ c.m. and 98/degree/ c.m. at 341, 366, and 398MeV. At 473 MeV, only /ital P//sub /ital n/000/ and /ital D//sub /ital s//prime/0/ital k/0/ weremeasured between 34/degree/ c.m. and 62/degree/ c.m. The experiment was performed at SINusing a polarized proton beam and a polarized butanol target. The polarizationof the scattered proton was analyzed in a carbon polarimeter. The influence ofthese high-precision data on the Saclay-Geneva phase-shift analysis isdiscussed.
Small-slope scattering from rough elastic ocean floors: general theory and computational algorithm.
Gragg, R F; Wurmser, D; Gauss, R C
2001-12-01
In this article acoustic scattering by a random rough interface that separates a fluid incident medium from an underlying uniform scattering medium, either fluid or elastic solid, in cases for which the Bragg scale lies within the power-law tail of the roughness spectrum is dealt with. The physical foundation is an inherently reciprocity-preserving, local small-slope theory. A fully bistatic formulation is developed for the scattering strength, together with a robust numerical implementation that allows a wide range of spectral exponent values. The practical result for ocean acoustics is a significantly improved description of the interface component of sea floor scattering. Calculations are presented to demonstrate the advantage of this approach over perturbation theory, and to illustrate its dependence on frequency and environmental parameters as well as its operation in bistatic geometries.
Impact of Various Beam Parameters on Lateral Scattering in Proton and Carbon-ion Therapy
Ebrahimi Loushab, M.; Mowlavi, A.A.; Hadizadeh, M.H.; Izadi, R.; Jia, S.B.
2015-01-01
Background In radiation therapy with ion beams, lateral distributions of absorbed dose in the tissue are important. Heavy ion therapy, such as carbon-ion therapy, is a novel technique of high-precision external radiotherapy which has advantages over proton therapy in terms of dose locality and biological effectiveness. Methods In this study, we used Monte Carlo method-based Geant4 toolkit to simulate and calculate the effects of energy, shape and type of ion beams incident upon water on multiple scattering processes. Nuclear reactions have been taken into account in our calculation. A verification of this approach by comparing experimental data and Monte Carlo methods will be presented in an upcoming paper. Results Increasing particle energies, the width of the Bragg curve becomes larger but with increasing mass of particles, the width of the Bragg curve decreases. This is one of the advantages of carbon-ion therapy to treat with proton. The transverse scattering of dose distribution is increased with energy at the end of heavy ion beam range. It can also be seen that the amount of the dose scattering for carbon-ion beam is less than that of proton beam, up to about 160mm depth in water. Conclusion The distortion of Bragg peak profiles, due to lateral scattering of carbon-ion, is less than proton. Although carbon-ions are primarily scattered less than protons, the corresponding dose distributions, especially the lateral dose, are not much less. PMID:26688795
NASA Astrophysics Data System (ADS)
Silwal, Rupesh
Precision measurement of the parity-violating asymmetry in electron-hadron scattering has been an extremely useful tool to study the structure of the hadrons. This thesis reports work on two such measurements: the measurement of the strange form-factors (FFs), GsE and GsM , by the Hall A Proton Parity Experiment (HAPPEX)-III collaboration, and the first direct measurement of the nucleon skin thickness in a heavy nucleus by the Lead (208Pb) Radius Experiment (PREX) collaboration. In HAPPEX-III, the parity-violating cross-section asymmetry in the elastic scattering of polarized electrons from unpolarized protons was measured at an average four-momentum transfer squared,
The calibration of elastic scattering angular distribution at low energies on HIRFL-RIBLL
NASA Astrophysics Data System (ADS)
Zhang, G. X.; Zhang, G. L.; Lin, C. J.; Qu, W. W.; Yang, L.; Ma, N. R.; Zheng, L.; Jia, H. M.; Sun, L. J.; Liu, X. X.; Chu, X. T.; Yang, J. C.; Wang, J. S.; Xu, S. W.; Ma, P.; Ma, J. B.; Jin, S. L.; Bai, Z.; Huang, M. R.; Zang, H. L.; Yang, B.; Liu, Y.
2017-02-01
The precise calibration of angular distribution of heavy-ion elastic scattering induced by Radioactive Ion Beams (RIBs) at energies around Coulomb barrier on the Radioactive Ion Beam Line in Lanzhou (RIBLL) at the Heavy-Ion Research Facility in Lanzhou (HIRFL) is presented. The beam profile and the scattering angles on the target are deduced by a measurement with two Multi Wire Proportional Chambers (MWPC), and four sets of detector telescopes (including Double-sided Silicon Strip Detectors (DSSD) placed systematically along the beam line, incorporating with Monte Carlo simulation. The MWPCs were used to determine the beam trajectory before the target, and the energies and the positions of scattered particles on the detectors were measured by the DSSDs. Minor corrections on the beam spot and the detector position are performed by assuming the pure Rutherford scattering at angles which are smaller than the related grazing angle. This method is applied for the elastic scattering of 17F on 89Y target at Elab=59 MeV and 50 MeV.
Boyer, J.; Mourant, J.R.; Bigio, I.J.
1995-05-01
An optical-fiber-coupled, elastic-scatter spectrometer has proven effective in discriminating between malignant and non-malignant tissue in the human bladder and gastrointestinal tract. The system injects broadband light into the tissue with an optical fiber and spectrally analyzes the returning light collected by an adjacent fiber. The collected photons have experienced multiple scattering events and therefore arrive at the analysis fiber after traveling varied paths.the diameter of the source fiber is comparable to its separation from the collection fiber. The diffusion model is inappropriate for this geometry; therefore, Monte Carlo simulations are used. In addition, the size of the scattering sites in tissue are expected to be of the same order as the excitation wavelengths, and Mie theory is expected to provide the best description of the scattering and extinction. The authors will present and compare the results of simulations and measurements of the elastic scatter signal for suspensions of latex spheres in hemoglobin solutions of varying concentrations.
Low-energy elastic electron scattering from chloromethane, CH3Cl
NASA Astrophysics Data System (ADS)
Navarro, C.; Sakaamini, A.; Cross, J.; Hargreaves, L. R.; Khakoo, M. A.; Fedus, Kamil; Winstead, C.; McKoy, V.
2015-10-01
We report theoretical as well as (normalized) experimental differential and integral cross sections for vibrationally elastic scattering of low-energy electrons from chloromethane, CH3Cl, also known as methyl chloride. The theoretical cross sections were computed using the Schwinger multichannel variational method in the single-channel approximation, with polarization effects included via virtual excitations. Cross section measurements were made at incident energies ranging from 0.5 to 100 eV and at scattering angles from {5}\\circ to {125}\\circ . We compare our data to earlier previous results for this molecule.
Low-energy elastic electron scattering form chloroethane, C2H5Cl
NASA Astrophysics Data System (ADS)
Sakaamini, A.; Navarro, C.; Cross, J.; Hargreaves, L. R.; Khakoo, M. A.; Fedus, Kamil; Winstead, C.; McKoy, V.
2015-10-01
We report theoretical as well as (normalized) experimental differential and integral cross sections for vibrationally elastic scattering of low-energy electrons from chloroethane, C2H5Cl, also known as ethyl chloride. The theoretical cross sections were computed using the Schwinger multichannel variational method in the single-channel approximation, with polarization effects included via virtual excitations. Cross section measurements were made at incident energies ranging from 1 to 30 eV and at scattering angles from {10}\\circ to {125}\\circ . We compare our data to previous results for C2H5Cl and for the related molecule chloromethane.
Electromagnetic properties of massive neutrinos in low-energy elastic neutrino-electron scattering
NASA Astrophysics Data System (ADS)
Kouzakov, Konstantin A.; Studenikin, Alexander I.
2017-03-01
A thorough account of electromagnetic interactions of massive neutrinos in the theoretical formulation of low-energy elastic neutrino-electron scattering is given. The formalism of neutrino charge, magnetic, electric, and anapole form factors defined as matrices in the mass basis is employed under the assumption of three-neutrino mixing. The flavor change of neutrinos traveling from the source to the detector is taken into account and the role of the source-detector distance is inspected. The effects of neutrino flavor-transition millicharges and charge radii in the scattering experiments are pointed out.
Elastic scattering of low energy electrons in partially ionized dense semiclassical plasma
Dzhumagulova, K. N. Shalenov, E. O.; Ramazanov, T. S.
2015-08-15
Elastic scattering of electrons by hydrogen atoms in a dense semiclassical hydrogen plasma for low impact energies has been studied. Differential scattering cross sections were calculated within the effective model of electron-atom interaction taking into account the effect of screening as well as the quantum mechanical effect of diffraction. The calculations were carried out on the basis of the phase-function method. The influence of the diffraction effect on the Ramsauer–Townsend effect was studied on the basis of a comparison with results made within the effective polarization model of the Buckingham type.
Elastic scattering of low energy electrons in partially ionized dense semiclassical plasma
NASA Astrophysics Data System (ADS)
Dzhumagulova, K. N.; Shalenov, E. O.; Ramazanov, T. S.
2015-08-01
Elastic scattering of electrons by hydrogen atoms in a dense semiclassical hydrogen plasma for low impact energies has been studied. Differential scattering cross sections were calculated within the effective model of electron-atom interaction taking into account the effect of screening as well as the quantum mechanical effect of diffraction. The calculations were carried out on the basis of the phase-function method. The influence of the diffraction effect on the Ramsauer-Townsend effect was studied on the basis of a comparison with results made within the effective polarization model of the Buckingham type.
Elastic Scattering and Reaction Mechanisms of the Halo Nucleus {sup 11}Be around the Coulomb Barrier
Di Pietro, A.; Figuera, P.; Papa, M.; Santonocito, D.; Randisi, G.; Scuderi, V.; Amorini, F.; Fisichella, M.; Lattuada, M.; Pellegriti, M. G.; Rizzo, F.; Scalia, G.; Torresi, D.; Acosta, L.; Martel, I.; Perez-Bernal, F.; Borge, M. J. G.; Tengblad, O.; Vidal, A. Maira; Fraile, L. M.
2010-07-09
Collisions induced by {sup 9,10,11}Be on a {sup 64}Zn target at the same c.m. energy were studied. For the first time, strong effects of the {sup 11}Be halo structure on elastic-scattering and reaction mechanisms at energies near the Coulomb barrier are evidenced experimentally. The elastic-scattering cross section of the {sup 11}Be halo nucleus shows unusual behavior in the Coulomb-nuclear interference peak angular region. The extracted total-reaction cross section for the {sup 11}Be collision is more than double the ones measured in the collisions induced by {sup 9,10}Be. It is shown that such a strong enhancement of the total-reaction cross section with {sup 11}Be is due to transfer and breakup processes.
Telling, Mark T F; Neylon, Cameron; Kilcoyne, Susan H; Arrighi, Valeria
2008-09-04
Quasi-elastic neutron scattering (QENS) has been used to study the deviation from Debye-law harmonic behavior in lyophilized and hydrated apoferritin, a naturally occurring, multisubunit protein. Whereas analysis of the measured mean squared displacement (msd) parameter reveals a hydration-dependent inflection above 240 K, characteristic of diffusive motion, a hydration-independent inflection is observed at 100 K. The mechanism responsible for this low-temperature anharmonic response is further investigated, via analysis of the elastic incoherent neutron scattering intensity, by applying models developed to describe side-group motion in glassy polymers. Our results suggest that the deviation from harmonic behavior is due to the onset of methyl group rotations which exhibit a broad distribution of activated processes ( E a,ave = 12.2 kJ.mol (-1), sigma = 5.0 kJ x mol (-1)). Our results are likened to those reported for other proteins.
Fusion and quasi-elastic scattering in the Li6,7+Au197 systems
NASA Astrophysics Data System (ADS)
Palshetkar, C. S.; Thakur, Shital; Nanal, V.; Shrivastava, A.; Dokania, N.; Singh, V.; Parkar, V. V.; Rout, P. C.; Palit, R.; Pillay, R. G.; Bhattacharyya, S.; Chatterjee, A.; Santra, S.; Ramachandran, K.; Singh, N. L.
2014-02-01
Fusion and quasi-elastic scattering measurements have been carried out for Li6,7+Au197 systems in the energy range E /Vb˜0.7 to 1.5. Coupled-channel calculations including coupling to inelastic states of the target and projectiles are able to explain an enhancement in measured fusion cross sections at energies below the barrier. At energies above the barrier the complete fusion cross sections are found to be suppressed compared to the coupled-channel predictions for both systems. A systematic comparison of fusion cross sections of the weakly bound stable nuclei Li6,7 and halo nuclei He6,8 on a Au197 target is presented. Barrier distributions from quasi-elastic scattering are seen to shift towards higher energies with respect to fusion after inclusion of the breakup-α channel for both Li6 and Li7.
Two Photon Exchange in Quasi-elastic and Deep-inelastic Scattering
Averett, Todd D.; Katich, Joseph; Zhao Bo
2011-10-24
In this paper, I present an overview and preliminary results from three experiments at Jefferson Lab that were recently completed using a {sup 3}He gas target with polarization oriented normal to the scattering plane of unpolarized incident electrons. A target single spin asymmetry was formed by periodically flipping the direction of the target spin. In the reaction {up_arrow}{sup 3}He(e,e'), the Born contribution is expected to be zero, giving direct sensitivity to two photon exchange. This asymmetry was measured in the quasi-elastic and deep-inelastic regimes with 0.1 < Q{sup 2} < 1.0 GeV{sup 2}. The asymmetry is predicted to decrease by two-orders of magnitude for deep-inelastic versus quasi-elastic scattering. Preliminary results from these experiments will be presented.
Improved input for multi-reaction hadronic analyses from elastic pion-nucleon scattering
NASA Astrophysics Data System (ADS)
Revier, Joseph; Roenchen, Deborah; Doering, Michael; Workman`, Ronald
2017-01-01
In the search for missing baryonic resonances, many analyses include data from a variety of pion and photon induced reactions. For elastic πN scattering, however, usually the partial waves of the SAID or other groups are fitted, instead of data. We provide the partial-wave covariance matrices needed to perform correlated χ2 fits, in which the obtained χ2 equals the actual χ2 up to non-linear and normalization corrections. For any analysis relying on partial waves extracted from elastic pion scattering, this is a prerequisite to assess the significance of resonance signals and to assign any uncertainty on results. The compilation of the necessary data to improve hadronic analyses is presented in detail. Supported by the U.S. Department of Energy Grant DE-SC0014133, contract DE-AC05-06OR23177, and by the National Science Foundation (CAREER grant No. 1452055, PIF Grant No. 1415459).
Elastic {sup 16}O+{sup 20}Ne scattering from a folding model analysis
Yang Yongxu; Li Qingrun
2011-07-15
A folding potential for elastic {sup 16}O+{sup 20}Ne scattering is constructed based on the four-{alpha}-particle model for the {sup 16}O nucleus and the {alpha}+{sup 16}O model for the {sup 20}Ne nucleus. The elastic scattering angular distributions of the {sup 16}O+{sup 20}Ne system in the energy range of E{sub c.m.}=24.5-35.5 MeV are calculated by use of the {alpha}-folding potential obtained. The calculations show that the experimental data can be reasonably well described. The surface term in the imaginary potential has a significant effect on the calculations of the cross section at large angles for the energies considered.
Compton sources for the observation of elastic photon-photon scattering events
NASA Astrophysics Data System (ADS)
Micieli, D.; Drebot, I.; Bacci, A.; Milotti, E.; Petrillo, V.; Conti, M. Rossetti; Rossi, A. R.; Tassi, E.; Serafini, L.
2016-09-01
We present the design of a photon-photon collider based on conventional Compton gamma sources for the observation of elastic γ γ scattering. Two symmetric electron beams, generated by photocathodes and accelerated in linacs, produce two primary gamma rays through Compton backscattering with two high energy lasers. The elastic photon-photon scattering is analyzed by start-to-end simulations from the photocathodes to the detector. A new Monte Carlo code has been developed ad hoc for the counting of the QED events. Realistic numbers of the secondary gamma yield, obtained by using the parameters of existing or approved Compton devices, a discussion of the feasibility of the experiment and of the nature of the background are presented.
NASA Astrophysics Data System (ADS)
Oh, Ju-Won; Alkhalifah, Tariq
2016-09-01
Multiparameter full waveform inversion (FWI) applied to an elastic orthorhombic model description of the subsurface requires in theory a nine-parameter representation of each pixel of the model. Even with optimal acquisition on the Earth surface that includes large offsets, full azimuth, and multicomponent sensors, the potential for trade-off between the elastic orthorhombic parameters are large. The first step to understanding such trade-off is analysing the scattering potential of each parameter, and specifically, its scattering radiation patterns. We investigate such radiation patterns for diffraction and for scattering from a horizontal reflector considering a background isotropic model. The radiation patterns show considerable potential for trade-off between the parameters and the potentially limited resolution in their recovery. The radiation patterns of C11, C22, and C33 are well separated so that we expect to recover these parameters with limited trade-offs. However, the resolution of their recovery represented by recovered range of model wavenumbers varies between these parameters. We can only invert for the short wavelength components (reflection) of C33 while we can mainly invert for the long wavelength components (transmission) of the elastic coefficients C11 and C22 if we have large enough offsets. The elastic coefficients C13, C23, and C12 suffer from strong trade-offs with C55, C44, and C66, respectively. The trade-offs between C13 and C55, as well as C23 and C44, can be partially mitigated if we acquire P-SV and SV-SV waves. However, to reduce the trade-offs between C12 and C66, we require credible SH-SH waves. The analytical radiation patterns of the elastic constants are supported by numerical gradients of these parameters.
NASA Astrophysics Data System (ADS)
He, J. J.; Kubono, S.; Teranishi, T.; Hu, J.; Notani, M.; Baba, H.; Nishimura, S.; Moon, J. Y.; Nishimura, M.; Iwasaki, H.; Yanagisawa, Y.; Hokoiwa, N.; Kibe, M.; Lee, J. H.; Kato, S.; Gono, Y.; Lee, C. S.
2009-07-01
The excited states in Mg22 have been investigated by the resonant elastic scattering of Na21+p. A 4.0 MeV/nucleon Na21 beam was separated by the Center for Nuclear Study (CNS) radioactive ion beam separator (CRIB) and then used to bombard a thick (CH2)n target. The energy spectra of recoiled protons were measured at scattering angles of θc.m.≈172∘,146∘, and 134∘, respectively. A wide energy-range of excitation function in Mg22 (up to Ex~8.9 MeV) was obtained simultaneously with a thick-target method, and a state at 7.06 MeV was newly observed. The resonant parameters were deduced from an R-matrix analysis of the center-of-mass (c.m.) differential cross-section data with a SAMMY-M6-BETA code. The astrophysical resonant reaction rate for the Ne18(α,p)Na21 reaction was recalculated based on the present parameters. Generally speaking, the present rates are much smaller than the previous ones.
Elastic scattering of 9Be+51V near the Coulomb barrier
NASA Astrophysics Data System (ADS)
Morales-Rivera, J. C.; Martinez-Quiroz, E.; Belyaeva, T. L.; Aguilera, E. F.; Lizcano, D.; Amador-Valenzuela, P.
2016-05-01
Elastic scattering angular distributions for the 9Be+51V system were measured at three near Coulomb barrier energies, Elab = 16.35, 17.44 and 18.53 MeV. The data were analyzed by using a Semimicroscopic Optical Model. This combines a microscopic calculation of the mean-field double folding potential and a phenomenological construction of the dynamical polarization potential. The calculations reproduced the data very well and the total reaction cross sections were also calculated.
Direct experimental reconstruction of the pp elastic scattering matrix at 579 MeV
Aprile, E.; Eisenegger, C.; Hausammann, R.; Heer, E.; Hess, R.; Lechanoine-Leluc, C.; Leo, W.R.; Morenzoni, S.; Onel, Y.; Rapin, D.; Mango, S.
1981-04-20
We have made, for the first time, a direct reconstruction of the pp elastic scattering matrix at 579 MeV from a series of experiments performed with a polarized beam line. Fifteen observables consisting of the polarization, two-spin correlation and transfer parameters, and three-spin parameters were measured at seven angles between 66/sup 0/ and 90/sup 0/ center of mass. The experimental results and reconstructed amplitudes are presented and compared to a phase-shift analysis.
Spin cloud induced around an elastic scatterer by the intrinsic spin hall effect.
Mal'shukov, A G; Chu, C S
2006-08-18
Similar to the Landauer electric dipole created around an impurity by the electric current, a spin polarized cloud of electrons can be induced by the intrinsic spin Hall effect near a spin independent elastic scatterer. It is shown that in the ballistic range around the impurity, such a cloud appears in the case of Rashba spin-orbit interaction, even though the bulk spin Hall current is absent.
Köper, Ingo; Combet, Sophie; Petry, Winfried; Bellissent-Funel, Marie-Claire
2008-07-01
The molecular understanding of protein stabilization by the disaccharide trehalose in extreme temperature or hydration conditions is still debated. In the present study, we investigated the role of trehalose on the dynamics of the protein C-phycocyanin (C-PC) by neutron scattering. To single out the motions of C-PC hydrogen (H) atoms in various trehalose/water environments, measurements were performed in deuterated trehalose and heavy water (D2O). We report that trehalose decreases the internal C-PC dynamics, as shown by a reduced diffusion coefficient of protein H atoms. By fitting the Elastic Incoherent Structure Factor--which gives access to the "geometry" of the internal proton motions--with the model of diffusion inside a sphere, we found that the presence of trehalose induces a significantly higher proportion of immobile C-PC hydrogens. We investigated, by elastic neutron scattering, the mean square displacements (MSDs) of deuterated trehalose/D2O-embedded C-PC as a function of temperature in the range of 40-318 K. Between 40 and approximately 225 K, harmonic MSDs of C-PC are slightly smaller in samples containing trehalose. Above a transition temperature of approximately 225 K, we observed anharmonic motions in all trehalose/water-coated C-PC samples. In the hydrated samples, MSDs are not significantly changed by addition of 15% trehalose but are slightly reduced by 30% trehalose. In opposition, no dynamical transition was detected in dry trehalose-embedded C-PC, whose hydrogen motions remain harmonic up to 318 K. These results suggest that a role of trehalose would be to stabilize proteins by inhibiting some fluctuations at the origin of protein unfolding and denaturation.
Elastic scattering of 17O+208Pb at energies near the Coulomb barrier
NASA Astrophysics Data System (ADS)
Torresi, D.; Strano, E.; Mazzocco, M.; Boiano, A.; Boiano, C.; Di Meo, P.; La Commara, M.; Manea, C.; Nicoletto, M.; Grebosz, J.; Guglielmetti, A.; Molini, P.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Soramel, F.; Toniolo, N.; Filipescu, D.; Gheorghe, A.; Glodariu, T.; Jeong, S.; Kim, Y. H.; Lay, J. A.; Miyatake, H.; Pakou, A.; Sgouros, O.; Soukeras, V.; Stroe, L.; Vitturi, A.; Watanabe, Y.; Zerva, K.
2016-05-01
Within the frame of the commissioning of a new experimental apparatus EXPADES we undertook the measurement of the elastic scattering angular distribution for the system 17O+208Pb at energy around the Coulomb barrier. The reaction dynamics induced by loosely bound Radioactive Ion Beams is currently being extensively studied [4]. In particular the study of the elastic scattering process allows to obtain direct information on the total reaction cross section of the exotic nuclei. In order to understand the effect of the low binding energy on the reaction mechanism it is important to compare radioactive weakly bound nuclei with stable strongly-bound nuclei. In this framework the study of the 17O+208Pb elastic scattering can be considered to be complementary to a previous measurement of the total reaction cross section for the system 17F+208Pb at energies of 86, 90.4 MeV [5, 6]. The data will be compared with those obtained for the neighboring systems 16,18O+208Pb and others available in literature.
α-particle elastic scattering from 12C, 16O, 24Mg, and 28Si
NASA Astrophysics Data System (ADS)
Behairy, Kassem O.; Mahmoud, Zakaria M. M.; Anwar, M.
2017-01-01
The elastic scattering of α-particle is analyzed in terms of the optical model over the energy 104-172.2 MeV for 12C, 48.7-146 MeV for 16O, 50-119 MeV for 24Mg, and 104, 166, 120 and 240 MeV for 28Si. We generate the real part of the optical model potential using the single folding model. In the single folding procedure, the ground state density of the target is folded with an effective density dependent α-nucleon interaction. For the imaginary part, the usual Woods-Saxon form is used. The parameters of the effective density dependent α-nucleon interaction are determined by fitting the experimental data of elastic scattering. The effective interaction's parameters are optimized using the χ2 criterion. We reasonably reproduce the elastic scattering cross sections for all studied systems. The obtained results reflect the success of our obtained α-nucleon effective interaction.
NASA Astrophysics Data System (ADS)
Cantero, E. D.; Lantschner, G. H.; Eckardt, J. C.; Lovey, F. C.; Arista, N. R.
2010-04-01
Measurements of angular distributions and of the angular dependence of the energy loss of 4-, 6-, and 9-keV protons transmitted through thin Cu and Ag polycrystalline foils are presented. By means of standard multiple-scattering model calculations it is found that a V(r)∝r-2.8 potential leads to significantly better fits of the angular distributions than the standard Thomas Fermi, Lenz-Jensen, or Ziegler-Biersack-Littmark potentials. A theoretical model for the angular dependence of the energy loss based on considering geometric effects on a frictional inelastic energy loss plus an angular-dependent elastic contribution and the effects of foil roughness reproduces the experimental data. This agrees with previous results in Au and Al, therefore extending the applicability of the model to other metallic elements.
Proton heating via nonresonant scattering off intrinsic Alfvénic turbulence.
Wu, C S; Yoon, P H
2007-08-17
A novel yet unsophisticated theory is proposed to show that low-beta protons can be efficiently heated by enhanced Alfvén waves. The present research is motivated by a plasma physics issue relevant to the explanation of hot stellar coronas observed with x-ray telescopes. The efficient heating is attributed to nonresonant wave-particle scattering that tends to randomize proton motion in directions transverse to the ambient magnetic field.
Jet production in muon-proton and muon-nuclei scattering at Fermilab-E665
Salgado, C.W.; E665 Collaboration
1993-08-01
Measurements of multi-jet production rates from Muon-Proton Muon- Nuclei scattering at Fermilab-E665 are presented. Jet rates are defined by the JADE clustering algorithm. Rates in Muon-Proton deep-inelastic scattering are compared to perturbative Quantum Chromodynamics (PQCD) and Monte Carlo model predictions. We observe hadronic (2+1)-jet rates which are a factor of two higher than PQCD predictions at the partonic level. Preliminary results from jet production on heavy targets, in the shadowing region, show a suppression of the jet rates as compared to deuterium. The two- forward jet sample present higher suppression as compared to the one-forward jet sample.
Imaging the proton via hard exclusive production in diffractive pp scattering
Charles Hyde; Leonid Frankfurt; Mark Strikman; Christian Weiss
2007-05-21
We discuss the prospects for probing Generalized Parton Distributions (GPDs) via exclusive production of a high-mass system (H = heavy quarkonium, di-photon, di-jet, Higgs boson) in diffractive pp scattering, pp -> p + H + p. In such processes the interplay of hard and soft interactions gives rise to a diffraction pattern in the final-state proton transverse momenta, which is sensitive to the transverse spatial distribution of partons in the colliding protons. We comment on the plans for diffractive pp measurements at RHIC and LHC. Such studies could complement future measurements of GPDs in hard exclusive ep scattering (JLab, COMPASS, EIC).
{sup 7,9,10}Be elastic scattering and total reaction cross sections on a {sup 12}C target
Zamora, J. C.; Guimaraes, V.; Barioni, A.; Lepine-Szily, A.; Lichtenthaeler, R.; Faria, P. N. de; Mendes, D. R. Jr.; Gasques, L. R.; Scarduelli, V.; Pires, K. C. C.; Morcelle, V.; Leistenschneider, E.; Condori, R. P.; Zagatto, V. A.; Morais, M. C.; Crema, E.; Shorto, J. M. B.
2011-09-15
Elastic scattering angular distributions for {sup 7}Be, {sup 9}Be, and {sup 10}Be isotopes on {sup 12}C target were measured at laboratory energies of 18.8, 26.0, and 23.2 MeV, respectively. The analysis was performed in terms of optical model potentials using Woods-Saxon and double-folding form factors. Also, continuum discretized coupled-channels calculations were performed for {sup 7}Be and {sup 9}Be + {sup 12}C systems to infer the role of breakup in the elastic scattering. For the {sup 10}Be + {sup 12}C system, bound states coupled-channels calculations were considered. Moreover, total reaction cross sections were deduced from the elastic scattering analysis and compared with published data on other weakly and tightly bound projectiles elastically scattered on the {sup 12}C target, as a function of energy.
Rough surface scattering from an elastic scale model of an ocean bottom
NASA Astrophysics Data System (ADS)
Soukup, Raymond J.; Gragg, Robert F.; Wiley, Robert W.; Inanli, Burcin
2003-10-01
Monostatic and bistatic scattering strength measurements with a rough PVC surface were collected during two experiments in an acoustic tank facility at the Allied Geophysical Laboratories in the University of Houston. The PVC surface was analogous to limestone ocean bottoms in its two-dimensional power-law roughness spectrum and its large dependence of scattering strength on the roughness parameters. The experiments represent an initial effort to use physical models with ground-truth measurements of roughness and compressional/shear speeds and attenuations to verify the predicted effects of interface scattering models, e.g., the small-slope model developed at the Naval Research Laboratory for elastic bottoms. Comparisons between the small-slope model, perturbation theory, and the observed data are shown for the various geometries using acoustic transmissions in the 100-400 kHz band. The success in obtaining a good model-data fit is shown to be directly related to the ensonification of an area that represents a sufficient statistical sample of the roughness. Plans for a series of tank experiments with physical models for verifying predictions of rough surface scattering theories and elastic PE are described. [Work supported by ONR.
Antihydrogen-hydrogen elastic scattering at thermal energies using an atomic-orbital technique
Sinha, Prabal K.; Chaudhuri, Puspitapallab; Ghosh, A.S.
2003-05-01
In view of the recent interest in the trapping of antihydrogen atom H(bar sign), at very low temperatures, H-bar-H scattering has been investigated at low incident energies using a close-coupling model with the basis set H-bar(1s,2s,2p-bar)+H(1s,2s,2p-bar). The predicted s-wave elastic phase shifts, scattering length, and effective range are in a good agreement with the other recent predictions of Jonsell et al. and of Armour and Chamberlain. The results indicate that the atomic orbital expansion model is suitable to study the H-bar-H scattering at ultracold temperatures.
Electron-atomic-hydrogen ``elastic" scattering in the presence of a laser field
NASA Astrophysics Data System (ADS)
Li, S.-M.; Chen, J.; Zhou, Z.-F.
2002-05-01
Laser-assisted electron-atomic-hydrogen “elastic" scattering is studied in the first Born approximation. The initial and final states of projectile electron are described by the Volkov wavefunctions; the dressed state of target described by a time-dependent perturbative wavefunction in soft photon approximation. The laser modified cross-sections are calculated in two distinct geometries for laser polarization either parallel or perpendicular to the incident direction of electron. The numerical results shows that the multiphoton cross-sections oscillate by a few orders over the whole scattering angular region. The results for a parallel geometry oscillate more frequently in the intermediate angles; while the results for a perpendicular geometry oscillate more frequently in the forward and backward angles. At large scattering angles, the sum rule of Kroll and Watson is noticeably violated. The laser modification on summed total cross-section increases with field strength, but decreases with field frequency and polarization deviation from the incident direction.
NASA Astrophysics Data System (ADS)
Araki, Samuel J.
2016-11-01
In the plumes of Hall thrusters and ion thrusters, high energy ions experience elastic collisions with slow neutral atoms. These collisions involve a process of momentum exchange, altering the initial velocity vectors of the collision pair. In addition to the momentum exchange process, ions and atoms can exchange electrons, resulting in slow charge-exchange ions and fast atoms. In these simulations, it is particularly important to accurately perform computations of ion-atom elastic collisions in determining the plume current profile and assessing the integration of spacecraft components. The existing models are currently capable of accurate calculation but are not fast enough such that the calculation can be a bottleneck of plume simulations. This study investigates methods to accelerate an ion-atom elastic collision calculation that includes both momentum- and charge-exchange processes. The scattering angles are pre-computed through a classical approach with ab initio spin-orbit free potential and are stored in a two-dimensional array as functions of impact parameter and energy. When performing a collision calculation for an ion-atom pair, the scattering angle is computed by a table lookup and multiple linear interpolations, given the relative energy and randomly determined impact parameter. In order to further accelerate the calculations, the number of collision calculations is reduced by properly defining two cut-off cross-sections for the elastic scattering. In the MCC method, the target atom needs to be sampled; however, it is confirmed that initial target atom velocity does not play a significant role in typical electric propulsion plume simulations such that the sampling process is unnecessary. With these implementations, the computational run-time to perform a collision calculation is reduced significantly compared to previous methods, while retaining the accuracy of the high fidelity models.
Berezhnoy, Yu. A.; Mikhailyuk, V. P.; Pilipenko, V. V.
2011-04-15
Observables of the elastic and inelastic scattering of 800- and 250-MeV protons on {sup 20}Ne and {sup 24}Mg nuclei were calculated on the basis of the theory of multiple diffractive scattering and the dispersive {alpha}-cluster model. The {sup 20}Ne and {sup 24}Mg nuclei were assumed to consist of a core ({sup 16}O nucleus) and additional alpha-particle clusters, which could be situated with the highest probability both in the vicinity of the center of mass of the core and outside the core. The multiparticle densities of these nuclei and single-particle nucleon-distribution densities as obtained from the dispersive {alpha}-cluster model were used in the calculations. The differential cross sections and polarizations for elastic and inelastic p{sup 20}Ne and p{sup 24}Mg scattering at the energy of 800 MeV are in better agreement with experimental data than the analogous calculations at the energy of 250 MeV. The spin-rotation functions calculated in the singleparticle approximation for elastic p{sup 20}Ne and p{sup 24}Mg scattering at these two energy values differ qualitatively from their counterparts calculated on the basis of the dispersive {alpha}-cluster model.
Antiplane wave scattering from a cylindrical cavity in pre-stressed nonlinear elastic media
Shearer, Tom; Parnell, William J.; Abrahams, I. David
2015-01-01
The effect of a longitudinal stretch and a pressure-induced inhomogeneous radial deformation on the scattering of antiplane elastic waves from a cylindrical cavity is determined. Three popular nonlinear strain energy functions are considered: the neo-Hookean, the Mooney–Rivlin and a two-term Arruda–Boyce model. A new method is developed to analyse and solve the governing wave equations. It exploits their properties to determine an asymptotic solution in the far-field, which is then used to derive a boundary condition to numerically evaluate the equations local to the cavity. This method could be applied to any linear ordinary differential equation whose inhomogeneous coefficients tend to a constant as its independent variable tends to infinity. The effect of the pre-stress is evaluated by considering the scattering cross section. A longitudinal stretch is found to decrease the scattered power emanating from the cavity, whereas a compression increases it. The effect of the pressure difference depends on the strain energy function employed. For a Mooney–Rivlin material, a cavity inflation increases the scattered power and a deflation decreases it; for a neo-Hookean material, the scattering cross section is unaffected by the radial deformation; and for a two-term Arruda–Boyce material, both inflation and deflation are found to decrease the scattered power. PMID:26543398
Antiplane wave scattering from a cylindrical cavity in pre-stressed nonlinear elastic media.
Shearer, Tom; Parnell, William J; Abrahams, I David
2015-10-08
The effect of a longitudinal stretch and a pressure-induced inhomogeneous radial deformation on the scattering of antiplane elastic waves from a cylindrical cavity is determined. Three popular nonlinear strain energy functions are considered: the neo-Hookean, the Mooney-Rivlin and a two-term Arruda-Boyce model. A new method is developed to analyse and solve the governing wave equations. It exploits their properties to determine an asymptotic solution in the far-field, which is then used to derive a boundary condition to numerically evaluate the equations local to the cavity. This method could be applied to any linear ordinary differential equation whose inhomogeneous coefficients tend to a constant as its independent variable tends to infinity. The effect of the pre-stress is evaluated by considering the scattering cross section. A longitudinal stretch is found to decrease the scattered power emanating from the cavity, whereas a compression increases it. The effect of the pressure difference depends on the strain energy function employed. For a Mooney-Rivlin material, a cavity inflation increases the scattered power and a deflation decreases it; for a neo-Hookean material, the scattering cross section is unaffected by the radial deformation; and for a two-term Arruda-Boyce material, both inflation and deflation are found to decrease the scattered power.
Neutron scattered dose equivalent to a fetus from proton radiotherapy of the mother
Mesoloras, Geraldine; Sandison, George A.; Stewart, Robert D.; Farr, Jonathan B.; Hsi, Wen C.
2006-07-15
Scattered neutron dose equivalent to a representative point for a fetus is evaluated in an anthropomorphic phantom of the mother undergoing proton radiotherapy. The effect on scattered neutron dose equivalent to the fetus of changing the incident proton beam energy, aperture size, beam location, and air gap between the beam delivery snout and skin was studied for both a small field snout and a large field snout. Measurements of the fetus scattered neutron dose equivalent were made by placing a neutron bubble detector 10 cm below the umbilicus of an anthropomorphic Rando[reg] phantom enhanced by a wax bolus to simulate a second trimester pregnancy. The neutron dose equivalent in milliSieverts (mSv) per proton treatment Gray increased with incident proton energy and decreased with aperture size, distance of the fetus representative point from the field edge, and increasing air gap. Neutron dose equivalent to the fetus varied from 0.025 to 0.450 mSv per proton Gray for the small field snout and from 0.097 to 0.871 mSv per proton Gray for the large field snout. There is likely to be no excess risk to the fetus of severe mental retardation for a typical proton treatment of 80 Gray to the mother since the scattered neutron dose to the fetus of 69.7 mSv is well below the lower confidence limit for the threshold of 300 mGy observed for the occurrence of severe mental retardation in prenatally exposed Japanese atomic bomb survivors. However, based on the linear no threshold hypothesis, and this same typical treatment for the mother, the excess risk to the fetus of radiation induced cancer death in the first 10 years of life is 17.4 per 10 000 children.
Neutron scattered dose equivalent to a fetus from proton radiotherapy of the mother.
Mesoloras, Geraldine; Sandison, George A; Stewart, Robert D; Farr, Jonathan B; Hsi, Wen C
2006-07-01
Scattered neutron dose equivalent to a representative point for a fetus is evaluated in an anthropomorphic phantom of the mother undergoing proton radiotherapy. The effect on scattered neutron dose equivalent to the fetus of changing the incident proton beam energy, aperture size, beam location, and air gap between the beam delivery snout and skin was studied for both a small field snout and a large field snout. Measurements of the fetus scattered neutron dose equivalent were made by placing a neutron bubble detector 10 cm below the umbilicus of an anthropomorphic Rando phantom enhanced by a wax bolus to simulate a second trimester pregnancy. The neutron dose equivalent in milliSieverts (mSv) per proton treatment Gray increased with incident proton energy and decreased with aperture size, distance of the fetus representative point from the field edge, and increasing air gap. Neutron dose equivalent to the fetus varied from 0.025 to 0.450 mSv per proton Gray for the small field snout and from 0.097 to 0.871 mSv per proton Gray for the large field snout. There is likely to be no excess risk to the fetus of severe mental retardation for a typical proton treatment of 80 Gray to the mother since the scattered neutron dose to the fetus of 69.7 mSv is well below the lower confidence limit for the threshold of 300 mGy observed for the occurrence of severe mental retardation in prenatally exposed Japanese atomic bomb survivors. However, based on the linear no threshold hypothesis, and this same typical treatment for the mother, the excess risk to the fetus of radiation induced cancer death in the first 10 years of life is 17.4 per 10,000 children.
NASA Astrophysics Data System (ADS)
Csörgő, T.
2016-07-01
Recently published and preliminary results of the TOTEM experiment are presented, emphasizing a recent discovery of a non-exponential behaviour of the differential crosssection of elastic proton-proton scattering, that TOTEM measured with an unprecedented precision at the centre-of-mass energy √s = 8 TeV based on a high-statistics data sample obtained with the β* = 90 m optics of CERN LHC. Both the statistical and systematic uncertainties remained below 1%, except for the t-independent contribution from the overall normalisation. This measurement allowed TOTEM to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027 < |t| < 0.2 GeV2 with a significance greater than 7σ. In this context we also highlight the innovative TOTEM recalibration of LHC optics, that used elastic scattering data measured by the world's largest and most complex Roman Pot detector system, and discuss recent preliminary TOTEM data on the Coulomb-Nuclear interference region with its physics implications.
NOTE: Comparison of surface doses from spot scanning and passively scattered proton therapy beams
NASA Astrophysics Data System (ADS)
Arjomandy, Bijan; Sahoo, Narayan; Cox, James; Lee, Andrew; Gillin, Michael
2009-07-01
Proton therapy for the treatment of cancer is delivered using either passively scattered or scanning beams. Each technique delivers a different amount of dose to the skin, because of the specific feature of their delivery system. The amount of dose delivered to the skin can play an important role in choosing the delivery technique for a specific site. To assess the differences in skin doses, we measured the surface doses associated with these two techniques. For the purpose of this investigation, the surface doses in a phantom were measured for ten prostate treatment fields planned with passively scattered proton beams and ten patients planned with spot scanning proton beams. The measured doses were compared to evaluate the differences in the amount of skin dose delivered by using these techniques. The results indicate that, on average, the patients treated with spot scanning proton beams received lower skin doses by an amount of 11.8% ± 0.3% than did the patients treated with passively scattered proton beams. That difference could amount to 4 CGE per field for a prescribed dose of 76 CGE in 38 fractions treated with two equally weighted parallel opposed fields.
NASA Astrophysics Data System (ADS)
Nuruzzaman, FNU
The Q-weak experiment in Hall-C at the Thomas Jefferson National Accelerator Facility has made the first direct measurement of the weak charge of the proton through the precision measurement of the parity-violating asymmetry in elastic electron-proton scattering at low momentum transfer. There is also a parity conserving Beam Normal Single Spin Asymmetry or transverse asymmetry (Bn) on H2 with a sin(phi)-like dependence due to two-photon exchange. If the size of elastic Bn is a few ppm, then a few percent residual transverse polarization in the beam, combined with small broken azimuthal symmetries in the detector, would require a few ppb correction to the Q-weak data. As part of a program of Bn background studies, we made the first measurement of Bn in the N-to-Delta(1232) transition using the Q-weak apparatus. The final transverse asymmetry, corrected for backgrounds and beam polarization, was found to be Bn = 42.82 +- 2.45 (stat) +- 16.07 (sys) ppm at beam energy Ebeam = 1.155 GeV, scattering angle theta = 8.3 degrees, and missing mass W = 1.2 GeV. Bn from electron-nucleon scattering is a unique tool to study the gamma*DeltaDelta form factors, and this measurement will help to improve the theoretical models on beam normal single spin asymmetry and thereby our understanding of the doubly virtual Compton scattering process. To help correct false asymmetries from beam noise, a beam modulation system was implemented to induce small position, angle, and energy changes at the target to characterize detector response to the beam jitter. Two air-core dipoles separated by ˜10 m were pulsed at a time to produce position and angle changes at the target, for virtually any tune of the beamline. The beam energy was modulated using an SRF cavity. The hardware and associated control instrumentation will be described in this dissertation. Preliminary detector sensitivities were extracted which helped to reduce the width of the measured asymmetry. The beam modulation system has
., Nuruzzaman
2014-12-01
The Q-weak experiment in Hall-C at the Thomas Jefferson National Accelerator Facility has made the first direct measurement of the weak charge of the proton through the precision measurement of the parity-violating asymmetry in elastic electron-proton scattering at low momentum transfer. There is also a parity conserving Beam Normal Single Spin Asymmetry or transverse asymmetry (B_n) on H_2 with a sin(phi)-like dependence due to two-photon exchange. If the size of elastic B_n is a few ppm, then a few percent residual transverse polarization in the beam, combined with small broken azimuthal symmetries in the detector, would require a few ppb correction to the Q-weak data. As part of a program of B_n background studies, we made the first measurement of B_n in the N-to-Delta(1232) transition using the Q-weak apparatus. The final transverse asymmetry, corrected for backgrounds and beam polarization, was found to be B_n = 42.82 ± 2.45 (stat) ± 16.07 (sys) ppm at beam energy E_beam = 1.155 GeV, scattering angle theta = 8.3 deg, and missing mass W = 1.2 GeV. B_n from electron-nucleon scattering is a unique tool to study the gamma^* Delta Delta form factors, and this measurement will help to improve the theoretical models on beam normal single spin asymmetry and thereby our understanding of the doubly virtual Compton scattering process. To help correct false asymmetries from beam noise, a beam modulation system was implemented to induce small position, angle, and energy changes at the target to characterize detector response to the beam jitter. Two air-core dipoles separated by ~10 m were pulsed at a time to produce position and angle changes at the target, for virtually any tune of the beamline. The beam energy was modulated using an SRF cavity. The hardware and associated control instrumentation will be described in this dissertation. Preliminary detector sensitivities were extracted which helped to reduce the width of the measured asymmetry. The beam modulation system
Rorschach, H.E.
1993-05-25
Results that shed new light on the study of protein dynamics were obtained by quasi-elastic neutron scattering. The triple axis instrument H-9 supplied by the cold source was used to perform a detailed study of the quasi-elastic spectrum and the Debye-Waller factor for trypsin in powder form, in solution, and in crystals. A preliminary study of myoglobin crystals was also done. A new way to view the results of quasi-elastic scattering experiments is sketched, and the data on trypsin are presented and analyze according to this new picture.
Quasi-elastic neutron scattering studies of the slow dynamics of supercooled and glassy aspirin
NASA Astrophysics Data System (ADS)
Zhang, Yang; Tyagi, Madhusudan; Mamontov, Eugene; Chen, Sow-Hsin
2012-02-01
Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent β(Q) is independent of the wavevector transfer Q in the measured Q range and (ii) the structural relaxation time τ(Q) follows a power-law dependence on Q. Consequently, the Q-independent structural relaxation time τ0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of τ0 can be fitted with the mode-coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by Tokuyama in the measured temperature range. The calculated dynamic response function χT(Q, t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement langx2rang and the non-Gaussian parameter α2 extracted from the elastic scattering.
Quasi-Elastic Neutron Scattering Studies of the Slow Dynamics of Supercooled and Glassy Aspirin
Zhang, Yang; Tyagi, M.; Mamontov, Eugene; Chen, Sow-hsin H
2011-01-01
Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 K down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent (Q) is independent of the wave vector transfer Q in the measured Q-range, and (ii) the structural relaxation time (Q) follows a power law dependence on Q. Consequently, the Q-independent structural relaxation time 0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of 0 can be fitted with the mode coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by M. Tokuyama in the measured temperature range. The calculated dynamic response function T(Q,t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows a direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement x2 and non-Gaussian parameter 2 extracted from the elastic scattering.
Looking at hydrogen motions in confinement. The uniqueness of Quasi-Elastic Neutron Scattering
NASA Astrophysics Data System (ADS)
Fischer, J.; Tsapatsaris, N.; de Paula, E.; Bordallo, H. N.
2014-09-01
Why in a barren and hot desert, clays can contain a significant fraction of water? Why does concrete crack? How can we demonstrate that complexation of a drug does not alter its conformation in a way that affects its functionality? In this paper we present results on various studies using Quasi-Elastic Neutron Scattering aimed at clarifying these questions. To allow for a better understanding of neutron scattering, a brief introduction to the basics of its theory is presented. Following the theoretical part, experimental results dealing with the effects of confinement on the water dynamics caused by the interfaces in clays and the nano- and micro-pores of concrete are reviewed in detail. At the end, recent Quasi-Elastic Neutron Scattering investigations on the complexation of the local anesthetics Bupivacaine (BVC.HCl, C18H28N20.HCl.H2O) and Ropivacaine (RVC.HCl, C17H26N20.HCl.H2O) into the cyclic β-cyclodextrin oligosaccharide are presented. To conclude, the perspectives that the European Spallation Source brings to this subject are discussed.
Biophotonics of skin: method for correction of deep Raman spectra distorted by elastic scattering
NASA Astrophysics Data System (ADS)
Roig, Blandine; Koenig, Anne; Perraut, François; Piot, Olivier; Gobinet, Cyril; Manfait, Michel; Dinten, Jean-Marc
2015-03-01
Confocal Raman microspectroscopy allows in-depth molecular and conformational characterization of biological tissues non-invasively. Unfortunately, spectral distortions occur due to elastic scattering. Our objective is to correct the attenuation of in-depth Raman peaks intensity by considering this phenomenon, enabling thus quantitative diagnosis. In this purpose, we developed PDMS phantoms mimicking skin optical properties used as tools for instrument calibration and data processing method validation. An optical system based on a fibers bundle has been previously developed for in vivo skin characterization with Diffuse Reflectance Spectroscopy (DRS). Used on our phantoms, this technique allows checking their optical properties: the targeted ones were retrieved. Raman microspectroscopy was performed using a commercial confocal microscope. Depth profiles were constructed from integrated intensity of some specific PDMS Raman vibrations. Acquired on monolayer phantoms, they display a decline which is increasing with the scattering coefficient. Furthermore, when acquiring Raman spectra on multilayered phantoms, the signal attenuation through each single layer is directly dependent on its own scattering property. Therefore, determining the optical properties of any biological sample, obtained with DRS for example, is crucial to correct properly Raman depth profiles. A model, inspired from S.L. Jacques's expression for Confocal Reflectance Microscopy and modified at some points, is proposed and tested to fit the depth profiles obtained on the phantoms as function of the reduced scattering coefficient. Consequently, once the optical properties of a biological sample are known, the intensity of deep Raman spectra distorted by elastic scattering can be corrected with our reliable model, permitting thus to consider quantitative studies for purposes of characterization or diagnosis.
Forward pd elastic scattering and total spin-dependent pd cross sections at intermediate energies
Uzikov, Yu. N.; Haidenbauer, J.
2009-02-15
Spin-dependent total pd cross sections are considered using the optical theorem. For this aim the full spin dependence of the forward pd elastic scattering amplitude is considered in a model independent way. The single-scattering approximation is used to relate this amplitude to the elementary amplitudes of pp and pn scattering and the deuteron form factor. A formalism allowing to take into account Coulomb-nuclear interference effects in polarized pd cross sections is developed. Numerical calculations for the polarized total pd cross sections are performed at beam energies 20-300 MeV using the NN interaction models developed by the Juelich group. Double-scattering effects are estimated within the Glauber approach and found to be in the order of 10-20%. Existing experimental data on differential pd cross sections are in good agreement with the performed Glauber calculations. It is found that for the used NN models the total longitudinal and transversal pd cross sections are comparable in absolute value to those for pp scattering.
s-wave elastic scattering of antihydrogen off atomic alkali-metal targets
Sinha, Prabal K.; Ghosh, A. S.
2006-03-15
We have investigated the s-wave elastic scattering of antihydrogen atoms off atomic alkali-metal targets (Li, Na, K, and Rb) at thermal energies (10{sup -16}-10{sup -4} a.u.) using an atomic orbital expansion technique. The elastic cross sections of these systems at thermal energies are found to be very high compared to H-H and H-He systems. The theoretical models employed in this study are so chosen to consider long-range forces dynamically in the calculation. The mechanism of cooling suggests that Li may be considered to be a good candidate as a buffer gas for enhanced cooling of antihydrogen atoms to ultracold temperature.
Low-energy photodetachment of Ga- and elastic electron scattering from neutral Ga
NASA Astrophysics Data System (ADS)
Wang, Kedong; Zatsarinny, Oleg; Bartschat, Klaus
2016-08-01
We present a comprehensive study of the photodetachment of the negative gallium ion and elastic electron scattering from neutral Ga for photon and electron energies ranging from threshold to 12 eV. The calculations are carried out with the B -spline R -matrix method. A multiconfiguration Hartree-Fock method with nonorthogonal term-dependent orbitals is employed to generate accurate initial- and final-state wave functions. The close-coupling expansions include the 4 s 24 p n l (k l ) bound and continuum states of Ga and the 4 s -excited autoionizing states 4 s 4 p2 . The calculated photodetachment and elastic cross sections exhibit prominent resonance features. In order to clarify the origin of these resonances, the contributions of the major ionization channels to the partial cross sections are analyzed in detail.
Finite Element Prediction of Acoustic Scattering and Radiation from Submerged Elastic Structures
NASA Technical Reports Server (NTRS)
Everstine, G. C.; Henderson, F. M.; Lipman, R. R.
1984-01-01
A finite element formulation is derived for the scattering and radiation of acoustic waves from submerged elastic structures. The formulation uses as fundamental unknowns the displacement in the structure and a velocity potential in the field. Symmetric coefficient matrices result. The outer boundary of the fluid region is terminated with an approximate local wave-absorbing boundary condition which assumes that outgoing waves are locally planar. The finite element model is capable of predicting only the near-field acoustic pressures. Far-field sound pressure levels may be determined by integrating the surface pressures and velocities over the wet boundary of the structure using the Helmholtz integral. Comparison of finite element results with analytic results show excellent agreement. The coupled fluid-structure problem may be solved with general purpose finite element codes by using an analogy between the equations of elasticity and the wave equation of linear acoustics.
NASA Astrophysics Data System (ADS)
Sacchi, M.; Jaouen, N.; Popescu, H.; Gaudemer, R.; Tonnerre, J. M.; Chiuzbaian, S. G.; Hague, C. F.; Delmotte, A.; Dubuisson, J. M.; Cauchon, G.; Lagarde, B.; Polack, F.
2013-03-01
SEXTANTS is a new SOLEIL beamline dedicated to soft X-ray scattering techniques. The beamline, covering the 50-1700 eV energy range, features two Apple-II undulators for polarization control and a fixed-deviation monochromator. Two branch-lines host three end-stations for elastic, inelastic and coherent scattering experiments.
Elastic scattering and vibrational excitation of CO2 by 4, 10, 20 and 50 eV electrons
NASA Technical Reports Server (NTRS)
Register, D. F.; Trajmar, S.; Nishimura, H.
1980-01-01
Elastic and vibrationally inelastic differential, integral and momentum-transfer cross sections for electrons scattered by CO2 molecules are reported at 4, 10, 20 and 50 eV impact energies. The elastic cross sections are placed on an absolute scale by means of a relative flow technique. The inelastic cross sections are normalised to the elastic ones by using the inelastic to elastic intensity ratios. Data are reported for up to ten features in the 0.0 to 0.4 eV energy-loss region.
Kelly, J.J.
1983-01-01
Electron scattering measurements of the normal parity isoscalar collective excitations of N = Z nuclei completely specify the nuclear structure information required for the analysis of complementary proton scattering experiments. The analysis of the proton scattering data is then interpreted as a study of the medium modifications of the two-nucleon effective interaction. It has been found that the isoscalar spin-independent central component of the effective interaction is strongly dependent upon density and is well described by the local density approximation based upon nuclear matter effective interactions. The results are sensitive to the difference between effective interactions based upon the Hamad-Johnston and Paris potentials, and favor an intermediate interaction. The qualitative features of the medium corrections can be adequately represented by a few physically motivated parameters, which can be chosen so as to reproduce either the Hamada-Johnston or Paris results. 20 references, 10 figures.
Using EFT to analyze low-energy Compton scattering from protons and light nuclei
NASA Astrophysics Data System (ADS)
Phillips, Daniel R.; McGovern, Judith; Grießhammer, Harald W.
2013-10-01
We discuss the application of an effective field theory (EFT) which incorporates the chiral symmetry of QCD to Compton scattering from the proton and deuteron. We describe the chiral EFT analysis of the γp scattering database presented in our recent review [1], which gives: αE1(p) = 10.5±0.5(stat)±0.8(theory), βM1(p) = 2.7±0.5(stat)±0.8(theory), for the electric and magnetic dipole polarizability of the proton.We also summarize Ref. [1]'s chiral EFT analysis of the world data on coherent Compton scattering from deuterium, which yields: αE1(s) = 10.5±2.0(stat)±0.8(theory), βM1(s) = 3.6±1.0(stat)±0.8(theory).
Probing Proton Strangeness with Time-Like Virtual Compton Scattering
Stephen R. Cotanch; Robert A. Williams
2002-05-01
We document that p(gamma,e+e-)p measurements will yield new, important information about the off-shell time-like nucleon form factors, especially in the phi meson region (q{sup 2} = M{sup 2}{sub {phi}}) governing the phi N couplings g{sup V,T}{sub {phi}NN}. Calculations for p(gamma,e+e-)p, utilizing vector meson dominance, predict measurable phi enhancements at high |t| compared to the expected phi background production from pi, eta and Pomeron exchange. The phi form factor contribution generates a novel experimental signature for OZI violation and the proton strangeness content. The phi N couplings are determined independently from a combined analysis of the neutron electric form factor and recent high |t| phi photoproduction. The pi, eta and Pomeron transition form factors are also predicted and the observed pi and eta transition moments are reproduced.
Zatsarinny, O.; Bartschat, K.; Allan, M.
2011-03-15
In a joint experimental and theoretical effort, we carried out a detailed study of elastic electron scattering from Kr atoms. Absolute angle-differential cross sections for elastic electron scattering were measured over the energy range 0.3-9.8 eV with an energy width of about 13 meV at scattering angles between 0 deg. and 180 deg. Excellent agreement is obtained between our experimental data and predictions from a fully relativistic Dirac B-spline R-matrix (close-coupling) model that accounts for the atomic dipole polarizability through a specially designed pseudostate.
Study of proton-induced reactions and correlation with fast-neutron scattering
Hansen, L.F.
1982-01-19
The generation of cross sections for fast neutron-nucleon interactions obtained from elastic and charge-exchange proton data is discussed in terms of the Lane model formalism. A general description of the interaction of nucleons with nuclei is presented in terms of the optical model and the extended (or coupled-channel) optical model, together with the relation of these models to microscopic calculations of the nucleon-nucleon interaction. Comparisons between neutron elastic data and calculations carried out with optical model potentials obtained from (p,p) and (p,n) data are presented for a large number of nuclei. The validity of the Lane model and the importance of coupled effects in the actinide region are shown in a detailed comparison of calculations for elastic and inelastic neutron differential cross sections and measurements for /sup 232/Th and /sup 238/U.
Arbanas, Goran; Dunn, Michael E; Larson, Nancy M; Leal, Luiz C; Williams, Mark L
2012-01-01
Convergence properties of Legendre expansion of a Doppler-broadened double-differential elastic neutron scattering cross section of {sup 238}U near the 6.67 eV resonance at temperature 10{sup 3} K are studied. A variance of Legendre expansion from a reference Monte Carlo computation is used as a measure of convergence and is computed for as many as 15 terms in the Legendre expansion. When the outgoing energy equals the incoming energy, it is found that the Legendre expansion converges very slowly. Therefore, a supplementary method of computing many higher-order terms is suggested and employed for this special case.
Double Folding Potential of Different Interaction Models for 16O + 12C Elastic Scattering
NASA Astrophysics Data System (ADS)
Hamada, Sh.; Bondok, I.; Abdelmoatmed, M.
2016-12-01
The elastic scattering angular distributions for 16O + 12C nuclear system have been analyzed using double folding potential of different interaction models: CDM3Y1, CDM3Y6, DDM3Y1 and BDM3Y1. We have extracted the renormalization factor N r for the different concerned interaction models. Potential created by BDM3Y1 model of interaction has the shallowest depth which reflects the necessity to use higher renormalization factor. The experimental angular distributions for 16O + 12C nuclear system in the energy range 115.9-230 MeV exhibited unmistakable refractive features and rainbow phenomenon.
Scattering resonance of elastic wave and low-frequency equivalent slow wave
NASA Astrophysics Data System (ADS)
Meng, X.; Liu, H.; Hu, T.; Yang, L.
2015-12-01
Transmitted wave occurs as fast p-wave and slow p-wave in certain conditions when seismic waves travel through inhomogeneous layers. Energy of slow p-waves is strongest at some frequency band, but rather weak at both high frequency band and low frequency band, called scattering resonance. For practical seismic exploration, the frequency of slow p-wave occurs is below 10Hz, which cannot be explained by Biot's theory which predicts existence of the slow p-wave at ultrasonic band in the porous media. The slow p-wave equation have been derived, but which only adapted to explaining slow p-wave in the ultrasonic band. Experimental observations exhibit that slow p-wave also exists in nonporous media but with enormous low-velocity interbeds. When vertical incidence, elastic wave is simplified as compressing wave, the generation of slow waves is independent on shear wave. In the case of flat interbed and gas bubble, Liu (2006) has studied the transmission of acoustic waves, and found that the slow waves below the 10Hz frequency band can be explained. In the case of general elastic anisotropy medium, the tiheoretical research on the generation of slow waves is insufficient. Aiming at this problem, this paper presents an exponential mapping method based on transmitted wave (Magnus 1954), which can successfully explain the generation of the slow wave transmission in that case. Using the prediction operator (Claerbout 1985) to represent the transmission wave, this can be derived as first order partial differential equation. Using expansions in the frequency domain and the wave number domain, we find that the solutions have different expressions in the case of weak scattering and strong scattering. Besides, the method of combining the prediction operator and the exponential map is needed to extend to the elastic wave equation. Using the equation (Frazer and Fryer 1984, 1987), we derive the exponential mapping solution for the prediction operator of the general elastic medium
Bousset, Luc; Brewee, Clémence; Melki, Ronald; Migliardo, Federica
2014-07-01
In the present paper, Quasi Elastic Neutron Scattering (QENS) results, gathered at different energy resolution values at the ISIS Facility (RAL, UK), on α-synuclein in soluble and fibrillar forms as a function of temperature and exchanged wave-vector Q are shown. The measurements reveal a different dynamic behavior of the soluble and fibrillar forms of α-synuclein as a function of thermal stress. In more detail, the dynamics of each protein form reflects its own complex conformational heterogeneity. Furthermore, the effect of a well known bioprotectant, trehalose, that influences α-synuclein fibrillation, on both soluble and fibrillar forms of α-synuclein is discussed.
Elastic scattering for the system {sup 6}Li+p at near barrier energies with MAGNEX
Soukeras, V.; Pakou, A.; Sgouros, O.; Cappuzzello, F.; Bondi, M.; Nicolosi, D.; Acosta, L.; Marquinez-Duran, G.; Martel, I.; Agodi, C.; Carbone, D.; Cavallaro, M.; Cunsolo, A.; Di Pietro, A.; Fernández-García, J. P.; Figuera, P.; Fisichella, M.; Alamanos, N.; De Napoli, M.; Foti, A.; and others
2015-02-24
Elastic scattering measurements have been performed for the {sup 6}Li+p system in inverse kinematics at the energies of 16, 20, 25 and 29 MeV. The heavy ejectile was detected by the large acceptance MAGNEX spectrometer at the Laboratori Nazionali del Sud (LNS) in Catania, in the angular range between ∼2{sup 0} and 12{sup 0} in the laboratory system, giving us the possibility to span almost a full angular range in the center of mass system. Results will be presented and discussed for one of the energies.
NASA Astrophysics Data System (ADS)
Patton, Kelly; McLaughlin, Gail; Scholberg, Kate; Engel, Jon; Schunck, Nicolas
2017-01-01
Coherent elastic neutrino-nucleus scattering is a potential probe of nuclear neutron form factors. We show that the neutron root-mean-square (RMS) radius can be measured with tonne-scale detectors of argon, germanium, or xenon. In addition, the fourth moment of the neutron distribution can be studied experimentally using this method. The impacts of both detector size and detector shape uncertainty on such a measurement were considered. The important limiting factor was found to be the detector shape uncertainty. In order to measure the neutron RMS radius to 5%, comparable to current experimental uncertainties, the detector shape uncertainty needs to be known to 1% or better.
Elastic scattering of {sup 9}Li on {sup 208}Pb at energies around the Coulomb barrier
Cubero, M.; Fernandez-Garcia, J. P.; Alvarez, M. A. G.; Lay, J. A.; Moro, A. M.; Acosta, L.; Martel, I.; Sanchez-Benitez, A. M.; Alcorta, M.; Borge, M. J. G.; Tengblad, O.; Buchmann, L.; Shotter, A.; Walden, P.; Diget, D. G.; Fulton, B.; Fynbo, H. O. U.; Galaviz, D.; Gomez-Camacho, J.; Mukha, I.
2011-10-28
We have studied the dynamical effects of the halo structure of {sup 11}Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated {sup 11}Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. {sup 9}Li on {sup 208}Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions.
Short Range Correlations in Nuclei at Large xbj through Inclusive Quasi-Elastic Electron Scattering
Ye, Zhihong
2013-12-01
The experiment, E08-014, in Hall-A at Jefferson Lab aims to study the short-range correlations (SRC) which are necessary to explain the nuclear strength absent in the mean field theory. The cross sections for 2H, 3He, 4He, 12C, 40Ca and 48Ca, were measured via inclusive quasi-elastic electron scattering from these nuclei in a Q2 range between 0.8 and 2.8 (GeV/c)^{2} for x>1. The cross section ratios of heavy nuclei to 2H were extracted to study two-nucleon SRC for 1
Systematic analysis of α elastic scattering with the São Paulo potential
NASA Astrophysics Data System (ADS)
Charry-Pastrana, F. E.; Pinilla, E. C.
2016-07-01
We describe systematically by collision energy and target mass, alpha elastic scattering angular distributions by using the São Paulo potential as the real part of the optical potential. The imaginary part is proportional to the real one by a factor Ni. We find this parameter by fitting the theoretical angular distributions to the experimental cross sections through a χ2 minimization. The Ni and their respective uncertainties, σNi, fall in the range 0.4 ≤ Ni ± σNi ≤ 0.8 for all the systems studied.
David Abbott; Abdellah Ahmidouch; Heinz Anklin; Francois Arvieux; Jacques Ball; S. Beedoe; Elizabeth Beise; Louis Bimbot; Werner Boeglin; Herbert Breuer; Roger Carlini; Nicholas Chant; Samuel Danagoulian; K. Dow; Jean-Eric Ducret; James Dunne; Lars Ewell; Laurent Eyraud; Christophe Furget; Michel Garcon; Ronald Gilman; Charles Glashausser; Paul Gueye; Kenneth Gustafsson; Kawtar Hafidi; Adrian Honegger; Juerg Jourdan; Serge Kox; Gerfried Kumbartzki; L. Lu; Allison Lung; David Mack; Pete Markowitz; Justin McIntyre; David Meekins; Fernand Merchez; Joseph Mitchell; R. Mohring; Sekazi Mtingwa; Hamlet Mkrtchyan; David Pitz; Liming Qin; Ronald Ransome; Jean-Sebastien Real; Philip Roos; Paul Rutt; Reyad Sawafta; Samuel Stepanyan; Raphael Tieulent; Egle Tomasi-Gustafsson; William Turchinetz; Kelley Vansyoc; Jochen Volmer; Eric Voutier; William Vulcan; Claude Williamson; Stephen Wood; Chen Yan; Jie Zhao; Wenxia Zhao
2000-05-01
Tensor polarization observables (t20, t21 and t22) have been measured in elastic electron-deuteron scattering for six values of momentum transfer between 0.66 and 1.7 (GeV/c){sup 2}. The experiment was performed at the Jefferson Laboratory in Hall C using the electron HMS Spectrometer, a specially designed deuteron magnetic channel and the recoil deuteron polarimeter POLDER. The new data determine to much larger Q{sup 2} the deuteron charge form factors G{sub C} and G{sub Q}. They are in good agreement with relativistic calculations and disagree with pQCD predictions.
Elastic scattering research at a 1 MW long pulse spallation neutron source
Crawford, R.K.
1995-12-31
The elastic scattering working group investigated instrumentation for powder diffraction, single-crystal diffraction, small-angle diffraction, and reflectometry. For this purpose, three subgroups were formed; one for powder diffraction and single-crystal diffraction, one for small-angle diffraction, and one for reflectometry. For the most part these subgroups worked separately, but for part of the time the reflectometry and small-angle diffraction subgroups met together to discuss areas of common interest. Contributors in each of these subgroups are indicated below along with the discussion of these subgroup deliberations.
Inelastic Proton Scattering on 21Na in Inverse Kinematics
NASA Astrophysics Data System (ADS)
Austin, Roby
2009-10-01
R.A.E. Austin, R. Kanungo, S. Reeve, Saint Mary's University; D.G. Jenkins, C.Aa.Diget, A. Robinson, A.G. Tuff, O. Roberts, University of York, UK; P.J. Woods, T. Davinson, G. J. Lotay, University of Edinburgh; C.-Y. Wu, Lawrence Livermore National Laboratory; H. Al Falou, G.C. Ball, M. Djongolov, A. Garnsworthy, G. Hackman, J.N. Orce, C.J. Pearson, S. Triambak, S.J. Williams, TRIUMF; C. Andreiou, D.S. Cross, N. Galinski, R. Kshetri, Simon Fraser University; C. Sumithrarachchi, M.A. Schumaker, University of Guelph; M.P. Jones, S.V. Rigby, University of Liverpool; D. Cline, A. Hayes, University of Rochester; T.E. Drake, University of Toronto; We describe an experiment and associated technique [1] to measure resonances of interest in astrophysical reactions. At the TRIUMF ISAC-II radioactive beam accelerator facility in Canada, particles inelastically scattered in inverse kinematics are detected with Bambino, a δE-E silicon telescope spanning 15-40 degrees in the lab. We use the TIGRESS to detect gamma rays in coincidence with the charged particles to cleanly select inelastic scattering events. We measured resonances above the alpha threshold in ^22Mg of relevance to the rate of break-out from the hot-CNO cycle via the reaction ^ 18Ne(α,p)^21Na. [1] PJ Woods et al. Rex-ISOLDE proposal 424 Cern (2003).
Osti, Naresh C.; Mamontov, Eugene; Ramirez-cuesta, A.; ...
2015-12-10
Understanding the molecular behavior of water in spatially restricted environments is important to better understanding its role in many biological, chemical and geological processes. Here we examine the translational diffusion of water confined to a variety of substrates, from flat surfaces to nanoporous media, in the context of a recently proposed universal scaling law (Chiavazzo 2014) [1]. Using over a dozen previous neutron scattering results, we test the validity of this law, evaluating separately the influence of the hydration amount, and the effects of the size and morphology of the confining medium. Additionally, we investigate the effects of changing instrumentmore » resolutions and fitting models on the applicability of this law. Finally, we perform quasi-elastic neutron scattering measurements on water confined inside nanoporous silica to further evaluate this predictive law, in the temperature range 250≤T≤290 K.« less
Swimming speed distributions of bull spermatozoa as determined by quasi-elastic light scattering.
Hallett, F R; Craig, T; Marsh, J
1978-01-01
88 semen samples from 39 bulls have been investigated by the quasi-elastic light scattering technique. Normal, defective, and dead cells each yielded characteristic autocorrelation functions. The form of these functions indicates that the swimming speed distribution of normal cells is a gamma distribution with two degrees of freedom while that for defective or circular swimmers is a gamma distribution with one degree of freedom. The resulting analysis of the experimental autocorrelation functions yields the fraction of the sample that is normal, the fraction that is defective, and the average speed of each group. The average helical swimming speed of normal cells was found to be 384 micron/s, while the average trajectory speed of the circular swimmers was found to be 103 micron/s. The overall quality of the semen samples as determined by light scattering is compared to quality determination on the same samples by technicians from the artificial insemination industry. PMID:630041
Analyses of PION-40Ca Elastic Scattering Data Using the Klein-Gordon Equation
NASA Astrophysics Data System (ADS)
Shehadeh, Zuhair F.
The elastic scattering data for incident pion energies of 130, 163.3, 180, and 230 MeV on 40Ca have been analyzed using the full Klein-Gordon equation (KGE), as opposed to its approximate form which renders it to the format of a Schrödinger equation with an energy-dependent potential (RSE). Calculated angular distributions, using KGE and RSE, for all four cases are nearly the same up to about 70° but differ significantly at larger angles. To fit the large-angle data of 163.3 MeV, the nature of the old potential determined by using RSE needs to be revised. The new potentials in four cases are presented and they are compatible with those determined from the inverse scattering theory at a fixed energy in the surface region.
Metzler, Adam M; Siegmann, William L; Collins, Michael D
2012-02-01
The parabolic equation method with a single-scattering correction allows for accurate modeling of range-dependent environments in elastic layered media. For problems with large contrasts, accuracy and efficiency are gained by subdividing vertical interfaces into a series of two or more single-scattering problems. This approach generates several computational parameters, such as the number of interface slices, an iteration convergence parameter τ, and the number of iterations n for convergence. Using a narrow-angle approximation, the choices of n=1 and τ=2 give accurate solutions. Analogous results from the narrow-angle approximation extend to environments with larger variations when slices are used as needed at vertical interfaces. The approach is applied to a generic ocean waveguide that includes the generation of a Rayleigh interface wave. Results are presented in both frequency and time domains.
Hydration of NaDNA by neutron quasi-elastic scattering.
Schreiner, L J; Pintar, M M; Dianoux, A J; Volino, F; Rupprecht, A
1988-01-01
Preliminary results of neutron quasi-elastic scattering experiments are reported for hydrated paracrystals of sodium deoxyribonucleic acid (NaDNA). The samples were investigated at two water contents: 3.5 +/- 1.0 and 9.5 +/- 1.5 mol H2O per mole nucleotide. The results of the scattering experiments were almost independent of whether the NaDNA fibers were oriented parallel or perpendicular to the momentum transfer. The data indicate that at the lower hydration the water molecules do not diffuse appreciably on the time scale of the neutron measurements (approximately 3 X 10(-10) s). At the higher hydration the water molecules diffuse isotropically in a sphere of 9 A in diameter with a diffusion coefficient of (5 +/- 2) X 10(-6) cm2 s-1. PMID:3342269
Osti, Naresh C.; Mamontov, Eugene; Ramirez-cuesta, A.; Wesolowski, David J.; Diallo, S. O.
2015-12-10
Understanding the molecular behavior of water in spatially restricted environments is important to better understanding its role in many biological, chemical and geological processes. Here we examine the translational diffusion of water confined to a variety of substrates, from flat surfaces to nanoporous media, in the context of a recently proposed universal scaling law (Chiavazzo 2014) [1]. Using over a dozen previous neutron scattering results, we test the validity of this law, evaluating separately the influence of the hydration amount, and the effects of the size and morphology of the confining medium. Additionally, we investigate the effects of changing instrument resolutions and fitting models on the applicability of this law. Finally, we perform quasi-elastic neutron scattering measurements on water confined inside nanoporous silica to further evaluate this predictive law, in the temperature range 250≤T≤290 K.
NASA Astrophysics Data System (ADS)
Magazù, S.; Migliardo, F.; Vertessy, B. G.; Caccamo, M. T.
2013-10-01
In the present paper the results of a wavevector and thermal analysis of Elastic Incoherent Neutron Scattering (EINS) data collected on water mixtures of three homologous disaccharides through a wavelet approach are reported. The wavelet analysis allows to compare both the spatial properties of the three systems in the wavevector range of Q = 0.27 Å-1 ÷ 4.27 Å-1. It emerges that, differently from previous analyses, for trehalose the scalograms are constantly lower and sharper in respect to maltose and sucrose, giving rise to a global spectral density along the wavevector range markedly less extended. As far as the thermal analysis is concerned, the global scattered intensity profiles suggest a higher thermal restrain of trehalose in respect to the other two homologous disaccharides.
Absolute differential cross sections for elastic scattering of electrons from pyrimidine
Maljkovic, J. B.; Milosavljevic, A. R.; Sevic, D.; Marinkovic, B. P.; Blanco, F.
2009-05-15
Differential cross sections (DCSs) for elastic scattering of electrons from pyrimidine (C{sub 4}H{sub 4}N{sub 2}) are presented for incident energies from 50 to 300 eV. The measurements were performed using a cross beam technique, for scattering angles from 20 deg. to 110 deg. The relative DCSs were measured as a function of both the angle and incident energy and the absolute DCSs were determined using the relative flow method. The calculations of electron interaction cross sections are based on a corrected form of the independent-atom method, known as the screen corrected additivity rule procedure and using an improved quasifree absorption model. Calculated results agree very well with the experiment.
Optical elastic scattering for early label-free identification of clinical pathogens
NASA Astrophysics Data System (ADS)
Genuer, Valentin; Gal, Olivier; Méteau, Jérémy; Marcoux, Pierre; Schultz, Emmanuelle; Lacot, Éric; Maurin, Max; Dinten, Jean-Marc
2016-03-01
We report here on the ability of elastic light scattering in discriminating Gram+, Gram- and yeasts at an early stage of growth (6h). Our technique is non-invasive, low cost and does require neither skilled operators nor reagents. Therefore it is compatible with automation. It is based on the analysis of the scattering pattern (scatterogram) generated by a bacterial microcolony growing on agar, when placed in the path of a laser beam. Measurements are directly performed on closed Petri dishes. The characteristic features of a given scatterogram are first computed by projecting the pattern onto the Zernike orthogonal basis. Then the obtained data are compared to a database so that machine learning can yield identification result. A 10-fold cross-validation was performed on a database over 8 species (15 strains, 1906 scatterograms), at 6h of incubation. It yielded a 94% correct classification rate between Gram+, Gram- and yeasts. Results can be improved by using a more relevant function basis for projections, such as Fourier-Bessel functions. A fully integrated instrument has been installed at the Grenoble hospital's laboratory of bacteriology and a validation campaign has been started for the early screening of MSSA and MRSA (Staphylococcus aureus, methicillin-resistant S. aureus) carriers. Up to now, all the published studies about elastic scattering were performed in a forward mode, which is restricted to transparent media. However, in clinical diagnostics, most of media are opaque, such as blood-supplemented agar. That is why we propose a novel scheme capable of collecting back-scattered light which provides comparable results.
Elastic and inelastic neutron scattering cross sections for fission reactor applications
NASA Astrophysics Data System (ADS)
Hicks, S. F.; Chakraborty, A.; Combs, B.; Crider, B. P.; Downes, L.; Girgis, J.; Kersting, L. J.; Kumar, A.; Lueck, C. J.; McDonough, P. J.; McEllistrem, M. T.; Peters, E. E.; Prados-Estevz, F. M.; Schniederjan, J.; Sidwell, L.; Sigillito, A. J.; Vanhoy, J. R.; Watts, D.; Yates, S. W.
2013-04-01
Nuclear data important for the design and development of the next generation of light-water reactors and future fast reactors include neutron elastic and inelastic scattering cross sections on important structural materials, such as Fe, and on coolant materials, such as Na. These reaction probabilities are needed since neutron reactions impact fuel performance during irradiations and the overall efficiency of reactors. While neutron scattering cross sections from these materials are available for certain incident neutron energies, the fast neutron region, particularly above 2 MeV, has large gaps for which no measurements exist, or the existing uncertainties are large. Measurements have been made at the University of Kentucky Accelerator Laboratory to measure neutron scattering cross sections on both Fe and Na in the region where these gaps occur and to reduce the uncertainties on scattering from the ground state and first excited state of these nuclei. Results from measurements on Fe at incident neutron energies between 2 and 4 MeV will be presented and comparisons will be made to model calculations available from data evaluators.
Elastic light single-scattering spectroscopy for detection of dysplastic tissues
NASA Astrophysics Data System (ADS)
Canpolat, Murat; Denkçeken, Tuba; Akman, Ayşe.; Alpsoy, Erkan; Tuncer, Recai; Akyüz, Mahmut; Baykara, Mehmet; Yücel, Selçuk; Başsorgun, Ibrahim; ćiftçioǧlu, M. Akif; Gökhan, Güzide Ayşe.; Gürer, ElifInanç; Peştereli, Elif; Karaveli, Šeyda
2013-11-01
Elastic light single-scattering spectroscopy (ELSSS) system has been developed and tested in diagnosis of cancerous tissues of different organs. ELSSS system consists of a miniature visible light spectrometer, a single fiber optical probe, a halogen tungsten light source and a laptop. Measurements were performed on excised brain, skin, cervix and prostate tumor specimens and surrounding normal tissues. Single fiber optical probe with a core diameter of 100 μm was used to deliver white light to and from tissue. Single optical fiber probe mostly detects singly scattered light from tissue rather than diffused light. Therefore, measured spectra are sensitive to size of scatters in tissue such as cells, nuclei, mitochondria and other organelles of cells. Usually, nuclei of tumor cells are larger than nuclei of normal cells. Therefore, spectrum of singly scattered light of tumor tissue is different than normal tissue. The spectral slopes were shown to be positive for normal brain, skin and prostate and cervix tissues and negative for the tumors of the same tissues. Signs of the spectral slopes were used as a discrimination parameter to differentiate tumor from normal tissues for the three organ tissues. Sensitivity and specificity of the system in differentiation between tumors from normal tissues were 93% and %100 for brain, 87% and 85% for skin, 93.7% and 46.1% for cervix and 98% and 100% for prostate.
NASA Astrophysics Data System (ADS)
He, J. J.; Kubono, S.; Teranishi, T.; Notani, M.; Baba, H.; Nishimura, S.; Moon, J. Y.; Nishimura, M.; Iwasaki, H.; Yanagisawa, Y.; Hokoiwa, N.; Kibe, M.; Lee, J. H.; Kato, S.; Gono, Y.; Lee, C. S.
2007-11-01
Proton resonant states in Al23 have been investigated for the first time by the resonant elastic and inelastic scattering of Mg22+p with a Mg22 beam at 4.38 MeV/nucleon bombarding a thick (CH2)n target. The low-energy Mg22 beam was separated by the CNS radioactive ion beam separator (CRIB). The energy spectra of recoiled protons were measured at average scattering angles of θlab≈4°,17° and 23°. A new state has been observed at Ex=3.00 MeV with a spin-parity assignment of (3/2+). In addition, resonant inelastic scattering has populated three more states at excitation energies of 3.14, 3.26, and 3.95 MeV, with proton decay to the first excited state in Mg22 being observed. The new state at 3.95 MeV has been assigned a spin-parity of Jπ=(7/2+). The resonant parameters were determined by an R-matrix analysis of the excitation functions with a SAMMY-M6-BETA code. The core-excited structure of Al23 is discussed within a shell-model picture. The stellar reaction rate of the Mg22(p,γ)Al23 reaction has been reevaluated, and the revised total reaction rate is about 40% greater than the previous result for temperatures beyond T9=0.3.
Pérez-Andújar, A.; Newhauser, W. D.; DeLuca, P. M.
2010-01-01
Proton therapy offers low integral dose and good tumor comformality in many deep-seated tumors. However, secondary particles generated during proton therapy, such as neutrons, are a concern, especially for passive scattering systems. In this type of system, the proton beam interacts with several components of the treatment nozzle that lie along the delivery path and can produce secondary neutrons. Neutron production along the beam's central axis in a double scattering passive system was examined using Monte Carlo simulations. Neutron fluence and energy distribution were determined downstream of the nozzle's major components at different radial distances from the central axis. In addition, the neutron absorbed dose per primary proton around the nozzle was investigated. Neutron fluence was highest immediately downstream of the range modulator wheel (RMW) but decreased as distance from the RMW increased. The nozzle's final collimator and snout also contributed to the production of high-energy neutrons. In fact, for the smallest treatment volume simulated, the neutron absorbed dose per proton at isocenter increased by a factor of 20 due to the snout presence when compared with a nozzle without a snout. The presented results can be used to design more effective local shielding components inside the treatment nozzle as well as to better understand the treatment room shielding requirements. PMID:20871789
Chen, Wei-kang; Fang, Hui
2016-03-01
The basic principle of polarization-differentiation elastic light scattering spectroscopy based techniques is that under the linear polarized light incidence, the singlely scattered light from the superficial biological tissue and diffusively scattered light from the deep tissue can be separated according to the difference of polarization characteristics. The novel point of the paper is to apply this method to the detection of particle suspension and, to realize the simultaneous measurement of its particle size and number density in its natural status. We design and build a coaxial cage optical system, and measure the backscatter signal at a specified angle from a polystyrene microsphere suspension. By controlling the polarization direction of incident light with a linear polarizer and adjusting the polarization direction of collected light with another linear polarizer, we obtain the parallel polarized elastic light scattering spectrum and cross polarized elastic light scattering spectrum. The difference between the two is the differential polarized elastic light scattering spectrum which include only the single scattering information of the particles. We thus compare this spectrum to the Mie scattering calculation and extract the particle size. We then also analyze the cross polarized elastic light scattering spectrum by applying the particle size already extracted. The analysis is based on the approximate expressions taking account of light diffusing, from which we are able to obtain the number density of the particle suspension. We compare our experimental outcomes with the manufacturer-provided values and further analyze the influence of the particle diameter standard deviation on the number density extraction, by which we finally verify the experimental method. The potential applications of the method include the on-line particle quality monitoring for particle manufacture as well as the fat and protein density detection of milk products.
Precise measurement of near-barrier 8He+208Pb elastic scattering: Comparison with 6He
NASA Astrophysics Data System (ADS)
Marquínez-Durán, G.; Martel, I.; Sánchez-Benítez, A. M.; Acosta, L.; Berjillos, R.; Dueñas, J.; Rusek, K.; Keeley, N.; Álvarez, M. A. G.; Borge, M. J. G.; Chbihi, A.; Cruz, C.; Cubero, M.; Fernández-García, J. P.; Fernández-Martínez, B.; Flores, J. L.; Gómez-Camacho, J.; Kemper, K. W.; Labrador, J. A.; Marqués, M.; Moro, A. M.; Mazzocco, M.; Pakou, A.; Parkar, V. V.; Patronis, N.; Pesudo, V.; Pierroutsakou, D.; Raabe, R.; Silvestri, R.; Soic, N.; Standyło, Ł.; Strojek, I.; Tengblad, O.; Wolski, R.; Abou-Haidar, Z.
2016-12-01
Dramatic differences in the elastic scattering of the neutron rich nuclei 6He and 8He are found when new high quality data for the 8He+208Pb system are compared with previously published 6He+208Pb data at the same laboratory frame incident energy. The new 8He data are of the same level of detail as for stable beams. When comparing them with those previously obtained for 6He+208Pb at the same energy, it is possible to determine from the data alone that 6He has a much longer range absorption than 8He. However, both nuclei show significant absorption beyond their strong absorption radii. While it has been known for a long time that elastic scattering at energies around the barrier only determines the optical potential over a small distance in radial space, typically ±0.5 fm or so, both the 6He and the 8He imaginary potentials obtained from various optical model fits to these data are the same over a much wider range of ±1.5 fm.
Low energy elastic electron scattering from CF{sub 3}Br molecules
Hargreaves, L. R.; Brunton, J. R.; Maddern, T. M.; Brunger, M. J.
2015-03-28
CF{sub 3}Br is a potentially valuable precursor molecule for generating beams of gas phase Br radicals suitable for electron collisions studies. However, the utility of CF{sub 3}Br for this purpose depends critically on the availability of sound scattering cross sections to allow the contribution of the precursor to be isolated within the total scattering signal. To this end, here we present elastic differential cross section (DCS) measurements for CF{sub 3}Br at incident energies between 15 and 50 eV. Comparison of these DCSs to those from the only other available experimental study [Sunohara et al., J. Phys. B: At., Mol. Opt. Phys. 36, 1843 (2003)] and a Schwinger multichannel with pseudo potentials (SMCPPs) calculation [Bettega et al., J. Phys. B: At., Mol. Opt. Phys. 36, 1263 (2003)] shows generally a very good accord. Integral elastic and momentum transfer cross sections, derived from our DCSs, are also found to be in quite good agreement with the SMCPP results.
Deeply virtual Compton scattering on longitudinally polarized protons and neutrons at CLAS
Silvia Niccolai
2012-04-01
This paper focuses on a measurement of deeply virtual Compton scattering (DVCS) performed at Jefferson Lab using a nearly-6-GeV polarized electron beam, two longitudinally polarized (via DNP) solid targets of protons (NH{sub 3}) and deuterons (ND{sub 3}) and the CEBAF Large Acceptance Spectrometer. Here, preliminary results for target-spin asymmetries and double (beam-target) asymmetries for proton DVCS, as well as a very preliminary extraction of beam-spin asymmetry for neutron DVCS, are presented and linked to Generalized Parton Distributions.
NASA Astrophysics Data System (ADS)
Fedus, Kamil
2016-12-01
A simple potential model of a rigid sphere combined with an adiabatic dipole polarization ( r -4) is tested for positron-atom and positron-molecule elastic collisions. The numerical model, which is based on the analytical solution of radial Schrödinger equation for r -4 potential, depends solely upon the average dipole polarizability of the target and one adjustable parameter - the radius of a hard core. The validity of model is assessed by an extensive comparative study against numerous experimental cross-sections and theoretical phase-shifts of angular momentum partial waves for positrons scattered elastically by He, Ne, Ar, Kr, Xe, H2, N2 and CH4. In particular it is shown that this very simple approach can be used to model positron elastic collisions with targets characterized by moderate dipole polarizabilities (Ar, Kr, H2, N2) in good agreement with experiments for impact energies covering almost entire range from the positronium formation threshold down to the zero energy.
Models of the elastic x-ray scattering feature for warm dense aluminum
NASA Astrophysics Data System (ADS)
Starrett, C. E.; Saumon, D.
2015-09-01
The elastic feature of x-ray scattering from warm dense aluminum has recently been measured by Fletcher et al. [Nature Photonics 9, 274 (2015)], 10.1038/nphoton.2015.41 with much higher accuracy than had hitherto been possible. This measurement is a direct test of the ionic structure predicted by models of warm dense matter. We use the method of pseudoatom molecular dynamics to predict this elastic feature for warm dense aluminum with temperatures of 1-100 eV and densities of 2.7 -8.1 g/cm 3 . We compare these predictions to experiments, finding good agreement with Fletcher et al. and corroborating the discrepancy found in analyses of an earlier experiment of Ma et al. [Phys. Rev. Lett. 110, 065001 (2013)], 10.1103/PhysRevLett.110.065001. We also evaluate the validity of the Thomas-Fermi model of the electrons and of the hypernetted chain approximation in computing the elastic feature and find them both wanting in the regime currently probed by experiments.
Models of the elastic x-ray scattering feature for warm dense aluminum
Starrett, Charles Edward; Saumon, Didier
2015-09-03
The elastic feature of x-ray scattering from warm dense aluminum has recently been measured by Fletcher et al. [Nature Photonics 9, 274 (2015)] with much higher accuracy than had hitherto been possible. This measurement is a direct test of the ionic structure predicted by models of warm dense matter. We use the method of pseudoatom molecular dynamics to predict this elastic feature for warm dense aluminum with temperatures of 1–100 eV and densities of 2.7–8.1g/cm3. We compare these predictions to experiments, finding good agreement with Fletcher et al. and corroborating the discrepancy found in analyses of an earlier experiment ofmore » Ma et al. [Phys. Rev. Lett. 110, 065001 (2013)]. Lastly, we also evaluate the validity of the Thomas-Fermi model of the electrons and of the hypernetted chain approximation in computing the elastic feature and find them both wanting in the regime currently probed by experiments.« less
Models of the elastic x-ray scattering feature for warm dense aluminum
Starrett, Charles Edward; Saumon, Didier
2015-09-03
The elastic feature of x-ray scattering from warm dense aluminum has recently been measured by Fletcher et al. [Nature Photonics 9, 274 (2015)] with much higher accuracy than had hitherto been possible. This measurement is a direct test of the ionic structure predicted by models of warm dense matter. We use the method of pseudoatom molecular dynamics to predict this elastic feature for warm dense aluminum with temperatures of 1–100 eV and densities of 2.7–8.1g/cm^{3}. We compare these predictions to experiments, finding good agreement with Fletcher et al. and corroborating the discrepancy found in analyses of an earlier experiment of Ma et al. [Phys. Rev. Lett. 110, 065001 (2013)]. Lastly, we also evaluate the validity of the Thomas-Fermi model of the electrons and of the hypernetted chain approximation in computing the elastic feature and find them both wanting in the regime currently probed by experiments.
Dorman, Mark Edward
2008-04-01
The Main Injector Neutrino Oscillation Search (MINOS) is a long baseline neutrino oscillation experiment based at the Fermi National Accelerator Laboratory (FNAL) in Chicago, Illinois. MINOS measures neutrino interactions in two large iron-scintillator tracking/sampling calorimeters; the Near Detector on-site at FNAL and the Far Detector located in the Soudan mine in northern Minnesota. The Near Detector has recorded a large number of neutrino interactions and this high statistics dataset can be used to make precision measurements of neutrino interaction cross sections. The cross section for charged-current quasi-elastic scattering has been measured by a number of previous experiments and these measurements disagree by up to 30%. A method to select a quasi-elastic enriched sample of neutrino interactions in the MINOS Near Detector is presented and a procedure to fit the kinematic distributions of this sample and extract the quasi-elastic cross section is introduced. The accuracy and robustness of the fitting procedure is studied using mock data and finally results from fits to the MINOS Near Detector data are presented.
Mourant, J.R.; Boyer, J.; Johnson, T.M.; Lacey, J.; Bigio, I.J.; Bohorfoush, A.; Mellow, M.
1995-03-01
The Los Alamos National Laboratory has continued the development of the Optical Biopsy System (OBS) for noninvasive, real-time in situ diagnosis of tissue pathologies. In proceedings of earlier SPIE conferences we reported on clinical measurements in the bladder, and we report here on recent results of clinical tests in the gastrointestinal tract. With the OBS, tissue pathologies are detected/diagnosed using spectral measurements of the elastic optical transport properties (scattering and absorption) of the tissue over a wide range of wavelengths. The use of elastic scattering as the key to optical tissue diagnostics in the OBS is based on the fact that many tissue pathologies, including a majority of cancer forms, exhibit significant architectural changes at the cellular and sub-cellular level. Since the cellular components that cause elastic scattering have dimensions typically on the order of visible to near-IR wavelengths, the elastic (Mie) scattering properties will be wavelength dependent. Thus, morphology and size changes can be expected to cause significant changes m an optical signature that is derived from the wavelength-dependence of elastic scattering. Additionally, the optical geometry of the OBS beneficially enhances its sensitivity for measuring absorption bands. The OBS employs a small fiber-optic probe that is amenable to use with any endoscope or catheter, or to direct surface examination, as well as interstitial needle insertion. Data acquistion/display time is <1 second.
Multilevel fast multipole algorithm for elastic wave scattering by large three-dimensional objects
NASA Astrophysics Data System (ADS)
Tong, Mei Song; Chew, Weng Cho
2009-02-01
Multilevel fast multipole algorithm (MLFMA) is developed for solving elastic wave scattering by large three-dimensional (3D) objects. Since the governing set of boundary integral equations (BIE) for the problem includes both compressional and shear waves with different wave numbers in one medium, the double-tree structure for each medium is used in the MLFMA implementation. When both the object and surrounding media are elastic, four wave numbers in total and thus four FMA trees are involved. We employ Nyström method to discretize the BIE and generate the corresponding matrix equation. The MLFMA is used to accelerate the solution process by reducing the complexity of matrix-vector product from O(N2) to O(NlogN) in iterative solvers. The multiple-tree structure differs from the single-tree frame in electromagnetics (EM) and acoustics, and greatly complicates the MLFMA implementation due to the different definitions for well-separated groups in different FMA trees. Our Nyström method has made use of the cancellation of leading terms in the series expansion of integral kernels to handle hyper singularities in near terms. This feature is kept in the MLFMA by seeking the common near patches in different FMA trees and treating the involved near terms synergistically. Due to the high cost of the multiple-tree structure, our numerical examples show that we can only solve the elastic wave scattering problems with 0.3-0.4 millions of unknowns on our Dell Precision 690 workstation using one core.
Range verification of passively scattered proton beams based on prompt gamma time patterns
NASA Astrophysics Data System (ADS)
Testa, Mauro; Min, Chul Hee; Verburg, Joost M.; Schümann, Jan; Lu, Hsiao-Ming; Paganetti, Harald
2014-07-01
We propose a proton range verification technique for passive scattering proton therapy systems where spread out Bragg peak (SOBP) fields are produced with rotating range modulator wheels. The technique is based on the correlation of time patterns of the prompt gamma ray emission with the range of protons delivering the SOBP. The main feature of the technique is the ability to verify the proton range with a single point of measurement and a simple detector configuration. We performed four-dimensional (time-dependent) Monte Carlo simulations using TOPAS to show the validity and accuracy of the technique. First, we validated the hadronic models used in TOPAS by comparing simulations and prompt gamma spectrometry measurements published in the literature. Second, prompt gamma simulations for proton range verification were performed for the case of a water phantom and a prostate cancer patient. In the water phantom, the proton range was determined with 2 mm accuracy with a full ring detector configuration for a dose of ~2.5 cGy. For the prostate cancer patient, 4 mm accuracy on range determination was achieved for a dose of ~15 cGy. The results presented in this paper are encouraging in view of a potential clinical application of the technique.
NASA Astrophysics Data System (ADS)
Sun, B.; Winey, J. M.; Gupta, Y. M.; Hooks, D. E.
2009-09-01
The second-order elastic constants for cyclotetramethylene tetranitramine (β-HMX) single crystals were determined using the impulsive stimulated thermal scattering (ISTS) method. Despite the low symmetry of these crystals, the complete set of 13 elastic constants were determined accurately from acoustic velocity measurements using samples cut parallel to three different crystal planes. Our acoustic velocities are consistent with the limited sound speed data available from ultrasonic measurements. However, significant differences are observed between the elastic constants determined from our experiments and those obtained previously using Brillouin scattering. Our results demonstrate the usefulness and efficiency of the ISTS method for determining the full set of elastic constants of low-symmetry molecular crystals, including energetic crystals.
Parity nonconservation in proton-water scattering at 800 MeV
Nagle, D.E.; Bowman, J.D.; Carlini, R.; Mischke, R.E.; Frauenfelder, H.; Harper, R.W.; Yuan, V.; McDonald, A.B.; Talaga, R.
1982-01-01
A search has been made for parity nonconservation in the scattering of 800 MeV polarized protons from an unpolarized water target. The result is for the longitudinal asymmetry, A/sub L/ = +(6.6 +- 3.2) x 10/sup -7/. Control runs with Pb, using a thickness which gave equivalent beam broadening from Coulomb multiple scattering, but a factor of ten less nuclear interactions than the water target, gave A/sub L/ = -(0.5 +- 6.0) x 10/sup -7/.
Parity Nonconservation in Proton-water Scattering at 800 MeV
DOE R&D Accomplishments Database
Nagle, D. E.; Bowman, J. D.; Carlini, R.; Mischke, R. E.; Frauenfelder, H.; Harper, R. W.; Yuan, V.; McDonald, A. B.; Talaga, R.
1982-01-01
A search has been made for parity nonconservation in the scattering of 800 MeV polarized protons from an unpolarized water target. The result is for the longitudinal asymmetry, A{sub L} = +(6.6 +- 3.2) x 10{sup -7}. Control runs with Pb, using a thickness which gave equivalent beam broadening from Coulomb multiple scattering, but a factor of ten less nuclear interactions than the water target, gave A{sub L} = -(0.5 +- 6.0) x 10{sup -7}.
Backward-forward reaction asymmetry of neutron elastic scattering on deuterium
NASA Astrophysics Data System (ADS)
Pirovano, E.; Beyer, R.; Junghans, A. R.; Nankov, N.; Nolte, R.; Nyman, M.; Plompen, A. J. M.
2017-02-01
A new measurement of the angular distribution of neutron elastic scattering on deuterium was carried out at the neutron time-of-flight facility nELBE. The backward-forward asymmetry of the reaction was investigated via the direct detection of neutrons scattered at the laboratory angle of 15∘ and 165∘ from a polyethylene sample enriched with deuterium. In order to extend the measurement to neutron energies below 1 MeV, 6Li glass scintillators were employed. The data were corrected for the background and the multiple scattering in the target, the events due to scattering on deuterium were separated from those due to carbon, and the ratio of the differential cross section at 15∘ and 165∘ was determined. The results, covering the energy range from 200 keV to 2 MeV, were found to be in agreement with the theoretical predictions calculated by Canton et al. [Eur. Phys. J. A 14, 225 (2002)], 10.1140/epja/i2001-10122-3 and by Golak et al. [Eur. Phys. J. A 50, 177 (2014)], 10.1140/epja/i2014-14177-7. The comparison with the evaluated nuclear data libraries indicated CENDL-3.1, JEFF-3.2, and JENDL-4.0 as the evaluations that best describe the asymmetry of n -d scattering. ENDF/B-VII.1 is compatible with the data for energies below 700 keV, but above the backward to forward ratio is higher than measured. ROSFOND-2010 and BROND-2.2 resulted to have little compatibility with the data.
Berlin, Asher; Hooper, Dan; McDermott, Samuel D.
2015-12-28
We consider a complete list of simplifieed models in which Majorana dark matter particles annihilate at tree level to hh or hZ finnal states, and calculate the loop-induced elastic scattering cross section with nuclei in each case. Expressions for these annihilation and elastic scattering cross sections are provided, and can be easily applied to a variety of UV complete models. We identify several phenomenologically viable scenarios, including dark matter that annihilates through the s-channel exchange of a spin-zero mediator or through the t-channel exchange of a fermion. Although the elastic scattering cross sections predicted in this class of models are generally quite small, XENON1Tand LZ should be sensitive to significant regions of this parameter space. Models in which the dark matter annihilates to hh or hZ can also generate a gamma-ray signal that is compatible with the excess observed from the Galactic Center.
Lohn, Andrew J.; Doyle, Barney L.; Stein, Gregory J.; ...
2014-04-03
We present a novel ion beam analysis technique combining Rutherford forward scattering and elastic recoil detection (RFSERD) and demonstrate its ability to increase efficiency in determining stoichiometry in ultrathin (5-50 nm) films as compared to Rutherford backscattering. In the conventional forward geometries, scattering from the substrate overwhelms the signal from light atoms but in RFSERD, scattered ions from the substrate are ranged out while forward scattered ions and recoiled atoms from the thin film are simultaneously detected in a single detector. Lastly, the technique is applied to tantalum oxide memristors but can be extended to a wide range of materialsmore » systems.« less
Lohn, Andrew J.; Doyle, Barney L.; Stein, Gregory J.; Mickel, Patrick R.; Stevens, Jim E.; Marinella, Matthew J.
2014-04-03
We present a novel ion beam analysis technique combining Rutherford forward scattering and elastic recoil detection (RFSERD) and demonstrate its ability to increase efficiency in determining stoichiometry in ultrathin (5-50 nm) films as compared to Rutherford backscattering. In the conventional forward geometries, scattering from the substrate overwhelms the signal from light atoms but in RFSERD, scattered ions from the substrate are ranged out while forward scattered ions and recoiled atoms from the thin film are simultaneously detected in a single detector. Lastly, the technique is applied to tantalum oxide memristors but can be extended to a wide range of materials systems.
Enrico Fermi: The First Chain Reactor (with Film) and Pion-Proton Scattering
Martin, Ron
2003-01-08
A twenty minute film will be shown depicting the first nuclear chain reactor at the University of Chicago on December 2, 1942. The film was made of a re-enactment in 1952 and is narrated by Arthur Compton and Enrico Fermi. After the film, Ronald Martin will talk about his experiences on pion-proton scattering with Enrico Fermi at the Chicago synchrocyclotron in the fifties.
Multi-jet production rates in deep-inelastic muon-proton scattering
Salgado, C.W. )
1992-02-01
Measurements of forward multi-jet production rates in deep-inelastic muon-proton scattering are presented. Data were taken with a 490 GeV muon beam incident on a hydrogen target. Jets were defined using the JADE jet finding algorithm. The measured rates are presented as function of W, the hadronic center-of-mass energy and the jet resolution parameter, [ital y][sub [ital cut
Toward a QCD analysis of jet rates in deep-inelastic Muon-Proton scattering
Salgado, C.W.; E665 Collaboration
1993-08-01
Measurements of multi-jet production rates in deep-inelastic Muon-Proton scattering at Fermilab-E665 are presented. Jet rates defined by the JADE clustering algorithm are compared to perturbative Quantum chromodynamics (PQCD) and different Monte Carlo model predictions. The applicability of the jet-parton duality hypothesis is studied. We obtain hadronic jet rates which are approximately a factor of two higher than PQCD predictions at the parton level. Possible causes for this discrepancy are discussed.
Elastic pion-nucleon scattering in chiral perturbation theory: A fresh look
NASA Astrophysics Data System (ADS)
Siemens, D.; Bernard, V.; Epelbaum, E.; Gasparyan, A.; Krebs, H.; Meißner, Ulf-G.
2016-07-01
Elastic pion-nucleon scattering is analyzed in the framework of chiral perturbation theory up to fourth order within the heavy-baryon expansion and a covariant approach based on an extended on-mass-shell renormalization scheme. We discuss in detail the renormalization of the various low-energy constants and provide explicit expressions for the relevant β functions and the finite subtractions of the power-counting breaking terms within the covariant formulation. To estimate the theoretical uncertainty from the truncation of the chiral expansion, we employ an approach which has been successfully applied in the most recent analysis of the nuclear forces. This allows us to reliably extract the relevant low-energy constants from the available scattering data at low energy. The obtained results provide clear evidence that the breakdown scale of the chiral expansion for this reaction is related to the Δ resonance. The explicit inclusion of the leading contributions of the Δ isobar is demonstrated to substantially increase the range of applicability of the effective field theory. The resulting predictions for the phase shifts are in an excellent agreement with the predictions from the recent Roy-Steiner-equation analysis of pion-nucleon scattering.
SU-E-T-523: On the Radiobiological Impact of Lateral Scatter in Proton Beams
Heuvel, F Van den; Deruysscher, D
2014-06-01
Introduction: In proton therapy, justified concern has been voiced with respect to an increased efficiency in cell kill at the distal end of the Bragg peak. This coupled with range uncertainty is a counter indication to use the Bragg peak to define the border of a treated volume with a critical organ. An alternative is to use the lateral edge of the proton beam, obtaining more robust plans. We investigate the spectral and biological effects of the lateral scatter . Methods: A general purpose Monte Carlo simulation engine (MCNPX 2.7c) installed on a Scientific Linux cluster, calculated the dose deposition spectrum of protons, knock on electrons and generated neutrons for a proton beam with maximal kinetic energy of 200MeV. Around the beam at different positions in the beam direction the spectrum is calculated in concentric rings of thickness 1cm. The deposited dose is converted to a double strand break map using an analytical expression.based on micro dosimetric calculations using a phenomenological Monte Carlo code (MCDS). A strict version of RBE is defined as the ratio of generation of double strand breaks in the different modalities. To generate the reference a Varian linac was modelled in MCNPX and the generated electron dose deposition spectrum was used . Results: On a pristine point source 200MeV beam the RBE before the Bragg peak was of the order of 1.1, increasing to 1.7 right behind the Bragg peak. When using a physically more realistic beam of 10cm diameter the effect was smaller. Both the lateral dose and RBE increased with increasing beam depth, generating a dose deposition with mixed biological effect. Conclusions: The dose deposition in proton beams need to be carefully examined because the biological effect will be different depending on the treatment geometry. Deeply penetrating proton beams generate more biologically effective lateral scatter.
Radiative Corrections for Lepton-Proton Scattering: When the Mass Matters
NASA Astrophysics Data System (ADS)
Afanasev, Andrei
2015-04-01
Radiative corrections procedures for electron-proton and muon-proton scattering are well established under the assumption that the leptons are considered in an ultra-relativistic approximation. MUSE experiment at PSI and COMPASS experiment at CERN entered the regions of kinematics where explicit dependence of radiative corrections on the lepton mass becomes important. MUSE will consider the scattering of muons with momenta of the order 100 MeV/c, therefore lepton mass corrections become important for the entire kinematic domain. COMPASS experiment uses scattering of 100 GeV/c muons, and the muon mass effects are especially relevant in the quasi-real photo production limit, Q2 --> 0. A dedicated Monte Carlo generator of radiative events is being developed for MUSE, which also includes effects of interference between the lepton and proton bremsstrahlung. Parts of the radiative corrections are expected to be suppressed for muons due to the larger muon mass. Two-photon exchange corrections are generally expected to be small, and should be similar for electrons and muons. We classify the radiative corrections into two categories, C-even and C-odd under the lepton charge reversal, and discuss their role separately for the above experiments.
NASA Astrophysics Data System (ADS)
Pakou, A.; Keeley, N.; Pierroutsakou, D.; Mazzocco, M.; Acosta, L.; Aslanoglou, X.; Boiano, A.; Boiano, C.; Carbone, D.; Cavallaro, M.; Grebosz, J.; La Commara, M.; Manea, C.; Marquinez-Duran, G.; Martel, I.; Parascandolo, C.; Rusek, K.; Sánchez-Benítez, A. M.; Sgouros, O.; Signorini, C.; Soramel, F.; Soukeras, V.; Stiliaris, E.; Strano, E.; Torresi, D.; Trzcińska, A.; Watanabe, Y. X.; Yamaguchi, H.
2015-07-01
Quasi-elastic scattering data were obtained for the radioactive nucleus 8Li on a 90Zr target at the near-barrier energy of 18.5MeV over the angular range to 80°. They were analyzed within the coupled channels and coupled reaction channels frameworks pointing to a strong coupling effect for single neutron stripping, in contrast to 6, 7 Li + 90 Zr elastic scattering at similar energies, a non-trivial result linked to detailed differences in the structure of these Li isotopes.
Results for quasi-elastic anti-neutrino scattering on scintillator from the MINERvA experiment
NASA Astrophysics Data System (ADS)
Schellman, Heidi; Minerva Collaboration
2016-09-01
We present a new preliminary measurement of the charge-current quasi-elastic scattering cross section for anti-neutrinos on scintillator (CH) over the energy range 1.5-10 GeV. The data were taken with the MINERvA detector in the NuMI beamline at Fermilab and cover the energy range of interest for the proposed DUNE long-baseline neutrino oscillation experiment and of JLAB elastic scattering experiments. Of particular interest to the nuclear community are possible signatures for short range correlations and/or meson exchange currents in these data. We present comparisons to a range of nuclear models.
Qattan, Issam A.
2005-12-01
Due to the inconsistency in the results of the mupGEp/GMp ratio of the proton, as extracted from the Rosenbluth and recoil polarization techniques, high precision measurements of the e-p elastic scattering cross sections were made at Q^{2} = 2.64, 3.20, and 4.10 GeV^{2}. Protons were detected, in contrast to previous measurements where the scattered electrons were detected, which dramatically decreased-dependent systematic uncertainties and corrections. A single spectrometer measured the scattered protons of interest while simultaneous measurements at Q^{2} = 0.5 GeV^{2} were carried out using another spectrometer which served as a luminosity monitor in order to remove any uncertainties due to beam charge and target density fluctuations. The absolute uncertainty in the measured cross sections is ~3% for both spectrometers and with relative uncertainties, random and slope, below 1% for the higher Q^{2} protons, and below 1% random and 6% slope for the monitor spectrometer. The extracted electric and magnetic form factors were determined to 4%-7% for GEp and 1.5% for GMp. The ratio mupGEp/GMp was determined to 4%-7% and showed mupGEp/GMp ~ 1.0. The results of this work are in agreement with the previous Rosenbluth data and inconsistent with high-Q^{2} recoil polarization results, implying a systematic difference between the two techniques.
Mitri, Farid G
2009-05-01
The exact analytical solution for the acoustic scattering of a high-order (commonly known as generalized) Bessel beam (HOBB) by an elastic sphere immersed in an ideal fluid and centered along the beam axis is revisited. The far-field acoustic scattering field is expressed as a partial wave series involving the scattering angle relative to the beam axis, the order, and the half-conical angle of the wave number components of the generalized Bessel beam. Using an appropriate grouping of terms, the expressions for the incident and scattered pressures, as well as the scattering (complex) form function provided in a recent work are transformed into expressions involving the partial wave series starting from the order m of the generalized Bessel beam. In this new formulation, the scattering coefficients for a HOBB are found to equal those obtained from the study of sound scattering of plane progressive waves by an elastic sphere. This suggests that the (complex) form function presented here may be used to advantage toward studying the acoustic scattering of a HOBB by spherical shells, coated spheres, and coated spherical shells using their corresponding scattering partial wave coefficients available in standard and recent literature texts.
Keeley, N.; Lapoux, V.
2008-01-15
To explore the nature of the coupling effects on p+{sup 10}Be and p+{sup 11}Be elastic scattering at incident energies of 39.1A and at 38.4A MeV, respectively, coupled reaction channels (CRC) calculations were performed for the {sup 10}Be(p,d){sup 9}Be and {sup 11}Be(p,d){sup 10}Be* pickup to the ground state of {sup 9}Be and the 5.960 MeV 1{sup -} and 6.263 MeV 2{sup -} doublet of excited states in {sup 10}Be at the corresponding incident energies. We show that within the CRC framework, the coupling effect on the elastic scattering is significant in both cases and produces effective absorption in the entrance channel. This suggests that the use of a fitted p+{sup 10}Be optical model potential may lead to too much absorption in the core plus proton interaction in extended coupled discretized continuum channels type of calculations for the p+{sup 11}Be system and that coupling to the {sup 11}Be(p,d){sup 10}Be* pickup should be explicitly included in such studies.
Al-Wahish, Amal; Armitage, D.; Hill, B.; Mills, R.; Santodonato, L.; Herwig, K. W.; Al-Binni, U.; Jalarvo, N.; Mandrus, D.
2015-09-15
A design for a sample cell system suitable for high temperature Quasi-Elastic Neutron Scattering (QENS) experiments is presented. The apparatus was developed at the Spallation Neutron Source in Oak Ridge National Lab where it is currently in use. The design provides a special sample cell environment under controlled humid or dry gas flow over a wide range of temperature up to 950 °C. Using such a cell, chemical, dynamical, and physical changes can be studied in situ under various operating conditions. While the cell combined with portable automated gas environment system is especially useful for in situ studies of microscopic dynamics under operational conditions that are similar to those of solid oxide fuel cells, it can additionally be used to study a wide variety of materials, such as high temperature proton conductors. The cell can also be used in many different neutron experiments when a suitable sample holder material is selected. The sample cell system has recently been used to reveal fast dynamic processes in quasi-elastic neutron scattering experiments, which standard probes (such as electrochemical impedance spectroscopy) could not detect. In this work, we outline the design of the sample cell system and present results demonstrating its abilities in high temperature QENS experiments.
Folding model analysis of pion elastic and inelastic scattering from {sup 6}Li and {sup 12}C
Ebrahim, A. A.
2013-04-15
{pi}{sup {+-}}-Nucleus scattering cross sections are calculated applying the Watanabe superposition model with a phenomenological Woods-Saxon potential. The phenomenological potential parameters are searched for {pi}{sup {+-}} scattering from {sup 6}Li and {sup 12}C to reproduce not only differential elastic cross sections but also inelastic and total and reaction cross sections at pion kinetic energies from 50 to 672 MeV. The optical potentials of {sup 6}Li and {sup 12}C are calculated in terms of the alpha particle and deuteron optical potentials. Inelastic scattering has been analyzed using the distorted waves from elastic-scattering data. The values of deformation lengths thus obtained compare very well with the ones reported earlier.
NASA Astrophysics Data System (ADS)
Khakoo, Murtadha A.
2011-10-01
The near-threshold scattering of electrons from polyatomic molecules of fundamental interest, e.g. water, primary alcohols and ring molecules e.g. furan, benzene are important in plasma fuel processes, plasmas used in biological processes e.g. in the treatment of skin diseases, astrophysical plasmas, etc. The determination of cross-sections for such molecules has gathered impetus because of the increasing number of applications industrial plasma and biomedical processes and the need to understand and model these complex processes. It is now possible to determine accurate differential cross-sections for electron scattering from these polyatomic molecules. We will present recent normalized, absolute low energy electron scattering differential cross-sections for near-threshold elastic and inelastic scattering from water, primary alcohols, furan and benzene using a well-tested electron spectrometer apparatus. We will also compare our results with those of other experiments and available theoretical models, which show an encouragingly overall improved picture in terms of agreement between the different research groups. Funded by the National Science Foundation Research in an Undergraduate Institution Grant #s 0653452 and 1135203. This work was done collaboratively with Drs. V. Mckoy and C. Winstead, Caltech, USA (National Science Foundation Grant # 0653396 and Office of Basic Energy Sciences, US DOE Grant) and Dr. M. C. A. Lopes, U. Fed. de Juiz de Fora, Minas Gerais, Brazil; Dr. M. H. F. Bettega, U. Fed. do Parana, Curitiba, Brazil Drs. R. F. da Costa and M. A. P. Lima, Universidade Estadual de Campinas UNICAMP and CTBE, Campinas, Brazil (CNPq, FAPESP, FAPEMG, Finep, CENAPAD-SP and CAPES grants). Funded by US-NSF Grant #s 0653452 and 1135203.
Anelastic Attenuation and Elastic Scattering of Seismic Waves in the Los Angeles Region
NASA Astrophysics Data System (ADS)
Song, X.; Jordan, T. H.
2013-12-01
The accuracy of earthquake simulations needed for physics-based seismic hazard analysis depends on good information about crustal structure. For low-frequency (f < 0.3 Hz) simulations, the most important structural parameters are the seismic wave velocities, but as the frequencies increase, seismic wave attenuation becomes more important. We compare attenuation models that have been recently used in the CyberShake hazard model (Graves et al., 2011) and other simulation studies for the Los Angeles region (Olsen et al., 2009; Taborda & Bielak, 2013) with constraints from local earthquake data out to 10 Hz, which include those from Hauksson & Shearer's (2006) attenuation tomography as well as our own measurements. We show that the velocity-attenuation scaling relationship for shear waves employed by CyberShake (QS = 50VS, where VS is in km/s) provides a good approximation to the average crustal structure at f = 0.3 Hz, but it does not capture the lateral variations in QS at shallow depths. Moreover, this frequency-independent model is inconsistent with the high QS values observed throughout most of the crust at f > 1 Hz. The data indicate a frequency-dependent attenuation of the form QS ~ f γ, where 0.5 ≤ γ ≤ 0.8. Anomalously low QS factors are observed at very shallow depths, which can be explained by a combination of anelastic attenuation and elastic scattering. The scattering parameters are roughly consistent with small-scale, near-surface heterogeneities observed in well-logs and seismic reflection surveys in the Los Angeles basin. High-frequency scattering may also play a role in explaining Hauksson & Shearer's (2006) observation that the QP/QS ratio is anomalously low (~ unity). We summarize the observations in a new attenuation and scattering model for the CyberShake region that is laterally heterogeneous and frequency dependent.
NASA Astrophysics Data System (ADS)
Dell'Orto, E.; Barbera, M.; Bulgarelli, A.; Fioretti, V.; Malaguti, G.; Mineo, T.; Pareschi, G.; Rigato, V.; Spiga, D.; Tagliaferri, G.
2009-05-01
X-ray telescopes equipped with focusing optics in high eccentric orbit, as e.g. Newton-XMM and Chandra, showed a degradation of the detector performance and an important increase of the noise due to soft protons with energy between a few tens of keV and a few MeV, that are focused on the detector through the mirror module. It should be noted that the focusing of the protons by Wolter optics was an unexpected phenomenon. In Simbol-X a magnetic diverter will be implemented to deflect protons, in order to reduce the flux of charged particles impinging upon the focal plane. Obviously the design of the diverter should take into consideration the protons distribution at the exit of the mirror module; for this reason a detailed simulation about the interaction of particles with the mirror surface is necessary. Here we will present the scattering protons models currently under consideration, suggesting a preliminary solution for the design of the magnetic diverter. We will also discuss an ad hoc experiment to study this problem.
Dell'Orto, E.; Barbera, M.; Bulgarelli, A.; Fioretti, V.; Malaguti, G.; Mineo, T.; Pareschi, G.; Spiga, D.; Tagliaferri, G.; Rigato, V.
2009-05-11
X-ray telescopes equipped with focusing optics in high eccentric orbit, as e.g. Newton-XMM and Chandra, showed a degradation of the detector performance and an important increase of the noise due to soft protons with energy between a few tens of keV and a few MeV, that are focused on the detector through the mirror module. It should be noted that the focusing of the protons by Wolter optics was an unexpected phenomenon. In Simbol-X a magnetic diverter will be implemented to deflect protons, in order to reduce the flux of charged particles impinging upon the focal plane. Obviously the design of the diverter should take into consideration the protons distribution at the exit of the mirror module; for this reason a detailed simulation about the interaction of particles with the mirror surface is necessary. Here we will present the scattering protons models currently under consideration, suggesting a preliminary solution for the design of the magnetic diverter. We will also discuss an ad hoc experiment to study this problem.
Soft and hard Pomerons in hadron elastic scattering at small t
Cudell, J.R.; Lengyel, A.; Martynov, E.
2006-02-01
We consider simple-pole descriptions of soft elastic scattering for pp, pp, {pi}{sup {+-}}p and K{sup {+-}}p. We work at t and s small enough for rescatterings to be effectively absorbed in a simple-pole parametrization, and allow for the presence of a hard Pomeron. After building and discussing an exhaustive dataset, we show that simple poles provide an excellent description of the data in the region -0.5 GeV{sup 2}{<=}t{<=}-0.1 GeV{sup 2}, 6 GeV{<=}{radical}(s){<=}63 GeV. We show that new form factors have to be used, and get information on the trajectories of the soft and hard Pomerons.
Abrahamyan, S; Afanasev, A; Ahmed, Z; Albataineh, H; Aniol, K; Armstrong, D S; Armstrong, W; Arrington, J; Averett, T; Babineau, B; Bailey, S L; Barber, J; Barbieri, A; Beck, A; Bellini, V; Beminiwattha, R; Benaoum, H; Benesch, J; Benmokhtar, F; Bertin, P; Bielarski, T; Boeglin, W; Bosted, P; Butaru, F; Burtin, E; Cahoon, J; Camsonne, A; Canan, M; Carter, P; Chang, C C; Cates, G D; Chao, Y -C; Chen, C; Chen, J -P; Choi, Seonho; Chudakov, E; Cisbani, E; Craver, B; Cusanno, F; Dalton, M M; De Leo, R; de Jager, K; Deconinck, W; Decowski, P; Deepa, D; Deng, X; Dutta, D; Etile, A; Ferdi, C; Feuerbach, J; Finn, J M; Flay, D; Franklin, G B; Friend, M; Frullani, S; Fuchey, E; Fuchs, S A; Fuoti, K; Garibaldi, F; Gasser, E; Gilman, R; Guisa, A; Glamazdin, A; Glesener, L E; Gomez, J; Gorchtein, M; Grames, J; Grimm, K; Gu, C; Hansen, O; Hansknecht, J; Hen, O; Higinbotham, D W; Holmes, R S; Holmstrom, T; Horowitz, C J; Hoskins, J; Huang, J; Humensky, T B; Hyde, C E; Ibrahim, H; Itard, F; Jen, C -M; Jensen, E; Jiang, X; Jin, G; Johnston, S; Katich, J; Kaufman, L J; Kelleher, A; Kliakhandler, K; King, P M; Kolarkar, A; Kowalski, S; Kuchina, E; Kumar, K S; Lagamba, L; Lambert, D; LaViolette, P; Leacock, J; Leckey IV, J; Lee, J H; LeRose, J J; Lhuillier, D; Lindgren, R; Liyanage, N; Lubinsky, N; Mammei, J; Mammoliti, F; Margaziotis, D J; Markowitz, P; Mazouz, M; McCormick, K; McCreary, A; McNulty, D; Meekins, D G; Mercado, L; Meziani, Z -E; Michaels, R W; Mihovilovic, M; Moffit, B; Monaghan, P; Muangma, N; Munoz-Camacho, C; Nanda, S; Nelyubin, V; Neyret, D; Nuruzzaman,; Oh, Y; Otis, K; Palmer, A; Parno, D; Paschke, K D; Phillips, S K; Poelker, M; Pomatsalyuk, R; Posik, M; Potokar, M; Prok, K; Puckett, A.J.R.; Qian, X; Qiang, Y; Quinn, B; Rakhman, A; Reimer, P E; Reitz, B; Riordan, S; Roche, J; Rogan, P; Ron, G; Russo, G; Saenboonruang, K; Saha, A; Sawatzky, B; Shahinyan, A; Silwal, R; Singh, J; Sirca, S; Slifer, K; Snyder, R; Solvignon, P; Souder, P A; Sperduto, M L; Subedi, R; Stutzman, M L; Suleiman, R; Sulkosky, V; Sutera, C M; Tobias, W A; Troth, W; Urciuoli, G M; Ulmer, P; Vacheret, A; Voutier, A; Waidyawansa, B; Wang, D; Wang, K; Wexler, J; Whitbeck, A; Wilson, R; Wojtsekhowski, B; Yan, X; Yao, H; Ye, Y; Ye, Z; Yim, V; Zana, L; Zhan, X; Zhang, J; Zhang, Y; Zheng, X; Ziskin, V; Zhu, P
2012-11-05
Here we have measured the beam-normal single-spin asymmetry A{sub n} in the elastic scattering of 1-3 GeV transversely polarized electrons from ^{1}H and for the first time from ^{4}He, ^{12}C, and ^{208}Pb. For ^{1}H, ^{4}He and ^{12}C, the measurements are in agreement with calculations that relate A_{n} to the imaginary part of the two-photon exchange amplitude including inelastic intermediate states. Surprisingly, the ^{208}Pb result is significantly smaller than the corresponding prediction using the same formalism. Our results suggest that a systematic set of new A^{n} measurements might emerge as a new and sensitive probe of the structure of heavy nuclei.
Quasi-elastic light scattering of platinum dendrimer-encapsulated nanoparticles.
Wales, Christina H; Berger, Jacob; Blass, Samuel; Crooks, Richard M; Asherie, Neer
2011-04-05
Platinum dendrimer-encapsulated nanoparticles (DENs) containing an average 147 atoms were prepared within sixth-generation, hydroxyl-terminated poly(amidoamine) dendrimers (G6-OH). The hydrodynamic radii (R(h)) of the dendrimer/nanoparticle composites (DNCs) were determined by quasi-elastic light scattering (QLS) at high (pH ∼10) and neutral pH for various salt concentrations and identities. At high pH, the size of the DNC (R(h) ∼4 nm) is close to that of the empty dendrimer. At neutral pH, the size of the DNC approximately doubles (R(h) ∼8 nm) whereas that of the empty dendrimer remains unchanged. Changes in ionic strength also alter the size of the DNCs. The increase in size of the DNC is likely due to electrostatic interactions involving the metal nanoparticle.
Cross sections for elastic electron scattering by tetramethylsilane in the intermediate-energy range
Sugohara, R. T.; Lee, M.-T.; Iga, I.; Souza, G. L. C. de; Homem, M. G. P.
2011-12-15
Organosilicon compounds are of current interest due to the numerous applications of these species in industries. Some of these applications require the knowledge of electron collision cross sections, which are scarce for such compounds. In this work, we report absolute values of differential, integral, and momentum-transfer cross sections for elastic electron scattering by tetramethylsilane (TMS) measured in the 100-1000 eV energy range. The relative-flow technique is used to normalize our data. In addition, the independent-atom-model (IAM) and the additivity rule (AR), widely used to model electron collisions with light hydrocarbons, are also applied for e{sup -}-TMS interaction. The comparison of our measured results of cross sections and the calculated data shows good agreement, particularly near the higher-end of incident energies.
{ital S}-matrix analysis of heavy-ion elastic scattering
Chiste, V.; Lichtenthaeler, R.; Villari, A.C.; Gomes, L.C.
1996-08-01
A procedure to minimize {chi}{sup 2} is described which explores the fact that the {chi}{sup 2} distribution is of the fourth degree in the {ital S}-matrix elements. The fact that all three roots of the scale parameter for the minimum of {chi}{sup 2} in its gradient direction are algebraically determined gives the present procedure some global features that previous methods did not contemplate. The automatic search procedure also preserves the unitary bound constraint of the {ital S}-matrix at every step. When the search in the gradient direction slows down, the procedure reverts to the traditional quadratic approximation with zero-order regularization. The method is applied to the elastic scattering of the {sup 12}C+{sup 16}O reaction near the Coulomb barrier. {copyright} {ital 1996 The American Physical Society.}
Khurgin, Jacob B.; Bajaj, Sanyam; Rajan, Siddharth
2015-12-28
Longitudinal optical (LO) phonons in GaN generated in the channel of high electron mobility transistors (HEMT) are shown to undergo nearly elastic scattering via collisions with hot electrons. The net result of these collisions is the diffusion of LO phonons in the Brillouin zone causing reduction of phonon and electron temperatures. This previously unexplored diffusion mechanism explicates how an increase in electron density causes reduction of the apparent lifetime of LO phonons, obtained from the time resolved Raman studies and microwave noise measurements, while the actual decay rate of the LO phonons remains unaffected by the carrier density. Therefore, the saturation velocity in GaN HEMT steadily declines with increased carrier density, in a qualitative agreement with experimental results.
NASA Astrophysics Data System (ADS)
Khurgin, Jacob B.; Bajaj, Sanyam; Rajan, Siddharth
2015-12-01
Longitudinal optical (LO) phonons in GaN generated in the channel of high electron mobility transistors (HEMT) are shown to undergo nearly elastic scattering via collisions with hot electrons. The net result of these collisions is the diffusion of LO phonons in the Brillouin zone causing reduction of phonon and electron temperatures. This previously unexplored diffusion mechanism explicates how an increase in electron density causes reduction of the apparent lifetime of LO phonons, obtained from the time resolved Raman studies and microwave noise measurements, while the actual decay rate of the LO phonons remains unaffected by the carrier density. Therefore, the saturation velocity in GaN HEMT steadily declines with increased carrier density, in a qualitative agreement with experimental results.
Fully microscopic description of elastic and inelastic scattering at intermediate incident energies
NASA Astrophysics Data System (ADS)
Minomo, Kosho; Kohno, Michio; Toyokawa, Masakazu; Yahiro, Masanobu; Ogata, Kazuyuki
2016-06-01
We aim for fully microscopic understanding of many-body nuclear reactions starting from two- and three-nucleon forces based on chiral effective field theory (Ch-EFT). We first construct a g-matrix with the nuclear forces based on Ch-EFT using Brueckner-Hartree-Fock theory, in which the three-nucleon force effects are represented through the density dependence of the g-matrix. Then, the folding model and microscopic coupled-channels method with the g-matrix are applied to nucleon-nucleus and nucleus-nucleus scattering at intermediate incident energies. This new microscopic framework well describes the elastic and inelastic cross sections with no ad-hoc parameters. In addition, the three-nucleon force and coupled-channels effects on many-body nuclear reactions are clarified.
Spin-Momentum Correlations in Quasi-Elastic Electron Scattering from Deuterium
I. Passchier; L.D. van Buuren; D. Szczerba; R. Alarcon; Th.S. Bauer; D. Boersma; J.F.J. van den Brand; H.J. Bulten; R. Ent; M. Ferro-Luzzi; M. Harvey; P. Heimberg; D.W. Higinbotham; S. Klous; H. Kolster; J. Lang; B.L. Militsyn; D. Nikolenko; G.J.L. Nooren; B.E. Norum; H.R. Poolman; I. Rachek; M.C. Simani; E. Six; H. de Vries; K. Wang; Z.-L. Zhou
2002-02-25
We report on a measurement of spin-momentum correlations in quasi-elastic scattering of longitudinally polarized electrons with an energy of 720 MeV from vector-polarized deuterium. The spin correlation parameter A{sub ed}{sup V} was measured for the 2{rvec H}({rvec e},e{prime}p)n reaction for missing momenta up to 350 MeV/c at a four-momentum transfer squared of 0.21 (GeV/c){sup 2}. The data give detailed information about the spin structure of the deuteron, and are in good agreement with the predictions of microscopic calculations based on realistic nucleon-nucleon potentials and including various spin-dependent reaction mechanism effects. The experiment demonstrates in a most direct manner the effects of the D-state in the deuteron ground-state wave function and shows the importance of isobar configurations for this reaction.
Background Neutron Studies for Coherent Elastic Neutrino-Nucleus Scattering Measurements at the SNS
NASA Astrophysics Data System (ADS)
Markoff, Diane; Coherent Collaboration
2015-10-01
The COHERENT collaboration has proposed to measure coherent, elastic neutrino-nucleus scattering (CE νNS) cross sections on several nuclear targets using neutrinos produced at the Spallation Neutron Source (SNS) located at the Oak Ridge National Laboratory. The largest background of concern arises from beam-induced, fast neutrons that can mimic a nuclear recoil signal event in the detector. Multiple technologies of neutron detection have been employed at prospective experiment sites at the SNS. Analysis of these data have produced a consistent picture of the backgrounds expected for a CE νNS measurement. These background studies show that at suitable locations, the fast neutrons of concern arrive mainly in the prompt 1.3 μs window and the neutrons in the delayed window are primarily of lower energies that are relatively easier to shield.
NASA Astrophysics Data System (ADS)
Tayloe, Rex; Cenns Collaboration
2015-04-01
The coherent elastic neutrino-nucleus scattering (CENNS) process is important to understand supernovae, nuclear form factors, and low-energy behavior of the Standard Model. It will also become more important as a background in direct-detection dark matter experiments. The process has yet to be observed because of the low-energy detection thresholds and neutron background reduction required. Recent advances in cryogenic detector technology now make it possible. The CENNS collaboration proposes to deploy a 1-ton-scale, single-phase, liquid argon scintillation detector near the Fermilab Booster Neutrino Beam (BNB) for a first measurement. A detector near the neutrino production target at 90 degrees off-axis will observe a low-energy flux of 10-50 MeV stopped-pion neutrinos for CENNS. The details of this effort including prototype detectors and neutron background measurements will be presented.
mQfit, a new program for analyzing quasi-elastic neutron scattering data
NASA Astrophysics Data System (ADS)
Martinez, Nicolas; Natali, Francesca; Peters, Judith
2015-01-01
Analysis of Quasi-elastic Neutron Scattering (QENS) data of complex systems such as biological or soft matter samples in a comprehensive and explicit way often requires great efforts. Most popular software only allows to fit spectra originating from one single instrument and does not permit to extract parameters from a model that is fitted simultaneously to data taken at different instrumental resolutions. We present here a new program, mQfit (multiple QENS dataset fitting), that enables to fit QENS data taken at different spectrometers (with typical resolutions between 0.01 and 0.1 meV) and momentum transfer ranges. This allows drastically reducing the number of fitting parameters. The routine is implemented with a user friendly Graphical User's Interface (GUI), and freely available. As an example, we will present results obtained on E. coli bacterial pellets, and compare them to values published in the literature.
Low-energy electron elastic scattering cross sections for excited Au and Pt atoms
NASA Astrophysics Data System (ADS)
Felfli, Zineb; Eure, Amanda R.; Msezane, Alfred Z.; Sokolovski, Dmitri
2010-05-01
Electron elastic total cross sections (TCSs) and differential cross sections (DCSs) in both impact energy and scattering angle for the excited Au and Pt atoms are calculated in the electron impact energy range 0 ⩽ E ⩽ 4.0 eV. The cross sections are found to be characterized by very sharp long-lived resonances whose positions are identified with the binding energies of the excited anions formed during the collisions. The recent novel Regge-pole methodology wherein is embedded through the Mulholland formula the electron-electron correlations is used together with a Thomas-Fermi type potential incorporating the crucial core-polarization interaction for the calculations of the TCSs. The DCSs are evaluated using a partial wave expansion. The Ramsauer-Townsend minima, the shape resonances and the binding energies of the excited Au - and Pt - anions are extracted from the cross sections, while the critical minima are determined from the DCSs.
Rahbar, A.A.
1982-09-01
A specific set of spin dependent parameters for elastic scattering of polarized protons from an unpolarized deuterium target have been measured over the angular range of 15/sup 0/ and 65/sup 0/ in the Laboratory system. The experiment was performed at the Los Alamos Meson Physics Facility (LAMPF) using a polarized proton beam of 0.5 and 0.8 GeV incident kinetic energy. A carbon analyzer was used to measure the scattered proton polarization. This comprises the first set of measurements in the intermediate energy range. Of particular interest, the analyzing power, (A/sub y/), has been measured for the pd elastic scattering reaction at both energies. A test of Time-Reversal Invariance (TRI) has been made for this reaction. This was accomplished by comparing the polarization (P) with the analyzing power A/sub y/ together with the depolarization parameter, (D), which was measured in this experiment. No evidence of time-reversal violation was found for this reaction in the region of non-zero spin flip probability. The measurements also furnished very useful and selective information on the p-d collision matrix, as well as the double-spin-flip nucleon-nucleon amplitudes.
Structure of 8B from elastic and inelastic 7Be+p scattering
NASA Astrophysics Data System (ADS)
Mitchell, J. P.; Rogachev, G. V.; Johnson, E. D.; Baby, L. T.; Kemper, K. W.; Moro, A. M.; Peplowski, P.; Volya, A. S.; Wiedenhöver, I.
2013-05-01
Background: Detailed experimental knowledge of the level structure of light weakly bound nuclei is necessary to guide the development of new theoretical approaches that combine nuclear structure with reaction dynamics.Purpose: The resonant structure of 8B is studied in this work.Method: Excitation functions for elastic and inelastic 7Be+p scattering were measured using a 7Be rare isotope beam. Excitation energies ranging between 1.6 and 3.4 MeV were investigated. An R-matrix analysis of the excitation functions was performed.Results: New low-lying resonances at 1.9, 2.54, and 3.3 MeV in 8B are reported with spin-parity assignment 0+, 2+, and 1+, respectively. Comparison to the time-dependent continuum shell (TDCSM) model and ab initio no-core shell model/resonating-group method (NCSM/RGM) calculations is performed. This work is a more detailed analysis of the data first published as a Rapid Communication. J. P. Mitchell, G. V. Rogachev, E. D. Johnson, L. T. Baby, K. W. Kemper , [Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.82.011601 82, 011601(R) (2010)].Conclusions: Identification of the 0+, 2+, 1+ states that were predicted by some models at relatively low energy but never observed experimentally is an important step toward understanding the structure of 8B. Their identification was aided by having both elastic and inelastic scattering data. Direct comparison of the cross sections and phase shifts predicted by the TDCSM and ab initio no-core shell model coupled with the resonating group method is of particular interest and provides a good test for these theoretical approaches.
Ambiguities in the elastic scattering of 8 MeV neutrons from adjacent nuclei
Smith, A.B.; Lawson, R.D.; Guenther, P.T.
1989-10-01
Ratios of the cross sections for elastic scattering of 8 MeV neutrons from adjacent nuclei are measured over the angular range {approx}20{degree} {minus} 160{degree} for the target pairs {sup 51}V/Cr, {sup 59}Co/{sup 58}Ni, Cu/Zn, {sup 89}Y/{sup 93}Nb, {sup 89}Y/Zr, {sup 93}Nb/Zr, In/Cd and {sup 209}Bi/Pb. The observed ratios vary from unity by as much as a factor of {approx}2 at some angles for the lighter target pairs. Approximately half the measured ratios are reasonably explained by a simple spherical optical model, including size and isospin contributions. In all cases, the geometry of the real optical--model potential is essentially the same for neighboring nuclei, and the real--potential strengths are consistent with the Lane model. In contrast, it is found that the imaginary potential may be quite different for adjacent nuclei, and the nature of this difference is examined. It is shown that the spin--spin interaction has a negligible effect on the calculation of the elastic--scattering ratios, but that channel coupling, leading to a large reorientation of the target ground state, can be a consideration, particularly in the {sup 59}Co/{sup 58}Ni case. In the A {approx} 50--60 region the calculated ratios are sensitive to spin--orbit effects, but the exact nature of this interaction must await more definitive polarization measurements. The measured and calculated results suggest that the concept of a conventional global'' or even regional'' optical potential provides no more than a qualitative representation of the physical reality for a number of cases. 48 refs., 14 figs., 3 tabs.
Aoun, Bachir; Pellegrini, Eric; Trapp, Marcus; Natali, Francesca; Cantù, Laura; Brocca, Paola; Gerelli, Yuri; Demé, Bruno; Marek Koza, Michael; Johnson, Mark; Peters, Judith
2016-04-01
Neutron scattering techniques have been employed to investigate 1,2-dimyristoyl-sn -glycero-3-phosphocholine (DMPC) membranes in the form of multilamellar vesicles (MLVs) and deposited, stacked multilamellar-bilayers (MLBs), covering transitions from the gel to the liquid phase. Neutron diffraction was used to characterise the samples in terms of transition temperatures, whereas elastic incoherent neutron scattering (EINS) demonstrates that the dynamics on the sub-macromolecular length-scale and pico- to nano-second time-scale are correlated with the structural transitions through a discontinuity in the observed elastic intensities and the derived mean square displacements. Molecular dynamics simulations have been performed in parallel focussing on the length-, time- and temperature-scales of the neutron experiments. They correctly reproduce the structural features of the main gel-liquid phase transition. Particular emphasis is placed on the dynamical amplitudes derived from experiment and simulations. Two methods are used to analyse the experimental data and mean square displacements. They agree within a factor of 2 irrespective of the probed time-scale, i.e. the instrument utilized. Mean square displacements computed from simulations show a comparable level of agreement with the experimental values, albeit, the best match with the two methods varies for the two instruments. Consequently, experiments and simulations together give a consistent picture of the structural and dynamical aspects of the main lipid transition and provide a basis for future, theoretical modelling of dynamics and phase behaviour in membranes. The need for more detailed analytical models is pointed out by the remaining variation of the dynamical amplitudes derived in two different ways from experiments on the one hand and simulations on the other.
A study of quasi-elastic muon neutrino and antineutrino scattering in the NOMAD experiment
NASA Astrophysics Data System (ADS)
Lyubushkin, V.; Popov, B.; Kim, J. J.; Camilleri, L.; Levy, J.-M.; Mezzetto, M.; Naumov, D.; Alekhin, S.; Astier, P.; Autiero, D.; Baldisseri, A.; Baldo-Ceolin, M.; Banner, M.; Bassompierre, G.; Benslama, K.; Besson, N.; Bird, I.; Blumenfeld, B.; Bobisut, F.; Bouchez, J.; Boyd, S.; Bueno, A.; Bunyatov, S.; Cardini, A.; Cattaneo, P. W.; Cavasinni, V.; Cervera-Villanueva, A.; Challis, R.; Chukanov, A.; Collazuol, G.; Conforto, G.; Conta, C.; Contalbrigo, M.; Cousins, R.; Daniels, D.; Degaudenzi, H.; Del Prete, T.; de Santo, A.; Dignan, T.; di Lella, L.; Do Couto E Silva, E.; Dumarchez, J.; Ellis, M.; Feldman, G. J.; Ferrari, R.; Ferrère, D.; Flaminio, V.; Fraternali, M.; Gaillard, J.-M.; Gangler, E.; Geiser, A.; Geppert, D.; Gibin, D.; Gninenko, S.; Godley, A.; Gomez-Cadenas, J.-J.; Gosset, J.; Gößling, C.; Gouanère, M.; Grant, A.; Graziani, G.; Guglielmi, A.; Hagner, C.; Hernando, J.; Hubbard, D.; Hurst, P.; Hyett, N.; Iacopini, E.; Joseph, C.; Juget, F.; Kent, N.; Kirsanov, M.; Klimov, O.; Kokkonen, J.; Kovzelev, A.; Krasnoperov, A.; Kulagin, S.; Kustov, D.; Lacaprara, S.; Lachaud, C.; Lakić, B.; Lanza, A.; La Rotonda, L.; Laveder, M.; Letessier-Selvon, A.; Ling, J.; Linssen, L.; Ljubičić, A.; Long, J.; Lupi, A.; Marchionni, A.; Martelli, F.; Méchain, X.; Mendiburu, J.-P.; Meyer, J.-P.; Mishra, S. R.; Moorhead, G. F.; Nédélec, P.; Nefedov, Yu.; Nguyen-Mau, C.; Orestano, D.; Pastore, F.; Peak, L. S.; Pennacchio, E.; Pessard, H.; Petti, R.; Placci, A.; Polesello, G.; Pollmann, D.; Polyarush, A.; Poulsen, C.; Rebuffi, L.; Rico, J.; Riemann, P.; Roda, C.; Rubbia, A.; Salvatore, F.; Samoylov, O.; Schahmaneche, K.; Schmidt, B.; Schmidt, T.; Sconza, A.; Seaton, M.; Sevior, M.; Sillou, D.; Soler, F. J. P.; Sozzi, G.; Steele, D.; Stiegler, U.; Stipčević, M.; Stolarczyk, Th.; Tareb-Reyes, M.; Taylor, G. N.; Tereshchenko, V.; Toropin, A.; Touchard, A.-M.; Tovey, S. N.; Tran, M.-T.; Tsesmelis, E.; Ulrichs, J.; Vacavant, L.; Valdata-Nappi, M.; Valuev, V.; Vannucci, F.; Varvell, K. E.; Veltri, M.; Vercesi, V.; Vidal-Sitjes, G.; Vieira, J.-M.; Vinogradova, T.; Weber, F. V.; Weisse, T.; Wilson, F. F.; Winton, L. J.; Wu, Q.; Yabsley, B. D.; Zaccone, H.; Zuber, K.; Zuccon, P.
2009-10-01
We have studied the muon neutrino and antineutrino quasi-elastic (QEL) scattering reactions ( ν μ n→ μ - p and bar{ν }_{μ}ptoμ+n ) using a set of experimental data collected by the NOMAD Collaboration. We have performed measurements of the cross-section of these processes on a nuclear target (mainly carbon) normalizing it to the total ν μ ( bar{ν}_{μ} ) charged-current cross section. The results for the flux-averaged QEL cross sections in the (anti)neutrino energy interval 3-100 GeV are < σ_{qel}rangle_{ν_{μ}}=(0.92±0.02(stat)±0.06(syst))×10^{-38} cm2 and <σ_{qel}rangle_{bar{ν}_{μ}}=(0.81±0.05(stat)±0.09(syst))×10^{-38} cm2 for neutrino and antineutrino, respectively. The axial mass parameter M A was extracted from the measured quasi-elastic neutrino cross section. The corresponding result is M A =1.05±0.02(stat)±0.06(syst) GeV. It is consistent with the axial mass values recalculated from the antineutrino cross section and extracted from the pure Q 2 shape analysis of the high purity sample of ν μ quasi-elastic 2-track events, but has smaller systematic error and should be quoted as the main result of this work. Our measured M A is found to be in good agreement with the world average value obtained in previous deuterium filled bubble chamber experiments. The NOMAD measurement of M A is lower than those recently published by K2K and MiniBooNE Collaborations. However, within the large errors quoted by these experiments on M A , these results are compatible with the more precise NOMAD value.
A study of quasi-elastic muon (anti)neutrino scattering in he NOMAD experiment
NASA Astrophysics Data System (ADS)
Lyubushkin, Vladimir
2009-11-01
We have studied the muon neutrino and antineutrino quasi-elastic (QEL) scattering reactions (vμn→μ-p and v¯μp→μ+n using a set of experimental data collected by the NOMAD collaboration. We have performed measurements of the cross-section of these processes on a nuclear target (mainly Carbon) normalizing it to the total vμ (v¯μ) charged current cross-section. The results for the flux averaged QEL cross-sections in the (anti)neutrino energy interval 3-100 GeV are <σqel>vμ = (0.92±0.02(stat)±0.06(syst))×10-38 cm2 and <σqel>v¯μ = (0.81±0.05(stat)±0.09(syst))×10-38 cm2 for neutrino and antineutrino, respectively. The axial mass parameter MA was extracted from the measured quasi-elastic neutrino cross-section. The corresponding result is MA = 1.05±0.02(stat)±0.06(syst) GeV. It is consistent with the axial mass values recalculated from the antineutrino cross-section and extracted from the pure Q2 shape analysis of the high purity sample of vμ quasi-elastic 2-track events, but has smaller systematic error and should be quoted as the main result of this work. Our measured MA is found to be in good agreement with the world average value obtained in previous deuterium filled bubble chamber experiments. The NOMAD measurement of MA is lower than those recently published by K2K and MiniBooNE collaborations. However, within the large errors quoted by these experiments on MA, these results are compatible with the more precise NOMAD value.
A linear sampling approach to inverse elastic scattering in piecewise-homogeneous domains
NASA Astrophysics Data System (ADS)
Guzina, Bojan B.; Madyarov, Andrew I.
2007-08-01
The focus of this study is a 3D inverse scattering problem underlying non-invasive reconstruction of piecewise-homogeneous (PH) defects in a layered semi-infinite solid from near-field, surface elastic waveforms. The solution approach revolves around the use of Green's function for the layered reference domain and a generalization of the linear sampling method to deal with the featured class of PH configurations. For a rigorous treatment of the full-waveform integral equation that is used as a basis for obstacle reconstruction, the developments include an extension of the Holmgren's uniqueness theorem to piecewise-homogeneous domains and an in-depth analysis of the situation when the sampling point is outside the support of the obstacle that employs the method of topological sensitivity. Owing to the ill-posed nature of the featured integral equation, a stable approximate solution is sought via Tikhonov regularization. A set of numerical examples is included to demonstrate the feasibility of 3D obstacle reconstruction when the defects are buried in a multi-layered elastic solid.
NASA Astrophysics Data System (ADS)
Feng, X.; Lorton, C.
2017-03-01
This paper develops and analyzes an efficient Monte Carlo interior penalty discontinuous Galerkin (MCIP-DG) method for elastic wave scattering in random media. The method is constructed based on a multi-modes expansion of the solution of the governing random partial differential equations. It is proved that the mode functions satisfy a three-term recurrence system of partial differential equations (PDEs) which are nearly deterministic in the sense that the randomness only appears in the right-hand side source terms, not in the coefficients of the PDEs. Moreover, the same differential operator applies to all mode functions. A proven unconditionally stable and optimally convergent IP-DG method is used to discretize the deterministic PDE operator, an efficient numerical algorithm is proposed based on combining the Monte Carlo method and the IP-DG method with the $LU$ direct linear solver. It is shown that the algorithm converges optimally with respect to both the mesh size $h$ and the sampling number $M$, and practically its total computational complexity is only amount to solving very few deterministic elastic Helmholtz equations using the $LU$ direct linear solver. Numerically experiments are also presented to demonstrate the performance and key features of the proposed MCIP-DG method.
NASA Astrophysics Data System (ADS)
Signorini, C.; Mazzocco, M.; Molini, P.; Pierroutsakou, D.; Boiano, C.; Manea, C.; Strano, E.; Torresi, D.; Di Meo, P.; Nicoletto, M.; Boiano, A.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; La Commara, M.; Parascandolo, C.; Parascandolo, L.; Sandoli, M.; Soramel, F.; Stroe, L.; Toniolo, N.; Veronese, F.
2013-03-01
The quasi elastic scattering of a 17O projectile from a 58Ni target has been studied at beam energies ranging from 42.5 to 55.0 MeV in 2.5 MeV steps. The total reaction cross sections were derived from the measured angular distributions by using an optical model fit within the coupled-channel code FRESCO. These cross sections are very similar to those measured for 17F (loosely bound by 0.6 MeV), mirror nucleus of 17O (tightly bound by 4.14 MeV). This outcome points out that, in this energy range, the small binding energy of the 17F valence proton has negligible influence onto the reactivity of such a loosely bound projectile, contrary to simple expectations, and to what observed for other loosely bound nuclei. The reaction dynamics seems to be influenced mainly by the Coulomb interaction which is similar for both mirror projectiles.
Range verification of passively scattered proton beams using prompt gamma-ray detection.
Verburg, Joost M; Testa, Mauro; Seco, Joao
2015-02-07
We performed an experimental study to verify the range of passively scattered proton beams by detecting prompt gamma-rays emitted from proton-nuclear interactions. A method is proposed using a single scintillation detector positioned near the distal end of the irradiated target. Lead shielding was used to attenuate gamma-rays emitted along most of the entrance path of the beam. By synchronizing the prompt gamma-ray detector to the rotation of the range modulation wheel, the relation between the gamma emission from the distal part of the target and the range of the incident proton beam was determined. In experiments with a water phantom and an anthropomorphic head phantom, this relation was found to be sensitive to range shifts that were introduced. The wide opening angle of the detector enabled a sufficient signal-to-background ratio to be achieved in the presence of neutron-induced background from the scattering and collimating devices. Uniform range shifts were detected with a standard deviation of 0.1 mm to 0.2 mm at a dose level of 30 cGy to 50 cGy (RBE). The detectable magnitude of a range shift limited to a part of the treatment field area was approximately proportional to the ratio between the field area and the area affected by the range shift. We conclude that it is feasible to detect changes in the range of passively scattered proton beams using a relatively simple prompt gamma-ray detection system. The method can be employed for in vivo verification of the consistency of the delivered range in fractionated treatments.
NASA Astrophysics Data System (ADS)
Dale, Daniel Stanton
This experiment used highly polarized tagged photons to measure polarization asymmetries for elastic scattering in ^{208}Pb in the energy region of the isovector giant quadrupole resonance (IVGQR). These measurements were performed at excitation energies between 16 and 30 MeV. Photons with enhanced linear polarization were obtained from an off-axis tagged photon beam by making a kinematic selection on the post-bremsstrahlung electrons. Scattered photons were detected in two large NaI(Tl) crystals. The polarization asymmetries clearly show the signature for interference between the isovector giant quadrupole resonance and the underlying electric dipole strength. The gross features of the IVGQR strength distribution were obtained in a relatively model independent manner. An isovector giant quadrupole resonance was observed at an excitation energy of 20.1 +/- 0.5 MeV, with a width of 6.3 +/- 0.5 MeV, and an energy weighted strength of 1.4 +/- 0.3 isovector sum rule units.
The total, elastic and inelastic scattering fast neutron cross sections of natural chromium
Guenther, P.T.; Smith, J.F.; Whalen, A.B.
1982-12-01
The present experimental results comprise a comprehensive intermediate resolution neutron total and scattering cross-section data base for elemental chromium over the energy range from 1.5 to 4.0 MeV. Nonetheless, due to the fluctuating nature of the cross sections involved, the definition of energy-averaged cross sections is uncertain. The consequences of these energy-dependent fluctuations and attendant complications influence the data analysis and interpretation. All finite sample total crosssection measurements result in effective cross sections that have to be corrected to yield the true energyaveraged cross sections. This was accomplished by concurrent multiple sample thickness measurements the results of which were then linearly extrapolated to the zero thickness cross section. It was noted that the resulting sample thickness correction showed marked local fluctuations necessitating an energy by energy treatment. Furthermore, the cross sections, even after averaging over wide energy intervals, retained undulations that complicated comparisons with model calculations. Quantitative comparisons of the present elastic and inelastic scattering results with those obtained at isolated energies by other authors were difficult, if not deceptive, due to persistent fluctuations.
Scanning elastic scattering spectroscopy detects metastatic breast cancer in sentinel lymph nodes
NASA Astrophysics Data System (ADS)
Austwick, Martin R.; Clark, Benjamin; Mosse, Charles A.; Johnson, Kristie; Chicken, D. Wayne; Somasundaram, Santosh K.; Calabro, Katherine W.; Zhu, Ying; Falzon, Mary; Kocjan, Gabrijela; Fearn, Tom; Bown, Stephen G.; Bigio, Irving J.; Keshtgar, Mohammed R. S.
2010-07-01
A novel method for rapidly detecting metastatic breast cancer within excised sentinel lymph node(s) of the axilla is presented. Elastic scattering spectroscopy (ESS) is a point-contact technique that collects broadband optical spectra sensitive to absorption and scattering within the tissue. A statistical discrimination algorithm was generated from a training set of nearly 3000 clinical spectra and used to test clinical spectra collected from an independent set of nodes. Freshly excised nodes were bivalved and mounted under a fiber-optic plate. Stepper motors raster-scanned a fiber-optic probe over the plate to interrogate the node's cut surface, creating a 20×20 grid of spectra. These spectra were analyzed to create a map of cancer risk across the node surface. Rules were developed to convert these maps to a prediction for the presence of cancer in the node. Using these analyses, a leave-one-out cross-validation to optimize discrimination parameters on 128 scanned nodes gave a sensitivity of 69% for detection of clinically relevant metastases (71% for macrometastases) and a specificity of 96%, comparable to literature results for touch imprint cytology, a standard technique for intraoperative diagnosis. ESS has the advantage of not requiring a pathologist to review the tissue sample.
Quasi-elastic light scattering determination of the size distribution of extruded vesicles.
Kölchens, S; Ramaswami, V; Birgenheier, J; Nett, L; O'Brien, D F
1993-04-01
The size distribution of phospholipid vesicles prepared by the freeze thaw-extrusion method were determined by the non-perturbing technique of quasi-elastic light scattering (QELS) and compared to latex particles of known size. Multiangle QELS experiments were performed to avoid errors due to the angular dependence of the scattering function of the particles. The experimentally determined autocorrelation function was analyzed by multiple mathematical procedures, i.e. single exponential, CUMULANT, exponential sampling, non-negatively constrained least square and CONTIN, in order to select suitable models for vesicle characterization. The most consistent results were obtained with CUMULANT, non-negatively constrained least square and CONTIN. In many instances single exponential analysis gave comparable results to these procedures, which indicates the vesicles have a narrow distribution of sizes. The influence of filter pore size, extrusion pressure and lipid concentration on the size and size distribution of extruded vesicles was determined. Extrusion through 100-, 200- and 400-nm pore size filters produced a unimodal distribution of vesicles, with somewhat smaller diameters as the extrusion pressure increased. The larger the filter pore size, the more dependent the vesicle size was on applied pressure. The observed vesicle size was independent of the lipid concentration between 0.1 and 10 mg ml-1.
Flow Visualization by Elastic Light Scattering in the Boundary Layer of a Supersonic Flow
NASA Technical Reports Server (NTRS)
Herring, G. C.; Hillard, Mervin E., Jr.
2000-01-01
We demonstrate instantaneous flow visualization of the boundary layer region of a Mach 2.5 supersonic flow over a flat plate that is interacting with an impinging shock wave. Tests were performed in the Unitary Plan Wind Tunnel (UPWT) at NASA Langley Research Center. The technique is elastic light scattering using 10-nsec laser pulses at 532 nm. We emphasize that no seed material of any kind, including water (H2O), is purposely added to the flow. The scattered light comes from a residual impurity that normally exists in the flow medium after the air drying process. Thus, the technique described here differs from the traditional vapor-screen method, which is typically accomplished by the addition of extra H2O vapor to the airflow. The flow is visualized with a series of thin two-dimensional light sheets (oriented perpendicular to the streamwise direction) that are located at several positions downstream of the leading edge of the model. This geometry allows the direct observation of the unsteady flow structure in the spanwise dimension of the model and also allows the indirect observation of the boundary layer growth in the streamwise dimension.
Elastic alpha scattering experiments and the alpha-nucleus optical potential at low energies
Mohr, P.; Kiss, G.G.; Fülöp, Zs.; Galaviz, D.; Gyürky, Gy.; Somorjai, E.
2013-11-15
High precision angular distribution data of (α,α) elastic scattering are presented for the nuclei {sup 89}Y, {sup 92}Mo, {sup 106,110,116}Cd, {sup 112,124}Sn, and {sup 144}Sm at energies around the Coulomb barrier. Such data with small experimental uncertainties over the full angular range (20–170°) are the indispensable prerequisite for the extraction of local optical potentials and for the determination of the total reaction cross section σ{sub reac}. A systematic fitting procedure was applied to the experimental scattering data presented to obtain comprehensive local potential parameter sets that are composed of a real folding potential and an imaginary potential of Woods–Saxon surface type. The potential parameters obtained were used in turn to construct a new systematic α-nucleus potential with very few parameters. Although this new potential cannot reproduce the angular distributions with the same small deviations as the local potential, the new potential is able to predict the total reaction cross sections for all cases under study.
Chatrchyan, Serguei
2014-03-05
Double parton scattering is investigated in proton-proton collisions at √s = 7 TeV where the final state includes a W boson, which decays into a muon and a neutrino, and two jets. The data sample corresponds to an integrated luminosity of 5 fb^{–1}, collected with the CMS detector at the LHC. Observables sensitive to double parton scattering are investigated after being corrected for detector effects and selection efficiencies. The fraction of W + 2-jet events due to double parton scattering is measured to be 0.055 +/- 0.002 (stat.) +/- 0.014 (syst.). Finally, the effective cross section, σ_{eff}, characterizing the effective transverse area of hard partonic interactions in collisions between protons is measured to be 20.7 +/- 0.8 (stat.) +/- 6.6 (syst.) mb.
Chatrchyan, Serguei
2014-03-05
Double parton scattering is investigated in proton-proton collisions at √s = 7 TeV where the final state includes a W boson, which decays into a muon and a neutrino, and two jets. The data sample corresponds to an integrated luminosity of 5 fb–1, collected with the CMS detector at the LHC. Observables sensitive to double parton scattering are investigated after being corrected for detector effects and selection efficiencies. The fraction of W + 2-jet events due to double parton scattering is measured to be 0.055 +/- 0.002 (stat.) +/- 0.014 (syst.). Finally, the effective cross section, σeff, characterizing the effectivemore » transverse area of hard partonic interactions in collisions between protons is measured to be 20.7 +/- 0.8 (stat.) +/- 6.6 (syst.) mb.« less
NASA Technical Reports Server (NTRS)
Register, D. F.; Trajmar, S.; Srivastava, S. K.
1980-01-01
Absolute differential, integral, and momentum-transfer cross sections for electrons elastically scattered from helium are reported for the impact energy range of 5 to 200 eV. Angular distributions for elastically scattered electrons are measured in a crossed-beam geometry using a collimated, differentially pumped atomic-beam source which requires no effective-path-length correction. Below the first inelastic threshold the angular distributions were placed on an absolute scale by use of a phase-shift analysis. Above this threshold, the angular distributions from 10 to 140 deg were fitted using the phase-shift technique, and the resulting integral cross sections were normalized to a semiempirically derived integral elastic cross section. Depending on the impact energy, the data are estimated to be accurate to within 5 to 9%.
NASA Astrophysics Data System (ADS)
Linzey, Andrew Joseph
Here we report on a precise study of the ratio of elastic scattering cross sections of electrons and positrons from ^{12}C and ^{208}Pb, in an effort to observe and quantify deviations from the predictions of a phase shift calculation of the scattering from a static charge density. Any deviations observed can be attributed to higher-order processes sensitive to the sign of the charge of the scattered particle. The beam energies were ~450 MeV and the angular ranges covered were 26-37^circ for ^{12}C and 26-53^ circ for ^{208}Pb. No deviations were observed within the uncertainties of the measurement.
Elastic Scattering of Low Energy Pions by Nuclei and the In-Medium Isovector πN Amplitude
NASA Astrophysics Data System (ADS)
Friedman, E.; Bauer, M.; Breitschopf, J.; Clement, H.; Denz, H.; Doroshkevich, E.; Erhardt, A.; Hofman, G. J.; Kritchman, S.; Meier, R.; Wagner, G. J.; Yaari, G.
2006-07-01
Measurements of elastic scattering of 21.5 MeV π± by Si, Ca, Ni and Zr were made using a single arm magnetic spectrometer and absolute calibration was made by parallel measurements of Coulomb scattering of muons. Optical model fits to the data reveal the `anomalous' s-wave repulsion known from pionic atoms. Introducing a chiral-motivated density dependence of the isovector scattering amplitude, and considering the energy dependence of the free πN interaction greatly improve fits to the data and remove the `anomaly'.
Song, Ji Eun; Park, Ji Hoon; La, Ju A; Park, Seyeon; Jeong, Min Kuk; Cho, Eun Chul
2016-08-07
We present a route that estimates the scattering/absorption characteristics of plasmonic nanoparticles by using fluorescence and UV-visible spectroscopy. Because elastic scattering of nanoparticles caused by a monochromatic incident light is reflected in fluorescence emission spectra when recording at the excitation wavelength, the scattering intensities at the excitation wavelength during fluorescence emission scans are used to compare the scattering characteristics of various plasmonic nanoparticles under conditions where the extinction values of all of the nanoparticles are kept constant at this wavelength. For the two excitation wavelengths (519 and 560 nm) we investigated, the scattering intensities of spherical gold nanoparticles increase with increasing size (15, 33, 51, 73, and 103 nm in diameter). These results are correlated with the nanoparticles' scattering efficiencies (the ratios of scattering to the extinction cross-sections), which are theoretically calculated in the literature using Mie theory. Then, linear calibration equations at each wavelength are derived to estimate the scattering efficiencies of two Au nanorods, Au nanocages, and spherical Ag nanoparticles (15, 25, 37, and 62 nm). The values are very comparable with literature values. For various purposes such as biomedicine and optoelectronics, the present method could be beneficial to those who wish to easily compare and determine the scattering characteristics of various plasmonic nanoparticles at a certain wavelength by using commercially-available spectroscopic techniques.
Measuring the Spin-Polarizabilities of the Proton in Polarized Compton scattering at MAMI-Mainz
NASA Astrophysics Data System (ADS)
Miskimen, Rory; A2 Collaboration
2013-10-01
At O (ω3) four new structure constants are present in the nucleon Compton scattering amplitude; these are the spin-polarizabilities γE 1 E 1, γM 1 M 1, γE 1 M 2, and γM 1 E 2. The most model independent way to determine the spin-polarizabilities is by measuring a double-polarized Compton scattering asymmetry with polarized target and circularly polarized photons, and by measuring an in-plane/transverse-plane Compton scattering asymmetry with linearly polarized photons (Σ3) . This talk will present new Compton scattering asymmetry data taken in the Δ region by the A2 Collaboration using the Crystal Ball at Mainz, with transverse polarized proton target and circularly polarized photons, the Σ2 x asymmetry (1). A dispersion model and an EFT calculation of Compton scattering are used to fit the four spin-polarizabilities to the new experimental data on Σ2 x, earlier results (2) on Σ3, and previous determinations of γ0 and γπ. The results of the fits are compared with theoretical calculations.
NASA Astrophysics Data System (ADS)
Downie, E. J.
2016-03-01
The proton radius puzzle is the difference between the proton radius as measured with electron scattering and in the excitation spectrum of atomic hydrogen, and that measured with muonic hydrogen spectroscopy. Since the inception of the proton radius puzzle in 2010 by the measurement of Pohl et al.[1], many possible resolutions to the puzzle have been postulated, but, to date, none has been generally accepted. New data are therefore necessary to resolve the issue. We briefly review the puzzle, the proposed solutions, and the new electron scattering and spectroscopy experiments planned and underway. We then introduce the MUSE experiment, which seeks to resolve the puzzle by simultaneously measuring elastic electron and muon scattering on the proton, in both charge states, thereby providing new information to the puzzle. MUSE addresses issues of two-photon effects, lepton universality and, possibly, new physics, while providing simultaneous form factor, and therefore radius, measurements with both muons and electrons.
NASA Astrophysics Data System (ADS)
Auger, J.-C.; Fernandes, G. E.; Aptowicz, K. B.; Pan, Y.-L.; Chang, R. K.
2010-04-01
The relation between the surface roughness of aerosol particles and the appearance of island-like features in their angle-resolved elastic-light scattering patterns is investigated both experimentally and with numerical simulation. Elastic scattering patterns of polystyrene spheres, Bacillus subtilis spores and cells, and NaCl crystals are measured and statistical properties of the island-like intensity features in their patterns are presented. The island-like features for each class of particle are found to be similar; however, principal-component analysis applied to extracted features is able to differentiate between some of the particle classes. Numerically calculated scattering patterns of Chebyshev particles and aggregates of spheres are analyzed and show qualitative agreement with experimental results.
Resonant proton scattering on 46Ar using the Active-Target Time Projection Chamber
NASA Astrophysics Data System (ADS)
Bradt, J.; Ahn, T.; Ayyad Limonge, Y.; Bazin, D.; Beceiro Novo, S.; Carpenter, L.; Kuchera, M. P.; Lynch, W.; Mittig, W.; Rost, S.; Watwood, N.; Barney, J.; Datta, U.; Estee, J.; Gillibert, A.; Manfredi, J.; Morfouace, P.; Perez Loureiro, D.; Pollacco, E.; Sammut, J.; Sweany, S.
2016-09-01
A well-known technique for studying the single-particle properties of neutron-rich nuclei is to use resonant proton scattering on a parent nucleus to populate the isobaric analog states of the corresponding neutron-rich nucleus. The locations and amplitudes of these resonances are directly related to the structure of the nucleus of interest by isospin symmetry. We performed an experiment of this type at the National Superconducting Cyclotron Laboratory to commission the recently completed Active-Target Time Projection Chamber (AT-TPC). A 4.6-MeV/u radioactive beam of 46Ar was injected into the AT-TPC. The detector was filled with isobutane gas-which provided the protons for the reaction and served as the tracking medium-and placed inside a 2-T magnetic field. We will present preliminary results from this experiment and discuss the benefits of the active-target method for this type of measurement.
Liengsawangwong, Praimakorn; Sahoo, Nanayan; Ding, Xiaoning; Lii, MingFwu; Gillin, Michale T.; Zhu, Xiaorong Ronald
2015-01-01
Purpose: To evaluate the dosimetric characteristics of a two-dimensional (2D) diode array detector irradiated with passively scattered proton beams. Materials and Methods: A diode array detector, MapCHECK (Model 1175, Sun Nuclear, Melbourne, FL, USA) was characterized in passive-scattered proton beams. The relative sensitivity of the diodes and absolute dose calibration were determined using a 250 MeV beam. The pristine Bragg curves (PBCs) measured by MapCHECK diodes were compared with those of an ion chamber using a range shift method. The water-equivalent thickness (WET) of the diode array detector’s intrinsic buildup also was determined. The inverse square dependence, linearity, and other proton dosimetric quantities measured by MapCHECK were also compared with those of the ion chambers. The change in the absolute dose response of the MapCHECK as a function of accumulated radiation dose was used as an indicator of radiation damage to the diodes. 2D dose distribution with and without the compensator were measured and compared with the treatment planning system (TPS) calculations. Results: The WET of the MapCHECK diode’s buildup was determined to be 1.7 cm. The MapCHECK-measured PBC were virtually identical to those measured by a parallel-plate ion chamber for 160, 180, and 250 MeV proton beams. The inverse square results of the MapCHECK were within ±0.4% of the ion chamber results. The linearity of MapCHECK results was within 1% of those from the ion chamber as measured in the range between 10 and 300 MU. All other dosimetric quantities were within 1.3% of the ion chamber results. The 2D dose distributions for non-clinical fields without compensator and the patient treatment fields with the compensator were consistent with the TPS results. The absolute dose response of the MapCHECK was changed by 7.4% after an accumulated dose increased by 170 Gy. Conclusions: The MapCHECK is a convenient and useful tool for 2D dose distribution measurements using passively
Compton Scattering Cross Section on the Proton at High Momentum Transfer
A. Danagoulian; V.H. Mamyan; M. Roedelbronn; K.A. Aniol; J.R.M. Annand; P.Y. Bertin; L. Bimbot; P. Bosted; J.R. Calarco; A. Camsonne; C.C. Chang; T.-H. Chang; J.-P. Chen; Seonho Choi; E. Chudakov; P. Degtyarenko; C.W. de Jager; A. Deur; D. Dutta; K. Egiyan; H. Gao; F. Garibaldi; O. Gayou; R. Gilman; A. Glamazdin; C. Glashausser; J. Gomez; D.J. Hamilton; J.-O. Hansen; D. Hayes; D.W. Higinbotham; W. Hinton; T. Horn; C. Howell; T. Hunyady; C.E. Hyde-Wright; X. Jiang; M.K. Jones; M. Khandaker; A. Ketikyan; V. Koubarovski; K. Kramer; G. Kumbartzki; G. Laveissiere; J. LeRose; R.A. Lindgren; D.J. Margaziotis; P. Markowitz; K. McCormick; Z.-E. Meziani; R. Michaels; P. Moussiegt; S. Nanda; A.M. Nathan; D.M. Nikolenko; V. Nelyubin; B.E. Norum; K. Paschke; L. Pentchev; C.F. Perdrisat; E. Piasetzky; R. Pomatsalyuk; V.A. Punjabi; I. Rachek; A. Radyushkin; B. Reitz; R. Roche; G. Ron; F. Sabatie; A. Saha; N. Savvinov; A. Shahinyan; Y. Shestakov; S. Sirca; K. Slifer; P. Solvignon; P. Stoler; S. Tajima; V. Sulkosky; L. Todor; B. Vlahovic; L.B. Weinstein; K. Wang; B. Wojtsekhowski; H. Voskanyan; H. Xiang; X. Zheng; L. Zhu
2007-01-29
Cross-section values for Compton scattering on the proton were measured at 25 kinematic settings over the range s = 5-11 and -t = 2-7 GeV2 with statistical accuracy of a few percent. The scaling power for the s-dependence of the cross section at fixed center of mass angle was found to be 8.0 +/- 0.2, strongly inconsistent with the prediction of perturbative QCD. The observed cross section values are in fair agreement with the calculations using the handbag mechanism, in which the external photons couple to a single quark.
Compton-Scattering Cross Section on the Proton at High Momentum Transfer
Danagoulian, A.; Roedelbronn, M.; Chang, T.-H.; Nathan, A. M.; Mamyan, V. H.; Aniol, K. A.; Margaziotis, D. J.; Annand, J. R. M.; Hamilton, D. J.; Bertin, P. Y.; Camsonne, A.; Laveissiere, G.; Bosted, P.; Paschke, K.; Calarco, J. R.; Chang, C. C.; Horn, T.; Savvinov, N.; Chen, J.-P.
2007-04-13
Cross-section values for Compton scattering on the proton were measured at 25 kinematic settings over the range s=5-11 and -t=2-7 GeV{sup 2} with a statistical accuracy of a few percent. The scaling power for the s dependence of the cross section at fixed center-of-mass angle was found to be 8.0{+-}0.2, strongly inconsistent with the prediction of perturbative QCD. The observed cross-section values are in fair agreement with the calculations using the handbag mechanism, in which the external photons couple to a single quark.
Medium modified two-body scattering amplitude from proton-nucleus total cross-sections
NASA Astrophysics Data System (ADS)
Tripathi, R. K.; Wilson, J. W.; Cucinotta, F. A.
2001-02-01
Recently (R.K. Tripathi, J.W. Wilson, F.A. Cucinotta, Nucl. Instr. and Meth. B 145 (1998) 277; R.K. Tripathi, F.A. Cucinotta, J.W. Wilson, NASA-TP-1998-208438), we have extracted nucleon-nucleon (N-N) cross-sections in the medium directly from experiment. The in-medium N-N cross-sections form the basic ingredients of several heavy-ion scattering approaches including the coupled-channel approach developed at the NASA Langley Research Center. Here, we investigate the ratio of real to imaginary part of the two-body scattering amplitude in the medium. These ratios are used in combination with the in-medium N-N cross-sections to calculate total proton-nucleus cross-sections. The agreement is excellent with the available experimental data. These cross-sections are needed for the radiation risk assessment of space missions.
Analyzing Powers and Cross Sections of Inclusive Polarized Proton Scattering on LEAD-208.
NASA Astrophysics Data System (ADS)
Chen, Xiao-Yan
Inclusive polarized proton-nucleus scattering at 290 and 500 MeV was performed using a ^ {208}Pb(51 mg/cm^2) target. A broad range (0-250 MeV) of excitation energy has been studied over the 4^circ -27^circ angular range. The measured analyzing power and cross section of the continuum are compared with the recent DWIA model calculations. The analyzing power and cross section of low-lying states are compared with the DWBA model calculation. The cross section in the continuum region is found to be dominated by single -step quasifree scattering. The analyzing power angular distributions of continuum peaks support RIA model predictions, and indicate the presence of relativistic medium effects.
High-precision measurement of the proton elastic form factor ratio μpGE/GM at low Q2
Zhan, X.; Allada, K.; Armstrong, D. S.; ...
2011-10-06
Here, we report a new high precision measurement of the proton elastic form factor ratio μpGE/GM for the four-momentum transfer squared Q2 = 0.3-0.7 (GeV/c)2. The measurement was performed at Jefferson Lab (JLab) in Hall A using recoil polarimetry. With the achieved ~1% total uncertainty, the new data clearly show that the deviation of the ratio μpGE/GM from unity observed in previous polarization measurements at high Q2 continues down to the lowest Q2 value of this measurement. The updated global fit that includes the new results yields in this Q2 range an electric (magnetic) form factor ~2% smaller (~1% larger)more » than the previous global fit. We obtain new extractions of the proton electric and magnetic radii, which are (rE2)1/2 = 0.875 ± 0.010 fm and (rM2)1/2 = 0.867 ± 0.020 fm. Moreover, the charge radius is consistent with other recent extractions based on the electron-proton interaction, including the atomic hydrogen Lamb shift measruements, which suggests a missing correction in the comparison of measurements of the proton charge radius using electron probes and the recent extraction from the muonic hydrogen Lamb shift.« less