Nonuniform radiation damage in permanent magnet quadrupoles

Energy Technology Data Exchange (ETDEWEB)

Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

2014-08-15

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

Simple model for deriving sdg interacting boson model Hamiltonians: 150Nd example

Science.gov (United States)

Devi, Y. D.; Kota, V. K. B.

1993-07-01

A simple and yet useful model for deriving sdg interacting boson model (IBM) Hamiltonians is to assume that single-boson energies derive from identical particle (pp and nn) interactions and proton, neutron single-particle energies, and that the two-body matrix elements for bosons derive from pn interaction, with an IBM-2 to IBM-1 projection of the resulting p-n sdg IBM Hamiltonian. The applicability of this model in generating sdg IBM Hamiltonians is demonstrated, using a single-j-shell Otsuka-Arima-Iachello mapping of the quadrupole and hexadecupole operators in proton and neutron spaces separately and constructing a quadrupole-quadrupole plus hexadecupole-hexadecupole Hamiltonian in the analysis of the spectra, B(E2)'s, and E4 strength distribution in the example of 150Nd.

Simple model for deriving sdg interacting boson model Hamiltonians: 150Nd example

International Nuclear Information System (INIS)

Devi, Y.D.; Kota, V.K.B.

1993-01-01

A simple and yet useful model for deriving sdg interacting boson model (IBM) Hamiltonians is to assume that single-boson energies derive from identical particle (pp and nn) interactions and proton, neutron single-particle energies, and that the two-body matrix elements for bosons derive from pn interaction, with an IBM-2 to IBM-1 projection of the resulting p-n sdg IBM Hamiltonian. The applicability of this model in generating sdg IBM Hamiltonians is demonstrated, using a single-j-shell Otsuka-Arima-Iachello mapping of the quadrupole and hexadecupole operators in proton and neutron spaces separately and constructing a quadrupole-quadrupole plus hexadecupole-hexadecupole Hamiltonian in the analysis of the spectra, B(E2)'s, and E4 strength distribution in the example of 150 Nd

Effective proton-neutron interaction near the drip line from unbound states in $^{25,26}$F

OpenAIRE

Vandebrouck, M.; Lepailleur, A.; Sorlin, O.; Aumann, T.; Caesar, C.; Holl, M.; Panin, V.; Wamers, F.; Stroberg, S. R.; Holt, J. D.; Santos, F. De Oliveira; Alvarez-Pol, H.; Atar, L.; Avdeichikov, V.; Beceiro-Novo, S.

2017-01-01

14 pages, 7 figures, 3 tables, submitted to PRC; International audience; Background: Odd-odd nuclei, around doubly closed shells, have been extensively used to study proton-neutron interactions. However, the evolution of these interactions as a function of the binding energy, ultimately when nuclei become unbound, is poorly known. The $^{26}$F nucleus, composed of a deeply bound $\\pi0d_{5/2}$ proton and an unbound $\

Effective neutron-proton interaction in rare earth odd-odd nuclei

International Nuclear Information System (INIS)

Boisson, Jean-Paul.

1975-01-01

The effective neutron-proton interaction V(np) in the rare earth odd-odd deformed nuclei is studied. The parameters of the effective interaction are determined from least square fits of calculated matrix elements compared to the ones extracted from experiment. These fits show the existence of a long range repulsive component as well the importance of the even term of the tensor part of V(np). Some informations are obtained concerning the influence of the choice of the sample of experimental data, of the average field and finally, of the radial shape of the effective interaction. Some predictions are made concerning as yet unconfirmed V(np) matrix elements [fr

Interaction of 14 MeV neutrons with hydrogenated target proton emission calculation

International Nuclear Information System (INIS)

Martin, G.; Perez, N.; Desdin.

1996-01-01

Using neutron emission data of a 14 MeV neutron generator, a paraffin target, and based on the n + H 1 → n '+ p reaction, have been obtained the characteristics of the proton emission in a proton-neutron mixed field. It was used Monte Carlo simulation and it was obtained the proton output as function of the converter width and the energy spectrum of protons corresponding to different converter thickness. Among 0.07 and 0.2 cm there is a maximum zone for the proton emission. The energy spectrum agrees with obtained on previous papers. Figures showing these results are provided

Quadrupole moment and a proton halo structure in 17F (Iπ = 5/2+)

International Nuclear Information System (INIS)

Zhou Dongmei; Zheng Yongnan; Yuan Daqing; Xizhen, Zhang; Zuo Yi; Minamisono, T; Matsuta, M; Fukuda, M; Mihara, M; Zhang Chunlei; Zhiqiang, Wang; Du Enpeng; Luo Hailong; Xu Guoji; Zhu Shengyun

2007-01-01

The quadrupole moment of light nuclei 17 F in the ground state (I π = 5/2 + ) is measured by the β-NMR method. The effective charge of the last proton in a d 5/2 orbit for 17 F is extracted from the measured quadrupole moment Q( 17 F) divided by the quadrupole moment Q sp calculated with a single particle model. A proton effective charge of e eff p = 1.12 ± 0.07e is obtained, which is in agreement with that given by a particle-vibration coupling model calculation within the experimental error. The present value of the proton effective charge is strong evidence for the existence of a proton skin in 17 F (I π = 5/2 + )

Polarization of very cold neutron using a permanent magnet quadrupole

Energy Technology Data Exchange (ETDEWEB)

Yoshioka, Tamaki, E-mail: tyosioka@post.kek.j [High Energy Accelerator Research Organization, Ibaraki 305-0801 (Japan); Mishima, Kenji; Ino, Takashi; Taketani, Kaoru; Muto, Suguru; Morishima, Takahiro; Shimizu, Hirohiko M. [High Energy Accelerator Research Organization, Ibaraki 305-0801 (Japan); Oku, Takayuki; Suzuki, Junichi; Shinohara, Takenao; Sakai, Kenji [Japan Atomic Energy Agency, Ibaraki 319-1195 (Japan); Sato, Hiromi; Hirota, Katsuya; Otake, Yoshie [RIKEN, Saitama 351-0198 (Japan); Kitaguchi, Masaaki; Hino, Masahiro [Research Reactor Institute, Kyoto University, Osaka 590-0494 (Japan); Seki, Yoshichika [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Iwashita, Yoshihisa; Yamada, Masako [Institute for Chemical Research, Kyoto University, Kyoto 611-0011 (Japan); Ichikawa, Masahiro [Department of Physics, The University of Tokyo, Tokyo 113-0033 (Japan)

2011-04-01

For the future fundamental physics experiments by using cold neutrons, we are developing a device which can measure the neutron polarization degree by accuracy significantly below 10{sup -3}. A quadrupole magnet is one of the promising candidate to measure the neutron polarization degree by such extremely high precision. We have performed a polarization experiment by using the quadrupole magnets at the Very Cold Neutron (VCN) port of the PF-2 in the Institute Laue-Langevin (ILL). As a result, we obtained the polarization degree P with very high accuracy P=0.9994{+-}0.0001(stat.){+-}0.0003(syst.), which meet our requirement significantly.

Accelerator-Based Boron Neutron Capture Therapy and the Development of a Dedicated Tandem-Electrostatic-Quadrupole

International Nuclear Information System (INIS)

Kreiner, A. J.; Di Paolo, H.; Burlon, A. A.; Valda, A. A.; Debray, M. E.; Somacal, H. R.; Minsky, D. M.; Kesque, J. M.; Giboudot, Y.; Levinas, P.; Fraiman, M.; Romeo, V.

2007-01-01

There is a generalized perception that the availability of suitable particle accelerators installed in hospitals, as neutron sources, may be crucial for the advancement of Boron Neutron Capture Therapy (BNCT). Progress on an ongoing project to develop a Tandem-ElectroStatic-Quadrupole (TESQ) accelerator for Accelerator-Based (AB)-BNCT is described here. The project goal is a machine capable of delivering 30 mA of 2.5 MeV protons to be used in conjunction with a neutron production target based on the 7 Li(p,n) 7 Be reaction slightly beyond its resonance at 2.25 MeV. A folded tandem, with 1.25 MV terminal voltage, combined with an ESQ chain is being designed and constructed. A 30 mA proton beam of 2.5 MeV are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the 7 Li(p,n) 7 Be reaction, to perform BNCT treatment for deep-seated tumors in less than an hour. The first design and construction of an ESQ module is discussed and its electrostatic fields are investigated theoretically and experimentally. Also new beam transport calculations through the accelerator are presented

Neutron-proton bremsstrahlung experiments

Energy Technology Data Exchange (ETDEWEB)

Koster, J.E. (Los Alamos National Lab., NM (United States)); Nelson, R.O. (Los Alamos National Lab., NM (United States)); Schillaci, M.E. (Los Alamos National Lab., NM (United States)); Wender, S.A. (Los Alamos National Lab., NM (United States)); Mayo, D. (Univ. of California at Davis, CA (United States)); Brady, F.P. (Univ. of California at Davis, CA (United States)); Romero, J. (Univ. of California at Davis, CA (United States)); Krofcheck, D. (Lawrence Livermore National Lab., CA (United States)); Blann, M. (Lawrence Livermore National Lab., CA (United States)); Anthony, P. (Lawrence Livermore National Lab., CA (United States)); Brown, V.R. (Lawrence Livermore National Lab., CA (United States)); Hansen, L. (Lawrence Livermore National Lab., CA (United States)); Pohl, B. (Lawrence Livermore National Lab., CA (United States)); Sangster, T.C. (Lawrence Livermore National Lab., CA (United States)); Nifenecker, H. (Inst. des Sciences Nucleaires, Grenoble (France)); Pinston,

1993-06-01

It is well known that charged particles emit bremsstrahlung radiation when they are accelerated. Classical electron bremsstrahlung occurs when a proton is emitted by an electron accelerated in the field of a nucleus. The bremsstrahlung process also occurs in the scattering of nucleons, for which it is the lowest energy inelastic process that can occur. Like electron bremsstrahlung, nucleon-nucleon bremsstrahlung also requires the exchange of a virtual particle to conserve energy and momentum. In electron bremsstrahlung a virtual photon is exchanged but with two nucleons a meson can be exchanged. Unlike electron bremsstrahlung, in nucleon-nucleon bremsstrahlung the photon can originate from the exchanged meson. This exchange contribution has been shown in calculations to be a significant fraction of bremsstrahlung events. Thus bremsstrahlung serves as a probe of exchange currents in the nucleon-nucleon interaction. Because of a lack of a free neutron target or an intense neutron beam, few measurements of neutron-proton bremsstrahlung exist, each having poor statistical accuracy and poor energy resolution. The white neutron source at the Weapons Neutron Research (WNR) target area at the Los Alamos Meson Physics Facility (LAMPF) produces neutrons with energies from below 50 to above 400 MeV. Using time-of-flight techniques and a liquid hydrogen target, we are measuring the outgoing photons of energies up to 250 MeV at gamma ray angles of around 90 relative to the incident beam. Protons scattered at very forward angles are also detected in coincidence with the gamma rays. (orig.)

Unexpected alignment patterns in high-j intruder bands evidence for a strong residual neutron proton interaction?

International Nuclear Information System (INIS)

Wyss, R.; Johnson, A.; Royal Inst. of Tech., Stockholm

1990-01-01

The alignment of h 11/12 protons in νi 13/2 intruder bands in mass A = 130 region is investigated. The lack of a clear h 11/12 band crossing is compared with the alignment pattern of i 13/2 neutrons in πi 13/2 intruder bands in mass A = 180 region. The very smooth rise in angular momentum in the intruder bands is related to a possible neutron proton interaction between the single intruder orbital and the aligned two-quasiparticle configuration. 36 refs., 3 figs

Development of a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy

International Nuclear Information System (INIS)

Kreiner, A.J.; Castell, W.; Di Paolo, H.; Baldo, M.; Bergueiro, J.

2011-01-01

We describe the present status of an ongoing project to develop a Tandem-ElectroStatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based (AB)-BNCT. The project final goal is a machine capable of delivering 30 mA of 2.4 MeV protons to be used in conjunction with a neutron production target based on the 7 Li(p,n) 7 Be reaction. The machine currently being constructed is a folded TESQ with a high-voltage terminal at 0.6 MV. We report here on the progress achieved in a number of different areas.

High energy proton induced radiation damage of rare earth permanent magnet quadrupoles

Science.gov (United States)

Schanz, M.; Endres, M.; Löwe, K.; Lienig, T.; Deppert, O.; Lang, P. M.; Varentsov, D.; Hoffmann, D. H. H.; Gutfleisch, O.

2017-12-01

Permanent magnet quadrupoles (PMQs) are an alternative to common electromagnetic quadrupoles especially for fixed rigidity beam transport scenarios at particle accelerators. Using those magnets for experimental setups can result in certain scenarios, in which a PMQ itself may be exposed to a large amount of primary and secondary particles with a broad energy spectrum, interacting with the magnetic material and affecting its magnetic properties. One specific scenario is proton microscopy, where a proton beam traverses an object and a collimator in which a part of the beam is scattered and deflected into PMQs used as part of a diagnostic system. During the commissioning of the PRIOR (Proton Microscope for Facility for Antiproton and Ion Research) high energy proton microscope facility prototype at Gesellschaft für Schwerionenforschung in 2014, a significant reduction of the image quality was observed which was partially attributed to the demagnetization of the used PMQ lenses and the corresponding decrease of the field quality. In order to study this phenomenon, Monte Carlo simulations were carried out and spare units manufactured from the same magnetic material—single wedges and a fully assembled PMQ module—were deliberately irradiated by a 3.6 GeV intense proton beam. The performed investigations have shown that in proton radiography applications the above described scattering may result in a high irradiation dose in the PMQ magnets. This did not only decrease the overall magnetic strength of the PMQs but also caused a significant degradation of the field quality of an assembled PMQ module by increasing the parasitic multipole field harmonics which effectively makes PMQs impractical for proton radiography applications or similar scenarios.

Design study of a medical proton linac for neutron therapy

International Nuclear Information System (INIS)

Machida, S.; Raparia, D.

1988-01-01

This paper describes a design study which establishes the physical parameters of the low energy beam transport, radiofrequency quadrupole, and linac, using computer programs available at Fermilab. Beam dynamics studies verify that the desired beam parameters can be achieved. The machine described here meets the aforementioned requirements and can be built using existing technology. Also discussed are other technically feasible options which could be attractive to clinicians, though they would complicate the design of the machine and increase construction costs. One of these options would allow the machine to deliver 2.3 MeV protons to produce epithermal neutrons for treating brain tumors. A second option would provide 15 MeV protons for isotope production. 21 refs., 33 figs

Study of the proton-neutron interaction around $^{68}$Ni : Vibrational structure of $^{72,74}$Zn

CERN Multimedia

Hass, M; Blazhev, A A; Kruecken, R; Muecher, D; Kumar, V; Srebrny, J; Albers, M; Gernhaeuser, R A; Hadynska-klek, K; Eberth, J H; Lo bianco, G; Napiorkowski, P J; Bettermann, L; Das gupta, S; Kroell, T; Leske, J; Iwanicki, J S

We propose to study the $^{72}$Zn nucleus, 2 protons and 2 neutrons away from the possible double-magic $^{68}$Ni nucleus, by means of Coulomb Excitation in inverse kinematics. Current data suggest almost degenerated 2$^{+}$ states of 2-phonon and mixed-symmetric character, respectively. The identification of the 2$^+_{ms}$ state in $^{72}$Zn will be a direct measure of the interaction between valence protons and neutrons, which is the key to understand the nature of $^{68}$Ni. We furthermore propose to study the unusual behavior of the first excited 0$^{+}$ state in this region using the t($^{72}$Zn,p)$\\,^{74}$Zn reaction.

Proton impurity in the neutron matter: a nuclear polaron problem

Energy Technology Data Exchange (ETDEWEB)

Kutschera, M [Institute of Nuclear Physics, Cracow (Poland); Wojcik, W [Politechnika Krakowska, Cracow (Poland)

1992-10-01

We study interactions of a proton impurity with density oscillations of the neutron matter in a Debye approximation. The proton-phonon coupling is of the deformation-potential type at long wavelengths. It is weak at low density and increases with the neutron matter density. We calculate the proton`s effective mass perturbatively for a weak coupling, and use a canonical transformation technique for stronger couplings. The proton`s effective mass grows significantly with density, and at higher densities the proton impurity can be localized. This behaviour is similar to that of the polaron in solids. We obtain properties of the localized proton in the strong coupling regime from variational calculations, treating the neutron in the Thomas-Fermi approximation. (author). 14 refs, 8 figs.

A Tandem-electrostatic-quadrupole for accelerator-based BNCT

International Nuclear Information System (INIS)

Kreiner, A.J.; Kwan, J.W.; Burlon, A.A.; Di Paolo, H.; Henestroza, E.; Minsky, D.M.; Valda, A.A.; Debray, M.E.; Somacal, H.

2007-01-01

A project to develop a Tandem-electrostatic-quadrupole (TESQ) accelerator for accelerator-based boron neutron capture therapy (AB-BNCT) is described. A folded Tandem, with 1.25 MV terminal voltage, combined with an electrostatic quadrupole (ESQ) chain is being proposed. The project goal is a machine capable of delivering 30 mA of 2.5 MeV protons to be used in conjunction with a neutron production target based on the 7 Li(p, n) 7 Be reaction slightly beyond its resonance at 2.25 MeV. This machine is conceptually shown to be capable of accelerating a 30 mA proton beam to 2.5 MeV. These are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the 7 Li(p, n) 7 Be reaction, to perform BNCT treatment for deep-seated tumors in less than an hour. This electrostatic machine is the technologically simplest and cheapest solution for optimized AB-BNCT

Neutron production in interactions of relativistic protons and deuterons with lead targets

International Nuclear Information System (INIS)

Yurevich, V.I.; Amelin, N.S.; Yakovlev, R.M.; Nikolaev, V.A.; Lyapin, V.G.; Tsvetkov, I.O.

2005-01-01

Results on the neutron double-differential cross sections and yields obtained in the time-of-flight measurements with different lead targets and beams of protons and deuterons at an energy of about 2 GeV are discussed. The neutron spatial-energy distribution for an extended lead target was studied by the threshold detector method in the energy range of protons and deuterons 1-3.7 GeV. A dependence of the mean neutron multiplicity, energy of neutrons, and process of neutron multiplication in lead on the target dimension, and the type and energy of the beam particle is analyzed. (author)

Development of a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy.

Science.gov (United States)

Kreiner, A J; Castell, W; Di Paolo, H; Baldo, M; Bergueiro, J; Burlon, A A; Cartelli, D; Vento, V Thatar; Kesque, J M; Erhardt, J; Ilardo, J C; Valda, A A; Debray, M E; Somacal, H R; Sandin, J C Suarez; Igarzabal, M; Huck, H; Estrada, L; Repetto, M; Obligado, M; Padulo, J; Minsky, D M; Herrera, M; Gonzalez, S J; Capoulat, M E

2011-12-01

We describe the present status of an ongoing project to develop a Tandem-ElectroStatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based (AB)-BNCT. The project final goal is a machine capable of delivering 30 mA of 2.4 MeV protons to be used in conjunction with a neutron production target based on the (7)Li(p,n)(7)Be reaction. The machine currently being constructed is a folded TESQ with a high-voltage terminal at 0.6 MV. We report here on the progress achieved in a number of different areas. Copyright © 2011 Elsevier Ltd. All rights reserved.

(Anti-)deuteron formation and neutron-proton correlation

International Nuclear Information System (INIS)

Mrowczynski, S.

1995-01-01

The neutron-proton correlation, deuteron and antideuteron formation in nuclear collisions are all due to the final state interactions. The neutron-proton correlation function and the (anti-)deuteron formation rate are calculated in parallel. These quantities are expressed through the space-time parameters of the particle source created in nucleus-nucleus collisions. In the case of baryon reach sources, the nucleons are emitted from the whole source volume while the antinucleons dominantly from the surface due to the antinucleon absorption in the baryon environment. Thus, the shape of the antinucleon source is different from the nucleon one, and consequently the antideuteron formation rate is substantially smaller than that one of deuterons. The correlation function satisfies the sum rule, which, in particular, connects the number of correlated neutron-proton pairs with the number of produced deuterons. (author). 18 refs., 4 figs

Description of spectrum and electromagnetic transitions in 94Mo through the proton-neutron interacting boson model

Science.gov (United States)

Mu, ChengFu; Zhang, DaLi

2018-01-01

We investigated the properties of low-lying states in 94Mo within the framework of the proton-neutron interacting boson model (IBM-2), with special focus on the characteristics of mixed-symmetry states. We calculated level energies and M1 and E2 transition strengths. The IBM-2 results agree with the available quantitative and qualitative experimental data on 94Mo. The properties of mixed-symmetry states can be well described by IBM-2 given that the energy of the d proton boson is different from that of the neutron boson, especially for the transition of B( M1; 4 2 + → 4 1 + ).

Measurements of electric quadrupole moments of neutron-deficient Au, Pt, and Ir nuclei with NMR-ON in hcp-Co

CERN Multimedia

Smolic, E; Hagn, E; Zech, E; Seewald, G

2002-01-01

The aim of the experiments is the measurement of $\\,$i) nuclear magnetic moments and electric quadrupole moments of neutron-deficient isotopes in the region Os-Ir-Pt-Au with the methods of quadrupole-interaction-resolved NMR on oriented nuclei " QI-NMR-ON " and modulated adiabatic passage on oriented nuclei " MAPON " and $\\,$ii) the magnetic hyperfine field, electric field gradient (EFG), and spin-lattice relaxation of 5d elements in ferromagnetic Fe, Ni, fcc-Co and hcp-Co.\\\\ The measurements on Au isotopes have been finished successfully. The quadrupole moments of $^{186}$Au, $^{193m}$Au, $^{195}$Au, $^{195m}$Au, $^{197m}$Au, $^{198}$Au and $^{199}$Au were determined with high precision.\\\\ For neutron-deficient Ir isotopes QI-NMR-ON measurements were performed after implantation of Hg precursors. The EFG of Ir in hcp-Co has been calibrated. Thus precise values for the spectroscopic quadrupole mo...

Investigation of the proton-neutron interaction by high-precision nuclear mass measurements

CERN Multimedia

Savreux, R P; Akkus, B

2007-01-01

We propose to measure the atomic masses of a series of short-lived nuclides, including $^{70}$Ni, $^{122-130}$Cd, $^{134}$Sn, $^{138,140}$Xe, $^{207-210}$Hg, and $^{223-225}$Rn, that contribute to the investigation of the proton-neutron interaction and its role in nuclear structure. The high-precision mass measurements are planned for the Penning trap mass spectrometer ISOLTRAP that reaches the required precision of 10 keV in the nuclear mass determination.

Boson representations of fermion systems: Proton-neutron systems

International Nuclear Information System (INIS)

Sambataro, M.

1988-01-01

Applications of a procedure recently proposed to construct boson images of fermion Hamiltonians are shown for proton-neutron systems. First the mapping from SD fermion onto sd boson spaces is discussed and a Q/sub π/xQ/sub ν/ interaction investigated. A Hermitian one-body Q boson operator is derived and analytical expressions for its coefficients are obtained. A (Q/sub π/+Q/sub ν/)x(Q/sub π/+Q/sub ν/) interaction is, then, studied for particle-hole systems and the connections with the SU/sup */(3) dynamical symmetry of the neutron-proton interacting boson model are discussed. Finally, an example of mapping from SDG onto sdg spaces is analyzed. Fermion spectra and E2 matrix elements are well reproduced in the boson spaces

Production of the charmed baryon Λc+ in neutron-proton interactions

International Nuclear Information System (INIS)

Vecko, M.; Novak, M.; Hladky, J.; Krasova, J.; Klabun, J.; Nowak, H.; Nowak, S.; Rysek, H.-E.; Abashidze, L.I.; Abesalashvili, L.N.; Amaglobeli, N.S.; Chasnikov, I.Ya; Kamburian, A.F.; Loktionov, A.A.; Nazarenko, V.D.; Potrebenikov, Yu.K.; Sliusareva, V.B.; Skorobogatova, V.I.

1989-01-01

The inclusive production was studied of charmed baryon Λ c + in interactions of 40 to 70 GeV/c neutrons with protons of a hydrogen target. The experiment was performed with the use of magnetic spectrometer BIS-2 located in the neutron beam of the Serpukhov accelerator. The signal of Λ c + was observed in the effective mass spectra of Λ 0 π + π + π - . After the removal of interactions occurring on the container of liquid hydrogen, the signal consisted of 14 combinations corresponding to ∼4 standard deviations of background. Its mean value was 2262 MeV/c 2 , the width of the bin containing signal was 20 MeV/c 2 . On the basis of this signal the value was determined of the cross section of Λ c + production times the branching ratio of its observed decay mode σxBr(Λ c + →Λ 0 π + π + π - ) = 0.26±0.11 μb in the kinematic region of x F >0.5 and p T <1 GeV/c. (author). 10 figs., 15 refs

On the proton spectrum in free neutron β-decay

International Nuclear Information System (INIS)

Bunatyan, G.G.

2000-01-01

We consider the calculations which are appropriate to acquire with a high precision, of ∼ 1% or better, the general characteristics of weak interactions from the experiments on the free neutron β-decay; the principle emphasis is placed on the phenomena associated with the recoil of protons. The part played by electromagnetic interactions in β-decay is visualized, with special attention drawn to the influence of the γ-radiation on the momentum distribution of the particles in the final state. The effect of electromagnetic interactions on the proton recoil spectrum is studied, in the light of the experiments which are carried out and planned for now. The results of the calculations, which are to be confronted with the experimental data, are presented upright in terms of the effective Lagrangian underlying the inquiry. Owing to electromagnetic interactions, the corrections to the energy distribution of protons prove to amount to the value of a few per cent. Nowadays, this is substantial to obtain with a high accuracy the characteristics of weak interactions by processing the data of the experiments on the proton distribution in the free neutron β-decay

Coulomb Excitation of Neutron-Rich $A\\approx$140 Nuclei

CERN Multimedia

Van duppen, P L E

2002-01-01

Investigating the isospin dependence of the product between the B( E2; 0$_{1}^{+} \\rightarrow 2_{1}^{+}$)-value and the 2$_{1}^{+}$-excitation energy E$_{2^{+}}$ in even-even nuclei around $A\\!\\approx$140 one observes a rather smooth trend close to the valley of stability but clear indication for a reduction from the extrapolated B(E2)-values by one order of magnitude for some very neutron-rich nuclei. While close to the valley of stability the strong neutron-proton interaction results in an equilibration of the neutron and proton deformations with a predominate isoscalar character of the collective 2$^{+}$ excitation, it is conceivable that more loosely bound neutrons cannot polarize a close-to-magic proton core that well any more. This might result in a decoupling of the shape of the outer neutrons from the core and in a strong isovector admixture to the lowest lying 2$^{+}$ level. In this way the 2$^{+}$ -energies could be further lowered in neutron-rich nuclei, while the quadrupole moments of the proton c...

On the exchange term of the interacting boson-fermion hamiltonian

International Nuclear Information System (INIS)

Gelberg, A.

1983-01-01

The exchange term of the Interacting Boson Fermion Model is investigated by using I. Talmi's method based on the shell model. A quadrupole operator of a three-proton system is formed; the protons are quadrupole-coupled to the neutron-bosons. Seniority conserving and seniority non conserving terms are considered. The particle number dependence of the parameters is investigated for the single-j shell. The relation between exchange and direct, seniority non conserving terms is examined. Approximate formulas are given for the multi-j shell. (orig.)

Excitations of one-valence-proton, one-valence-neutron nucleus {sup 210}Bi from cold-neutron capture

Energy Technology Data Exchange (ETDEWEB)

Cieplicka-Oryńczak, N. [INFN sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Kraków (Poland); Fornal, B.; Szpak, B. [Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Kraków (Poland); Leoni, S.; Bottoni, S. [INFN sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Bazzacco, D. [Dipartimento di Fisica e Astronomia dell’Università, I-35131 Padova (Italy); INFN Sezione di Padova, I-35131 Padova (Italy); Blanc, A.; Jentschel, M.; Köster, U.; Mutti, P.; Soldner, T. [Institute Laue-Langevin, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Bocchi, G. [Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); France, G. de [GANIL, Bd. Becquerel, BP 55027, 14076 CAEN Cedex 05 (France); Simpson, G. [LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, F-38026 Grenoble Cedex (France); Ur, C. [INFN Sezione di Padova, Via F. Marzolo 8, I-35131 Padova (Italy); Urban, W. [Faculty of Physics, University of Warsaw, ul. Hoża 69, 02-681, Warszawa (Poland)

2015-10-15

The low-spin structure of one-proton, one-neutron {sup 210}Bi nucleus was investigated in cold-neutron capture reaction on {sup 209}Bi. The γ-coincidence measurements were performed with use of EXILL array consisted of 16 HPGe detectors. The experimental results were compared to shell-model calculations involving valence particles excitations. The {sup 210}Bi nucleus offers the potential to test the effective proton-neutron interactions because most of the states should arise from the proton-neutron excitations. Additionally, it was discovered that a few states should come from the couplings of valence particles to the 3{sup −} octupole vibration in {sup 208}Pb which provides also the possibility of testing the calculations involving the core excitations.

Neutron-Proton Scattering Experiments at ANKE-COSY

Science.gov (United States)

Kacharava, A.; Chiladze, D.; Chiladze, B.; Keshelashvili, I.; Lomidze, N.; Macharashvili, G.; McHedlishvili, D.; Nioradze, M.; Rathmann, F.; Ströher, H.; Wilkin, C.

2010-04-01

The nucleon-nucleon interaction (NN) is fundamental for the whole of nuclear physics and hence to the composition of matter as we know it. It has been demonstrated that stored, polarised beams and polarised internal targets are experimental tools of choice to probe spin effects in NN-scattering experiments. While the EDDA experiment has dramatically improved the proton-proton date base, information on spin observables in neutron-proton scattering is very incomplete above 800 MeV, resulting in large uncertainties in isoscalar n p phase shifts. Experiments at COSY, using a polarised deuteron beam or target, can lead to significant improvements in the situation through the study of quasi-free reactions on the neutron in the deuteron. Such a measurements has already been started at ANKE by using polarised deuterons on an unpolarised target to study the dp → ppn deuteron charge-exchange reaction and the full program with a polarised storage cell target just has been conducted. At low excitation energies of the final pp system, the spin observables are directly related to the spin- dependent parts of the neutron-proton charge-exchange amplitudes. Our measurement of the deuteron-proton spin correlations will allow us to determine the relative phases of these amplitudes in addition to their overall magnitudes.

Neutron scattering cross sections for 204,206Pb and neutron and proton amplitudes of E2 and E3 excitations

International Nuclear Information System (INIS)

Hicks, S.F.; Hanly, J.M.; Hicks, S.E.; Shen, G.R.; McEllistrem, M.T.

1994-01-01

Differential elastic and inelastic scattering cross sections have been measured for neutrons incident on 204 Pb and 206 Pb at energies of 2.5, 4.6, and 8.0 MeV and total cross sections in 100-keV steps from 250 keV to 4.0 MeV. Both spherical and coupled-channels analyses have been used to interpret this large set of data, together with other cross sections extending to 8 MeV. Several purposes motivate this work. The first is to establish the dispersion-corrected mean field appropriate for these nuclei. A consistent description of the energy dependent neutron scattering potential includes a dispersion relation connecting the real and imaginary parts of the potential; the resultant potential relates the energy dependent scattering field to one representing bound single particle levels. Dispersion relations using both the single channel and coupled-channels models have been examined; both give very similar results. The second motivation is to deduce neutron and proton excitation strengths of the lowest-energy quadrupole and octupole excitations seen via neutron scattering, and to compare those strengths with similar values derived from electromagnetic exciton, heavy-ion and pion scattering. The role of target neutrons in both collective excitations was found to be enhanced compared to the proton role

Measurement of the weak nucleon-nucleon interaction by polarized cold neutron capture on protons

Directory of Open Access Journals (Sweden)

Alarcon R.

2014-03-01

Full Text Available The NPDGamma Experiment at the Spallation Neutron Source at Oak Ridge National Laboratory is measuring the parity-odd correlation between the neutron spin and the direction of the emitted photon in the capture of polarized cold neutrons on protons. A parity violating asymmetry from this process is directly related to the strength of the hadronic weak interaction between nucleons. The experiment was run first with heavier nuclear targets to check systematic effects, false asymmetries, and backgrounds. Since early 2012 the experiment has been collecting data with a 16-liter liquid parahydrogen target. Data taking will continue through 2013 until statistics for a 10−8 asymmetry measurement are expected. The experiment performance will be discussed as well as the status of the asymmetry measurements.

Quadrupole collectivity beyond N = 50 in neutron- rich Se and Kr isotopes

Science.gov (United States)

Elman, Brandon; Gade, A.; Barofsky, D.; Bender, P. C.; Bowry, M.; Hjorth-Jensen, M.; Kemper, K. W.; Lipschutz, S.; Lunderberg, E.; Sachmpazidi, N.; Terpstra, N.; Walters, W. B.; Weisshaar, D.; Westerberg, A.; Williams, S. J.; Wimmer, K.

2017-09-01

We will present results on measuring the B (E 2 ;01+ ->2n+) strength for the neutron-rich 88,90Kr and 86Se isotopes from intermediate-energy Coulomb excitation. The electric quadrupole transition strengths to the first 2+ state complete, with considerably improved uncertainties, the evolution of quadrupole collectivity in the Kr and Se isotopes approaching N = 60 , for which 90Kr and 86Se had previously been the most uncertain. We also report significant excitation strength to several higher lying 2+ states in the krypton isotopes. The results confirm shell model calculations in the π (fpg) - ν (sdg) shell with only a minimally tuned shell model setup that is based on a nucleon-nucleon interaction derived from effective field theory with effective charges adjusted to 86Kr.

Proton energy dependence of slow neutron intensity

International Nuclear Information System (INIS)

Teshigawara, Makoto; Harada, Masahide; Watanabe, Noboru; Kai, Tetsuya; Sakata, Hideaki; Ikeda, Yujiro

2001-01-01

The choice of the proton energy is an important issue for the design of an intense-pulsed-spallation source. The optimal proton beam energy is rather unique from a viewpoint of the leakage neutron intensity but no yet clear from the slow-neutron intensity view point. It also depends on an accelerator type. Since it is also important to know the proton energy dependence of slow-neutrons from the moderators in a realistic target-moderator-reflector assembly (TMRA). We studied on the TMRA proposed for Japan Spallation Neutron Source. The slow-neutron intensities from the moderators per unit proton beam power (MW) exhibit the maximum at about 1-2 GeV. At higher proton energies the intensity per MW goes down; at 3 and 50 GeV about 0.91 and 0.47 times as low as that at 1 GeV. The proton energy dependence of slow-neutron intensities was found to be almost the same as that of total neutron yield (leakage neutrons) from the same bare target. It was also found that proton energy dependence was almost the same for the coupled and decoupled moderators, regardless the different moderator type, geometry and coupling scheme. (author)

Nuclear quadrupole-quadrupole interaction in the inelastic scattering of aligned deuterons from deformed nuclei

International Nuclear Information System (INIS)

Clement, H.; Frick, R.; Graw, G.; Schiemenz, P.; Seichert, N.

1983-01-01

The 2 1 + -excitation of deformed nuclei by tensor polarized deuterons provides an alignment of both nuclei and thus a means to study specifically the quadrupole-quadrupole interaction between both nuclei. The tensor analyzing power Asub(xz)(theta) has been measured for the elastic and inelastic scattering on 24 Mg and 28 Si. The coupled channel analysis including a deformed tensor potential reveals a clear signature of the quadrupole-quadrupole part of the nuclear projectile-target interaction. (orig.)

Studies of neutron emission from relativistic nuclear interactions

CERN Document Server

Guo, S L; Wang, Y L; Guo, H Y; Sá Ben-Hao; Zheng, Y M; Brandt, R; Vater, P; Wan, J S; Ochs, M; Kulakov, B A; Sosnin, A N; Krivopustov, M I; Butsev, V S; Bradnova, V

1999-01-01

Studies were carried out on the yields and spatial distributions of secondary neutrons produced in the relativistic nuclear interactions of 1.5 GeV to 14.4 GeV projectiles p, d and alpha-particles with targets Pb and U/Pb. CR-39 track detectors were used to measure the neutrons. It shows that: (1) Secondary neutrons are produced in the whole length of Pb or U targets having a thickness of 20 cm. The neutron intensities produced by proton bombardments are reduced along the proton beam direction in the targets. The higher the energy of protons, the lower the reduction rate of the neutrons. The reduction rate of neutrons in U target is higher than in Pb target for the same energy of protons. (2) The radial intensities of neutrons decrease as the distance increases from the target central line. (3) The neutron yield in U target by proton bombardments is approx 55% higher than in Pb target. (4) The ratio of neutron yield by 14.4 GeV alpha to 7.3 GeV d bombardment in Pb target is 1.74+-0.20.

Development of high intensity ion sources for a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy

International Nuclear Information System (INIS)

Bergueiro, J.; Igarzabal, M.; Suarez Sandin, J.C.; Somacal, H.R.; Thatar Vento, V.; Huck, H.; Valda, A.A.; Repetto, M.

2011-01-01

Several ion sources have been developed and an ion source test stand has been mounted for the first stage of a Tandem-Electrostatic-Quadrupole facility For Accelerator-Based Boron Neutron Capture Therapy. A first source, designed, fabricated and tested is a dual chamber, filament driven and magnetically compressed volume plasma proton ion source. A 4 mA beam has been accelerated and transported into the suppressed Faraday cup. Extensive simulations of the sources have been performed using both 2D and 3D self-consistent codes.

Development of high intensity ion sources for a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy

Energy Technology Data Exchange (ETDEWEB)

Bergueiro, J. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica (Argentina)] [CONICET, Buenos Aires (Argentina); Igarzabal, M.; Suarez Sandin, J.C. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica (Argentina); Somacal, H.R. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica (Argentina)] [Escuela de Ciencia y Tecnologia, Universidad Nacional de San Martin (Argentina); Thatar Vento, V. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica (Argentina)] [CONICET, Buenos Aires (Argentina); Huck, H.; Valda, A.A. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica (Argentina)] [Escuela de Ciencia y Tecnologia, Universidad Nacional de San Martin (Argentina); Repetto, M. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica (Argentina)

2011-12-15

Several ion sources have been developed and an ion source test stand has been mounted for the first stage of a Tandem-Electrostatic-Quadrupole facility For Accelerator-Based Boron Neutron Capture Therapy. A first source, designed, fabricated and tested is a dual chamber, filament driven and magnetically compressed volume plasma proton ion source. A 4 mA beam has been accelerated and transported into the suppressed Faraday cup. Extensive simulations of the sources have been performed using both 2D and 3D self-consistent codes.

Stabilized operation of the Spallation Neutron Source radio-frequency quadrupole

Directory of Open Access Journals (Sweden)

Sang-ho Kim

2010-07-01

Full Text Available The Spallation Neutron Source (SNS radio-frequency quadrupole (RFQ had resonance control instabilities at duty factors higher than approximately 4%. Systematic investigations have been carried out to understand the cause of the instability and to ensure the operational stability of the RFQ. The most critical source of the instability is revealed to be an interaction between hydrogen released by beam bombardments and the RFQ rf field resulting in a discharge, which consumes additional rf power and could cause the RFQ to operate in an unstable region. This paper reports improvement of the SNS RFQ operational stability based on the findings during the SNS operation.

Proton Neutron Gamma-X Detection (PNGXD): An introduction to contrast agent detection during proton therapy via prompt gamma neutron activation

Science.gov (United States)

Gräfe, James L.

2017-09-01

Proton therapy is an alternative external beam cancer treatment modality to the conventional linear accelerator-based X-ray radiotherapy. An inherent by-product of proton-nuclear interactions is the production of secondary neutrons. These neutrons have long been thought of as a secondary contaminant, nuisance, and source of secondary cancer risk. In this paper, a method is proposed to use these neutrons to identify and localize the presence of the tumor through neutron capture reactions with the gadolinium-based MRI contrast agent. This could provide better confidence in tumor targeting by acting as an additional quality assurance tool of tumor position during treatment. This effectively results in a neutron induced nuclear medicine scan. Gadolinium (Gd), is an ideal candidate for this novel nuclear contrast imaging procedure due to its unique nuclear properties and its widespread use as a contrast agent in MRI. Gd has one of the largest thermal neutron capture cross sections of all the stable nuclides, and the gadolinium-based contrast agents localize in leaky tissues and tumors. Initial characteristics of this novel concept were explored using the Monte Carlo code MCNP6. The number of neutron capture reactions per Gy of proton dose was found to be approximately 50,000 neutron captures/Gy, for a 8 cm3 tumor containing 300 ppm Gd at 8 cm depth with a simple simulation designed to represent the active delivery method. Using the passive method it is estimated that this number can be up to an order of magnitude higher. The thermal neutron distribution was found to not be localized within the spread out Bragg peak (SOBP) for this geometrical configuration and therefore would not allow for the identification of a geometric miss of the tumor by the proton SOBP. However, this potential method combined with nuclear medicine imaging and fused with online CBCT and prior MRI or CT imaging could help to identify tumor position during treatment. More computational and

Theory of nuclear quadrupole interactions in solid hydrogen fluoride

International Nuclear Information System (INIS)

Mohamed, N.S.; Sahoo, N.; Das, T.P.; Kelires, P.C.

1990-01-01

The nuclear quadrupole interaction of 19 F * (I=5/2) nucleus in solid hydrogen fluoride has been studied using the Hartree Fock cluster technique to understand the influence of both intrachain hydrogen bonding effects and the weak interchain interaction. On the basis of our investigations, the 34.04 MHz coupling constant observed by TDPAD measurements has been ascribed to the bulk solid while the observed 40.13 MHz coupling constant is suggested as arising from a small two- or three-molecule cluster produced during the proton irradiation process. Two alternate explanations are offered for the origin of coupling constants close to 40 MHz in a number of solid hydrocarbons containing hydrogen and fluorine ligands. (orig.)

CONSIDERATIONS ABOUT PROTON - NEUTRON INTERACTIONS IN THE INTERSECTING STORAGE RINGS

CERN Document Server

Bartl, W; Steuer, M; Hubner, K

1969-01-01

The pos'sibility of proton-neutron scattering experiments at the CERN Intersecting Storage Rings is studied. The use of proton-deuteron collisions to measure the reaction p+d •*• p*pv+n,witheitherp.orn,asspectator nucléon is discussed. An analysing magnet around the deuteron beamline allows to detect both nucléons of the deuteron up to the zero-momentum-transfer" région. Accélération and storage of deuteron beams is considered.

A special type of neutron-proton pairing interaction and the moments of inertia of some deformed even-even nuclei in the rare earth region

International Nuclear Information System (INIS)

Meftunoglu, E.; Gerceklioglu, M.; Erbil, H.H.; Kuliev, A.A.

1998-01-01

In this work, the effect of a special type of neutron-proton pairing interaction on the moments of inertia of some deformed nuclei in the rare earth region is investigated. First, making a perturbative approximation, we assume that the form of the equations of the BCS theory and usual Bogolyubov transformations are unchanged. Second, we use a phenomenological method for the strength of this neutron-proton pairing interaction introducing a parameter. Calculations show that this interaction is important for the ground-state moments of inertia and that it could be effectual in other nuclear phenomena. (author)

Development of high intensity ion sources for a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy.

Science.gov (United States)

Bergueiro, J; Igarzabal, M; Sandin, J C Suarez; Somacal, H R; Vento, V Thatar; Huck, H; Valda, A A; Repetto, M; Kreiner, A J

2011-12-01

Several ion sources have been developed and an ion source test stand has been mounted for the first stage of a Tandem-Electrostatic-Quadrupole facility For Accelerator-Based Boron Neutron Capture Therapy. A first source, designed, fabricated and tested is a dual chamber, filament driven and magnetically compressed volume plasma proton ion source. A 4 mA beam has been accelerated and transported into the suppressed Faraday cup. Extensive simulations of the sources have been performed using both 2D and 3D self-consistent codes. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effect of energy level sequences and neutron–proton interaction on α-particle preformation probability

International Nuclear Information System (INIS)

Ismail, M.; Adel, A.

2013-01-01

A realistic density-dependent nucleon–nucleon (NN) interaction with finite-range exchange part which produces the nuclear matter saturation curve and the energy dependence of the nucleon–nucleus optical model potential is used to calculate the preformation probability, S α , of α-decay from different isotones with neutron numbers N=124,126,128,130 and 132. We studied the variation of S α with the proton number, Z, for each isotone and found the effect of neutron and proton energy levels of parent nuclei on the behavior of the α-particle preformation probability. We found that S α increases regularly with the proton number when the proton pair in α-particle is emitted from the same level and the neutron level sequence is not changed during the Z-variation. In this case the neutron–proton (n–p) interaction of the two levels, contributing to emission process, is too small. On the contrary, if the proton or neutron level sequence is changed during the emission process, S α behaves irregularly, the irregular behavior increases if both proton and neutron levels are changed. This behavior is accompanied by change or rapid increase in the strength of n–p interaction

Magnetic quadrupoles lens for hot spot proton imaging in inertial confinement fusion

Energy Technology Data Exchange (ETDEWEB)

Teng, J. [Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900 (China); Gu, Y.Q., E-mail: yqgu@caep.cn [Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900 (China); Center for Applied Physics and Technology, HEDPS, Peking University, Beijing 100871 (China); Chen, J.; Zhu, B.; Zhang, B.; Zhang, T.K.; Tan, F.; Hong, W.; Zhang, B.H. [Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900 (China); Wang, X.Q. [Academy of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026 (China)

2016-08-01

Imaging of DD-produced protons from an implosion hot spot region by miniature permanent magnetic quadrupole (PMQ) lens is proposed. Corresponding object-image relation is deduced and an adjust method for this imaging system is discussed. Ideal point-to-point imaging demands a monoenergetic proton source; nevertheless, we proved that the blur of image induced by proton energy spread is a second order effect therefore controllable. A proton imaging system based on miniature PMQ lens is designed for 2.8 MeV DD-protons and the adjust method in case of proton energy shift is proposed. The spatial resolution of this system is better than 10 μm when proton yield is above 10{sup 9} and the spectra width is within 10%.

Proton mixing in -condensed phase of neutron star matter

Energy Technology Data Exchange (ETDEWEB)

Takatsuka, Tatsuyuki

1984-08-01

The mixing of protons in neutron star matter under the occurrence of condensation is studied in the framework of the ALS (Alternating Layer Spin) model and with the effective interaction approach. It is found that protons are likely to mix under the situation and cause a remarkable energy gain from neutron matter as the density increases. The extent of proton mixing becomes larger by about a factor (1.5-2.5) according to the density rho asymptotically equals (2-5)rho0, rho0 being the nuclear density, as compared with that for the case without pion condensation. The reason can be attributed to the two-dimensional nature of the Fermi gas state characteristic of the nucleon system under condensation.

Collinear Laser Spectroscopy of Manganese Isotopes using the Radio Frequency Quadrupole Cooler and Buncher at ISOLDE

CERN Document Server

AUTHOR|(CDS)2083426

The hyperfine structure of the odd-even $^{51−63}$Mn isotopes (N = 26 − 38) were measured using bunched beam collinear laser spectroscopy with the COLLAPS experimental setup at ISOLDE, CERN. The properties of these nuclei were investigated over the course of two experiments. During the first experiment, nuclear spins and magnetic dipole moments were extracted from spectroscopy on manganese atoms. These nuclear properties were then compared to the predictions of two large-scale shell model effective interactions (GXPF1A [1, 2] and LNPS [3]) which use different model spaces. In the case of $^{61,63}$Mn, these results show the increasing importance of neutron excitations across the proposed N = 40 subshell closure, and of proton excitations across the Z = 28 shell gap. These measurements provide the first direct proof that proton and neutron excitations across shell gaps are playing an important role in the ground state wave functions of the neutron-rich Mn isotopes. The electric quadrupole moment provides c...

Quadrupole moments of odd-A 53−63Mn: Onset of collectivity towards N=40

Directory of Open Access Journals (Sweden)

C. Babcock

2016-09-01

Full Text Available The spectroscopic quadrupole moments of the odd–even Mn isotopes between N=28 and N=38 have been measured using bunched-beam collinear laser spectroscopy at ISOLDE, CERN. In order to increase sensitivity to the quadrupole interaction, the measurements have been done using a transition in the ion rather than in the atom, with the additional advantage of better spectroscopic efficiency. Since the chosen transition is from a metastable state, optical pumping in ISOLDE's cooler and buncher (ISCOOL was used to populate this state. The extracted quadrupole moments are compared to large-scale shell model predictions using three effective interactions, GXPF1A, LNPS and modified A3DA. The inclusion of both the 1νg9/2 and 2νd5/2 orbitals in the model space is shown to be necessary to reproduce the observed increase in the quadrupole deformation from N=36 onwards. Specifically, the inclusion of the 2νd5/2 orbital induces an increase in neutron and proton excitations across the reduced gaps at N=40 and Z=28, leading to an increase in deformation above N=36.

Effective interactions and coupling schemes in nuclei

International Nuclear Information System (INIS)

Talmi, I.

1994-01-01

Eigenstates of the shell model are obtained by diagonalization of the Hamiltonian submatrix defined by a given shell model subspace. Matrix elements of the effective nuclear interaction can be determined from experiment in a consistent way. This approach was introduced in 1956 with the 38 Cl- 40 K spectra, has been applied in many cases and its latest success is in the s, d shell. This way, general features of the effective interaction have been determined. The T=1 interaction is diagonal in the seniority scheme as clearly demonstrated in proton 1g 9/2 n and 1h 11/2 n configurations and in the description of semimagic nuclei by generalized seniority. Apart from a strong and attractive pairing term, T=1 interactions are repulsive on the average. The T=0 interaction is attractive and is the origin of the central potential well in which nucleons are bound. It breaks seniority in a major way leading to deformed nuclei and rotational spectra. Such an interaction may be approximated by a quadrupole-quadrupole interaction which is the basis of the interacting boson model. Identical nucleons with pairing and quadrupole interactions cannot be models of actual nuclei. Symmetry properties of states with maximum T are very different from those of ground states of actual nuclei. The T=1 interaction between identical nucleons cannot be approximated by pairing and quadrupole interactions. The rich variety of nuclear spectra is due to the competition between seniority conserving T=1 interactions and the T=0 quadrupole interaction between protons and neutrons. (orig.)

Dipole-dipole dispersion interactions between neutrons

OpenAIRE

Babb, James F.; Higa, Renato; Hussein, Mahir S.

2016-01-01

We investigate the long-range interactions between two neutrons utilizing recent data on the neutron static and dynamic electric and magnetic dipole polarizabilities. The resulting long-range potentials are used to make quantitative comparisons between the collisions of a neutron with a neutron and a neutron with a proton. We also assess the importance of the first pion production threshold and first excited state of the nucleon, the $\\Delta$-resonance ($J^{\\pi}$ = + 3/2, I = 3/2). We found b...

Free neutron-proton analyzing power at medium energies

International Nuclear Information System (INIS)

Newsom, C.R.

1980-01-01

In recent years, increasing efforts have been made to measure the nucleon-nucleon polarization parameters. To date, no free neutron-proton spin correlated parameters have been published in the energy range 500 to 800 MeV. Existing analyzing power data is of low precision and in most cases was obtained by quasi-free proton scattering. As a first step in determining the neutron-proton scattering matrix, the free neutron-proton analyzing power has been measured at the Los Alamos Physics Facility as a function of energy and angle. The experiment was performed by scattering a neutron beam from a polarized proton target. The neutron beam was generated by scattering 800 MeV protons from a Beryllium target and using the neutrons produced at 0 degrees. The incident energy ranged from 300 MeV to 800 MeV. The energy spread of the neutron beam made it possible to measure the analyzing power at different energies simultaneously. Angular distributions were taken from 60 to 170 degrees in the center of mass system (c.m.)

Study on neutron interactions with protons and carbon nuclei at p=4.2 GeV/c

International Nuclear Information System (INIS)

Bekmirzaev, R.N.; Muminov, M.M.; Sultanov, M.U.; Grishina, O.V.; Dolejsi, J.; Tas, P.; Trka, Z.

1988-01-01

The production of neutrons with p=4.2 GeV/c in d(C 3 H 8 ) collisions and their interaction with proton and carbon nuclei are studied. The experimental material has been obtained using the 2m propane bubble chamber irradiated by deuterons with p=4.2 GeV/c per nucleon at the Dubna synchrophasotron, JINR. The data on multiplicity and momentum characteristics of secondary particles in np and nC interactions compared with the calculations on the LUND model are obtained

Development of a Tandem-ElectroStatic-Quadrupole accelerator facility for Boron Neutron Capture Therapy (BNCT)

International Nuclear Information System (INIS)

Kreiner, A.J.; Thatar Vento, V.; Levinas, P.; Bergueiro, J.; Burlon, A.A.; Di Paolo, H.; Kesque, J.M.; Valda, A.A.; Debray, M.E.; Somacal, H.R.; Minsky, D.M.; Estrada, L.; Hazarabedian, A.; Johann, F.; Suarez Sandin, J.C.; Castell, W.; Davidson, J.; Davidson, M.; Repetto, M.; Obligado, M.; Nery, J.P.; Huck, H.; Igarzabal, M.; Fernandez Salares, A.

2008-01-01

There is a generalized perception that the availability of suitable particle accelerators installed in hospitals, as neutron sources, may be crucial for the advancement of Boron Neutron Capture Therapy (BNCT). An ongoing project to develop a Tandem-ElectroStatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based (AB)-BNCT is described here. The project goal is a machine capable of delivering 30 mA of 2.4-2.5 MeV protons to be used in conjunction with a neutron production target based on the 7 Li(p,n) 7 Be reaction slightly beyond its resonance at 2.25 MeV. A folded tandem, with 1.20-1.25 MV terminal voltage, combined with an ESQ chain is being designed and constructed. This machine is conceptually shown to be capable of accelerating a 30 mA proton beam to 2.5 MeV. These are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the 7 Li(p,n) 7 Be reaction, to perform BNCT treatment for deep-seated tumors in less than an hour. This electrostatic machine is one of the technologically simplest and cheapest solutions for optimized AB-BNCT. At present there is no BNCT facility in the world with the characteristics presented in this work. For the accelerator, results on its design, construction and beam transport calculations are discussed. Taking into account the peculiarities of the expected irradiation field, the project also considers a specific study of the treatment room. This study aims at the design of the treatment room emphasizing aspects related to patient, personnel and public radiation protection; dose monitoring; patient positioning and room construction. The design considers both thermal (for the treatment of shallow tumors) and epithermal (for deep-seated tumors) neutron beams entering the room through a port connected to the accelerator via a moderation and neutron beam shaping assembly. Preliminary results of dose calculations for the treatment room design, using the MCNP program, are presented

Inclusive production of protons, anti-protons, neutrons, deuterons and tritons in p+C collisions at 158 GeV/c beam momentum

CERN Document Server

Baatar, B.; Bartke, J.; Betev, L.; Chvala, O.; Dolejsi, J.; Eckardt, V.; Fischer, H.G.; Fodor, Z.; Karev, A.; Kolesnikov, V.; Kowalski, M.; Makariev, M.; Malakhov, A.; Mateev, M.; Melkumov, G.; Rybicki, A.; Schmitz, N.; Seyboth, P.; Stock, R.; Tinti, G.; Varga, D.; Vesztergombi, G.; Wenig, S.

2013-04-09

The production of protons, anti-protons, neutrons, deuterons and tritons in minimum bias p+C interactions is studied using a sample of 385 734 inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The data cover a phase space area ranging from 0 to 1.9 GeV/c in transverse momentum and in Feynman x from -0.80 to 0.95 for protons, from -0.2 to 0.4 for anti-protons and from 0.2 to 0.95 for neutrons. Existing data in the far backward hemisphere are used to extend the coverage for protons and light nuclear fragments into the region of intranuclear cascading. The use of corresponding data sets obtained in hadron-proton collisions with the same detector allows for the detailed analysis and model-independent separation of the three principle components of hadronization in p+C interactions, namely projectile fragmentation, target fragmentation of participant nucleons and intranuclear cascading.

Collective neutrino-pair emission due to Cooper pairing of protons in superconducting neutron stars

International Nuclear Information System (INIS)

Leinson, L.B.

2001-01-01

The neutrino emission due to formation and breaking of Cooper pairs of protons in superconducting cores of neutron stars is considered with taking into account the electromagnetic coupling of protons to ambient electrons. It is shown that collective response of electrons to the proton quantum transition contributes coherently to the complete interaction with a neutrino field and enhances the neutrino-pair production. Our calculation shows that the contribution of the vector weak current to the ννbar emissivity of protons is much larger than that calculated by different authors without taking into account the plasma effects. Partial contribution of the pairing protons to the total neutrino radiation from the neutron star core is very sensitive to the critical temperatures for the proton and neutron pairing. We show domains of these parameters where the neutrino radiation, caused by a singlet-state pairing of protons is dominating

First- and second-chance proton emission in the interactions of fast neutrons with 92Mo

International Nuclear Information System (INIS)

Qaim, S.M.; Wolfle, R.; Strohmaier, B.

1989-01-01

Cross sections were measured radiochemically for the 92 Mo(n,p) 92 Nb m and 92 Mo(n,n'p +pn+d) 91 Nb m reactions over the neutron energy range of 9.0--10.6 MeV, and for the latter reaction also between 12.6 and 14.4 MeV. Use was made of high-resolution γ-ray and x-ray spectroscopy. Statistical-model calculations taking into account precompound effects were performed for fast neutron induced reactions on 92 Mo. The calculational results agree well with the experimental data on emitted proton spectra as well as on the excitation functions of various reaction channels. The second-chance proton emission is significant for incident neutron energies above 11 MeV; between 13 and 14 MeV it is comparable to the first-chance proton emission

Proton and neutron structure functions

International Nuclear Information System (INIS)

Rock, S.

1991-01-01

New result on charged lepton scattering from hydrogen and deuterium targets by the BCDMS, NMC and SLAC collaborations have greatly increased our knowledge of the structure functions of protons and neutrons. The disagreement between the high energy muon scattering cross sections obtained by the EMC and BCDMS collaborations have been almost completely resolved by comparison with a global analysis of old and new SLAC data and a reanalysis of EMC data. We now have a consistent set of structure functions which covers an approximate range 1 ≤ Q 2 ≤ 200 (GeV/c) 2 and 0.07 ≤ x ≤ 0.7. The ratio of neutron to proton structure functions decreases with increasing Q 2 for values of x ≥ 0.1. The difference between proton and neutron structure functions approaches zero as x decreases, consistent with the expected √x behavior. (orig.)

Spatial distribution of moderated neutrons along a Pb target irradiated by high-energy protons

International Nuclear Information System (INIS)

Fragopoulou, M.; Manolopoulou, M.; Stoulos, S.; Brandt, R.; Westmeier, W.; Kulakov, B.A.; Krivopustov, M.I.; Sosnin, A.N.; Debeauvais, M.; Adloff, J.C.; Zamani Valasiadou, M.

2006-01-01

High-energy protons in the range of 0.5-7.4 GeV have irradiated an extended Pb target covered with a paraffin moderator. The moderator was used in order to shift the hard Pb spallation neutron spectrum to lower energies and to increase the transmutation efficiency via (n,γ) reactions. Neutron distributions along and inside the paraffin moderator were measured. An analysis of the experimental results was performed based on particle production by high-energy interactions with heavy targets and neutron spectrum shifting by the paraffin. Conclusions about the spallation neutron production in the target and moderation through the paraffin are presented. The study of the total neutron fluence on the moderator surface as a function of the proton beam energy shows that neutron cost is improved up to 1 GeV. For higher proton beam energies it remains constant with a tendency to decline

Proton-neutron interaction at N≅Z. First observation of the Tz = 1 nucleus 4694Pd48 in beam

International Nuclear Information System (INIS)

Gorska, M.; Grzywacz, R.; Rejmund, M.; Foltescu, D.; Roth, H.; Skeppstedt, Oe.; Schubart, R.; Grawe, H.; Heese, J.; Maier, K.H.; Spohr, K.; Fossan, D.B.

1996-01-01

Neutron deficient nuclei close to N ≅ Z are expected to exhibit a new kind of pairing based on the T=0, I=1, I max configuration, which in the (p 1/2 , g 9/2 )shell model space below 100 Sn is governed by the g 2 9/2 proton (π)-neutron(ν) interaction. The experimental data exhibit strongly bound g 2 9/2 , T=0, I=1 + ,9 + . In the experimentally barely studied far from stability upper πg 9/2 shell due to the hole-hole character of the πν interaction spin gap isomers are expected. For this reason the γ decay of isomers produced in the 58 Ni ion beams interaction with 40 Ca target. The 94 Pd isomer has been found as an example of mentioned above spin gap isomers

On the Proton Spectrum in Free Neutron beta-decay

CERN Document Server

Bunatian, G G

2000-01-01

We consider the calculations which are appropriate to acquire with a high precision, of ~1% or better, the general characteristics of weak interactions from the experiments on the free neutron beta-decay; the principle emphasis is placed on the phenomena associated with the recoil of protons. The part played by electromagnetic interactions in beta-decay is visualized, with special attention drawn to the influence of the gamma-radiation on the momentum distribution of the particles in the final state. The effect of electromagnetic interactions on the proton recoil spectrum is studied, in the light of the experiments which are carried out and planned for now. The results of the calculations, which are to be confronted with the experimental data, are presented upright in terms of the effective Lagrangian underlying the inquiry. Owing to electromagnetic interactions, the corrections to the energy distribution of protons prove to amount to the value of a few per cent. Nowadays, this is substantial to obtain with a...

A New Measurement of the 1S0 Neutron-Neutron Scattering Length using the Neutron-Proton Scattering Length as a Standard

OpenAIRE

Trotter, D. E. Gonzalez; Salinas, F.; Chen, Q.; Crowell, A. S.; Gloeckle, W.; Howell, C. R.; Roper, C. D.; Schmidt, D.; Slaus, I.; Tang, H.; Tornow, W.; Walter, R. L.; Witala, H.; Zhou, Z.

1999-01-01

The present paper reports high-accuracy cross-section data for the 2H(n,nnp) reaction in the neutron-proton (np) and neutron-neutron (nn) final-state-interaction (FSI) regions at an incident mean neutron energy of 13.0 MeV. These data were analyzed with rigorous three-nucleon calculations to determine the 1S0 np and nn scattering lengths, a_np and a_nn. Our results are a_nn = -18.7 +/- 0.6 fm and a_np = -23.5 +/- 0.8 fm. Since our value for a_np obtained from neutron-deuteron (nd) breakup agr...

Neutron polarization measurements using the pulsed-polarized proton and deuteron beams at TUNL

International Nuclear Information System (INIS)

Walter, R.L.

1981-01-01

Nanosecond wide pulses of polarized protons or deuterons at a repetition rate of 4 MHz are now routinely available for studying interactions involving outgoing neutrons. Up to 90 nA of protons and 200 nA of deuterons have been observed on target. The authors' first experiments involved the determination of the analyzing power A /SUB y/ (UJ) for a few (→p,n) and (→d,n) reactions using conventional neutron time-of-flight detection. A major program for observing polarization effects in neutron elastic scattering has been initiated. The source of polarized neutrons for this program is the 2 H(→d,n→) 3 He reaction which yields a neutron beam having 90% of the polarization of the incident deuterons

Nuclear electric quadrupole interactions in liquids entrapped in cavities

Energy Technology Data Exchange (ETDEWEB)

Furman, Gregory B., E-mail: gregoryf@bgu.ac.il; Meerovich, Victor M.; Sokolovsky, Vladimir L. [Ben Gurion University of the Negev, Physics Department (Israel)

2016-12-15

Liquids entrapped in cavities and containing quadrupole nuclei are considered. The interaction of the quadrupole moment of a nucleus with the electric field gradient is studied. In such a system, molecules are in both rotational and translational Brownian motions which are described by the diffusion equation. Solving this equation, we show that the intra- and intermolecular nuclear quadrupole interactions are averaged to zero in cavities with the size larger than several angstroms.

Neutron field characterization and dosimetry at the TRIUMF proton therapy facility

International Nuclear Information System (INIS)

Mukherjee, B.

2002-01-01

Full text: In 1972 the 500 MeV H' Cyclotron of the TRIUMF (Tri University Meson Factory) located in Vancouver, Canada became operational. Beside Meson Physics, high-energy protons of various energy and beam current levels from the TRIUMF Cyclotron are used for scientific research and biomedical applications. Recently, a 500 MeV proton beam from the cyclotron was used as the booster beam for the radioactive ion beam facility, ISAC (Isotope Separator Accelerator) and a second beam as primary irradiation source for the Proton Irradiation Facility (PIF). The major commercial applications of the PIF are the provision of high-energy proton beams for radiation hardness testing of electronic components used in space applications (NASA) and proton therapy of ocular tumors (British Columbia Proton Therapy Facility). The PIF vault was constructed within the main accelerator hall of the TRIUMF using stacks of large concrete blocks. An intense field of fast neutrons is produced during the interaction of high-energy proton beam with target materials, such as, beam stops, collimators and beam energy degraders. The leakage of such neutrons due to insufficient radiological shielding or through the shielding discontinuities may constitute a major share of the personnel radiation exposure of the radiation workers. The neutron energy distribution and dose equivalent near a lead beam stopper bombarded with 116 MeV and 65 MeV collimated proton beams at the Ocular Tumor irradiation facility were evaluated using a Bonner-Sphere Spectrometer and a REM counter respectively. The results were utilized to investigate efficacy of the existing radiological shielding of the PIF. This paper highlights experimental methods to analyze the high-energy accelerator produced neutron beam and basic guideline for the radiological shielding designs of irradiation vault of Proton Therapy facilities

Preliminary results of neutron spectroscopy in proton therapy treatment room in Ithemba Labs (South Africa); Resultados preliminares de espectrometria de neutrones en la sala de tratamiento de protonterapia en Ithemba Labs (Sudafrica)

Energy Technology Data Exchange (ETDEWEB)

Domingo, C.; Garcia-Fuste, M. J.; Amgarou, K.; Sanchez-Doblado, F.; Nieto-Camero, J.

2011-07-01

Proton beams originating from accelerators high energy hadrons lead to the production of neutrons when protons interact with the elements present in the beam line. Furthermore, when these protons are used for proton therapy treatments, their interaction with the patient also involves production of neutrons, mainly due to interactions with the C, O and N. This represents a source of unwanted radiation that increases the risk of developing second cancers by the patient. Assessment of risk factors is one of the goals of our project.

Evidence for Increased neutron and proton excitations between Mn51−63

Directory of Open Access Journals (Sweden)

C. Babcock

2015-11-01

Full Text Available The hyperfine structures of the odd-even 51−63Mn atoms (N=26−38 were measured using bunched beam collinear laser spectroscopy at ISOLDE, CERN. The extracted spins and magnetic dipole moments have been compared to large-scale shell-model calculations using different model spaces and effective interactions. In the case of 61,63Mn, the results show the increasing importance of neutron excitations across the N=40 subshell closure, and of proton excitations across the Z=28 shell gap. These measurements provide the first direct proof that proton and neutron excitations across shell gaps are playing an important role in the ground state wave functions of the neutron-rich Mn isotopes.

Quadrupole moment in the excited 2Psub(1/2) state

International Nuclear Information System (INIS)

Amusia, M.Ya.; Yakhontov, V.L.

1984-01-01

Computation of the quadrupole moment values in the 2Psub(1/2) states of hydrogen and meso-hydrogen is carried out. It is shown that allowance for the hyperfine interaction of the electron with the proton in the first order of perturbation theory results in giant values of the quadrupole moment of the atoms. (author)

Conception of a New Recoil Proton Telescope for Real-Time Neutron Spectrometry in Proton-Therapy

Science.gov (United States)

Combe, Rodolphe; Arbor, Nicolas; el Bitar, Ziad; Higueret, Stéphane; Husson, Daniel

2018-01-01

Neutrons are the main type of secondary particles emitted in proton-therapy. Because of the risk of secondary cancer and other late occurring effects, the neutron dose should be included in the out-of-field dose calculations. A neutron spectrometer has to be used to take into account the energy dependence of the neutron radiological weighting factor. Due to its high dependence on various parameters of the irradiation (beam, accelerator, patient), the neutron spectrum should be measured independently for each treatment. The current reference method for the measurement of the neutron energy, the Bonner Sphere System, consists of several homogeneous polyethylene spheres with increasing diameters equipped with a proportional counter. It provides a highresolution reconstruction of the neutron spectrum but requires a time-consuming work of signal deconvolution. New neutron spectrometers are being developed, but the main experimental limitation remains the high neutron flux in proton therapy treatment rooms. A new model of a real-time neutron spectrometer, based on a Recoil Proton Telescope technology, has been developed at the IPHC. It enables a real-time high-rate reconstruction of the neutron spectrum from the measurement of the recoil proton trajectory and energy. A new fast-readout microelectronic integrated sensor, called FastPixN, has been developed for this specific purpose. A first prototype, able to detect neutrons between 5 and 20 MeV, has already been validated for metrology with the AMANDE facility at Cadarache. The geometry of the new Recoil Proton Telescope has been optimized via extensive Geant4 Monte Carlo simulations. Uncertainty sources have been carefully studied in order to improve simultaneously efficiency and energy resolution, and solutions have been found to suppress the various expected backgrounds. We are currently upgrading the prototype for secondary neutron detection in proton therapy applications.

Measurement of the angular distribution of neutron-proton scattering at 10 MeV

International Nuclear Information System (INIS)

Haight, R.C.; Bateman, F.B.; Grimes, S.M.; Brient, C.E.; Massey, T.N.; Wasson, O.A.; Carlson, A.D.; Zhou, H.

1995-01-01

The relative angular distribution of neutrons scattered from protons was measured at an incident neutron energy of 10 MeV at the Ohio University Accelerator Laboratory. An array of 11 detector telescopes at laboratory angles of 0 to 60 degrees was used to detect recoil protons from neutron interactions with a CH 2 (polypropylene) target. Data for 7 of these telescopes were obtained with one set of electronics and are presented here. These data, from 108 to 180 degrees for the center-of-mass scattering angles, have a small slope which agrees better with angular distributions predicted by the Arndt phase shifts than with the ENDF/B-VI angular distribution

The unusual high-spin isomer in 182Os and the proton-neutron interaction in high-j orbitals

International Nuclear Information System (INIS)

Tajima, Naoki; Onishi, Naoki

1986-01-01

An intermediate-coupling model of particle-plus-γ-soft-rotor is applied to a qualitative interpretation of the recently observed isomer of 182 Os and the characteristic decay pattern. In the model h 11/2 protons and i 13/2 neutrons are incorporated at the same time. The isomer is realized as the bandhead of a two-proton - two-neutron-aligned band from the present calculation. (orig.)

Spin, quadrupole moment, and deformation of the magnetic-rotational band head in (193)Pb

CERN Document Server

Balabanski, D L; Iordachescu, A; Bazzacco, D; Brandolini, F; Bucurescu, D; Chmel, S; Danchev, M; De Poli, M; Georgiev, G; Haas, H; Hubel, H; Marginean, N; Menegazzo, R; Neyens, G; Pavan, P; Rossi Alvarez, C; Ur, C A; Vyvey, K; Frauendorf, S

2011-01-01

The spectroscopic quadrupole moment of the T(1/2) = 9.4(5) ns isomer in (193)Pb at an excitation energy E(ex) = (2585 + x) keV is measured by the time-differential perturbed angular distribution method as vertical bar Q(s)vertical bar = 2.6(3) e b. Spin and parity I(pi) = 27/2(-) are assigned to it based on angular distribution measurements. This state is the band head of a magnetic-rotational band, described by the coupling of a neutron hole in the 1i(13/2) subshell with the (3s(1/2)(-2)1h(9/2)1i(13/2))(11-) proton excitation. The pairing-plus-quadrupole tilted-axis cranking calculations reproduce the measured quadrupole moment with a moderate oblate deformation epsilon(2) = -0.11, similar to that of the 11(-)proton intruder states, which occur in the even-even Pb nuclei in the region. This is the first direct measurement of a quadrupole moment and thus of the deformation of a magnetic-rotational band head.

Recoil-proton fast-neutron counter telescope

Energy Technology Data Exchange (ETDEWEB)

Pavan, P.; Toniolo, D.; Zago, G.; Zannoni, R. (Padua Univ. (Italy). Ist. di Fisica); Galeazzi, G.; Bressanini, G.

1981-12-01

A recoil-proton neutron counter telescope is described composed of a solid-state silicon transmission detector and a NE 102 A plastic scintillator, measuring the energy loss, the energy of the recoil protons and the time of flight between the two detectors. The counter exposed to monoenergetic neutron beams of energy from 6 to 20 MeV presents a low background and a moderate energy resolution. Its absolute efficiency is calculated up to 50 MeV.

Recoil-proton fast-neutron-counter telescope

Energy Technology Data Exchange (ETDEWEB)

Galeazzi, G.; Pavan, P.; Toniolo, D.; Zago, G.; Zannoni, R.; Bressanini, G.

1981-01-01

A proton-recoil neutron counter telescope is described composed of a solid state silicon transmission detector and a NE 102 A plastic scintillator, measuring the energy loss, the energy of the recoil protons and the time-of-flight between the two detectors. The counter exposed to monoenergetic neutron beams of energy from 6 to 20 MeV, presents a low background and a moderate energy resolution. Its absolute efficiency is calculated up to 50 MeV.

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

Science.gov (United States)

Pahlavani, M. R.; Firoozi, B.

2016-09-01

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

Measurement of the quadrupole moments of the strongly deformed nuclei 18173Ta108 and 18375Re108 by hyperfine interaction in metals

International Nuclear Information System (INIS)

Netz, G.

1974-01-01

The quadrupole moments of two single particle proton states were measured in the strongly deformed nuclei region. Both measurements are independent of model because the field gradient is known in a rhenium lattice as well as at the nucleus site of a rhenium atom and also at the nucleus site of an incorporated tantalum atom. The quadrupole moments could thus be directly extracted from the quadrupole interaction frequency, the product of quadrupole moment and field gradient. For the 482 keV state (I = 5/2 + ) in 181 73 Ta 108 one obtains a quadrupole moment of: Q (5/2) = 2.5 +- 0.2 barn. For the 496 keV state (I = 9/2 - ) in 183 75 Re 108 , a quadrupole moment of: Q (0/2) = 3.6 +- 0.4 barn is found. This value agrees well with other experimental data within the framework of the collective model. (orig./LH) [de

Dipole-dipole dispersion interactions between neutrons

Energy Technology Data Exchange (ETDEWEB)

Babb, James F. [Harvard-Smithsonian Center for Astrophysics, ITAMP, Cambridge, MA (United States); Higa, Renato [Universidade de Sao Paulo, Instituto de Fisica, Sao Paulo (Brazil); Hussein, Mahir S. [Universidade de Sao Paulo, Instituto de Fisica, Sao Paulo (Brazil); Universidade de Sao Paulo, Instituto de Estudos Avancados, Sao Paulo (Brazil); Departamento de Fisica, Instituto Tecnologico de Aeronautica, CTA, Sao Jose dos Campos (Brazil)

2017-06-15

We investigate the long-range interactions between two neutrons utilizing recent data on the neutron static and dynamic electric and magnetic dipole polarizabilities. The resulting long-range potentials are used to make quantitative comparisons between the collisions of a neutron with a neutron and a neutron with a proton. We also assess the importance of the first pion production threshold and first excited state of the nucleon, the Δ-resonance (J{sup π} = +3/2, I = 3/2). We found both dynamical effects to be quite relevant for distances r between ∝ 50 fm up to ∝ 10{sup 3} fm in the nn system, the neutron-wall system and in the wall-neutron-wall system, reaching the expected asymptotic limit beyond that. Relevance of our findings to the confinement of ultra cold neutrons inside bottles is discussed. (orig.)

Two-proton knockout on neutron-rich nuclei

International Nuclear Information System (INIS)

Bazin, D.; Brown, B.A.; Campbell, C.M.; Church, J.A.; Dinca, D.C.; Enders, J.; Gade, A.; Glasmacher, T.; Hansen, P.G.; Mueller, W.F.; Olliver, H.; Perry, B.C.; Sherrill, B.M.; Terry, J.R.; Tostevin, J.A.

2004-01-01

Two-proton knockout reactions on neutron-rich nuclei [Phys. Rev. Lett. 91 (2003) 012501] have been studied in inverse kinematics at intermediate energy. Strong evidence that the two-proton removal from a neutron-rich system proceeds as a direct reaction is presented, together with a preliminary theoretical discussion of the partial cross sections based on eikonal reaction theory and the many-body shell model. They show that this reaction can be used to characterize the wave functions of the projectiles and holds great promise for the study of neutron-rich nuclei

Properties of Localized Protons in Neutron Star Matter at Finite Temperatures

Science.gov (United States)

Szmaglinski, A.; Kubis, S.; Wójcik, W.

2014-02-01

We study properties of the proton component of neutron star matter for realistic nuclear models. Vanishing of the nuclear symmetry energy implies proton-neutron separation in dense nuclear matter. Protons which form admixture tend to be localized in potential wells. Here, we extend the description of proton localization to finite temperatures. It appears that the protons are still localized at temperatures typical for hot neutron stars. That fact has important astrophysical consequences. Moreover, the temperature inclusion leads to unexpected results for the behavior of the proton localized state.

On the properties of nuclear matter with an excess of neutrons, of spin-up neutrons and of spin-up protons using the Skyrme interaction

International Nuclear Information System (INIS)

Hassan, M.Y.M.; Ramadan, S.

1983-11-01

The binding energy of nuclear matter with an excess of neutrons, of spin-up neutrons, and of spin-up protons (characterized by the corresponding parameters, αsub(tau)=(N-Z/A), αsub(n)=(Nup-Ndown)/A, and αsub(rho)=(Zup-Zdown)/A), contains three symmetry energies: the isospin symmetry energy Esub(tau), the spin symmetry energy Esub(σ), and spin-isospin symmetry energy Esub(σtau). General expressions for Esub(σ), Esub(tau) and Esub(σtau) are given in the case of the Skyrme interaction. These values are compared with previous results obtained by Dabrowski and Haensel (DH) with Brueckner-Gammel-Thaler, the Hamada-Johnston, and the Reid soft core nucleon-nucleon potentials. The spin, isospin and spin-isospin dependent parts of the single-particle potential in nuclear matter are also calculated using the Skyrme interaction. The spin, isospin and spin-isospin incompressibility are calculated using the Skyrme interaction. The spin-spin part of the optical model potential is estimated. The results are compared with those of Dabrowski and Haensel (DH) and Hassan and Ramadan. (author)

Proton induction linacs as high-intensity neutron sources

International Nuclear Information System (INIS)

Keefe, D.; Hoyer, E.

1981-01-01

Proton induction linacs are explored as high intensity neutron sources. The induction linac - concept, properties, experience with electrons, and possibilities - and its limitations for accelerating ions are reviewed. A number of proton induction linac designs are examined with the LIACEP program and general conclusions are given. Results suggest that a proton induction accelerator of the lowest voltage, consistent with good neutron flux, is preferred and could well be cost competitive with the usual rf linac/storage ring designs. (orig.)

Study of proton-induced reactions and correlation with fast-neutron scattering

International Nuclear Information System (INIS)

Hansen, L.F.

1982-01-01

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 232 Th and 238 U

Measurements of quadrupole interaction frequencies of long-lived isomers with the level mixing spectroscopy (LEMS) method

International Nuclear Information System (INIS)

Neyens, G.; Nouwen, R.; S'heeren, G.; Bergh, M. van den; Coussement, R.

1993-01-01

The level mixing spectroscopy (LEMS) method has proven to be a very useful method to determine the quadrupole interaction frequency of an isomer in a solid host. Especially in the 'difficult' cases, e.g. when the isomeric lifetime is very long or its spin is very high, the method yields valuable information which is not accessible with other methods (such as TDPAD). Since the development of the method some years ago, many experiments have been performed on high spin isomers in the lead region. The static quadrupole moment of isomers with lifetimes ranging from 20 ns up to 13 ms and spins up to 65/2h have been determined in neutron deficient isotopes of Bi, At, Fr and Ra. (orig.)

1S0 proton superfluidity in neutron star matter: Impact of bulk properties

International Nuclear Information System (INIS)

Tanigawa, Tomonori; Matsuzaki, Masayuki; Chiba, Satoshi

2004-01-01

We study the 1 S 0 proton pairing gap in neutron star matter putting emphasis on influence of the Dirac effective mass and the proton fraction on the gap within the relativistic Hartree-Bogoliubov model. The gap equation is solved using the Bonn-B potential as a particle-particle channel interaction. It is found that the maximal pairing gap Δ max is 1-2 MeV, which has a strong correlation with the Dirac effective mass. Hence we suggest that it serves as a guide to narrow down parameter sets of the relativistic effective field theory. Furthermore, the more slowly protons increase with density in the core region of neutron stars, the wider the superfluid range and the slightly lower the peak of the gap become

Neutron detection efficiency determinations for the TUNL neutron-neutron and neutron-proton scattering-length measurements

International Nuclear Information System (INIS)

Trotter, D.E. Gonzalez; Meneses, F. Salinas; Tornow, W.; Crowell, A.S.; Howell, C.R.; Schmidt, D.; Walter, R.L.

2009-01-01

The methods employed and the results obtained from measurements and calculations of the detection efficiency for the neutron detectors used at Triangle Universities Nuclear Laboratory (TUNL) in the simultaneous determination of the 1 S 0 neutron-neutron and neutron-proton scattering lengths a nn and a np , respectively, are described. Typical values for the detector efficiency were 0.3. Very good agreement between the different experimental methods and between data and calculation has been obtained in the neutron energy range below E n =13MeV.

Spin observables in proton-neutron scattering at intermediate energy

International Nuclear Information System (INIS)

Spinka, H.

1986-05-01

A summary of np elastic scattering spin measurements at intermediate energy is given. Preliminary results from a LAMPF experiment to measure free neutron-proton elastic scattering spin-spin correlation parameters are presented. A longitudinally polarized proton target was used. These measurements are part of a program to determine the neutron-proton amplitudes in a model independent fashion at 500, 650, and 800 MeV. Some new proton-proton total cross sections in pure helicity states (Δσ/sub L/(pp)) near 3 GeV/c are also given. 37 refs., 2 figs

The isovector quadrupole resonance in yttrium excited by neutron radiative capture

International Nuclear Information System (INIS)

Zorro, R.; Bergqvist, I.

1987-01-01

In order to investigate the properties of the isovector giant quadrupole resonance (ΔT=1, ΔS=0) in the A=90 mass region, gamma-ray spectra from the reaction 89 Y(n,γ) 90 Y were recorded at several neutron energies in the energy range 12 to 27 MeV at 55 0 , 90 0 and 125 0 . The measured fore-aft asymmetry for the ground-state transition is very small in the low-energy region, but becomes appreciable above a neutron energy of 18 MeV. The observed asymmetry is attributed to interference between radiation from the isovector giant quadrupole resonance and radiation of opposite parity (from the high-energy tail of the giant dipole resonance and direct E1 capture). The data obtained in the present work, interpreted in terms of the direct-semidirect capture model, indicate that the excitation energy of the isovector E2 resonance in 90 Y is 26 ± 1 MeV. The data are consistent with a resonance width of 10 ± 2 MeV and with complete exhaustion of the energy-weighted sum rule for the lower isospin component of the resonance. (orig.)

Particle-number fluctuations and neutron-proton pairing effects on proton and neutron radii of even-even N Almost-Equal-To Z nuclei

Energy Technology Data Exchange (ETDEWEB)

Douici, M.; Allal, N. H.; Fellah, M.; Benhamouda, N.; Oudih, M. R. [Laboratoire de Physique Theorique, Faculte de Physique, USTHB BP 32 El-Alia, 16111 Bab-Ezzouar, Alger (Algeria) and Institut des Sciences et Technologie, Centre Universitaire de Khemis Miliana, Route de Theniet-El-Had, 44225 Khemis-Milia (Algeria); Laboratoire de Physique Theorique, Faculte de Physique, USTHB BP 32 El-Alia, 16111 Bab-Ezzouar, Alger (Algeria) and Centre de Recherche Nucleaire d' Alger, COMENA, BP399 Alger-Gare, Alger (Algeria); Laboratoire de Physique Theorique, Faculte de Physique, USTHB BP 32 El-Alia, 16111 Bab-Ezzouar, Alger (Algeria)

2012-10-20

The particle-number fluctuation effect on the root-mean-square (rms) proton and neutron radii of even-even N Almost-Equal-To Z nuclei is studied in the isovector neutron-proton (np) pairing case using an exact particle-number projection method and the Woods-Saxon model.

Neutron detection efficiency determinations for the TUNL neutron-neutron and neutron-proton scattering-length measurements

Energy Technology Data Exchange (ETDEWEB)

Trotter, D.E. Gonzalez [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)], E-mail: crowell@tunl.duke.edu; Meneses, F. Salinas [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Tornow, W. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)], E-mail: tornow@tunl.duke.edu; Crowell, A.S.; Howell, C.R. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Schmidt, D. [Physikalisch-Technische Bundesanstalt, D-38116, Braunschweig (Germany); Walter, R.L. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

2009-02-11

The methods employed and the results obtained from measurements and calculations of the detection efficiency for the neutron detectors used at Triangle Universities Nuclear Laboratory (TUNL) in the simultaneous determination of the {sup 1}S{sub 0} neutron-neutron and neutron-proton scattering lengths a{sub nn} and a{sub np}, respectively, are described. Typical values for the detector efficiency were 0.3. Very good agreement between the different experimental methods and between data and calculation has been obtained in the neutron energy range below E{sub n}=13MeV.

Effects of the residual proton-neutron interaction in the development of collectivity in nuclei

International Nuclear Information System (INIS)

Casten, R.F.

1990-01-01

The widespread effects of the residual T=0 proton-neutron (p-n) interaction in the evolution of nuclear structure are discussed. Although these effects in inducing single nucleon configuration mixing, and hence in the development of non-spherical nuclear shapes, collectivity, and the associated shape and phase transitions have been known for four decades, it is only in recent years that their deep ramifications have become more fully appreciated. This had led to a unified phenomenological understanding of the role of the p-n interaction in nuclear collectivity and to, for example, the proposal of the N p N n scheme and the associated concept of the P factor, which is a normalized value of N p N n reflecting the average number of p-n interactions per valence nucleon. Simultaneously, experimentally-determined p-n matrix elements for many nuclei have been extracted: they disclose striking anomalies for N=Z nuclei, and intriguing microstructure. These developments and empirical results will be discussed along with microscopic calculations that can be used to interpret them. 18 refs., 13 figs

Neutron-proton bremsstrahlung studies using the white neutron source at the LAMPF/WNR

International Nuclear Information System (INIS)

Wender, S.A.; Nelson, R.O.; Schillaci, M.E.; Blann, M.

1990-01-01

Nucleon-nucleon bremsstrahlung is a few-body radiative process that provides insight into several areas of nuclear physics. It is one of the simplest systems for studying the off-shell behavior of the nucleon-nucleon potential. The physics involved in neutron-proton bremsstrahlung (NPB) is significantly different from that of proton-proton bremsstrahlung (PPB). In particular, NPB cross sections are much larger than PPB cross sections because NPB allows E1 radiation, and the contribution to the cross section from the meson exchange currents has been calculated to be as large as the contributions from external radiation. To date there have been essentially four NPB experiments. These measurements have covered only a small part of the available phase space. A major experimental problem in performing these measurements has been the lack of a suitable intense, high-energy neutron beam. We are planning a measurement of the NPB cross section using the white neutron source at the WNR target area at the LAMPF accelerator. We plant to implement the experiment in three phases. In this first state, we shall measure inclusive hard-photon production using a multi-element gamma-ray telescope that is insensitive to neutrons. In the second phase, we shall measure the bremsstrahlung gamma-rays in coincidence with recoil protons. In the last phase, we shall detect the scattered neutrons in coincidence with the recoil protons and gamma rays. 8 refs., 6 figs

Estimation dose of secondary neutrons in proton therapy

International Nuclear Information System (INIS)

Urban, T.

2014-01-01

Most of proton therapy centers for cancer treatment are still based on the passive scattering, in some of them there is system of the active scanning installed as well. The aim of this study is to compare secondary neutron doses in and around target volumes in proton therapy for both treatment techniques and for different energies and profile of incident proton beam. The proton induced neutrons have been simulated in the very simple geometry of tissue equivalent phantom (imitate the patient) and scattering and scanning nozzle, respectively. In simulations of the scattering nozzle, different types of scattering filters and brass collimators have been used as well. 3D map of neutron doses in and around the chosen/potential target volume in the phantom/patient have been evaluated and compared in the context of the dose deposited in the target volume. Finally, the simulation results have been compared with published data. (author)

A recoil-proton fast-neutron counter telescope

International Nuclear Information System (INIS)

Pavan, P.; Toniolo, D.; Zago, G.; Zannoni, R.; Galeazzi, G.; Bressanini, G.

1981-01-01

A recoil-proton neutron counter telescope is described composed of a solid-state silicon transmission detector and a NE 102 A plastic scintillator, measuring the energy loss, the energy of the recoil protons and the time of flight between the two detectors. The counter exposed to monoenergetic neutron beams of energy from 6 to 20 MeV presents a low background and a moderate energy resolution. Its absolute efficiency is calculated up to 50 MeV. (author)

Poster - 25: Neutron Spectral Measurements around a Scanning Proton Beam

Energy Technology Data Exchange (ETDEWEB)

Kildea, John; Enger, Shirin; Maglieri, Robert; Mirzakhanian, Lalageh; Dahlgren, Christina Vallhagen; Dubeau, Jacques; Witharana, Sanjeeva [Medical Physics Unit, McGill University Health Centre, Medical Physics Unit, McGill University, Medical Physics Unit, McGill University, Medical Physics Unit, McGill University, Skandion Clinic, Detec Inc., Gatineau, Quebec, Detec Inc., Gatineau, Quebec (Canada)

2016-08-15

We describe the measurements of neutron spectra that we undertook around a scanning proton beam at the Skandion proton therapy clinic in Uppsala, Sweden. Measurements were undertaken using an extended energy range Nested Neutron Spectrometer (NNS, Detec Inc., Gatineau, QC) operated in pulsed and current mode. Spectra were measured as a function of location in the treatment room and for various Bragg peak depths. Our preliminary unfolded data clearly show the direct, evaporation and thermal neutron peaks and we can show the effect on the neutron spectrum of a water phantom in the primary proton beam.

Reduction of the secondary neutron dose in passively scattered proton radiotherapy, using an optimized pre-collimator/collimator

International Nuclear Information System (INIS)

Brenner, David J; Elliston, Carl D; Hall, Eric J; Paganetti, Harald

2009-01-01

Proton radiotherapy represents a potential major advance in cancer therapy. Most current proton beams are spread out to cover the tumor using passive scattering and collimation, resulting in an extra whole-body high-energy neutron dose, primarily from proton interactions with the final collimator. There is considerable uncertainty as to the carcinogenic potential of low doses of high-energy neutrons, and thus we investigate whether this neutron dose can be significantly reduced without major modifications to passively scattered proton beam lines. Our goal is to optimize the design features of a patient-specific collimator or pre-collimator/collimator assembly. There are a number of often contradictory design features, in terms of geometry and material, involved in an optimal design. For example, plastic or hybrid plastic/metal collimators have a number of advantages. We quantify these design issues, and investigate the practical balances that can be achieved to significantly reduce the neutron dose without major alterations to the beamline design or function. Given that the majority of proton therapy treatments, at least for the next few years, will use passive scattering techniques, reducing the associated neutron-related risks by simple modifications of the collimator assembly design is a desirable goal.

Neutron and proton optical potentials

International Nuclear Information System (INIS)

Hansen, L.F.

1985-11-01

The neutron and proton optical model potentials (OMP) are discussed in terms of microscopic (MOMP) and phenomenological (POMP) models. For the MOMP, two approaches are discussed, the nucleus matter approach [Jeukenne-Lejeune-Mahaux (JLM) and Brieva-Rook-von Geramb (BRVG), potentials] and the finite nuclei approach (Osterfeld and Madsen). For the POMP, the Lane charge-exchange potential and its validity over a wide mass range is reviewed. In addition to the Lane symmetry term, the Coulomb correction to both the real and imaginary parts of the OMP is discussed for the above models. The use of the OMP to calculate collective inelastic scattering and observed differences between the neutron- and proton-deformation parameters is also illustrated. 25 refs., 3 figs

Fe/sup 57/ polarimetry based on quadrupole interaction

Energy Technology Data Exchange (ETDEWEB)

Gonser, U; Sakai, H; Keune, W [Universitaet des Saarlandes, Saarbruecken (F.R. Germany). Fachbereich Angewandte Physik

1976-01-01

A quadrupole Fe/sup 57/ polarimeter consisting of single crystals of LiNbO/sub 3/:Co/sup 57/ as source (polarizer) and of FeCO/sub 3/ (siderite) as absorber (analyzer) is described. The quadrupole interactions of the two materials are nearly equal in magnitude but opposite in sign and in addition the asymmetry parameter eta equal approximately 0.

Effect of large neutron excess in the region of the Giant Dipole and Quadrupole Resonance

CERN Document Server

Lanza, E G

1999-01-01

We study the dipole and quadrupole modes of neutron rich nuclei within the selfconsistent HF + RPA. The presence of neutron skin enhances the mixing of isoscalar and isovector modes. Then it is possible to excite modes of isovector character by an isoscalar probe. In particular we analize the excitation of dipole modes by alpha scattering. The excitation of compressional isoscalar mode is also studied.

Neutrons in active proton therapy. Parameterization of dose and dose equivalent

Energy Technology Data Exchange (ETDEWEB)

Schneider, Uwe; Haelg, Roger A. [Univ. of Zurich (Switzerland). Dept. of Physics; Radiotherapy Hirslanden AG, Aarau (Switzerland); Lomax, Tony [Paul Scherrer Institute, Villigen (Switzerland). Center for Proton Therapy

2017-08-01

One of the essential elements of an epidemiological study to decide if proton therapy may be associated with increased or decreased subsequent malignancies compared to photon therapy is an ability to estimate all doses to non-target tissues, including neutron dose. This work therefore aims to predict for patients using proton pencil beam scanning the spatially localized neutron doses and dose equivalents. The proton pencil beam of Gantry 1 at the Paul Scherrer Institute (PSI) was Monte Carlo simulated using GEANT. Based on the simulated neutron dose and neutron spectra an analytical mechanistic dose model was developed. The pencil beam algorithm used for treatment planning at PSI has been extended using the developed model in order to calculate the neutron component of the delivered dose distribution for each treated patient. The neutron dose was estimated for two patient example cases. The analytical neutron dose model represents the three-dimensional Monte Carlo simulated dose distribution up to 85 cm from the proton pencil beam with a satisfying precision. The root mean square error between Monte Carlo simulation and model is largest for 138 MeV protons and is 19% and 20% for dose and dose equivalent, respectively. The model was successfully integrated into the PSI treatment planning system. In average the neutron dose is increased by 10% or 65% when using 160 MeV or 177 MeV instead of 138 MeV. For the neutron dose equivalent the increase is 8% and 57%. The presented neutron dose calculations allow for estimates of dose that can be used in subsequent epidemiological studies or, should the need arise, to estimate the neutron dose at any point where a subsequent secondary tumour may occur. It was found that the neutron dose to the patient is heavily increased with proton energy.

Model-Independent Analysis of the Neutron-Proton Final-State Interaction Region in the $\\pi\\pi \\to pn\\pi^+$ Reaction

CERN Document Server

Uzikov, Yu N

2001-01-01

Experimental data on the \\pi\\pi\\to pn\\pi^+ reaction measured in an exclusive two-arm experiment at 800 MeV show a narrow peak arising from the strong proton-neutron final-state interaction. It was claimed, within the framework of a certain model, that this peak contained up to a 25 % spin-singlet final-state contribution. By comparing the data with those of \\pi\\pi\\to d\\pi^+ in a largely model-independent way, it is here demonstrated that at all the angles measured the whole of the peak could be explained as being due to spin-triplet final states, with the spin-singlet being at most a few percent. Good qualitative agreement with the measured proton analysing power is also found within this approach.

Measurement of the North-South asymmetry in the solar proton albedo neutron flux

International Nuclear Information System (INIS)

Ifedili, S.O.

1979-01-01

The solar proton albedo neutron flux in the range 10 -2 --10 7 eV measured by a neutron detector on board the Ogo 6 satellite was examined for north-south asymmetry. For the solar proton event of December 19, 1969, the S/N ratio of the solar proton albedo neutron rate at geomagnetic latitude lambda>70 0 was 1.61 +- 0.27 during the event, while for the November 2, 1969, event at 40 0 0 and altitudes ranging from 700 km to 800 km the solar proton albedo neutron rate was 0.40 +- 0.10 count/s in the north and 0.00 +- 0.10 count/s in the south. During the solar proton event of December 18, 1969, the N/S ratio of the solar proton albedo neutron rate at lambda>70 0 was 1.00 +- 0.26. The results are consistent with the expected N-S asymmetry in the solar proton flux. An interplanetary proton anisotropy with the interplanetary magnetic field polarity away from the sun corresponded to larger fluxes of solar proton albedo neutrons at the north polar cap than at the south, while an interplanetary proton anisotropy with the interplanetary magnetic field polarity toward the sun corresponded to larger fluxes of solar proton albedo neutrons at the south polar cap than at the north. This evidence favors the direct access of solar protons to the earth's polar caps via the merged interplanetary and geomagnetic field lines

Structural design study of a proton beam window for a 1-MW spallation neutron source

CERN Document Server

Teraoku, T; Ishikura, S; Kaminaga, M; Maekawa, F; Meigo, S I; Terada, A

2003-01-01

A 1-MW spallation neutron source aiming at materials and life science researches will be constructed under the JAERI-KEK High-intensity Proton Accelerator Project (J-PARC). A proton beam passes through a proton beam window, and be injected into a target of the neutron source. The proton beam window functions as a boundary wall between a high vacuum area in the proton beam line and a helium atmosphere at about atmospheric pressure in a helium vessel which contains the target and moderators. The proton beam window is cooled by light water because high heat-density is generated in the window material by interactions with the proton beam. Then, uniformity of the water flow is requested at the window to suppress a hot-spot that causes excessive thermal stress and cooling water boiling. Also, the window has to be strong enough in its structure for inner stress due to water pressure and thermal stress due to heat generation. In this report, we propose two types of proton beam windows; one flat-type that is easy to m...

A neutron beam polarizer for study of parity violation in neutron-nucleus interactions

International Nuclear Information System (INIS)

Penttilae, S.I.; Bowman, J.D.; Frankle, C.M.; Seestrom, S.J.; Yen, Yi-Fen; Delheij, P.P.J.; Haase, D.G.; Postma, H.

1994-01-01

A dynamically-polarized proton target operating at 5 Tesla and 1 K has been built to, neutron beam for studies of parity violation in compound-nuclear resonances. Nearly 0.9 proton polarization was obtained in an electron-beam irradiated ammonia target. This was used to produce a neutron beam polarization of 0.7 at epithermal energies. The combination of the polarized proton target and the LANSCE spallation neutron source produces the most intense pulsed polarized epithermal neutron beam in the world. The neutron-beam polarizer is described and methods to determine neutron beam polarization are presented

Neutron scattering from polarised proton domains

CERN Document Server

Van den Brandt, B; Kohbrecher, J; Konter, J A; Mango, S; Glattli, H; Leymarie, E; Grillo, I; May, R P; Jouve, H; Stuhrmann, H B; Stuhrmann, H B; Zimmer, O

2002-01-01

Time-dependent small-angle polarised neutron scattering from domains of polarised protons has been observed at the onset of dynamic nuclear polarisation in a frozen solution of 98% deuterated glycerol-water at 1 K containing a small concentration of paramagnetic centres (EHBA-Cr sup V). Simultaneous NMR measurements show that the observed scattering arises from protons around the Cr sup V -ions which are polarised to approx 10% in a few seconds, much faster than the protons in the bulk. (authors)

Emulation of neutron irradiation effects with protons: validation of principle

International Nuclear Information System (INIS)

Was, G.S.; Busby, J.T.; Allen, T.; Kenik, E.A.; Jensson, A.; Bruemmer, S.M.; Gan, J.; Edwards, A.D.; Scott, P.M.; Andreson, P.L.

2002-01-01

This paper presents the results of the irradiation, characterization and irradiation assisted stress corrosion cracking (IASCC) behavior of proton- and neutron-irradiated samples of 304SS and 316SS from the same heats. The objective of the study was to determine whether proton irradiation does indeed emulate the full range of effects of in-reactor neutron irradiation: radiation-induced segregation (RIS), irradiated microstructure, radiation hardening and IASCC susceptibility. The work focused on commercial heats of 304 stainless steel (heat B) and 316 stainless steel (heat P). Irradiation with protons was conducted at 360 deg. C to doses between 0.3 and 5.0 dpa to approximate those by neutron irradiation at 275 deg. C over the same dose range. Characterization consisted of grain boundary microchemistry, dislocation loop microstructure, hardness as well as stress corrosion cracking (SCC) susceptibility of both un-irradiated and irradiated samples in oxygenated and de-oxygenated water environments at 288 deg. C. Overall, microchemistry, microstructure, hardening and SCC behavior of proton- and neutron-irradiated samples were in excellent agreement. RIS analysis showed that in both heats and for both irradiating particles, the pre-existing grain boundary Cr enrichment transformed into a 'W' shaped profile at 1.0 dpa and then into a 'V' shaped profile between 3.0 and 5.0 dpa. Grain boundary segregation of Cr, Ni, Si, and Mo all followed the same trends and agreed well in magnitude. The microstructure of both proton- and neutron-irradiated samples was dominated by small, faulted dislocation loops. Loop size distributions were nearly identical in both heats over a range of doses. Saturated loop size following neutron irradiation was about 30% larger than that following proton irradiation. Loop density increased with dose through 5.0 dpa for both particle irradiations and was a factor of 3 greater in neutron-irradiated samples vs. proton-irradiated samples. Grain boundary

A neutron beam polarizer for study of parity violation in neutron-nucleus interactions

International Nuclear Information System (INIS)

Penttilae, S.I.; Bowman, J.D.; Delheij, P.P.; Frankle, C.M.; Haase, D.G.; Postma, H.; Seestrom, S.J.; Yen, Y.

1995-01-01

A dynamically-polarized proton target operating at 5 Tesla and 1 K has been built to polarize an epithermal neutron beam for studies of parity violation in compound-nuclear resonances. Nearly 0.9 proton polarization was obtained in an electron-beam irradiated ammonia target. This was used to produce a neutron beam polarization of 0.7 at epithermal energies. The combination of the polarized proton target and the LANSCE spallation neutron source produces the most intense pulsed polarized epithermal neutron beam in the world. The neutron-beam polarizer is described and methods to determine neutron beam polarization are presented. copyright 1995 American Institute of Physics

Measurement of neutrino and proton asymmetry in the decay of polarized neutrons

International Nuclear Information System (INIS)

Schumann, M.

2007-01-01

The Standard Model of Particle Physics is in excellent agreement with all experimental results. However, it is not believed to be the most fundamental theory. It requires, for example, too many free parameters and is not able to explain the existence of effects such as parity-violation or CP-violation. Thus measurements have to be performed to probe the Standard Model and to search for ''new physics''. An ideal laboratory for this is the decay of the free polarized neutron. In this thesis, we present measurements of the neutrino asymmetry B and the proton asymmetry C in neutron decay. These coefficients describe the correlation between neutron spin and momentum of the respective particle, and provide detailed information on the structure of the underlying theory. The experiment was performed using the electron spectrometer PERKEO II installed at the Institut Laue-Langevin (ILL). It was equipped with a combined electron-proton detector to reconstruct the neutrino in a coincidence measurement. The uncertainty of our neutrino asymmetry result, B=0.9802(50), is comparable to the present best measurement, and, for the first time ever, we obtained a precise value for the proton asymmetry, C=-0.2377(36). Both results are used to analyze neutron decay for hints on ''Physics beyond the Standard Model'' by studying possible admixtures of right-handed currents and of scalar and tensor couplings to the interaction. (orig.)

Neutron-decay Protons from Solar Flares as Seed Particles for CME-shock Acceleration in the Inner Heliosphere

Energy Technology Data Exchange (ETDEWEB)

Murphy, Ronald J. [Code 7650, Naval Research Laboratory, Washington, DC 20375 (United States); Ko, Yuan-Kuen, E-mail: ronald.murphy@nrl.navy.mil, E-mail: yuan-kuen.ko@nrl.navy.mil [Code 7680, Naval Research Laboratory, Washington, DC 20375 (United States)

2017-09-01

The protons in large solar energetic particle events are accelerated in the inner heliosphere by fast shocks produced by coronal mass ejections. Unless there are other sources, the protons these shocks act upon would be those of the solar wind (SW). The efficiency of the acceleration depends on the kinetic energy of the protons. For a 2000 km s{sup −1} shock, the most effective proton energies would be 30–100 keV; i.e., within the suprathermal tail component of the SW. We investigate one possible additional source of such protons: those resulting from the decay of solar-flare-produced neutrons that escape from the Sun into the low corona. The neutrons are produced by interactions of flare-accelerated ions with the solar atmosphere. We discuss the production of low-energy neutrons in flares and their decay on a interplanetary magnetic field line near the Sun. We find that even when the flaring conditions are optimal, the 30–100 keV neutron-decay proton density produced by even a very large solar flare would be only about 10% of that of the 30–100 keV SW suprathermal tail. We discuss the implication of a seed-particle source of more frequent, small flares.

Quasiparticle-phonon model and quadrupole mixed-symmetry states of 96Ru

Directory of Open Access Journals (Sweden)

Stoyanov Ch.

2016-01-01

Full Text Available The structure of low-lying quadrupole states of 96Ru was calculated within the Quasiparticle-Phonon Model. It is shown that symmetric and mixed-symmetry properties manifest themselves via the structure of the excited states. The first 2+ state is collective and neutron and proton transition matrix elements Mn and Mp are in-phase, while the neutron and proton transition matrix elements Mn and Mp have opposite signs for the third 2+ state. This property of the third 2+ state leads to a large M1 transition between the first and third 2+ states. It is an unambigous demonstration of the mixed-symmetry nature of the third 2+ state. The structure of the first 1+ state is calculated. The state is a member of the two-phonon multiplet generated by the coupling of the [21+]QRPA and the [22+]QRPA states.

Proton dynamics in oxides: insight into the mechanics of proton conduction from quasielastic neutron scattering.

Science.gov (United States)

Karlsson, Maths

2015-01-07

This article is concerned with the use of quasielastic neutron scattering as a technique for investigation of the dynamical properties of proton conducting oxides. Currently, the main interest in these materials comes from their promise as electrolytes in future electrochemical devices and particularly through their use as electrolytes in next-generation, intermediate-temperature, fuel cells. However, the realization of such devices depends critically on the development of new, more highly proton conducting oxides. Such a development depends on increasing the current understanding of proton conduction in oxides and for this purpose quasielastic neutron scattering is an important mean. The aim of this article is to introduce the non-specialist reader to the basic principles of quasielastic neutron scattering, its advantages and disadvantages, to summarize the work that has been done on proton conducting oxides using this technique, as well as to discuss future opportunities within this field of research.

Studies on neutron production in the interaction of 7.4 GeV protons with extended lead target

CERN Document Server

Hashemi-Nezhad, S R; Ochs, M; Wan, J S; Schmidt, T; Langrock, E J; Vater, P; Adam, J; Bamblevskij, V P; Bradnova, V; Gelovani, L K; Kalinnikov, V K; Krivopustov, M I; Kulakov, B A; Sosnin, A N; Perelygin, V P; Pronskikh, V S; Stegailov, V I; Tsoupko-Sitnikov, V M; Modolo, G; Odoj, R; Phlippen, P W; Adloff, J C; Debeauvais, M; Zamani-Valassiadou, M; Dwivedi, K K; Wilson, B

1999-01-01

A cylindrical lead target of diameter 8 cm and length 20 cm was irradiated with 7.4 GeV protons along the axis of the cylinder. The lead target was surrounded with a paraffin layer of thickness 6 cm to moderate the neutrons produced in p + Pb reactions. The spatial distribution of the slow and fast neutrons on different surfaces of the moderator were determined using LR 115 2B detectors (through sup 1 sup 0 B(n,alpha) sup 7 Li reactions) and CR39 detectors (through proton recoils) respectively. Such results can be valuable in the studies and design of Accelerator Driven Subcritical Nuclear Reactors and Nuclear Waste Incinerators.

Nuclear quadrupole interactions in ferroelectric compounds of HF181

International Nuclear Information System (INIS)

Kunzler, J.V.

1971-01-01

Measurements of nuclear quadrupole interaction constants in perovkite-type compounds of PbHfO 3 , SnhfO 3 , CaHfO 3 e SrHfO 3 have been performed using the perturbed angular correlation technique. A range of fundamental frequencies from 150 to 550 Megaradians persecond was determined. The variation of quadrupole constants has been discussed through the molecular orbital theory

Proton radioactivity lifetimes using Skyrme interactions

International Nuclear Information System (INIS)

Routray, T.R.; Tripathy, S.K.; Mishra, Abhishek; Basu, D.N.

2011-01-01

The phenomena of proton radioactivity is recent and has been possible with the advent of the radioactive ion beams facilities. The neutron deficient nuclei lying above the proton drip line has positive Q values for protons and are spontaneous proton emitters. This limits the possibilities of the creation of ever more exotic nuclei in the proton rich side of the β stability valley. Limited number of works have been done in calculating the half lives of proton emitting nuclei using different models. But calculation of lifetimes of the proton emitting nuclei using Skyrme interaction has not yet been reported. More than 110 Skyrme sets are available, constructed for different purposes, all having the common feature of giving finite nuclei ground state properties and saturation conditions in nuclear matter. Skyrme sets constructed in the late 90's, particularly the construction of SLy sets and others Skyrme sets developed thereafter, have additional care in constraining the parameters for applications to nuclear matter under extreme conditions. Stone et al. have analyzed the Skyrme sets on the basis of available constraints and have sorted out finally 27 Skyrmes sets which can be admitted for calculation of isospin rich dense nuclear matter. The objective of the work is to examine the predictions of the Skyrme sets on the half lives of the proton emitters

AA, shims and washers on quadrupole ends

CERN Multimedia

CERN PhotoLab

1981-01-01

Due to the fact that much of the field of the quadrupoles was outside the iron (in particular with the wide quadrupoles) and that thus the fields of quadrupoles and bending magnets interacted, the lattice properties of the AA could not be predicted with the required accuracy. After a first running period in 1980, during which detailed measurements were made with proton test beams, corrections to the quadrupoles were made in 1981, in the form of laminated shims at the ends of the poles, and with steel washers. With the latter ones, further refinements were made in an iterative procedure with measurements on the circulating beam. This eventually resulted, amongst other things, in a very low chromaticity, with the Q-values being constant to within +- 0.001 over the total momentum range of 6 %. Here we see the shims and washers on a narrow qudrupole (QFN, QDN). See also 8103203, 8103204, 8103205, 8103206.

Fan-beam intensity modulated proton therapy.

Science.gov (United States)

Hill, Patrick; Westerly, David; Mackie, Thomas

2013-11-01

falloff of a proton depth-dose distribution was found to provide sufficient control over the dose distribution to meet objectives, even with coarse lateral resolution and channel widths as large as 2 cm. Treatment plans on both phantom and patient data show that dose conformity suffers when treatments are delivered from less than approximately ten angles. Treatment time for a sample prostate delivery is estimated to be on the order of 10 min, and neutron production is estimated to be comparable to that found for existing collimated systems. Fan beam proton therapy is a method of delivering intensity modulated proton therapy which may be employed as an alternative to magnetic scanning systems. A fan beam of protons can be created by a set of quadrupole magnets and modified by a dual-purpose range and intensity modulator. This can be used to deliver inversely planned treatments, with spot intensities optimized to meet user defined dose objectives. Additionally, the ability of a fan beam delivery system to effectively treat multiple beam spots simultaneously may provide advantages as compared to spot scanning deliveries.

Design of the dipole and quadrupole magnets of the dedicated proton synchrotron for hadron therapy

International Nuclear Information System (INIS)

Kukarnikov, S.I.; Makoveev, V.K.; Minashkin, V.F.; Molodozhentsev, A.Yu.; Shevtsov, V.F.; Sidorov, G.I.

1998-01-01

The 2D-calculation results of magnetic elements of the PRAMES (Prague Medical Synchrotron) are presented. This machine is a dedicated accelerator for cancer therapy. The output energy of the beam should be variable in the range 60-220 MeV. The maximum magnetic field of the dipole magnet should be 1.2 T, the maximum magnetic field ramp - less than 8 T/s. The focusing structure of the proton synchrotron consists of 8 dipole and 18 quadrupole magnets. All magnets are laminated to minimize leakage currents. The dipoles are parallel-edge, H-type magnets. The field uniformity should be of the order of ± 1 x 10 -4 in the working area (± 63 mm and ± 27 mm in the horizontal and vertical planes, respectively). The maximum magnetic field on the pole of the quadrupole lenses should be less than 1 T. The gradient uniformity of quadrupole magnets in the working region should be less than ± 3.5 x 10 -4

Measurement of very forward neutron energy spectra for 7 TeV proton--proton collisions at the Large Hadron Collider

CERN Document Server

Adriani, O.; Bonechi, L.; Bongi, M.; Castellini, G.; D'Alessandro, R.; Del Prete, M.; Haguenauer, M.; Itow, Y.; Kasahara, K.; Kawade, K.; Makino, Y.; Masuda, K.; Matsubayashi, E.; Menjo, H.; Mitsuka, G.; Muraki, Y.; Okuno, Y.; Papini, P.; Perrot, A-L.; Ricciarini, S.; Sako, T.; Sakurai, N.; Sugiura, Y.; Suzuki, T.; Tamura, T.; Tiberio, A.; Torii, S.; Tricomi, A.; Turner, W.C.; Zhou, Q.D.

2015-01-01

The Large Hadron Collider forward (LHCf) experiment is designed to use the LHC to verify the hadronic-interaction models used in cosmic-ray physics. Forward baryon production is one of the crucial points to understand the development of cosmic-ray showers. We report the neutron-energy spectra for LHC $\\sqrt{s}$ = 7 TeV proton--proton collisions with the pseudo-rapidity $\\eta$ ranging from 8.81 to 8.99, from 8.99 to 9.22, and from 10.76 to infinity. The measured energy spectra obtained from the two independent calorimeters of Arm1 and Arm2 show the same characteristic feature before unfolding the difference in the detector responses. We unfolded the measured spectra by using the multidimensional unfolding method based on Bayesian theory, and the unfolded spectra were compared with current hadronic-interaction models. The QGSJET II-03 model predicts a high neutron production rate at the highest pseudo-rapidity range similar to our results and the DPMJET 3.04 model describes our results well at the lower pseudo-...

Measurement of neutron spectra generated from bombardment of 4 to 24 MeV protons on a thick 9Be target and estimation of neutron yields

International Nuclear Information System (INIS)

Paul, Sabyasachi; Sahoo, G. S.; Tripathy, S. P.; Sunil, C.; Bandyopadhyay, T.; Sharma, S. C.; Ramjilal,; Ninawe, N. G.; Gupta, A. K.

2014-01-01

A systematic study on the measurement of neutron spectra emitted from the interaction of protons of various energies with a thick beryllium target has been carried out. The measurements were carried out in the forward direction (at 0° with respect to the direction of protons) using CR-39 detectors. The doses were estimated using the in-house image analyzing program autoTRAK-n, which works on the principle of luminosity variation in and around the track boundaries. A total of six different proton energies starting from 4 MeV to 24 MeV with an energy gap of 4 MeV were chosen for the study of the neutron yields and the estimation of doses. Nearly, 92% of the recoil tracks developed after chemical etching were circular in nature, but the size distributions of the recoil tracks were not found to be linearly dependent on the projectile energy. The neutron yield and dose values were found to be increasing linearly with increasing projectile energies. The response of CR-39 detector was also investigated at different beam currents at two different proton energies. A linear increase of neutron yield with beam current was observed

Neutron yield and induced radioactivity: a study of 235-MeV proton and 3-GeV electron accelerators

International Nuclear Information System (INIS)

Hsu, Yung-Cheng; Lai, Bo-Lun; Sheu, Rong-Jiun

2016-01-01

This study evaluated the magnitude of potential neutron yield and induced radioactivity of two new accelerators in Taiwan: a 235-MeV proton cyclotron for radiation therapy and a 3-GeV electron synchrotron serving as the injector for the Taiwan Photon Source. From a nuclear interaction point of view, neutron production from targets bombarded with high-energy particles is intrinsically related to the resulting target activation. Two multi-particle interaction and transport codes, FLUKA and MCNPX, were used in this study. To ensure prediction quality, much effort was devoted to the associated benchmark calculations. Comparisons of the accelerators' results for three target materials (copper, stainless steel and tissue) are presented. Although the proton-induced neutron yields were higher than those induced by electrons, the maximal neutron production rates of both accelerators were comparable according to their respective beam outputs during typical operation. Activation products in the targets of the two accelerators were unexpectedly similar because the primary reaction channels for proton- and electron-induced activation are (p,pn) and (γ,n), respectively. The resulting residual activities and remnant dose rates as a function of time were examined and discussed. (authors)

Magnetic measurements on the ring dipoles and quadrupoles for the Los Alamos proton storage ring

International Nuclear Information System (INIS)

Schermer, R.I.; Blind, B.; Jason, A.J.; Sawyer, G.A.

1985-01-01

This paper discusses magnetic measurements and shimming performed on the ring dipoles and quadrupoles for the Los Alamos Proton Storage Ring (PSR). For the dipoles, point-by-point field maps were obtained using a search coil that could be scanned over a three-dimensional grid. By appropriate machining of removable end blocks, all magnet lengths were adjusted to within 0.01% of a nominal value and all integrated multipoles were set within tolerance. Integrated fields of 20 PSR quadrupoles were measured using a rotating ''Morgan Coil'' and a digital spectrum analyzer. The magnets were shimmed to specifications by adjusting steel bolts threaded through the field clamps. 3 refs., 5 figs., 4 tabs

Quadrupole beam-based alignment in the RHIC interaction regions

International Nuclear Information System (INIS)

Ziegler, J.; Satogata, T.

2011-01-01

Continued beam-based alignment (BBA) efforts have provided significant benefit to both heavy ion and polarized proton operations at RHIC. Recent studies demonstrated previously unknown systematic beam position monitor (BPM) offset errors and produced accurate measurements of individual BPM offsets in the experiment interaction regions. Here we describe the algorithm used to collect and analyze data during the 2010 and early 2011 RHIC runs and the results of these measurements. BBA data has been collected over the past two runs for all three of the active experimental IRs at RHIC, updating results from the 2005 run which were taken with incorrectly installed offsets. The technique was successfully applied to expose a systematic misuse of the BPM survey offsets in the control system. This is likely to benefit polarized proton operations as polarization transmission through acceleration ramps depends on RMS orbit control in the arcs, but a quantitative understanding of its impact is still under active investigation. Data taking is ongoing as are refinements to the BBA technique aimed at reducing systematic errors and properly accounting for dispersive effects. Further development may focus on non-triplet BPMs such as those located near snakes, or arc quadrupoles that do not have individually shunted power supplies (a prerequisite for the current method) and as such, will require a modified procedure.

Positron lifetime study of copper irradiated by energetic protons or energetic neutrons

International Nuclear Information System (INIS)

Howell, R.H.

1979-03-01

Positron lifetime measurements of pure copper damaged by irradiation with energetic protons and neutrons are presented. Lifetime determinations of the bulk material and various traps were made, and the dependence of the trapping rate on dose and irradiation energy were investigated. The results from the neutron- and proton-irradiated samples point to the existence of traps with similar but distinct lifetime parameters, not varying greatly from values reported in deformation studies. Also, a trap with long lifetime is seen for some proton irradiations, but is never seen for the neutron irradiations. The trapping rate of the short-lifetime trap is a linear function of dose for proton-irradiated samples and nearly so for the neutron irradiation. 1 figure

Off-axis dose equivalent due to secondary neutrons from uniform scanning proton beams during proton radiotherapy

Science.gov (United States)

Islam, M. R.; Collums, T. L.; Zheng, Y.; Monson, J.; Benton, E. R.

2013-11-01

The production of secondary neutrons is an undesirable byproduct of proton therapy and it is important to quantify the contribution from secondary neutrons to patient dose received outside the treatment volume. The purpose of this study is to investigate the off-axis dose equivalent from secondary neutrons experimentally using CR-39 plastic nuclear track detectors (PNTD) at ProCure Proton Therapy Center, Oklahoma City, OK. In this experiment, we placed several layers of CR-39 PNTD laterally outside the treatment volume inside a phantom and in air at various depths and angles with respect to the primary beam axis. Three different proton beams with max energies of 78, 162 and 226 MeV and 4 cm modulation width, a 5 cm diameter brass aperture, and a small snout located 38 cm from isocenter were used for the entire experiment. Monte Carlo simulations were also performed based on the experimental setup using a simplified snout configuration and the FLUKA Monte Carlo radiation transport code. The measured ratio of secondary neutron dose equivalent to therapeutic primary proton dose (H/D) ranged from 0.3 ± 0.08 mSv Gy-1 for 78 MeV proton beam to 37.4 ± 2.42 mSv Gy-1 for 226 MeV proton beam. Both experiment and simulation showed a similar decreasing trend in dose equivalent with distance to the central axis and the magnitude varied by a factor of about 2 in most locations. H/D was found to increase as the energy of the primary proton beam increased and higher H/D was observed at 135° compared to 45° and 90°. The overall higher H/D in air indicates the predominance of external neutrons produced in the nozzle rather than inside the body.

Off-axis dose equivalent due to secondary neutrons from uniform scanning proton beams during proton radiotherapy

International Nuclear Information System (INIS)

Islam, M R; Collums, T L; Monson, J; Benton, E R; Zheng, Y

2013-01-01

The production of secondary neutrons is an undesirable byproduct of proton therapy and it is important to quantify the contribution from secondary neutrons to patient dose received outside the treatment volume. The purpose of this study is to investigate the off-axis dose equivalent from secondary neutrons experimentally using CR-39 plastic nuclear track detectors (PNTD) at ProCure Proton Therapy Center, Oklahoma City, OK. In this experiment, we placed several layers of CR-39 PNTD laterally outside the treatment volume inside a phantom and in air at various depths and angles with respect to the primary beam axis. Three different proton beams with max energies of 78, 162 and 226 MeV and 4 cm modulation width, a 5 cm diameter brass aperture, and a small snout located 38 cm from isocenter were used for the entire experiment. Monte Carlo simulations were also performed based on the experimental setup using a simplified snout configuration and the FLUKA Monte Carlo radiation transport code. The measured ratio of secondary neutron dose equivalent to therapeutic primary proton dose (H/D) ranged from 0.3 ± 0.08 mSv Gy −1  for 78 MeV proton beam to 37.4 ± 2.42 mSv Gy −1  for 226 MeV proton beam. Both experiment and simulation showed a similar decreasing trend in dose equivalent with distance to the central axis and the magnitude varied by a factor of about 2 in most locations. H/D was found to increase as the energy of the primary proton beam increased and higher H/D was observed at 135° compared to 45° and 90°. The overall higher H/D in air indicates the predominance of external neutrons produced in the nozzle rather than inside the body. (paper)

The Biological Effect of Fast Neutrons and High-Energy Protons

International Nuclear Information System (INIS)

Moskalev, Ju.I.; Petrovich, I.K.; Strel'cova, V.N.

1964-01-01

The paper gives the results of comparative experiments on the effects of fast neutrons and high-energy protons (500 MeV) on life expectancy, peripheral blood, incidence and rate of appearance of tumours in the rat as a function of administered dose and time of observation. The neutron experiment was performed on 573 and the proton experiment on 490 white rats. The animals irradiated with fast neutrons were given doses between 8.5 and 510 rad, and those irradiated with protons received doses between 28 and 1008 rad. The effective doses for the acute, sub-acute and chronic forms of sickness were established for fast neutrons and for protons. LD 50/30 for neutrons was 408 and for protons 600 rad, and the corresponding LD 50 / 120 values were 380 and 600 rad. The conditions governing rat mortality were analysed both in the early and the later stages of the experiment. It is shown that the average life expectancy of rats irradiated with fast neutrons does not depend on sex. The shape of the dose-effect curve for the various peripheral-blood indexes is strongly dependent not only on the radiosensitivity of the blood cells in question but also on the time of observation. It may change greatly in time for one and the same index. A considerable time after irradiation with either fast neutrons or protons, benign and malignant tumours appear in different tissues of the rats, including the haemopoeitic tissues, mammary glands, pituitary, uterus, ovaries, prostate gland, testicles, liver, kidneys, lungs, gastro-intestinal tract, subcutaneous tissue, lymph nodes, urinary bladder, etc. The over-all incidence of tumours and the number of cases of multi centred neoplasms in females are two to three times higher than in males. The minimum tumour dose for the mammary glands with neutron irradiation is apparently rather less than 42.5 rad. The maximum incidence of tumours of the pituitary is found after irradiation with a dose of 42.5 rad.- At this same dose leucosis and tumour of the

Measurement of neutrino and proton asymmetry in the decay of polarized neutrons

Energy Technology Data Exchange (ETDEWEB)

Schumann, M.

2007-05-09

The Standard Model of Particle Physics is in excellent agreement with all experimental results. However, it is not believed to be the most fundamental theory. It requires, for example, too many free parameters and is not able to explain the existence of effects such as parity-violation or CP-violation. Thus measurements have to be performed to probe the Standard Model and to search for ''new physics''. An ideal laboratory for this is the decay of the free polarized neutron. In this thesis, we present measurements of the neutrino asymmetry B and the proton asymmetry C in neutron decay. These coefficients describe the correlation between neutron spin and momentum of the respective particle, and provide detailed information on the structure of the underlying theory. The experiment was performed using the electron spectrometer PERKEO II installed at the Institut Laue-Langevin (ILL). It was equipped with a combined electron-proton detector to reconstruct the neutrino in a coincidence measurement. The uncertainty of our neutrino asymmetry result, B=0.9802(50), is comparable to the present best measurement, and, for the first time ever, we obtained a precise value for the proton asymmetry, C=-0.2377(36). Both results are used to analyze neutron decay for hints on ''Physics beyond the Standard Model'' by studying possible admixtures of right-handed currents and of scalar and tensor couplings to the interaction. (orig.)

Electrostatic design and beam transport for a folded tandem electrostatic quadrupole accelerator facility for accelerator-based boron neutron capture therapy

International Nuclear Information System (INIS)

Thatar Vento, V.; Bergueiro, J.; Cartelli, D.; Valda, A.A.; Kreiner, A.J.

2011-01-01

Within the frame of an ongoing project to develop a folded Tandem-Electrostatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT), we discuss here the electrostatic design of the machine, including the accelerator tubes with electrostatic quadrupoles and the simulations for the transport and acceleration of a high intensity beam.

Reaction cross sections for 8He and 14B on proton target for the separation of proton and neutron density distributions

International Nuclear Information System (INIS)

Tanaka, Masaomi; Fukuda, Mitsunori; Nishimura, Daiki

2015-01-01

We utilized the proton-neutron asymmetry of nucleon–nucleon total cross sections in the intermediate energy region (σ pn ≠σ pp(nn) ) to obtain the information of proton and neutron distributions respectively. We have measured reaction cross sections (σ R ) for 14 B and 8 He on proton targets as isospin asymmetric targets in addition to symmetric ones. Proton and neutron density distributions were derived respectively through the χ 2 -fitting procedure with the modified Glauber calculation. The result suggests a necessity for 14 B of a long tail, and also a necessity for 8 He of a neutron tail. Root-mean-square proton, neutron and matter radii for 14 B and 8 He are also derived. Each radius is consistent with some of the other experimental values and also with some of the several theoretical values. (author)

EM Transition Sum Rules Within the Framework of sdg Proton-Neutron Interacting Boson Model, Nuclear Pair Shell Model and Fermion Dynamical Symmetry Model

Science.gov (United States)

Zhao, Yumin

1997-07-01

By the techniques of the Wick theorem for coupled clusters, the no-energy-weighted electromagnetic sum-rule calculations are presented in the sdg neutron-proton interacting boson model, the nuclear pair shell model and the fermion-dynamical symmetry model. The project supported by Development Project Foundation of China, National Natural Science Foundation of China, Doctoral Education Fund of National Education Committee, Fundamental Research Fund of Southeast University

Systematic studies of binding energy dependence of neutron-proton momentum correlation function

International Nuclear Information System (INIS)

Wei, Y B; Ma, Y G; Shen, W Q; Ma, G L; Wang, K; Cai, X Z; Zhong, C; Guo, W; Chen, J G; Fang, D Q; Tian, W D; Zhou, X F

2004-01-01

Hanbury Brown-Twiss (HBT) results of the neutron-proton correlation function have been systematically investigated for a series of nuclear reactions with light projectiles with the help of the isospin-dependent quantum molecular dynamics model. The relationship between the binding energy per nucleon of the projectiles and the strength of the neutron-proton HBT at small relative momentum has been obtained. Results show that neutron-proton HBT results are sensitive to the binding energy per nucleon

Matter-wave solitons supported by quadrupole-quadrupole interactions and anisotropic discrete lattices

Science.gov (United States)

Zhong, Rong-Xuan; Huang, Nan; Li, Huang-Wu; He, He-Xiang; Lü, Jian-Tao; Huang, Chun-Qing; Chen, Zhao-Pin

2018-04-01

We numerically and analytically investigate the formations and features of two-dimensional discrete Bose-Einstein condensate solitons, which are constructed by quadrupole-quadrupole interactional particles trapped in the tunable anisotropic discrete optical lattices. The square optical lattices in the model can be formed by two pairs of interfering plane waves with different intensities. Two hopping rates of the particles in the orthogonal directions are different, which gives rise to a linear anisotropic system. We find that if all of the pairs of dipole and anti-dipole are perpendicular to the lattice panel and the line connecting the dipole and anti-dipole which compose the quadrupole is parallel to horizontal direction, both the linear anisotropy and the nonlocal nonlinear one can strongly influence the formations of the solitons. There exist three patterns of stable solitons, namely horizontal elongation quasi-one-dimensional discrete solitons, disk-shape isotropic pattern solitons and vertical elongation quasi-continuous solitons. We systematically demonstrate the relationships of chemical potential, size and shape of the soliton with its total norm and vertical hopping rate and analytically reveal the linear dispersion relation for quasi-one-dimensional discrete solitons.

A hospital-based proton linac for neutron therapy and radioisotope production

International Nuclear Information System (INIS)

Lennox, A.J.

1988-10-01

Fermilab's Alvarez proton linac has been used routinely for neutron therapy since 1976. The Neutron Therapy Facility (NTF) operates in a mode parasitic to the laboratory's high energy physics program, which uses the linac as an injector for a synchrotron. Parasitic operation is possible because the linac delivers /approximately/1.2 /times/ 10 13 protons per pulse at a 15 Hz rate, while the high energy physics program requires beam at a rate not greater than 0.5 Hz. Protons not needed for physics experiments strike a beryllium target to produce neutrons for neutron therapy. Encouraging clinical results from NTF have led to a study of the issues involved in providing hospitals with a neutron beam of the type available at Fermilab. This paper describes the issues addressed by that study. 12 refs., 1 fig., 1 tab

Utilization of new 150-MeV neutron and proton evaluations in MCNP

International Nuclear Information System (INIS)

Little, R.C.; Frankle, S.C.; Hughes, H.G. III; Prael, R.E.

1997-01-01

MCNP trademark and LAHET trademark are two of the codes included in the LARAMIE (Los Alamos Radiation Modeling Interactive Environment) code system. Both MCNP and LAHET are three-dimensional continuous-energy Monte Carlo radiation transport codes. The capabilities of MCNP and LAHET are currently being merged into one code for the Accelerator Production of Tritium (APT) program at Los Alamos National Laboratory. Concurrently, a significant effort is underway to improve the accuracy of the physics in the merged code. In particular, full nuclear-data evaluations (in ENDF6 format) for many materials of importance to APT are being produced for incident neutrons and protons up to an energy of 150-MeV. After processing, cross-section tables based on these new evaluations will be available for use fin the merged code. In order to utilize these new cross-section tables, significant enhancements are required for the merged code. Neutron cross-section tables for MCNP currently specify emission data for neutrons and photons only; the new evaluations also include complete neutron-induced data for protons, deuterons, tritons, and alphas. In addition, no provision in either MCNP or LAHET currently exists for the use of incident charged-particle tables other than for electrons. To accommodate the new neutron-induced data, it was first necessary to expand the format definition of an MCNP neutron cross-section table. The authors have prepared a 150-MeV neutron cross-section library in this expanded format for 15 nuclides. Modifications to MCNP have been implemented so that this expanded neutron library can be utilized

Single event upset and charge collection measurements using high energy protons and neutrons

International Nuclear Information System (INIS)

Normand, E.; Oberg, D.L.; Wert, J.L.; Ness, J.D.; Majewski, P.P.; Wender, S.; Gavron, A.

1994-01-01

RAMs, microcontrollers and surface barrier detectors were exposed to beams of high energy protons and neutrons to measure the induced number of upsets as well as energy deposition. The WNR facility at Los Alamos provided a neutron spectrum similar to that of the atmospheric neutrons. Its effect on devices was compared to that of protons with energies of 200, 400, 500, and 800 MeV. Measurements indicate that SEU cross sections for 400 MeV protons are similar to those induced by the atmospheric neutron spectrum

Quadrupole interactions in pionic and muonic tantalum and rhenium

International Nuclear Information System (INIS)

Konijn, J.; Doesburg, W. van; Ewan, G.T; Johansson, T.; Tibell, G.

1981-01-01

The hyperfine splitting of pionic and muonic X-rays in natural Re has been studied using the known ratio (accurate to 1.6 parts in 10 5 ) of the quadrupole moments of the two naturally occurring 185 Re and 187 Re isotopes. From the hyperfine splitting of the 5g → 4f and 4f → 3d pionic X-rays the effective quadrupole hyperfine constants were determined to be 187 A 2 sup(e)sup(f)sup(f) (4f) = 1.163 +- 0.010 keV and 187 A 2 sup(e)sup(f)sup(f) (3d) = 5.39 +- 0.63 keV, giving strong interaction quadrupole shifts epsilon 2 (4f) = 46 +- 10 eV and epsilon 2 (3d) = 1.3 +- 0.6 keV. The strong interaction monopole shifts epsilon 0 and widths GAMMA 0 of the 5g, 4f and 3d levels have also been measured. For the two higher orbits, standard optical-potential calculations fit the measured shifts and widths quite well. The observed deeper-lying 3d state, however, has shifts and widths that differ by a factor of 2 or more from the predictions. From the measured quadrupole hyperfine constants of the 4f level we calculate the spectroscopic quadrupole moments to be 187 Qsup(μ) = 2.09 +- 0.04 b, 187 Qsup(π) = 2.07 +- 0.02 b, 185 Qsup(μ) = 2.21 +- 0.04 b, and 185 Qsup(π) = 2.18 +- 0.02 b. In addition, muonic X-rays from 181 Ta were observed; using the same methods for determining the quadrupole moments as above, a value of 181 Qsup(μ) = 3.28 +- 0.06 b was obtained, in good agreement with earlier published data. (orig.)

Relation between proton and neutron asymptotic normalization coefficients for light mirror nuclei and its relevance for nuclear astrophysics

International Nuclear Information System (INIS)

Timofeyuk, N.K.; Johnson, R.C.; Descouvemont, P.

2006-01-01

It has been realised recently that charge symmetry of the nucleon-nucleon interaction leads to a certain relation between Asymptotic Normalization Coefficients (ANCs) in mirror-conjugated one-nucleon overlap integrals. This relation can be approximated by a simple analytical formula that involves mirror neutron and proton separation energies, the core charge and the range of the strong nucleon-core interaction. We perform detailed microscopic multi-channel cluster model calculations and compare their predictions to the simple analytical formula as well as to calculations within a single-particle model in which mirror symmetry in potential wells and spectroscopic factors are assumed. The validity of the latter assumptions is verified on the basis of microscopic cluster model calculations. For mirror pairs in which one of the states is above the proton decay threshold, a link exists between the proton partial width and the ANC of the mirror neutron. This link is given by an approximate analytical formula similar to that for a bound-bound mirror pair. We compare predictions of this formula to the results of microscopic cluster model calculations. Mirror symmetry in ANCs can be used to predict cross sections for proton capture at stellar energies using neutron ANCs measured with stable or ''less radioactive'' beams. (orig.)

Neutron yield and induced radioactivity: a study of 235-MeV proton and 3-GeV electron accelerators.

Science.gov (United States)

Hsu, Yung-Cheng; Lai, Bo-Lun; Sheu, Rong-Jiun

2016-01-01

This study evaluated the magnitude of potential neutron yield and induced radioactivity of two new accelerators in Taiwan: a 235-MeV proton cyclotron for radiation therapy and a 3-GeV electron synchrotron serving as the injector for the Taiwan Photon Source. From a nuclear interaction point of view, neutron production from targets bombarded with high-energy particles is intrinsically related to the resulting target activation. Two multi-particle interaction and transport codes, FLUKA and MCNPX, were used in this study. To ensure prediction quality, much effort was devoted to the associated benchmark calculations. Comparisons of the accelerators' results for three target materials (copper, stainless steel and tissue) are presented. Although the proton-induced neutron yields were higher than those induced by electrons, the maximal neutron production rates of both accelerators were comparable according to their respective beam outputs during typical operation. Activation products in the targets of the two accelerators were unexpectedly similar because the primary reaction channels for proton- and electron-induced activation are (p,pn) and (γ,n), respectively. The resulting residual activities and remnant dose rates as a function of time were examined and discussed. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Neutron structures of the Helicobacter pylori 5'-methylthioadenosine nucleosidase highlight proton sharing and protonation states

Energy Technology Data Exchange (ETDEWEB)

Banco, Michael T.; Mishra, Vidhi; Ostermann, Andreas; Schrader, Tobias E.; Evans, Gary B.; Kovalevsky, Andrey; Ronning, Donald R.

2016-11-16

MTAN (5'-methylthioadenosine nucleosidase) catalyzes the hydrolysis of the N-ribosidic bond of a variety of adenosine-containing metabolites. The Helicobacter pylori MTAN (HpMTAN) hydrolyzes 6-amino-6-deoxyfutalosine in the second step of the alternative menaquinone biosynthetic pathway. Substrate binding of the adenine moiety is mediated almost exclusively by hydrogen bonds, and the proposed catalytic mechanism requires multiple proton-transfer events. Of particular interest is the protonation state of residue D198, which possesses a pKa above 8 and functions as a general acid to initiate the enzymatic reaction. In this study we present three corefined neutron/X-ray crystal structures of wild-type HpMTAN cocrystallized with S-adenosylhomocysteine (SAH), Formycin A (FMA), and (3R,4S)-4-(4-Chlorophenylthiomethyl)-1-[(9-deaza-adenin-9-yl)methyl]-3-hydroxypyrrolidine (p-ClPh-Thio-DADMe-ImmA) as well as one neutron/X-ray crystal structure of an inactive variant (HpMTAN-D198N) cocrystallized with SAH. These results support a mechanism of D198 pKa elevation through the unexpected sharing of a proton with atom N7 of the adenine moiety possessing unconventional hydrogen-bond geometry. Additionally, the neutron structures also highlight active site features that promote the stabilization of the transition state and slight variations in these interactions that result in 100-fold difference in binding affinities between the DADMe-ImmA and ImmA analogs.

Exact solution of equations for proton localization in neutron star matter

Science.gov (United States)

Kubis, Sebastian; Wójcik, Włodzimierz

2015-11-01

The rigorous treatment of proton localization phenomenon in asymmetric nuclear matter is presented. The solution of proton wave function and neutron background distribution is found by the use of the extended Thomas-Fermi approach. The minimum of energy is obtained in the Wigner-Seitz approximation of a spherically symmetric cell. The analysis of four different nuclear models suggests that the proton localization is likely to take place in the interior of a neutron star.

Is there an Ay problem in low-energy neutron-proton scattering?

International Nuclear Information System (INIS)

Gross, Franz; Stadler, Alfred

2008-01-01

We calculate Ay in neutron-proton scattering for the interactions models WJC-1 and WJC-2 in the Covariant Spectator Theory. We find that the recent 12 MeV measurements performed at TUNL are in better agreement with our results than with the Nijmegen Phase Shift Analysis of 1993, and after reviewing the low energy data, conclude that there is no Ay problem in low-energy np scattering.

Stabilization of the Electron-Nuclear Spin Orientation in Quantum Dots by the Nuclear Quadrupole Interaction

Science.gov (United States)

Dzhioev, R. I.; Korenev, V. L.

2007-07-01

The nuclear quadrupole interaction eliminates the restrictions imposed by hyperfine interaction on the spin coherence of an electron and nuclei in a quantum dot. The strain-induced nuclear quadrupole interaction suppresses the nuclear spin flip and makes possible the zero-field dynamic nuclear polarization in self-organized InP/InGaP quantum dots. The direction of the effective nuclear magnetic field is fixed in space, thus quenching the magnetic depolarization of the electron spin in the quantum dot. The quadrupole interaction suppresses the zero-field electron spin decoherence also for the case of nonpolarized nuclei. These results provide a new vision of the role of the nuclear quadrupole interaction in nanostructures: it elongates the spin memory of the electron-nuclear system.

Serber says: About nuclear physics

International Nuclear Information System (INIS)

Serber, R.

1986-01-01

This book is a distillation of a set of lecture notes used by the author at Columbia. Written with a pedagogical aim it emphasizes topics of current interest not only in nuclear physics but also in other branches of physics such as atomic physics and solid state physics. Contents: Some Arguments Concerning Nuclear Forces; The Neutron-Proton Force; Low Energy Neutron-Proton Scattering Experiments; Photo-Effect of the Deuteron; The Slowing Down and Diffusion of Neutrons; Nucleon Magnetic Moments and Quadrupole Moment of the Deuteron; Proton-Proton and Neutron-Neutron Interactions; Isotopic Spin Invariance; High Energy Reactions; Resonance Levels

SU-E-T-542: Measurement of Internal Neutrons for Uniform Scanning Proton Beams

Energy Technology Data Exchange (ETDEWEB)

Islam, M; Ahmad, S [University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (United States); Zheng, Y; Rana, S [Procure Proton Therapy Center, Oklahoma City, OK (United States); Collums, T [University of Iowa Hospitals and Clinics, Iowa City, IA (United States); Monsoon, J; Benton, E [Oklahoma State University, Stillwater, OK (United States)

2015-06-15

Purpose: In proton radiotherapy, the production of neutrons is a wellknown problem since neutron exposure can lead to increased risk of secondary cancers later in the patient’s lifetime. The assessment of neutron exposure is, therefore, important for the overall quality of proton radiotherapy. This study investigates the secondary neutrons created inside the patient from uniform scanning proton beams. Methods: Dose equivalent due to secondary neutrons was measured outside the primary field as a function of distance from beam isocenter at three different angles, 45, 90 and 135 degree, relative to beam axis. Plastic track nuclear detector (CR-39 PNTD) was used for the measurement of neutron dose. Two experimental configurations, in-air and cylindrical-phantom, were designed. In a cylindrical-phantom configuration, a cylindrical phantom of 5.5 cm diameter and 35 cm long was placed along the beam direction and in an in-air configuration, no phantom was used. All the detectors were placed at nearly identical locations in both configurations. Three proton beams of range 5 cm, 18 cm, and 32 cm with 4 cm modulation width and a 5 cm diameter aperture were used. The contribution from internal neutrons was estimated from the differences in measured dose equivalent between in-air and cylindrical-phantom configurations at respective locations. Results: The measured ratio of neutron dose equivalent to the primary proton dose (H/D) dropped off with distance and ranged from 27 to 0.3 mSv/Gy. The contribution of internal neutrons near the treatment field edge was found to be up to 64 % of the total neutron exposure. As the distance from the field edge became larger, the external neutrons from the nozzle appear to dominate and the internal neutrons became less prominent. Conclusion: This study suggests that the contribution of internal neutrons could be significant to the total neutron dose equivalent.

The RADEX facility as a tool for studies of radiation damage under proton and spallation neutron irradiation

Energy Technology Data Exchange (ETDEWEB)

Koptelov, E.A.; Lebedev, S.G.; Matveev, V.A.; Sobolevsky, N.M. [Institute for Nuclear Research of Russian Academy of Sciences, Moscow (Russian Federation); Strebkov, Yu.S.; Subbotin, A.V. [Research and Development Institute of Power Engineering, Moscow (Russian Federation)

2001-03-01

We present results of numerical modeling for processes of primary protons and spallation neutrons interactions with structural materials at the RADiation EXperiment facility of the Neutron Complex. The installation has a vertical irradiation channel inside the beam stop for horizontally incident protons with energies up to 600 MeV of the Moscow Meson Factory of the INR (Institute for Nuclear Research) RAS (Russian Academy of Science). The calculations are based on a set of computer codes SHIELD and RADDAM, which were developed in the INR RAS and give data on point defect generation by irradiation, rate of accumulation of H and He atoms produced in nuclear reactions, energetic spectra of primary knocked-off atoms in collision displacements, temperature of samples under irradiation. Different positions of the channel, which are available by rotation of a target relatively the vertical axis for angles 0, 60, 120 and 180 degrees to the proton beam direction, are considered. Changes of irradiation damage parameters due to various inputs of primary protons and spallation neutrons at different target orientations are demonstrated. It is shown also that the spallation neutron facility RADEX may provide with perspective experimental possibilities for modeling of irradiation conditions for fusion reactors ITER and DEMO. (author)

Monte Carlo simulation of secondary neutron dose for scanning proton therapy using FLUKA.

Directory of Open Access Journals (Sweden)

Chaeyeong Lee

Full Text Available Proton therapy is a rapidly progressing field for cancer treatment. Globally, many proton therapy facilities are being commissioned or under construction. Secondary neutrons are an important issue during the commissioning process of a proton therapy facility. The purpose of this study is to model and validate scanning nozzles of proton therapy at Samsung Medical Center (SMC by Monte Carlo simulation for beam commissioning. After the commissioning, a secondary neutron ambient dose from proton scanning nozzle (Gantry 1 was simulated and measured. This simulation was performed to evaluate beam properties such as percent depth dose curve, Bragg peak, and distal fall-off, so that they could be verified with measured data. Using the validated beam nozzle, the secondary neutron ambient dose was simulated and then compared with the measured ambient dose from Gantry 1. We calculated secondary neutron dose at several different points. We demonstrated the validity modeling a proton scanning nozzle system to evaluate various parameters using FLUKA. The measured secondary neutron ambient dose showed a similar tendency with the simulation result. This work will increase the knowledge necessary for the development of radiation safety technology in medical particle accelerators.

Proton detection in the neutron lifetime experiment PENeLOPE

Energy Technology Data Exchange (ETDEWEB)

Tietze, Christian [Technische Universitaet Muenchen, Physik Department E18 (Germany); Collaboration: PENeLOPE-Collaboration

2015-07-01

Although neutron lifetime plays an important role in the Standard Model of particle physics, τ{sub n} is not very precisely know and often discussed. The official PDG mean value has been lowered during the last years by more than 6σ to the new value of 880.3 ± 1.1 s. The new precision experiment PENeLOPE, which is currently developed at Technische Universitaet Muenchen, will help to clear this up. Ultra-cold neutrons are lossless stored in a magneto-gravitational trap, formed by superconducting coils. The combined determination of τ{sub n} by counting the surviving neutrons after each storage cycle on one side and in-situ detection of the decay protons on the other side together with a very good handle on systematic errors leads to an unprecedented precision of the neutron lifetime value of 0.1s. This contribution will give an overview of the challenges concerning proton detection under the exceptional requirements of this experiment. The developed concept of using avalanche photodiodes for direct proton detection will be presented as well as results from first measurements with a prototype detector read out by particular developed electronics.

Electrostatic design and beam transport for a folded tandem electrostatic quadrupole accelerator facility for accelerator-based boron neutron capture therapy.

Science.gov (United States)

Vento, V Thatar; Bergueiro, J; Cartelli, D; Valda, A A; Kreiner, A J

2011-12-01

Within the frame of an ongoing project to develop a folded Tandem-Electrostatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT), we discuss here the electrostatic design of the machine, including the accelerator tubes with electrostatic quadrupoles and the simulations for the transport and acceleration of a high intensity beam. Copyright © 2011 Elsevier Ltd. All rights reserved.

Characterization of the ELIMED Permanent Magnets Quadrupole system prototype with laser-driven proton beams

Science.gov (United States)

Schillaci, F.; Pommarel, L.; Romano, F.; Cuttone, G.; Costa, M.; Giove, D.; Maggiore, M.; Russo, A. D.; Scuderi, V.; Malka, V.; Vauzour, B.; Flacco, A.; Cirrone, G. A. P.

2016-07-01

Laser-based accelerators are gaining interest in recent years as an alternative to conventional machines [1]. In the actual ion acceleration scheme, energy and angular spread of the laser-driven beams are the main limiting factors for beam applications and different solutions for dedicated beam-transport lines have been proposed [2,3]. In this context a system of Permanent Magnet Quadrupoles (PMQs) has been realized [2] by INFN-LNS (Laboratori Nazionali del Sud of the Instituto Nazionale di Fisica Nucleare) researchers, in collaboration with SIGMAPHI company in France, to be used as a collection and pre-selection system for laser driven proton beams. This system is meant to be a prototype to a more performing one [3] to be installed at ELI-Beamlines for the collection of ions. The final system is designed for protons and carbons up to 60 MeV/u. In order to validate the design and the performances of this large bore, compact, high gradient magnetic system prototype an experimental campaign have been carried out, in collaboration with the group of the SAPHIR experimental facility at LOA (Laboratoire d'Optique Appliquée) in Paris using a 200 TW Ti:Sapphire laser system. During this campaign a deep study of the quadrupole system optics has been performed, comparing the results with the simulation codes used to determine the setup of the PMQ system and to track protons with realistic TNSA-like divergence and spectrum. Experimental and simulation results are good agreement, demonstrating the possibility to have a good control on the magnet optics. The procedure used during the experimental campaign and the most relevant results are reported here.

Fast neutron spectrometry based on proton detection in CR-39 detector

Energy Technology Data Exchange (ETDEWEB)

Dajko, G.; Somogyi, G.

1986-01-01

The authors have developed a home-made proton-sensitive CR-39 track detector called MA-ND/p. Using this and the n-p scattering process the performance of a fast neutron spectrometer has been studied by applying two different methods. These are based on track density determinations by using varying radiator thicknesses at constant etching time and by using varying etching times at fixed radiator thickness, respectively. For both methods studied a computer programme is made to calculate the theoretically expected neutron sensitivity as a function of neutron energy. For both methods the neutron sensitivities, expressed in terms of observable etched proton tracks per neutron, are determined experimentally for 3.3 and 14.7 MeV neutron energies. The theoretical and experimental data obtained are compared.

Fast neutron spectrometry based on proton detection in CR-39 detector

International Nuclear Information System (INIS)

Dajko, G.; Somogyi, G.

1986-01-01

The authors have developed a home-made proton-sensitive CR-39 track detector called MA-ND/p. Using this and the n-p scattering process the performance of a fast neutron spectrometer has been studied by applying two different methods. These are based on track density determinations by using varying radiator thicknesses at constant etching time and by using varying etching times at fixed radiator thickness, respectively. For both methods studied a computer programme is made to calculate the theoretically expected neutron sensitivity as a function of neutron energy. For both methods the neutron sensitivities, expressed in terms of observable etched proton tracks per neutron, are determined experimentally for 3.3 and 14.7 MeV neutron energies. The theoretical and experimental data obtained are compared. (author)

Nuclear quadrupole interactions in ferroelectric compounds of HF/sup 181/

Energy Technology Data Exchange (ETDEWEB)

Kunzler, J V

1971-01-01

Measurements of nuclear quadrupole interaction constants in perovkite-type compounds of PbHfO/sub 3/, SnhfO/sub 3/, CaHfO/sub 3/ e SrHfO/sub 3/ have been performed using the perturbed angular correlation technique. A range of fundamental frequencies from 150 to 550 Megaradians per second was determined. The variation of quadrupole constants has been discussed through the molecular orbital theory.

A research plan based on high intensity proton accelerator Neutron Science Research Center

International Nuclear Information System (INIS)

Mizumoto, Motoharu

1997-01-01

A plan called Neutron Science Research Center (NSRC) has been proposed in JAERI. The center is a complex composed of research facilities based on a proton linac with an energy of 1.5GeV and an average current of 10mA. The research facilities will consist of Thermal/Cold Neutron Facility, Neutron Irradiation Facility, Neutron Physics Facility, OMEGA/Nuclear Energy Facility, Spallation RI Beam Facility, Meson/Muon Facility and Medium Energy Experiment Facility, where high intensity proton beam and secondary particle beams such as neutron, pion, muon and unstable radio isotope (RI) beams generated from the proton beam will be utilized for innovative researches in the fields on nuclear engineering and basic sciences. (author)

A research plan based on high intensity proton accelerator Neutron Science Research Center

Energy Technology Data Exchange (ETDEWEB)

Mizumoto, Motoharu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1997-03-01

A plan called Neutron Science Research Center (NSRC) has been proposed in JAERI. The center is a complex composed of research facilities based on a proton linac with an energy of 1.5GeV and an average current of 10mA. The research facilities will consist of Thermal/Cold Neutron Facility, Neutron Irradiation Facility, Neutron Physics Facility, OMEGA/Nuclear Energy Facility, Spallation RI Beam Facility, Meson/Muon Facility and Medium Energy Experiment Facility, where high intensity proton beam and secondary particle beams such as neutron, pion, muon and unstable radio isotope (RI) beams generated from the proton beam will be utilized for innovative researches in the fields on nuclear engineering and basic sciences. (author)

Moment of inertia, quadrupole moment, Love number of neutron star and their relations with strange-matter equations of state

Science.gov (United States)

Bandyopadhyay, Debades; Bhat, Sajad A.; Char, Prasanta; Chatterjee, Debarati

2018-02-01

We investigate the impact of strange-matter equations of state involving Λ hyperons, Bose-Einstein condensate of K- mesons and first-order hadron-quark phase transition on moment of inertia, quadrupole moment and tidal deformability parameter of slowly rotating neutron stars. All these equations of state are compatible with the 2 M_{solar} constraint. The main findings of this investigation are the universality of the I- Q and I -Love number relations, which are preserved by the EoSs including Λ hyperons and antikaon condensates, but broken in the presence of a first-order hadron-quark phase transition. Furthermore, it is also noted that the quadrupole moment approaches the Kerr value of a black hole for maximum-mass neutron stars.

An intense neutron generator based on a proton accelerator

Energy Technology Data Exchange (ETDEWEB)

Bartholomew, G A; Milton, J C.D.; Vogt, E W

1964-07-01

A study has been made of the demand for a neutron facility with a thermal flux of {>=} 10{sup 16} n cm{sup -2} sec{sup -1} and of possible methods of producing such fluxes with existing or presently developing technology. Experimental projects proposed by neutron users requiring high fluxes call for neutrons of all energies from thermal to 100 MeV with both continuous-wave and pulsed output. Consideration of the heat generated in the source per useful neutron liberated shows that the (p,xn) reaction with 400 1000 MeV bombarding energies and heavy element targets (e.g. bismuth, lead) is capable of greater specific source strength than other possible methods realizable within the time scale. A preliminary parameter optimization carried through for the accelerator currently promising greatest economy (the separated orbit cyclotron or S.O.C.), reveals that a facility delivering a proton beam of about 65 mA at about 1 BeV would satisfy the flux requirement with a neutron cost significantly more favourable than that projected for a high flux reactor. It is suggested that a proton storage ring providing post-acceleration pulsing of the proton beam should be developed for the facility. With this elaboration, and by taking advantage of the intrinsic microscopic pulse structure provided by the radio frequency duty cycle, a very versatile source may be devised capable of producing multiple beams of continuous and pulsed neutrons with a wide range of energies and pulse widths. The source promises to be of great value for high flux irradiations and as a pilot facility for advanced reactor technology. The proposed proton accelerator also constitutes a meson source capable of producing beams of {pi} and {mu} mesons and of neutrinos orders of magnitude more intense than those of any accelerator presently in use. These beams, which can be produced simultaneously with the neutron beams, open vast areas of new research in fundamental nuclear structure, elementary particle physics

An intense neutron generator based on a proton accelerator

International Nuclear Information System (INIS)

Bartholomew, G.A.; Milton, J.C.D.; Vogt, E.W.

1964-01-01

A study has been made of the demand for a neutron facility with a thermal flux of ≥ 10 16 n cm -2 sec -1 and of possible methods of producing such fluxes with existing or presently developing technology. Experimental projects proposed by neutron users requiring high fluxes call for neutrons of all energies from thermal to 100 MeV with both continuous-wave and pulsed output. Consideration of the heat generated in the source per useful neutron liberated shows that the (p,xn) reaction with 400 1000 MeV bombarding energies and heavy element targets (e.g. bismuth, lead) is capable of greater specific source strength than other possible methods realizable within the time scale. A preliminary parameter optimization carried through for the accelerator currently promising greatest economy (the separated orbit cyclotron or S.O.C.), reveals that a facility delivering a proton beam of about 65 mA at about 1 BeV would satisfy the flux requirement with a neutron cost significantly more favourable than that projected for a high flux reactor. It is suggested that a proton storage ring providing post-acceleration pulsing of the proton beam should be developed for the facility. With this elaboration, and by taking advantage of the intrinsic microscopic pulse structure provided by the radio frequency duty cycle, a very versatile source may be devised capable of producing multiple beams of continuous and pulsed neutrons with a wide range of energies and pulse widths. The source promises to be of great value for high flux irradiations and as a pilot facility for advanced reactor technology. The proposed proton accelerator also constitutes a meson source capable of producing beams of π and μ mesons and of neutrinos orders of magnitude more intense than those of any accelerator presently in use. These beams, which can be produced simultaneously with the neutron beams, open vast areas of new research in fundamental nuclear structure, elementary particle physics, and perhaps also in

Dosimetry of clinical neutron and proton beams: An overview of recommendations

International Nuclear Information System (INIS)

Vynckier, S.

2004-01-01

Neutron therapy beams are obtained by accelerating protons or deuterons on Beryllium. These neutron therapy beams present comparable dosimetric characteristics as those for photon beams obtained with linear accelerators; for instance, the penetration of a p(65) + Be neutron beam is comparable with the penetration of an 8 MV photon beam. In order to be competitive with conventional photon beam therapy, the dosimetric characteristics of the neutron beam should therefore not deviate too much from the photon beam characteristics. This paper presents a brief summary of the neutron beams used in radiotherapy. The dosimetry of the clinical neutron beams is described. Finally, recent and future developments in the field of physics for neutron therapy is mentioned. In the last two decades, a considerable number of centres have established radiotherapy treatment facilities using proton beams with energies between 50 and 250 MeV. Clinical applications require a relatively uniform dose to be delivered to the volume to be treated, and for this purpose the proton beam has to be spread out, both laterally and in depth. The technique is called 'beam modulation' and creates a region of high dose uniformity referred to as the 'spread-out Bragg peak'. Meanwhile, reference dosimetry in these beams had to catch up with photon and electron beams for which a much longer tradition of dosimetry exists. Proton beam dosimetry can be performed using different types of dosemeters, such as calorimeters, Faraday cups, track detectors and ionisation chambers. National standard dosimetry laboratories will, however, not provide a standard for the dosimetry of proton beams. To achieve uniformity on an international level, the use of an ionisation chamber should be considered. This paper reviews and summarises the basic principles and recommendations for the absorbed dose determination in a proton beam, utilising ionisation chambers calibrated in terms of absorbed dose to water. These recommendations

Identification of the one-quadrupole phonon 21,ms+ state of 204Hg

Directory of Open Access Journals (Sweden)

R. Stegmann

2017-07-01

Full Text Available One-phonon states of vibrational nuclei with mixed proton–neutron symmetry have been observed throughout the nuclear chart besides the mass A≈200 region. Very recently, it has been proposed that the 22+ state of 212Po is of isovector nature. This nucleus has two valence protons and two valence neutrons outside the doubly-magic 208Pb nucleus. The stable isotope 204Hg, featuring two valence-proton and valence-neutron holes, with respect to 208Pb, is the particle-hole mirror of 212Po. In order to compare the properties of low-lying isovector excitations in these particle-hole mirror nuclei, we have studied 204Hg by using the projectile Coulomb-excitation technique. The measured absolute B(M1;22+→21+ strength of 0.20(2μN2 indicates that the 22+ level of 204Hg is at least the main fragment of the 21,ms+ state. For the first time in this mass region, both lowest-lying, one-quadrupole phonon excitations are established together with the complete set of their decay strengths. This allows for a microscopic description of their structures, achieved in the framework of the Quasi-particle Phonon Model.

Electron Cloud Generation and Trapping in a Quadrupole Magnet at the Los Alamos Proton Storage Ring

International Nuclear Information System (INIS)

Macek, Robert J.; Browman, Andrew A.; Ledford, John E.; TechSource, Santa Fe; Los Alamos; Borden, Michael J.; O'Hara, James F.; McCrady, Rodney C.; Rybarcyk, Lawrence J.; Spickermann, Thomas; Zaugg, Thomas J.; Pivi, Mauro T.F.

2008-01-01

Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR) have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the 'prompt' electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the 'swept' electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100 (micro)s. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole

Electron cloud generation and trapping in a quadrupole magnet at the Los Alamos proton storage ring

Directory of Open Access Journals (Sweden)

Robert J. Macek

2008-01-01

Full Text Available Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the “prompt” electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the “swept” electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100  μs. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole.

ELECTRON SCATTERING EXPERIMENTS ON THE NEUTRON AND PROTON

Energy Technology Data Exchange (ETDEWEB)

Berkelman, Karl

1963-06-15

The electric and magnetic helicity form factors of the proton are measured at 4-momentum transfers (squared) of 25 to 45 f/sup -2/, by means of electron scattering by protons at high energies. The results are combined with other e/sup -/--p and e/sup -/--d experimental findings in order to show the proton form fuctors from 0 to 45 f/sup -2/ and the neutron form factors from 0 to 25 f/sup -2/. (T.F.H.)

Study of neutron-proton pairing in N=Z unstable nuclei through transfer reactions

International Nuclear Information System (INIS)

Le Crom, B.

2016-01-01

A nucleus is described as a set of independent neutrons and protons linked by a mean-field potential. However, in order to have a better description one needs to take into account some residual interactions such as pairing. Neutron-neutron and proton-proton pairings are well-studied but neutron-proton pairing is not well-known. np pairing can be isovector pairing such as nn and pp pairing or isoscalar which is yet unknown. Over-binding of N=Z nuclei could be a manifestation of np pairing. We have studied np pairing through transfer reactions. In this case, the cross-section of np pair transfer is expected to be enhanced in the presence of important np pairing. np pairing is expected to be important in N=Z nuclei with high J orbitals. Since the development of radioactive beam facilities, such beams are only available. The experiment was performed at GANIL with an efficient set-up so as to detect products from the (p, 3 He) transfer reaction. This reaction is affected by isovector and isoscalar np pairing. We used 56 Ni and 52 Fe beams so as to see the effect of the occupancy of 0f 7/2 shell on the np pairing. First, we analysed the data from the 56 Ni(p,d) 55 Ni reaction and we compared the results with the literature to validate analysis procedure. After analysing data from the 56 Ni(p, 3 He) 54 Co reaction and extracting the population of the various states of 54 Co, we obtained information about the relative intensity between isoscalar and isovector np pairing in 56 Ni showing the predominance of isovector np pairing in this nucleus. Moreover, in the framework of developing a new charged particle detector, research on the discrimination of light nuclei using pulse shape analysis was performed and is also presented. (author)

Interactive and automated systems for nuclear track measurements with applications to fast neutron dosimetry

International Nuclear Information System (INIS)

Roberts, J.H.; Gold, R.; McNeece, J.P.; Preston, C.C.; Ruddy, F.H.

1983-12-01

Interactive and automatic track measuring systems have been developed primarily for fast neutron dosimetry in and around reactors. The interactive system is used for proton recoil measurements in nuclear research emulsions and the automatic systems for counting fission fragment tracks in Muscovite mica. The status of these systems, along with illustrative applications, are presented, particularly with regard to their relationship to neutron personnel dosimetry. 16 references, 12 figures

ELECTROMAGENTIC FORM FACTORS OF THE PROTON AND NEUTRON

Energy Technology Data Exchange (ETDEWEB)

Griffy, T. A.; Hofstadter, R.; Hughes, E. B.; Janssens, T.; Yearian, M. R.

1963-06-15

Proton form factors in the four-momentum-transfer range q/sup 2/ = 4.6 to 32.0 f/sup -2/ and neutron form factors in the range q/sup 2/ = 2.5 to 10.0 f/ sup -2/ are measured by means of electron elastic scattering by protons and electron inelastic scattering by deuterons. (T.F.H.)

Proton and neutron radiation in cancer treatment: clinical and economic outcomes

International Nuclear Information System (INIS)

Fleurette, F.; Charvet-Protat, S.

1996-01-01

The French National Agency for Medical Evaluation (ANDEM) was requested to assess the effectiveness of proton and neutron beam therapy in cancer treatment compared to conventional radiotherapy. This task was accomplished by a critical appraisal of the clinical and economic literature. According to the published economic literature and the capital and staffing cost analysis, it appears that the costs of proton therapy are likely to be two or three times greater than those conformal therapy. According to the published clinical literature, proton beam therapy should be proposed as a routine treatment only for uveal melanoma and skull base cancers. Neutron beam therapy should be proposed as a routine treatment for inoperable salivary gland tumors; its use may be also discussed in cases of stage C-D1 prostate cancers and soft tissue sarcomas. Based on the current scientific evidence and given the incidence rate of these tumors, the time and material requirements, the current French proton/neutron beam facilities are able to meet the current demand. FOr other cancers the medical and economic potential of proton therapy is still an open question. (author)

A strong focussing cylindrical electrostatic quadrupole

International Nuclear Information System (INIS)

Sheng Yaochang

1986-01-01

The construction and performance of small cylindrical electrostatic quadrupole, which is installed in JM-400 pulse electrostatic accelerator, are described. This electrostatic quadrupole is not only used in neutron generator, but also suitable for ion injector as well as for low energy electron accelerator

Stability of the coherent quadrupole oscillations excited by the beam-beam interaction

International Nuclear Information System (INIS)

Kamiya, Y.; Chao, A.W.

1983-10-01

We study the coherent quadrupole motion in the presence of beam-beam interaction, using a linear approximation to the beam-beam force. The corresponding beam-beam limit is determined by evaluating the eigenvalues of a system of linear equations describing the coherent quadrupole motion. We find that the stability of the quadrupole motions imposes severe limits on the beam current, as is the case for the dipole instability. Preliminary results of this study have appeared elsewhere

The influence of the Coulomb-distortion effect on proton-proton observables

International Nuclear Information System (INIS)

Plessas, W.; Mathelitsch, L.

1980-01-01

The effect of the Coulomb distortion of the strong interaction is studied on the basis of nucleon-nucleon observables. In particular, cross sections, polarizations, spin-correlation parameters, and spin-transfer coefficients are considered for proton-proton as well as neutron-neutron scattering at laboratory kinetic energies Esub(Lab) = 10, 20, and 50 MeV. The calculations are performed for the meson-theoretical PARIS potential, the nonlocal separable GRAZ potential and also using the Arndt-Hackman-Roper parametrization of proton-proton scattering phase shifts. Important conclusions are drawn with respect to phenomenological phase-shift analyses. (Auth.)

An Antiproton Ion Collider (AIC) for Measuring Neutron and Proton Distributions in Stable and Radioactive Nuclei

International Nuclear Information System (INIS)

Kienle, Paul

2005-01-01

An antiproton-ion collider is proposed to independently determine mean square radii for protons and neutrons in stable and short lived nuclei by means of antiproton absorption at medium energies. The experiment makes use of the electron ion collider complex (ELISE) of the GSI FAIR project with appropriate modifications of the electron ring to store, cool and collide antiprotons of 30 MeV energy with 740A MeV energy ions.The total absorption cross-section of antiprotons by the stored ions will be measured by detecting their loss by means of the Schottky noise spectroscopy method. Cross sections for the absorption on protons and neutrons, respectively, will be studied by detection of residual nuclei with A-1 either by the Schottky method or by analysing them in recoil detectors after the first dipole stage of the NESR following the interaction zone. With a measurement of the A-1 fragment momentum distribution, one can test the momentum wave functions of the annihilated neutron and proton, respectively. Furthermore by changing the incident ion energy the tails of neutron and proton distribution can be measured.The absorption cross section is at asymptotic energies in leading order proportional to the mean square radius of the nucleus. Predicted cross sections and luminosities show that the method is applicable to nuclei with production rates of about 105 s-1 or lower, depending on the lifetime of the ions in the NESR, and for half-lives down to 1 second

Photoproduction of π{sup 0} -pairs off protons and off neutrons

Energy Technology Data Exchange (ETDEWEB)

Dieterle, M.; Oberle, M.; Garni, S.; Kaeser, A.; Keshelashvili, I.; Krusche, B.; Maghrbi, Y.; Pheron, F.; Rostomyan, T.; Strub, T.; Walford, N.K.; Werthmueller, D.; Witthauer, L. [University of Basel, Department of Physics, Basel (Switzerland); Ahrens, J.; Arends, H.J.; Bartolome, P.A.; Heid, E.; Jahn, O.; Ostrick, M.; Otte, P.; Schumann, S.; Thomas, A. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); Annand, J.R.M.; Glazier, D.I.; Hamilton, D.; Howdle, D.; Livingston, K.; MacGregor, I.J.D.; Mancell, J.; McGeorge, J.C.; McNicoll, E.; Robinson, J. [University of Glasgow, SUPA School of Physics and Astronomy, Glasgow (United Kingdom); Bantawa, K.; Manley, D.M. [Kent State University, Kent, Ohio (United States); Beck, R.; Nikolaev, A. [University of Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Bekrenev, V. [Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Berghaeuser, H.; Drexler, P.; Metag, V.; Novotny, R.; Thiel, M. [University of Giessen, II. Physikalisches Institut, Giessen (Germany); Braghieri, A.; Costanza, S.; Mushkarenkov, A.; Pedroni, P. [INFN Sezione di Pavia, Pavia (Italy); Branford, D.; Jude, T.C.; Sikora, M.H.; Watts, D.P. [University of Edinburgh, SUPA School of Physics, Edinburgh (United Kingdom); Briscoe, W.J.; Demissie, B.; Marinides, Z. [The George Washington University, Center for Nuclear Studies, Washington, DC (United States); Brudvik, J.; Starostin, A. [University of California Los Angeles, Los Angeles, California (United States); Cherepnya, S.; Fil' kov, L.V. [Lebedev Physical Institute, Moscow (Russian Federation); Downie, E.J. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); University of Glasgow, SUPA School of Physics and Astronomy, Glasgow (United Kingdom); The George Washington University, Center for Nuclear Studies, Washington, DC (United States); Fix, A. [Tomsk Polytechnic University, Laboratory of Mathematical Physics, Tomsk (Russian Federation); Hornidge, D.; Middleton, D.G. [Mount Allison University, New Brunswick (Canada); Huber, G.M. [University of Regina, Regina (Canada); Kashevarov, V.L. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); Lebedev Physical Institute, Moscow (Russian Federation); Kondratiev, R.; Lisin, V.; Polonski, A. [Institute for Nuclear Research, Moscow (Russian Federation); Korolija, M.; Mekterovic, D.; Micanovic, S.; Supek, I. [Rudjer Boskovic Institute, Zagreb (Croatia); Oussena, B. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); The George Washington University, Center for Nuclear Studies, Washington, DC (United States); Prakhov, S. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); The George Washington University, Center for Nuclear Studies, Washington, DC (United States); University of California Los Angeles, Los Angeles, California (United States); Sober, D.I. [The Catholic University of America, Washington, DC (United States); Unverzagt, M. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); University of Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Collaboration: The A2 Collaboration

2015-11-15

Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of π{sup 0}π{sup 0} pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557MeV, which produced bremsstrahlung in thin radiator foils. The tagged photon beam covered energies up to 1400 MeV. The data from the free proton target are in good agreement with previous measurements and were only used to test the analysis procedures. The results for differential cross sections (angular distributions and invariant-mass distributions) for free and quasi-free protons are almost identical in shape, but differ in absolute magnitude up to 15%. Thus, moderate final-state interaction effects are present. The data for quasi-free neutrons are similar to the proton data in the second resonance region (final-state invariant masses up to ∼ 1550 MeV), where both reactions are dominated by the N(1520)3/2{sup -} → Δ(1232)3/2{sup +}π decay. At higher energies, angular and invariant-mass distributions are different. A simple analysis of the shapes of the invariant-mass distributions in the third resonance region is consistent with strong contributions of an N{sup *} → Nσ decay for the proton, while the reaction is dominated by a sequential decay via a Δπ intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis. (orig.)

Nuclear data for fast neutron and proton therapy

International Nuclear Information System (INIS)

Chadwick, M.B.; Jones, D.T.L.; Barschall, H.H.

2001-01-01

ICRU Report 63 entitled 'Nuclear Data for Neutron and Proton Radiotherapy and for Radiation Protection' has recently been published. The present paper presents an overview of this report, along with examples of some of the results obtained for evaluated nuclear cross sections and kerma coefficients. These cross sections are evaluated using a combination of measured data and the GNASH nuclear model code for elements of importance for biological, dosimetric, beam modification and shielding purposes. In the case of hydrogen both R-matrix and phase-shift scattering theories are used. Neutron cross sections and kerma coefficients were evaluated up to 100 MeV and proton cross sections up to 250 MeV. (author)

A method to calculate fission-fragment yields Y(Z,N) versus proton and neutron number in the Brownian shape-motion model. Application to calculations of U and Pu charge yields

Energy Technology Data Exchange (ETDEWEB)

Moeller, Peter [Los Alamos National Laboratory, Theoretical Division, Los Alamos, NM (United States); Ichikawa, Takatoshi [Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan)

2015-12-15

We propose a method to calculate the two-dimensional (2D) fission-fragment yield Y(Z,N) versus both proton and neutron number, with inclusion of odd-even staggering effects in both variables. The approach is to use the Brownian shape-motion on a macroscopic-microscopic potential-energy surface which, for a particular compound system is calculated versus four shape variables: elongation (quadrupole moment Q{sub 2}), neck d, left nascent fragment spheroidal deformation ε{sub f1}, right nascent fragment deformation ε{sub f2} and two asymmetry variables, namely proton and neutron numbers in each of the two fragments. The extension of previous models 1) introduces a method to calculate this generalized potential-energy function and 2) allows the correlated transfer of nucleon pairs in one step, in addition to sequential transfer. In the previous version the potential energy was calculated as a function of Z and N of the compound system and its shape, including the asymmetry of the shape. We outline here how to generalize the model from the ''compound-system'' model to a model where the emerging fragment proton and neutron numbers also enter, over and above the compound system composition. (orig.)

Calculation of nuclear data for fast neutron and proton radiotherapy: A new ICRU report

International Nuclear Information System (INIS)

Chadwick, M.B.

1997-01-01

The author discusses the determination of nuclear interaction cross sections that are needed for fast neutron and proton radiotherapy. Both nuclear theory and experimental results are used to evaluate these data. An International Commission on Radiation Units and Measurements (ICRU) report, which is expected to be issued in 1998 and which compiles these data, is described

Quadrupole moments of the 12+ isomers in 188Hg and 190Hg

International Nuclear Information System (INIS)

Dracoulis, G.D.; Lonnroth, T.; Vajda, S.; Dafni, E.; Schatz, G.

1984-01-01

The electric quadrupole interaction of the 12 + isomers in 188 Hg and 190 Hg has been measured in solid Hg. The quadrupole moments deduced, vertical strokeQ[ 188 Hg(12 + )]vertical stroke = 91(11) e fm 2 and vertical strokeQ[ 190 Hg(12 + )]vertical stroke = 117(14) e fm 2 suggest a possible change in γ-deformation due to the rotation alignment of the isub(13/2) quasi-neutrons. The temperature dependence of the electric field gradient tensor in Hg was also determined. (orig.)

High-energy neutron yields in interactions of carbon ions with 114Sn and 124Sn nuclei

International Nuclear Information System (INIS)

Blinov, M.B.; Gavrilov, B.P.; Kovalenko, S.S.; Kozulin, Eh.M.; Mozhaev, A.N.; Oganesyan, Yu.Ts.; Penionzhkevich, Yu.Eh.

1984-01-01

The measurements of the yields of neutrons (energy more than 5 MeV) emitted in the interactions of carbon-12 ions (9 MeV/nucl.) with nuclei of two tin isotopes are conducted. The results obtained prove the effect of nucleon composition of a nucleus on the process of formation of high-energy neutrons. To clarify the concrete interaction mechanism it is necessary to perform systematic research for a number of isotopes differing in the relation of the number of neutrons and protons and binding energies of the last neutron

Dependence of isospin fractionation process on the neutron-proton ratio of a colliding system in intermediate energy heavy-ion collisions

International Nuclear Information System (INIS)

Xing Yongzhong; Liu Jianye; Fang Yutian; Guo Wenjun

2004-01-01

The degree of isospin fractionation is measured by the ratio of saturated neutron-proton: i.e. the ratio of gas phase (nucleon emission) to that of liquid phase (fragment emission) in heavy ion collisions. The authors have studied the dependence of the degree of isospin fractionation on the neutron-proton ratio in the colliding system by using isospin-dependent quantum molecular dynamical model. The calculated results show that the degree of isospin fractionation depends sensitively on the symmetry potential and weakly on the isospin effect of nucleon-nucleon cross section. In particular, the degree of isospin fractionation increases with increasing neutron-proton ratio in the colliding system for the neutron-rich system, in this process the neutron-rich gas phase and neutron-poor liquid phase are produced. The degree of isospin fractionation is very sensitive to the degree of symmetry potential. On the contrary, for the neutron-poor system the neutron-poor gas phase and neutron-rich liquid phase are produced. In this case, the degree of isospin fractionation is not sensitive to the symmetry potential. The authors also find that the role of momentum dependent interaction in the isospin fractionation process is not obvious. The authors propose that our calculated results can compared directly with the experimental data to get the information about the symmetry potential in the intermediate energy heavy-ion collisions

Comparison of gamma, neutron and proton irradiations of multimode fibers

International Nuclear Information System (INIS)

Gingerich, M.E.; Dorsey, K.L.; Askins, C.G.; Friebele, E.J.

1987-01-01

The effects of pure gamma, pure proton, and mixed neutron-gamma irradiation fields on a set of both pure and doped silica core multimode fibers have been investigated. Only slight differences are found in the radiation response of pure and doped silica core fibers exposed to gamma or mixed neutron-gamma fields, indicating that Co-60 sources can be used to simulate the effects of the mixed field (except in the case of a pure neutron environment). Although it is noted that neither mix field nor gamma sources adequately simulate the effects of proton irradiation of doped silica core fibers, a good correspondence is found in the case of the pure silica core waveguide. 13 references

Consequences of the proposed near equality of neutron and proton radii in the calcium isotopes

International Nuclear Information System (INIS)

Zamick, L.

1976-01-01

If the difference in neutron and proton radii in the Calcium Isotopes is much less than has up to now been calculated, one does have a mechanism for solving the Nolen-Schiffer anomaly; but then one runs into difficulty with other quantities such as the renormalized effective interaction between identical nucleons. (B.G.)

Structure of neutron-rich nuclei

International Nuclear Information System (INIS)

Nazarewicz, W.

2000-01-01

Complete text of publication follows. The uncharted regions of the (N,Z) plane contain information that can answer many questions of fundamental importance for science: How many protons and neutrons can be clustered together by the strong interaction to form a bound nucleus? What are the proton and neutron magic numbers of the exotic nuclei? What are the properties of very short-lived exotic nuclei with extreme neutron-to-proton ratios? What is the effective nucleon-nucleon interaction in a nucleus that has a very large neutron excess? Nuclear life far from stability is different from that around the stability line; the promised access to completely new combinations of proton and neutron numbers offers prospects for new structural phenomena. The main objective of this talk is to discuss some of the challenges and opportunities of research with exotic nuclei. The covered topics will include: Theoretical challenges; Skins and halos in heavy nuclei; Shape coexistence in exotic nuclei; Beta-decays of neutron-rich nuclei. (author)

Neutron energy spectrum from 120 GeV protons on a thick copper target

Energy Technology Data Exchange (ETDEWEB)

Shigyo, Nobuhiro; /Kyushu U.; Sanami, Toshiya; /KEK, Tsukuba; Kajimoto, Tsuyoshi; /Kyushu U.; Iwamoto, Yosuke; /JAEA, Ibaraki; Hagiwara, Masayuki; Saito, Kiwamu; /KEK, Tsukuba; Ishibashi, Kenji; /Kyushu U.; Nakashima, Hiroshi; Sakamoto, Yukio; /JAEA, Ibaraki; Lee, Hee-Seock; /Pohang Accelerator Lab.; Ramberg, Erik; /Fermilab

2010-08-01

Neutron energy spectrum from 120 GeV protons on a thick copper target was measured at the Meson Test Beam Facility (MTBF) at Fermi National Accelerator Laboratory. The data allows for evaluation of neutron production process implemented in theoretical simulation codes. It also helps exploring the reasons for some disagreement between calculation results and shielding benchmark data taken at high energy accelerator facilities, since it is evaluated separately from neutron transport. The experiment was carried out using a 120 GeV proton beam of 3E5 protons/spill. Since the spill duration was 4 seconds, protoninduced events were counted pulse by pulse. The intensity was maintained using diffusers and collimators installed in the beam line to MTBF. The protons hit a copper block target the size of which is 5cm x 5cm x 60 cm long. The neutrons produced in the target were measured using NE213 liquid scintillator detectors, placed about 5.5 m away from the target at 30{sup o} and 5 m 90{sup o} with respect to the proton beam axis. The neutron energy was determined by time-of-flight technique using timing difference between the NE213 and a plastic scintillator located just before the target. Neutron detection efficiency of NE213 was determined on basis of experimental data from the high energy neutron beam line at Los Alamos National Laboratory. The neutron spectrum was compared with the results of multiparticle transport codes to validate the implemented theoretical models. The apparatus would be applied to future measurements to obtain a systematic data set for secondary particle production on various target materials.

Structural design study of a proton beam window for a 1-MW spallation neutron source

Energy Technology Data Exchange (ETDEWEB)

Teraoku, Takuji; Terada, Atsuhiko; Maekawa, Fujio; Meigo, Shin-ichiro; Kaminaga, Masanori; Ishikura, Syuichi; Hino, Ryutaro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2003-03-01

A 1-MW spallation neutron source aiming at materials and life science researches will be constructed under the JAERI-KEK High-intensity Proton Accelerator Project (J-PARC). A proton beam passes through a proton beam window, and be injected into a target of the neutron source. The proton beam window functions as a boundary wall between a high vacuum area in the proton beam line and a helium atmosphere at about atmospheric pressure in a helium vessel which contains the target and moderators. The proton beam window is cooled by light water because high heat-density is generated in the window material by interactions with the proton beam. Then, uniformity of the water flow is requested at the window to suppress a hot-spot that causes excessive thermal stress and cooling water boiling. Also, the window has to be strong enough in its structure for inner stress due to water pressure and thermal stress due to heat generation. In this report, we propose two types of proton beam windows; one flat-type that is easy to manufacture, and the other, curved-type that has high stress resistivity. As a part of design study for the windows, evaluation of strength of structure and thermal hydraulic analysis were conducted. As a result, it was found that sufficient heat removal was assured with uniform water flow at the window, and stress caused by internal water pressure and thermal stress could be maintained below allowable stress values. Accordingly, it was confirmed that the proton beam window designs were feasible. (author)

Possibilities for a neutron-proton bremsstrahlung experiment at WNR/LAMPF

International Nuclear Information System (INIS)

Wender, S.A.; Nelson, R.O.; Laymon, C.M.; Schillaci, M.; Gibson, B.F.

1990-01-01

The high energy and high intensity of the continuous energy (white) neutron source at the WNR target area of the Los Alamos Meson Physics Facility (LAMPF) may make possible a direct measurement of the neutron-proton bremsstrahlung (NPB) cross section. Several recent papers have discussed the operation of the WNR white neutron source in detail so we will just include a short description of the relevant properties of the source in this article. Next the authors will describe one possible method of measuring the NPB cross section which is based on two calorimetric detectors that measure the energies of the scattered neutrons and the recoil protons. Although there are many other possible experimental approaches and geometries, such as measuring the bremsstrahlung gamma ray directly with a multi-element possibilities in this paper. There are several advantages in using a white neutron source for this type of measurement. First, a wide range of incident neutron energies may be covered. In the case of the WNR, the energy range is from below 50 MeV to over 400 MeV which is above the pion production threshold. Second, all incident neutron energies are measure simultaneously. 6 refs., 5 figs

General quadrupole shapes in the Interacting Boson Model

International Nuclear Information System (INIS)

Leviatan, A.

1990-01-01

Characteristic attributes of nuclear quadrupole shapes are investigated within the algebraic framework of the Interacting Boson Model. For each shape the Hamiltonian is resolved into intrinsic and collective parts, normal modes are identified and intrinsic states are constructed and used to estimate transition matrix elements. Special emphasis is paid to new features (e.g. rigid triaxiality and coexisting deformed shapes) that emerge in the presence of the three-body interactions. 27 refs

Spectroscopic Quadrupole Moments in {96,98}Sr: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60.

Science.gov (United States)

Clément, E; Zielińska, M; Görgen, A; Korten, W; Péru, S; Libert, J; Goutte, H; Hilaire, S; Bastin, B; Bauer, C; Blazhev, A; Bree, N; Bruyneel, B; Butler, P A; Butterworth, J; Delahaye, P; Dijon, A; Doherty, D T; Ekström, A; Fitzpatrick, C; Fransen, C; Georgiev, G; Gernhäuser, R; Hess, H; Iwanicki, J; Jenkins, D G; Larsen, A C; Ljungvall, J; Lutter, R; Marley, P; Moschner, K; Napiorkowski, P J; Pakarinen, J; Petts, A; Reiter, P; Renstrøm, T; Seidlitz, M; Siebeck, B; Siem, S; Sotty, C; Srebrny, J; Stefanescu, I; Tveten, G M; Van de Walle, J; Vermeulen, M; Voulot, D; Warr, N; Wenander, F; Wiens, A; De Witte, H; Wrzosek-Lipska, K

2016-01-15

Neutron-rich {96,98}Sr isotopes have been investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross sections. These results allow, for the first time, the drawing of definite conclusions about the shape coexistence of highly deformed prolate and spherical configurations. In particular, a very small mixing between the coexisting states is observed, contrary to other mass regions where strong mixing is present. Experimental results have been compared to beyond-mean-field calculations using the Gogny D1S interaction in a five-dimensional collective Hamiltonian formalism, which reproduce the shape change at N=60.

Protonation states of histidine and other key residues in deoxy normal human adult hemoglobin by neutron protein crystallography

International Nuclear Information System (INIS)

Kovalevsky, Andrey; Chatake, Toshiyuki; Shibayama, Naoya; Park, Sam-Yong; Ishikawa, Takuya; Mustyakimov, Marat; Fisher, S. Zoe; Langan, Paul; Morimoto, Yukio

2010-01-01

Using neutron diffraction analysis, the protonation states of 35 of 38 histidine residues were determined for the deoxy form of normal human adult hemoglobin. Distal and buried histidines may contribute to the increased affinity of the deoxy state for hydrogen ions and its decreased affinity for oxygen compared with the oxygenated form. The protonation states of the histidine residues key to the function of deoxy (T-state) human hemoglobin have been investigated using neutron protein crystallography. These residues can reversibly bind protons, thereby regulating the oxygen affinity of hemoglobin. By examining the OMIT F o − F c and 2F o − F c neutron scattering maps, the protonation states of 35 of the 38 His residues were directly determined. The remaining three residues were found to be disordered. Surprisingly, seven pairs of His residues from equivalent α or β chains, αHis20, αHis50, αHis58, αHis89, βHis63, βHis143 and βHis146, have different protonation states. The protonation of distal His residues in the α 1 β 1 heterodimer and the protonation of αHis103 in both subunits demonstrates that these residues may participate in buffering hydrogen ions and may influence the oxygen binding. The observed protonation states of His residues are compared with their ΔpK a between the deoxy and oxy states. Examination of inter-subunit interfaces provided evidence for interactions that are essential for the stability of the deoxy tertiary structure

Neutron fragmentation and inclusive charge exchange in pd and π+d interactions at 195 GeV/c

International Nuclear Information System (INIS)

Eisenberg, Y.; Haber, B.; Hochman, D.; Koller, E.; Ronat, E.E.; Shapira, A.; Yaari, R.; Yekutieli, G.; Braun, H.; Etienne, F.; Fridman, A.; Gerber, J.P.; Jegham, E.; Juillot, P.; Maurer, G.; Voltolini, C.

1976-01-01

An excess of negative particles and depletion of positives in the cms backward hemisphere is observed in π + and p interactions on neutron target. dΣ - /dy is compared with pp interactions and the difference is related to the slow proton spectrum produced in the pn interactions. A neutron fragmentation component is observed and the inclusive charge exchange probability at the nucleon vertex is found to be about 0.4. (author)

Neutron, Proton, and Photonuclear Cross Sections for Radiation Therapy and Radiation Protection

International Nuclear Information System (INIS)

Chadwick, M.B.

1998-01-01

The authors review recent work at Los Alamos to evaluate neutron, proton, and photonuclear cross section up to 150 MeV (to 250 MeV for protons), based on experimental data and nuclear model calculations. These data are represented in the ENDF format and can be used in computer codes to simulate radiation transport. They permit calculations of absorbed dose in the body from therapy beams, and through use of kerma coefficients allow absorbed dose to be estimated for a given neutron energy distribution. For radiation protection, these data can be used to determine shielding requirements in accelerator environments, and to calculate neutron, proton, gamma-ray, and radionuclide production. Illustrative comparisons of the evaluated cross section and kerma coefficient data with measurements are given

On the difference between proton and neutron spin-orbit splittings in nuclei

International Nuclear Information System (INIS)

Isakov, V.I.; Erokhina, K.I.; Mach, H.; Sanchez-Vega, M.; Fogelberg, B.

2002-01-01

The latest experimental data on nuclei at 132 Sn permit us for the first time to determine the spin-orbit splittings of neutrons and protons in identical orbits in this neutron-rich doubly magic region and compare the case to that of 208 Pb. Using the new results, which are now consistent for the two neutron-rich doubly magic regions, a theoretical analysis defines the isotopic dependence of the mean-field spin-orbit potential and leads to a simple explicit expression for the difference between the spin-orbit splittings of neutrons and protons. The isotopic dependence is explained in the framework of different theoretical approaches. (orig.)

SU-E-T-566: Neutron Dose Cloud Map for Compact ProteusONE Proton Therapy

Energy Technology Data Exchange (ETDEWEB)

Syh, J; Patel, B; Syh, J; Rosen, L; Wu, H [Willis-Knighton Medical Center, Shreveport, LA (United States)

2015-06-15

Purpose: To establish the base line of neutron cloud during patient treatment in our new compact Proteus One proton pencil beam scanning (PBS) system with various beam delivery gantry angles, with or without range shifter (RS) at different body sites. Pencil beam scanning is an emerging treatment technique, for the concerns of neutron exposure, this study is to evaluate the neutron dose equivalent per given delivered dose under various treatment conditions at our proton therapy center. Methods: A wide energy neutron dose equivalent detector (SWENDI-II, Thermo Scientific, MA) was used for neutron dose measurements. It was conducted in the proton therapy vault during beam was on. The measurement location was specifically marked in order to obtain the equivalent dose of neutron activities (H). The distances of 100, 150 and 200 cm at various locations are from the patient isocenter. The neutron dose was measured of proton energy layers, # of spots, maximal energy range, modulation width, field radius, gantry angle, snout position and delivered dose in CGE. The neutron dose cloud is reproducible and is useful for the future reference. Results: When distance increased the neutron equivalent dose (H) reading did not decrease rapidly with changes of proton energy range, modulation width or spot layers. For cranial cases, the average mSv/CGE was about 0.02 versus 0.032 for pelvis cases. RS will induce higher H to be 0.10 mSv/CGE in average. Conclusion: From this study, neutron per dose ratio (mSv/CGE) slightly depends upon various treatment parameters for pencil beams. For similar treatment conditions, our measurement demonstrates this value for pencil beam scanning beam has lowest than uniform scanning or passive scattering beam with a factor of 5. This factor will be monitored continuously for other upcoming treatment parameters in our facility.

Automatic detection of recoil-proton tracks and background rejection criteria in liquid scintillator-micro-capillary-array fast neutron spectrometer

Science.gov (United States)

Mor, Ilan; Vartsky, David; Dangendorf, Volker; Tittelmeier, Kai.; Weierganz, Mathias; Goldberg, Mark Benjamin; Bar, Doron; Brandis, Michal

2018-06-01

We describe an analysis procedure for automatic unambiguous detection of fast-neutron-induced recoil proton tracks in a micro-capillary array filled with organic liquid scintillator. The detector is viewed by an intensified CCD camera. This imaging neutron detector possesses the capability to perform high position-resolution (few tens of μm), energy-dispersive transmission-imaging using ns-pulsed beams. However, when operated with CW or DC beams, it also features medium-quality spectroscopic capabilities for incident neutrons in the energy range 2-20 MeV. In addition to the recoil proton events which display a continuous extended track structure, the raw images exhibit complex ion-tracks from nuclear interactions of fast-neutrons in the scintillator, capillaries quartz-matrix and CCD. Moreover, as expected, one also observes a multitude of isolated scintillation spots of varying intensity (henceforth denoted "blobs") that originate from several different sources, such as: fragmented proton tracks, gamma-rays, heavy-ion reactions as well as events and noise that occur in the image-intensifier and CCD. In order to identify the continuous-track recoil proton events and distinguish them from all these background events, a rapid, computerized and automatic track-recognition-procedure was developed. Based on an appropriately weighted analysis of track parameters such as: length, width, area and overall light intensity, the method is capable of distinguishing a single continuous-track recoil proton from typically surrounding several thousands of background events that are found in each CCD frame.

Quadrupole interaction in zinc metal

International Nuclear Information System (INIS)

Vetterling, W.T.; Pound, R.V.

1977-01-01

To allow measurement of the quadrupole interaction in zinc metal, the enriched ZnO was reduced to zinc metal powder and compressed into a pill of thickness 1.4 gm/cm 2 . Sources were made by diffusing 20 mCi of 67 Ga into sintered copper pills. The transducer was based on a cylinder of PZT-4 with 1 / 2 -inch length and could cover linearly a velocity range of +-100 μ/s at 200 Hz. The multiscalar was a modified Northern model NS600, with a minimum dwell time of 20 μs, and with a 10-count buffer at the input to eliminate deadtime from memory cycling

Causality and the proton-neutron mass difference

International Nuclear Information System (INIS)

Abdel-Rahman, A.M.; Taha, M.O.

1977-01-01

The Cottingham formula for the electromagnetic proton-neutron mass difference is simplified by imposing certain casuality conditions. The Born contribution to the mass difference is calculated using the modified formula and is found to be insignificant. The divergent part and the deep-inelastic contribution are discussed

Neutron fragmentation and inclusive charge exchange in pd and π+d interactions at 195 GeV/c

International Nuclear Information System (INIS)

Eisenberg, Y.; Haber, B.; Hochman, D.; Koller, E.; Ronat, E.E.; Shapira, A.; Yaari, R.; Yekutieli, G.; Braun, H.; Etienne, F.; Fridman, A.; Gerber, J.P.; Jegham, E.; Juillot, P.; Maurer, G.; Voltolini, C.

1977-01-01

An excess of negative particles and depletion of positive particles in the backward hemisphere (c.m. system) is observed in π + and p interactions on neutron target. dsigma - /dy is compared with pp interactions and the difference is related to the slow-proton spectrum produced in the pn interactions. A neutron fragmentation component is observed, and the inclusive charge-exchange probability at the nucleon vertex is found to be about 0.4

Proton and Neutron Irradiation Tests of Readout Electronics of the ATLAS Hadronic Endcap Calorimeter

CERN Document Server

Menke, Sven; The ATLAS collaboration

2012-01-01

The readout electronics of the ATLAS Hadronic Endcap Calorimeter will have to withstand the about ten times larger radiation environment of the future high-luminosity LHC (HL-LHC) compared to their design values. The GaAs ASIC which comprises the heart of the readout electronics has been exposed to neutron and proton radiation with fluences up to ten times the total expected fluences for ten years of running of the HL-LHC. Neutron tests where performed at the NPI in Rez, Czech Republic, where a 36 MeV proton beam is directed on a thick heavy water target to produce neutrons. The proton irradiation was done with 200 MeV protons at the PROSCAN area of the Proton Irradiation Facility at the PSI in Villigen, Switzerland. In-situ measurements of S-parameters in both tests allow the evaluation of frequency dependent performance parameters - like gain and input impedance - as a function of the fluence. The linearity of the ASIC response has been measured directly in the neutron tests with a triangular input pulse of...

Proton and Neutron Irradiation Tests of Readout Electronics of the ATLAS Hadronic Endcap Calorimeter

CERN Document Server

INSPIRE-00106910

2012-01-01

The readout electronics of the ATLAS Hadronic Endcap Calorimeter will have to withstand the about ten times larger radiation environment of the future high-luminosity LHC (HL-LHC) compared to their design values. The GaAs ASIC which comprises the heart of the readout electronics has been exposed to neutron and proton radiation with fluences up to ten times the total expected fluences for ten years of running of the HL-LHC. Neutron tests were performed at the NPI in Rez, Czech Republic, where a 36 MeV proton beam is directed on a thick heavy water target to produce neutrons. The proton irradiation was done with 200 MeV protons at the PROSCAN area of the Proton Irradiation Facility at the PSI in Villigen, Switzerland. In-situ measurements of S-parameters in both tests allow the evaluation of frequency dependent performance parameters - like gain and input impedance - as a function of the fluence. The linearity of the ASIC response has been measured directly in the neutron tests with a triangular input pulse of ...

Response of combined albedo-track neutron personnel dosimeters behind IHEP proton synchrotron shielding

International Nuclear Information System (INIS)

Sannikov, A.V.; Korshunova, E.P.

1989-01-01

The method of readings interpretation of combined albedo-track neutron personnel dosemeters based on calculationsl analysis of the detector responses in various neutron spectra is described. The measurements of dose equivalent responses have been performed in various points behind IHEP proton synchrotron shielding. It is shown that CDs with fission track detectors have a small dose equivalent response dispersion behind IHEP proton synchrotron shielding, that shows the promise of their using for neutron personnel monitoring, that shows the promise of their using for neutron personnel monitoring at high energy accelerators. 16 refs.; 7 figs.; 3 tabs

The pygmy quadrupole resonance and neutron-skin modes in 124Sn

Directory of Open Access Journals (Sweden)

M. Spieker

2016-01-01

Full Text Available We present an extensive experimental study of the recently predicted pygmy quadrupole resonance (PQR in Sn isotopes, where complementary probes were used. In this study, (α,α′γ and (γ,γ′ experiments were performed on 124Sn. In both reactions, Jπ=2+ states below an excitation energy of 5 MeV were populated. The E2 strength integrated over the full transition densities could be extracted from the (γ,γ′ experiment, while the (α,α′γ experiment at the chosen kinematics strongly favors the excitation of surface modes because of the strong α-particle absorption in the nuclear interior. The excitation of such modes is in accordance with the quadrupole-type oscillation of the neutron skin predicted by a microscopic approach based on self-consistent density functional theory and the quasiparticle-phonon model (QPM. The newly determined γ-decay branching ratios hint at a non-statistical character of the E2 strength, as it has also been recently pointed out for the case of the pygmy dipole resonance (PDR. This allows us to distinguish between PQR-type and multiphonon excitations and, consequently, supports the recent first experimental indications of a PQR in 124Sn.

Recent research on nuclear reaction using high-energy proton and neutron

Energy Technology Data Exchange (ETDEWEB)

Shibata, Tokushi [Tokyo Univ., Tanashi (Japan). Inst. for Nuclear Study

1997-11-01

The presently available high-energy neutron beam facilities are introduced. Then some interesting research on nuclear reaction using high-energy protons are reported such as the intermediate mass fragments emission and neutron spectrum measurements on various targets. As the important research using high-energy neutron, the (p,n) reactions on Mn, Fe, and Ni, the elastic scattering of neutrons, and the shielding experiments are discussed. (author)

Semiempirical formulas for single-particle energies of neutrons and protons

International Nuclear Information System (INIS)

Lodhi, M.A.K.; Waak, B.T.

1978-01-01

The stepwise multiple linear regression technique has been used to analyze the single-particle energies of neutrons and protons in nuclei along the line of beta stability. Their regular and systematic trends lead to semiempirical model-independent formulas for single-particle energies of neutrons and protons in the bound nuclei as functions of nuclear parameters A and Z for given states specified by nl/sub j/. These formulas are almost as convenient as the harmonic oscillator energy formulas to use. The single-particle energies computed from these formulas have been compared with the experimental data and are found in reasonable agreement

Analysis of accelerator based neutron spectra for BNCT using proton recoil spectroscopy

International Nuclear Information System (INIS)

Wielopolski, L.; Ludewig, H.; Powell, J.R.; Raparia, D.; Alessi, J.G.; Lowenstein, D.I.

1998-01-01

Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by 10 B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to gain penetration depth in the brain Fairchild proposed, for this purpose, the use of energetic epithermal neutrons at about 10 keV. Phase I/II clinical trials of BNCT for GM are underway at the Brookhaven Medical Research Reactor (BMRR) and at the MIT Reactor, using these nuclear reactors as the source for epithermal neutrons. In light of the limitations of new reactor installations, e.g. cost, safety and licensing, and limited capability for modulating the reactor based neutron beam energy spectra alternative neutron sources are being contemplated for wider implementation of this modality in a hospital environment. For example, accelerator based neutron sources offer the possibility of tailoring the neutron beams, in terms of improved depth-dose distributions, to the individual and offer, with relative ease, the capability of modifying the neutron beam energy and port size. In previous work new concepts for compact accelerator/target configuration were published. In this work, using the Van de Graaff accelerator the authors have explored different materials for filtering and reflecting neutron beams produced by irradiating a thick Li target with 1.8 to 2.5 MeV proton beams. However, since the yield and the maximum neutron energy emerging from the Li-7(p,n)Be-7 reaction increase with increase in the proton beam energy, there is a need for optimization of the proton energy versus filter and shielding requirements to obtain the desired epithermal neutron beam. The MCNP-4A computer code was used for the initial design studies that were verified with benchmark experiments

Status of spallation neutron source program in High Intensity Proton Accelerator Project

International Nuclear Information System (INIS)

Oyama, Yukio

2001-01-01

Japan Atomic Energy Research Institute and High Energy Accelerator Organization are jointly designing a 1 MW spallation neutron source as one of the research facilities planned in the High Intensity Proton Accelerator Project. The spallation neutron source is driven by 3 GeV proton beam with a mercury target and liquid hydrogen moderators. The present status of design for these spallation source and relevant facility is overviewed. (author)

Measurement of the neutron lifetime by counting trapped protons

International Nuclear Information System (INIS)

Byrne, J.; Dawber, P.G.; Spain, J.A.; Williams, A.P.; Dewey, M.S.; Gilliam, D.M.; Greene, G.L.; Lamaze, G.P.; Scott, R.D.; Pauwels, J.; Eykens, R.; Lamberty, A.

1990-01-01

The neutron lifetime τ n has been measured by counting decay protons stored in a Penning trap whose magnetic axis coincided with a neutron-beam axis. The result of the measurement is τ n =893.6±5.3 s, which agrees well with the value predicted by precise measurements of the β-decay asymmetry parameter A and the standard model

Proton-rich nuclear statistical equilibrium

International Nuclear Information System (INIS)

Seitenzahl, I.R.; Timmes, F.X.; Marin-Lafleche, A.; Brown, E.; Magkotsios, G.; Truran, J.

2008-01-01

Proton-rich material in a state of nuclear statistical equilibrium (NSE) is one of the least studied regimes of nucleosynthesis. One reason for this is that after hydrogen burning, stellar evolution proceeds at conditions of an equal number of neutrons and protons or at a slight degree of neutron-richness. Proton-rich nucleosynthesis in stars tends to occur only when hydrogen-rich material that accretes onto a white dwarf or a neutron star explodes, or when neutrino interactions in the winds from a nascent proto-neutron star or collapsar disk drive the matter proton-rich prior to or during the nucleosynthesis. In this Letter we solve the NSE equations for a range of proton-rich thermodynamic conditions. We show that cold proton-rich NSE is qualitatively different from neutron-rich NSE. Instead of being dominated by the Fe-peak nuclei with the largest binding energy per nucleon that have a proton-to-nucleon ratio close to the prescribed electron fraction, NSE for proton-rich material near freezeout temperature is mainly composed of 56Ni and free protons. Previous results of nuclear reaction network calculations rely on this nonintuitive high-proton abundance, which this Letter explains. We show how the differences and especially the large fraction of free protons arises from the minimization of the free energy as a result of a delicate competition between the entropy and nuclear binding energy.

Determination of proton and neutron spectra in the LANSCE spallation irradiation facility

International Nuclear Information System (INIS)

James, M.R.; Maloy, S.A.; Sommer, W.F.; Fowler, M.M.; Dry, D.; Ferguson, P.D.; Mueller, G.; Corzine, R.K.

1999-01-01

Materials samples were recently irradiated in the Los Alamos Radiation Effects Facility (LASREF) at the Los Alamos Neutron Science Center (LANSCE) to provide data for the Accelerator Production of Tritium (APT) project on the effect of irradiation on the mechanical and physical properties of materials. The targets were configured to expose samples to a variety of radiation environments including, high-energy protons, mixed protons and high-energy neutrons, and low-energy neutrons. The samples were irradiated for approximately six months during a ten month period using an 800 MeV proton beam with a circular Gaussian shape of approximately 2σ = 3.0 cm. At the end of this period, the samples were extracted and tested. Activation foils were also extracted that had been placed in proximity to the materials samples. These were used to quantify the fluences in various locations

Study of proton and 2 protons emission from light neutron deficient nuclei around A=20

International Nuclear Information System (INIS)

Zerguerras, T.

2001-09-01

Proton and two proton emission from light neutron deficient nuclei around A=20 have been studied. A radioactive beam of 18 Ne, 17 F and 20 Mg, produced at the Grand Accelerateur National d'Ions Lourds by fragmentation of a 24 Mg primary beam at 95 MeV/A, bombarded a 9 Be target to form unbound states. Proton(s) and nuclei from the decay were detected respectively in the MUST array and the SPEG spectrometer. From energy and angle measurements, the invariant mass of the decaying nucleus could be reconstructed. Double coincidence events between a proton and 17 F, 16 O, 15 O, 14 O and 18 Ne were registered to obtain excitation energy spectra of 18 Ne, 17 F, 16 F, 15 F et 19 Na. Generally, the masses measures are in agreement with previous experiments. In the case of 18 Ne, excitation energy and angular distributions agree well with the predictions of a break up model calculation. From 17 Ne proton coincidences, a first experimental measurement of the ground state mass excess of 18 Na has been obtained and yields 24,19(0,15)MeV. Two proton emission from 17 Ne and 18 Ne excited states and the 19 Mg ground state was studied through triple coincidences between two proton and 15 O, 16 O and 17 Ne respectively. In the first case, the proton-proton relative angle distribution in the center of mass has been compared with model calculation. Sequential emission from excited states of 17 Ne, above the proton emission threshold, through 16 F is dominant but a 2 He decay channel could not be excluded. No 2 He emission from the 1.288 MeV 17 Ne state, or from the 6.15 MeV 18 Ne state has been observed. Only one coincidence event between 17 Ne and two proton was registered, the value of the one neutron stripping reaction cross section of 20 Mg being much lower than predicted. (author)

Hydrogen determination using secondary processes of recoil proton interaction with sample material

International Nuclear Information System (INIS)

Muminov, V.A.; Khajdarov, R.A.; Navalikhin, L.V.; Pardaev, Eh.

1980-01-01

Possibilities of hydrogen content determination in different materials according to secondary processes of interaction of recoil protons(irradiation in the field of fast neutrons) with sample material resulting in the appearance of characteristic X-ray irradiation are studied. Excitated irradiation is recorded with a detector placed in the protective screen and located at a certain distance from the object analyzed and neutron source. The method is tested taking as an example analysis of bromine-containing samples (30% Br, 0.5% H) and tungsten dioxide. The determination limit of hydrogen content constitutes 0.05% at confidence coefficient of 0.9. Neutron flux constituted 10 3 neutrons/cm 2 xs, the time of measurement being 15-20 minutes, the distance from the sample to the detector being 12-15 cm [ru

Dose conversion coefficients for high-energy photons, electrons, neutrons and protons

International Nuclear Information System (INIS)

Sakamoto, Yukio

2005-01-01

Dose conversion coefficients for photons, electrons and neutrons based on new ICRP recommendations were cited in the ICRP Publication 74, but the energy ranges of these data were limited and there are no data for high energy radiations produced in accelerator facilities. For the purpose of designing the high intensity proton accelerator facilities at JAERI, the dose evaluation code system of high energy radiations based on the HERMES code was developed and the dose conversion coefficients of effective dose were evaluated for photons, neutrons and protons up to 10 GeV, and electrons up to 100 GeV. The dose conversion coefficients of effective dose equivalent were also evaluated using quality factors to consider the consistency between radiation weighting factors and Q-L relationship. The effective dose conversion coefficients obtained in this work were in good agreement with those recently evaluated by using FLUKA code for photons and electrons with all energies, and neutrons and protons below 500 MeV. There were some discrepancy between two data owing to the difference of cross sections in the nuclear reaction models. The dose conversion coefficients of effective dose equivalents for high energy radiations based on Q-L relation in ICRP Publication 60 were evaluated only in this work. The previous comparison between effective dose and effective dose equivalent made it clear that the radiation weighting factors for high energy neutrons and protons were overestimated and the modification was required. (author)

Ab initio calculation of the neutron-proton mass difference

Science.gov (United States)

Borsanyi, Sz.; Durr, S.; Fodor, Z.; Hoelbling, C.; Katz, S. D.; Krieg, S.; Lellouch, L.; Lippert, T.; Portelli, A.; Szabo, K. K.; Toth, B. C.

2015-03-01

The existence and stability of atoms rely on the fact that neutrons are more massive than protons. The measured mass difference is only 0.14% of the average of the two masses. A slightly smaller or larger value would have led to a dramatically different universe. Here, we show that this difference results from the competition between electromagnetic and mass isospin breaking effects. We performed lattice quantum-chromodynamics and quantum-electrodynamics computations with four nondegenerate Wilson fermion flavors and computed the neutron-proton mass-splitting with an accuracy of 300 kilo-electron volts, which is greater than 0 by 5 standard deviations. We also determine the splittings in the Σ, Ξ, D, and Ξcc isospin multiplets, exceeding in some cases the precision of experimental measurements.

Ion, X-ray, UV and Neutron Microbeam Systems for Cell Irradiation.

Science.gov (United States)

Bigelow, A W; Randers-Pehrson, G; Garty, G; Geard, C R; Xu, Y; Harken, A D; Johnson, G W; Brenner, D J

2010-08-08

The array of microbeam cell-irradiation systems, available to users at the Radiological Research Accelerator Facility (RARAF), Center for Radiological Research, Columbia University, is expanding. The HVE 5MV Singletron particle accelerator at the facility provides particles to two focused ion microbeam lines: the sub-micron microbeam II and the permanent magnetic microbeam (PMM). Both the electrostatic quadrupole lenses on the microbeam II system and the magnetic quadrupole lenses on the PMM system are arranged as compound lenses consisting of two quadrupole triplets with "Russian" symmetry. Also, the RARAF accelerator is a source for a proton-induced x-ray microbeam (undergoing testing) and is projected to supply protons to a neutron microbeam based on the (7)Li(p, n)(7)Be nuclear reaction (under development). Leveraging from the multiphoton microscope technology integrated within the microbeam II endstation, a UV microspot irradiator - based on multiphoton excitation - is available for facility users. Highlights from radiation-biology demonstrations on single living mammalian cells are included in this review of microbeam systems for cell irradiation at RARAF.

Nuclear quadrupole interaction measurements of 19F* and 22Na* on Graphite

International Nuclear Information System (INIS)

Djoko-Surono, Th; Martin, Peter W

1996-01-01

Time differential perturbed angular distribution (TDPAD) technique has been used to investigate nuclear quadrupole interactions of 19 F * and 22 Na * in graphite. We concentrated the measurements on pseudo single crystal graphite called Highly Oriented Pyrolytic Graphite for it has an ordered structure in which the c-axes of the microcrystals aligned in a certain direction with the mosaic spread less than 1 o , while the a- and b-axes randomly oriented on a plane perpendicular to the c-axes. Interactions between quadrupole moment of 19 F * and 22 Na * with its surroundings electric field gradient were studied by detecting the γ-rays distribution, W(Θ,t). For 1 9F * we found one static interaction. The corresponding electric field gradient was V zz =3.24(19)x10 22 V/m 2 . In the case of 22 Na * we found no evidence of nuclear quadrupole interaction, however, we were able to conclude that |QV 22 | 19 bV/m 2 . Using theoretical calculation Q=0.06 barn, we find that |V zz | 20 V/m 2 . These results indicate that the value efg depend on two factors, the host crystal and the core electrons. The core electrons contribution to the total efg is considerably large

Development of a tandem-electrostatic-quadrupole accelerator facility for BNCT

International Nuclear Information System (INIS)

Kreiner, A.J.; Thatar Vento, V.; Levinas, P.; Bergueiro, J.; Di Paolo, H.; Burlon, A.A.; Kesque, J.M.; Valda, A.A.; Debray, M.E.; Somacal, H.R.; Minsky, D.M.

2009-01-01

In this work we describe the present status of an ongoing project to develop a tandem-electrostatic-quadrupole (TESQ) accelerator facility for accelerator-based (AB) BNCT at the Atomic Energy Commission of Argentina in Buenos Aires. The project final goal is a machine capable of delivering 30 mA of 2.4 MeV protons to be used in conjunction with a neutron production target based on the 7 Li(p,n) 7 Be reaction slightly beyond its resonance at 2.25 MeV. These are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the 7 Li(p,n) 7 Be reaction, to perform BNCT treatment for deep-seated tumors in less than an hour. An electrostatic machine is the technologically simplest and cheapest solution for optimized AB-BNCT. The machine being designed and constructed is a folded TESQ with a high-voltage terminal at 1.2 MV intended to work in air. Such a machine is conceptually shown to be capable of transporting and accelerating a 30 mA proton beam to 2.4 MeV. The general geometric layout, its associated electrostatic fields, and the acceleration tube are simulated using a 3D finite element procedure. The design and construction of the ESQ modules is discussed and their electrostatic fields are investigated. Beam transport calculations through the accelerator are briefly mentioned. Likewise, work related to neutron production targets, strippers, beam shaping assembly and patient treatment room is briefly described.

Development of a tandem-electrostatic-quadrupole accelerator facility for BNCT.

Science.gov (United States)

Kreiner, A J; Thatar Vento, V; Levinas, P; Bergueiro, J; Di Paolo, H; Burlon, A A; Kesque, J M; Valda, A A; Debray, M E; Somacal, H R; Minsky, D M; Estrada, L; Hazarabedian, A; Johann, F; Suarez Sandin, J C; Castell, W; Davidson, J; Davidson, M; Giboudot, Y; Repetto, M; Obligado, M; Nery, J P; Huck, H; Igarzabal, M; Fernandez Salares, A

2009-07-01

In this work we describe the present status of an ongoing project to develop a tandem-electrostatic-quadrupole (TESQ) accelerator facility for accelerator-based (AB) BNCT at the Atomic Energy Commission of Argentina in Buenos Aires. The project final goal is a machine capable of delivering 30 mA of 2.4 MeV protons to be used in conjunction with a neutron production target based on the (7)Li(p,n)(7)Be reaction slightly beyond its resonance at 2.25 MeV. These are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the (7)Li(p,n)(7)Be reaction, to perform BNCT treatment for deep-seated tumors in less than an hour. An electrostatic machine is the technologically simplest and cheapest solution for optimized AB-BNCT. The machine being designed and constructed is a folded TESQ with a high-voltage terminal at 1.2 MV intended to work in air. Such a machine is conceptually shown to be capable of transporting and accelerating a 30 mA proton beam to 2.4 MeV. The general geometric layout, its associated electrostatic fields, and the acceleration tube are simulated using a 3D finite element procedure. The design and construction of the ESQ modules is discussed and their electrostatic fields are investigated. Beam transport calculations through the accelerator are briefly mentioned. Likewise, work related to neutron production targets, strippers, beam shaping assembly and patient treatment room is briefly described.

Assessment of doses due to secondary neutrons received by patient treated by proton therapy

International Nuclear Information System (INIS)

Sayah, R.; Martinetti, F.; Donadille, L.; Clairand, I.; Delacroix, S.; De Oliveira, A.; Herault, J.

2010-01-01

Proton therapy is a specific technique of radiotherapy which aims at destroying cancerous cells by irradiating them with a proton beam. Nuclear reactions in the device and in the patient himself induce secondary radiations involving mainly neutrons which contribute to an additional dose for the patient. The author reports a study aimed at the assessment of these doses due to secondary neutrons in the case of ophthalmological and intra-cranial treatments. He presents a Monte Carlo simulation of the room and of the apparatus, reports the experimental validation of the model (dose deposited by protons in a water phantom, ambient dose equivalent due to neutrons in the treatment room, absorbed dose due to secondary particles in an anthropomorphic phantom), and the assessment with a mathematical phantom of doses dues to secondary neutrons received by organs during an ophthalmological treatment. He finally evokes current works of calculation of doses due to secondary neutrons in the case of intra-cranial treatments

Neutron-proton elastic scattering at high energies

Energy Technology Data Exchange (ETDEWEB)

Saleem, M.; Fazal-e-Aleem (Punjab Univ., Lahore (Pakistan). Dept. of Physics)

1980-09-06

The most recent measurements of the differential and total cross sections of neutron-proton elastic scattering from 70 to 400 GeV/c have been explained by using rho as a simple pole and pomeron as a dipole. The predictions are also made regarding the energy dependence of dip and bump structure in angular distribution.

A proton-driven, intense, subcritical, fission neutron source for radioisotope production

Energy Technology Data Exchange (ETDEWEB)

Jongen, Y. [Chemin du Cyclotron, Louvain-la-Neuve (Belgium)

1995-10-01

{sup 99m}Tc, the most frequently used radioisotope in nuclear medicine, is distributed as {sup 99}Mo=>{sup 99m}Tc generators. {sup 99}Mo is a fission product of {sup 235}U. To replace the aging nuclear reactors used today for this production, the author proposes to use a spallation neutron source, with neutron multiplication by fission. A 150 MeV, H{sup {minus}} cyclotron can produce a 225 kW proton beam with 50% total system energy efficiency. The proton beam would hit a molten lead target, surrounded by a water moderator and a graphite reflector, producing around 0.96 primary neutron per proton. The primary spallation neutrons, moderated, would strike secondary targets containing a subcritical amount of {sup 235}U. The assembly would show a k{sub eff} of 0.8, yielding a fivefold neutron multiplication. The thermal neutron flux at the targets location would be 2 {times} 10{sup 14} n/cm{sup 2}.s, resulting in a fission power of 500 to 750 kW. One such system could supply the world demand in {sup 99}Mo, as well as other radioisotopes. Preliminary indications show that the cost would be lower than the cost of a commercial 10 MW isotope production reactor. The cost of operation, of disposal of radiowaste and of decommissioning should be significantly lower as well. Finally, the non-critical nature of the system would make it more acceptable for the public than a nuclear reactor and should simplify the licensing process.

Inclusive production of hyperons, as well as of pions, charged kaons, protons, anti-protons and neutrons in p+p collisions at 158 GeV/c beam momentum

International Nuclear Information System (INIS)

Anticic, Tome

2010-01-01

New data on the production of hyperons, as well as of pions, charged kaons, protons, anti-protons, neutrons in p+p interactions are presented. The data come from a sample of 8.2 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The high statistics data sample allows the extraction of detailed differential distributions as a function of x f , y and p T . The results are compared with published data and models. Moreover, the measurements provide an important reference for studying effects of cold nuclear matter in proton-nucleus and hot dense matter in nucleus-nucleus collisions. (author)

Calibration of a compact magnetic proton recoil neutron spectrometer

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jianfu, E-mail: zhang_jianfu@163.com [School of Nuclear Science and Technology, Xi' an Jiaotong University, Xi' an 710049 (China); Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Ouyang, Xiaoping; Zhang, Xianpeng [School of Nuclear Science and Technology, Xi' an Jiaotong University, Xi' an 710049 (China); Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Ruan, Jinlu [Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Zhang, Guoguang [Applied Institute of Nuclear Technology, China Institute of Atomic Energy, Beijing 102413 (China); Zhang, Xiaodong [Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Qiu, Suizheng, E-mail: szqiu@mail.xjtu.edu.cn [School of Nuclear Science and Technology, Xi' an Jiaotong University, Xi' an 710049 (China); Chen, Liang; Liu, Jinliang; Song, Jiwen; Liu, Linyue; Yang, Shaohua [Northwest Institute of Nuclear Technology, Xi' an 710024 (China)

2016-04-21

Magnetic proton recoil (MPR) neutron spectrometer is considered as a powerful instrument to measure deuterium–tritium (DT) neutron spectrum, as it is currently used in inertial confinement fusion facilities and large Tokamak devices. The energy resolution (ER) and neutron detection efficiency (NDE) are the two most important parameters to characterize a neutron spectrometer. In this work, the ER calibration for the MPR spectrometer was performed by using the HI-13 tandem accelerator at China Institute of Atomic Energy (CIAE), and the NDE calibration was performed by using the neutron generator at CIAE. The specific calibration techniques used in this work and the associated accuracies were discussed in details in this paper. The calibration results were presented along with Monte Carlo simulation results.

A proton-recoil neutron spectrometer for time-dependent ion temperatures on the National Ignition Facility

International Nuclear Information System (INIS)

Murphy, T.J.

1995-01-01

Ion temperatures from inertial confinement fusion targets are usually determined by measuring the Doppler broadening of the neutron spectrum using the time-of-flight method. Measurement systems are generally designed so that the contribution of the duration of neutron production (∼100 ps) to the width of the neutron signal is negligible. This precludes the possibility of time-dependent ion temperature. If, however, one could measure the neutron energy and arrival time at a detector independently, then time-dependent neutron spectra could be obtained, and ion temperature information deduced. A concept utilizing a proton-recoil neutron spectrometer has been developed in which recoil protons from a small plastic foil are measured. From the energy, arrival time, and recoil angle of the recoil proton, the birth time and energy of the incident neutron can be deduced. The sensitivity of the system is low, but the higher anticipated neutron yields from the proposed National Ignition Facility may make the technique feasible. Large scintillator arrays currently in use on the Nova facility for neutron spectral measurements consist of ∼1,000 channels and detect between 50 and 500 counts for typical time-integrated data. Time-dependent results would then require about an order of magnitude larger system. Key issues for making this system feasible will be keeping the cost per channel low while allowing adequately time (∼ 50 ps), energy (20 keV), and angular resolution (2 mrad) for each of the proton detectors

Measured Neutron Spectra and Dose Equivalents From a Mevion Single-Room, Passively Scattered Proton System Used for Craniospinal Irradiation

Energy Technology Data Exchange (ETDEWEB)

Howell, Rebecca M., E-mail: rhowell@mdanderson.org [Department of Radiation Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas (United States); Burgett, Eric A.; Isaacs, Daniel [Department of Nuclear Engineering, Idaho State University, Pocatello, Idaho (United States); Price Hedrick, Samantha G.; Reilly, Michael P.; Rankine, Leith J.; Grantham, Kevin K.; Perkins, Stephanie; Klein, Eric E. [Department of Radiation Oncology, Washington University, St. Louis, Missouri (United States)

2016-05-01

Purpose: To measure, in the setting of typical passively scattered proton craniospinal irradiation (CSI) treatment, the secondary neutron spectra, and use these spectra to calculate dose equivalents for both internal and external neutrons delivered via a Mevion single-room compact proton system. Methods and Materials: Secondary neutron spectra were measured using extended-range Bonner spheres for whole brain, upper spine, and lower spine proton fields. The detector used can discriminate neutrons over the entire range of the energy spectrum encountered in proton therapy. To separately assess internally and externally generated neutrons, each of the fields was delivered with and without a phantom. Average neutron energy, total neutron fluence, and ambient dose equivalent [H* (10)] were calculated for each spectrum. Neutron dose equivalents as a function of depth were estimated by applying published neutron depth–dose data to in-air H* (10) values. Results: For CSI fields, neutron spectra were similar, with a high-energy direct neutron peak, an evaporation peak, a thermal peak, and an intermediate continuum between the evaporation and thermal peaks. Neutrons in the evaporation peak made the largest contribution to dose equivalent. Internal neutrons had a very low to negligible contribution to dose equivalent compared with external neutrons, largely attributed to the measurement location being far outside the primary proton beam. Average energies ranged from 8.6 to 14.5 MeV, whereas fluences ranged from 6.91 × 10{sup 6} to 1.04 × 10{sup 7} n/cm{sup 2}/Gy, and H* (10) ranged from 2.27 to 3.92 mSv/Gy. Conclusions: For CSI treatments delivered with a Mevion single-gantry proton therapy system, we found measured neutron dose was consistent with dose equivalents reported for CSI with other proton beamlines.

Evaluation of the Induced Activity in Air by the External Proton Beam in the Target Room of the Proton Accelerator Facility of Proton Engineering Frontier Project

International Nuclear Information System (INIS)

Lee, Cheol Woo; Lee, Young Ouk; Cho, Young Sik; Ahn, So Hyun

2007-01-01

One of the radiological concerns is the worker's exposure level and the concentration of the radionuclides in the air after shutdown, for the safety analysis on the proton accelerator facility. Although, the primary radiation source is the protons accelerated up to design value, all of the radio-nuclide is produced from the secondary neutron and photon induced reaction in air. Because, the protons don't penetrate the acceleration equipment like the DTL tank wall or BTL wall, secondary neutrons or photons are only in the air in the accelerator tunnel building because of the short range of the proton in the materials. But, for the case of the target rooms, external proton beams are occasionally used in the various experiments. When these external proton beams travel through air from the end of the beam transport line to the target, they interact directly with air and produce activation products from the proton induced reaction. The external proton beam will be used in the target rooms in the accelerator facility of the Proton Accelerator Frontier Project (PEFP). In this study, interaction characteristics of the external proton beam with air and induced activity in air from the direct interaction of the proton beam were evaluated

Measurement of the proton asymmetry (C) in free neutron β-decay with Perkeo III

Energy Technology Data Exchange (ETDEWEB)

Raffelt, Lukas Michael

2016-10-19

The decay of polarized neutrons can be used to search for Physics Beyond the Standard Model. The non-isotropic angular distributions of the decay particles are parity violating and reveal the true nature of the weak interaction. Many observables are available in the decay of polarized neutrons, but the decay itself is only described by three parameters, which allows searches for new physics in a combined analysis. Measurements of the electron angular correlation coefficient (A) can be used to precisely determine the ratio of the axial to the vector coupling constant. The proton angular correlation coefficient (C) has only been measured once by a predecessor of this experiment. We measured the proton asymmetry with a similar proton detector, but employed a new measuring scheme allowing the collection of the worlds first data on the proton energy dependence of the proton asymmetry. At the current state of the analysis, a statistical uncertainty on the value of C of 0.8 % in each of the two detectors can be reached. For a final value, studies of systematic effects based on field simulations and tracking are still missing. For this measurement I designed and constructed a new detector. For the first time the scintillator was coated with a transparent conductive coating and together with the new CAD milled light-guides in a four-side readout configuration the low energy performance of the detector could be increased. Several systematic effects have been studied, especially the Point Spread Function of the magnetic transport system.

Nuclear data relevant to single event upsets in semiconductor memories induced by cosmic-ray neutrons and protons

International Nuclear Information System (INIS)

Watanabe, Yukinobu

2008-01-01

The role of nuclear data is examined in the study of single event upset (SEU) phenomena in semiconductor memories caused by cosmic-ray neutrons and protons. Neutron and proton SEU cross sections are calculated with a simplified semi-empirical model using experimental heavy-ion SEU cross-sections and a dedicated database of neutron and proton induced reactions on 28 Si. Some impacts of the nuclear reaction data on SEU simulation are analyzed by investigating relative contribution of secondary ions and neutron elastic scattering to SEU and influence of simultaneous multiple ions emission on SEU. (author)

Study of beta-delayed neutron with proton-neutron QRPA plus statistical model

International Nuclear Information System (INIS)

Minato, Futoshi; Iwamoto, Osamu

2015-01-01

β-delayed neutron is known to be important for safety operation of nuclear reactor and prediction of elemental abundance after freeze-out of r-process. A lot of researches on it have been performed. However, the experimental data are far from complete since the lifetime of most of the relevant nuclei is so short that one cannot measure in a high efficiency. In order to estimate half-lives and delayed neutron emission probabilities of unexplored nuclei, we developed a new theoretical method which combines a proton-neutron quasi-particle random-phase-approximation and the Hauser-Feshbach statistical model. The present method reproduces experimentally known β-decay half-lives within a factor of 10 and about 40% of within a factor of 2. However it fails to reproduce delayed neutron emission probabilities. We discuss the problems and remedy for them to be made in future. (author)

Implementation of an Analytical Model for Leakage Neutron Equivalent Dose in a Proton Radiotherapy Planning System

Energy Technology Data Exchange (ETDEWEB)

Eley, John [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 (United States); Graduate School of Biomedical Sciences, The University of Texas, 6767 Bertner Ave., Houston, TX 77030 (United States); Newhauser, Wayne, E-mail: newhauser@lsu.edu [Department of Physics and Astronomy, Louisiana State University and Agricultural and Mechanical College, 202 Nicholson Hall, Tower Drive, Baton Rouge, LA 70803 (United States); Mary Bird Perkins Cancer Center, 4950 Essen Lane, Baton Rouge, LA 70809 (United States); Homann, Kenneth; Howell, Rebecca [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 (United States); Graduate School of Biomedical Sciences, The University of Texas, 6767 Bertner Ave., Houston, TX 77030 (United States); Schneider, Christopher [Department of Physics and Astronomy, Louisiana State University and Agricultural and Mechanical College, 202 Nicholson Hall, Tower Drive, Baton Rouge, LA 70803 (United States); Mary Bird Perkins Cancer Center, 4950 Essen Lane, Baton Rouge, LA 70809 (United States); Durante, Marco; Bert, Christoph [GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, Darmstadt 64291 (Germany)

2015-03-11

Equivalent dose from neutrons produced during proton radiotherapy increases the predicted risk of radiogenic late effects. However, out-of-field neutron dose is not taken into account by commercial proton radiotherapy treatment planning systems. The purpose of this study was to demonstrate the feasibility of implementing an analytical model to calculate leakage neutron equivalent dose in a treatment planning system. Passive scattering proton treatment plans were created for a water phantom and for a patient. For both the phantom and patient, the neutron equivalent doses were small but non-negligible and extended far beyond the therapeutic field. The time required for neutron equivalent dose calculation was 1.6 times longer than that required for proton dose calculation, with a total calculation time of less than 1 h on one processor for both treatment plans. Our results demonstrate that it is feasible to predict neutron equivalent dose distributions using an analytical dose algorithm for individual patients with irregular surfaces and internal tissue heterogeneities. Eventually, personalized estimates of neutron equivalent dose to organs far from the treatment field may guide clinicians to create treatment plans that reduce the risk of late effects.

A measurement of the neutron lifetime by counting trapped protons

CERN Document Server

Snow, W M; Dewey, M S; Fei, X; Gilliam, D M; Greene, G L; Nico, J S; Wietfeldt, F E

2000-01-01

A measurement of the neutron lifetime tau sub n performed by trapping and counting decay protons from in-beam neutron decays in a Penning trap is in progress at the National Institute of Standards and Technology (NIST). A description of the measurement technique, the status of the data analysis, and prospects for improvements in the measurement are discussed.

Systematics of β and γ parameters of O(6)-like nuclei in the interacting boson model

International Nuclear Information System (INIS)

Wang Baolin

1997-01-01

By comparing quadrupole moments between the interacting boson model (IBM) and the collective model, a simple calculation for the triaxial deformation parameters β and γ in the O(6)-like nuclei is presented, based on the intrinsic frame in the IBM. The systematics of the β and γ are studied. The realistic cases are calculated for the even-even Xe, Ba and Ce isotopes, and the smooth dependences of the strength ratios θ 3 /κ and the effective charges e 2 on the proton and neutron boson numbers N π and N ν are discovered

g-Boson renormalization effects in the interacting Boson model for nondegenerate orbits

Science.gov (United States)

Duval, P. D.; Pittel, S.; Barrett, B. R.; Druce, C. H.

1983-09-01

A nonperturbative model-space truncation procedure is utilized to include the effects of a single g boson on the parameters of the neutron-proton Interacting Boson Model in the realistic case of nondegenerate single-particle orbits. Particular emphasis is given to the single-boson energies ɛdϱ (ϱ = v, π), with numerical results presented for the even isotopes of Hg. Only part of the observed renormalization is obtained. Possible sources of further renormalizations to ɛdϱ are discussed. Results are also presented for the renormalizations of the boson quadrupole parameters κ and χϱ.

The Biological Effect of Fast Neutrons and High-Energy Protons; Effets Biologiques des Neutrons Rapides et des Protons de Haute Energie; Biologicheskoe dejstvie bystrykh nejtronov i protonov vysokikh ehnergii; Efectos Biologicos de los Neutrones Rapidos y de los Protones de Elevada Energia

Energy Technology Data Exchange (ETDEWEB)

Moskalev, Ju. I.; Petrovich, I. K.; Strel' cova, V. N.

1964-03-15

The paper gives the results of comparative experiments on the effects of fast neutrons and high-energy protons (500 MeV) on life expectancy, peripheral blood, incidence and rate of appearance of tumours in the rat as a function of administered dose and time of observation. The neutron experiment was performed on 573 and the proton experiment on 490 white rats. The animals irradiated with fast neutrons were given doses between 8.5 and 510 rad, and those irradiated with protons received doses between 28 and 1008 rad. The effective doses for the acute, sub-acute and chronic forms of sickness were established for fast neutrons and for protons. LD{sub 50/30} for neutrons was 408 and for protons 600 rad, and the corresponding LD{sub 50}/{sub 120} values were 380 and 600 rad. The conditions governing rat mortality were analysed both in the early and the later stages of the experiment. It is shown that the average life expectancy of rats irradiated with fast neutrons does not depend on sex. The shape of the dose-effect curve for the various peripheral-blood indexes is strongly dependent not only on the radiosensitivity of the blood cells in question but also on the time of observation. It may change greatly in time for one and the same index. A considerable time after irradiation with either fast neutrons or protons, benign and malignant tumours appear in different tissues of the rats, including the haemopoeitic tissues, mammary glands, pituitary, uterus, ovaries, prostate gland, testicles, liver, kidneys, lungs, gastro-intestinal tract, subcutaneous tissue, lymph nodes, urinary bladder, etc. The over-all incidence of tumours and the number of cases of multi centred neoplasms in females are two to three times higher than in males. The minimum tumour dose for the mammary glands with neutron irradiation is apparently rather less than 42.5 rad. The maximum incidence of tumours of the pituitary is found after irradiation with a dose of 42.5 rad.- At this same dose leucosis and

Experimental study on neutronics in bombardment of thick targets by high energy proton beams for accelerator-driven sub-critical system

CERN Document Server

Guo Shi Lun; Shi Yong Qian; Shen Qing Biao; Wan Jun Sheng; Brandt, R; Vater, P; Kulakov, B A; Krivopustov, M I; Sosnin, A N

2002-01-01

The experimental study on neutronics in the target region of accelerator-driven sub-critical system is carried out by using the high energy accelerator in Joint Institute for Nuclear Research, Dubna, Russia. The experiments with targets U(Pb), Pb and Hg bombarded by 0.533, 1.0, 3.7 and 7.4 GeV proton beams show that the neutron yield ratio of U(Pb) to Hg and Pb to Hg targets is (2.10 +- 0.10) and (1.76 +- 0.33), respectively. Hg target is disadvantageous to U(Pb) and Pb targets to get more neutrons. Neutron yield drops along 20 cm thick targets as the thickness penetrated by protons increases. The lower the energy of protons, the steeper the neutron yield drops. In order to get more uniform field of neutrons in the targets, the energy of protons from accelerators should not be lower than 1 GeV. The spectra of secondary neutrons produced by different energies of protons are similar, but the proportion of neutrons with higher energy gradually increases as the proton energy increases

Biological Effects of Neutron and Proton Irradiations. Vol. II. Proceedings of the Symposium on Biological Effects of Neutron Irradiations

International Nuclear Information System (INIS)

1964-01-01

During recent years the interest in biological effects caused by neutrons has been increasing steadily as a result of the rapid development of neutron technology and the great number of neutron sources being used. Neutrons, because of their specific physical characteristics and biological effects, form a special type of radiation hazard but, at the same time, are a prospective tool for applied radiobiology. This Symposium, held in Brookhaven at the invitation of the United States Government from 7-11 October 1963, provided an opportunity for scientists to discuss the experimental information at present available on the biological action of neutrons and to evaluate future possibilities. It was a sequel to the Symposium on Neutron Detection, Dosimetry and Standardization, which was organized by the International Atomic Energy Agency in December 1962 at Harwell. The Symposium was attended by 128 participants from 17 countries and 6 international organizations. Fifty-four papers were presented. The following subjects were discussed in various sessions: (1) Dosimetry. Estimation of absorbed dose of neutrons in biological material. (2) Biological effects of high-energy protons. (3) Cellular and genetic effects. (4) Pathology of neutron irradiation, including acute and chronic radiation syndromes (mortality, anatomical and histological changes, biochemical and metabolic disturbances) and delayed consequences. (5) Relative biological effectiveness of neutrons evaluated by different biological tests. A Panel on Biophysical Considerations in Neutron Experimentation, with special emphasis on informal discussions, was organized during the Symposium. The views of the Panel are recorded in Volume II of the Proceedings. Many reports were presented on the important subject of the relative effectiveness of the biological action of neutrons, as well as on the general pathology of neutron irradiation and the cellular and genetic effects related to it. Three survey papers considered

LHC interaction region quadrupole cryostat design

International Nuclear Information System (INIS)

Nicol, T.H.; Darve, Ch.; Huang, Y.; Page, T.M.

2002-01-01

The cryostat of a Large Hadron Collider (LHC) Interaction Region (IR) quadrupole magnet consists of all components of the inner triplet except the magnet assembly itself. It serves to support the magnet accurately and reliably within the vacuum vessel, to house all required cryogenic piping, and to insulate the cold mass from heat radiated and conducted from the environment. It must function reliably during storage, shipping and handling, normal magnet operation, quenches, and seismic excitations, and must be able to be manufactured at low cost. The major components of the cryostat are the vacuum vessel, thermal shield, multi-layer insulation system, cryogenic piping, and suspension system. The overall design of a cryostat for superconducting accelerator magnets requires consideration of fluid flow, proper selection of materials for their thermal and structural performance at both ambient and operating temperature, and knowledge of the environment to which the magnets will be subjected over the course of their expected operating lifetime. This paper describes the current LHC IR inner triplet quadrupole magnet cryostats being designed and manufactured at Fermilab as part of the US-LHC collaboration, and includes discussions on the structural and thermal considerations involved in the development of each of the major systems

Are neutron stars crushed? Gravitomagnetic tidal fields as a mechanism for binary-induced collapse

International Nuclear Information System (INIS)

Favata, Marc

2006-01-01

Numerical simulations of binary neutron stars by Wilson, Mathews, and Marronetti indicated that neutron stars that are stable in isolation can be made to collapse to black holes when placed in a binary. This claim was surprising as it ran counter to the Newtonian expectation that a neutron star in a binary should be more stable, not less. After correcting an error found by Flanagan, Wilson and Mathews found that the compression of the neutron stars was significantly reduced but not eliminated. This has motivated us to ask the following general question: Under what circumstances can general-relativistic tidal interactions cause an otherwise stable neutron star to be compressed? We have found that if a nonrotating neutron star possesses a current-quadrupole moment, interactions with a gravitomagnetic tidal field can lead to a compressive force on the star. If this current quadrupole is induced by the gravitomagnetic tidal field, it is related to the tidal field by an equation-of-state-dependent constant called the gravitomagnetic Love number. This is analogous to the Newtonian Love number that relates the strength of a Newtonian tidal field to the induced mass quadrupole moment of a star. The compressive force is almost never larger than the Newtonian tidal interaction that stabilizes the neutron star against collapse. In the case in which a current quadrupole is already present in the star (perhaps as an artifact of a numerical simulation), the compressive force can exceed the stabilizing one, leading to a net increase in the central density of the star. This increase is small (< or approx. 1%) but could, in principle, cause gravitational collapse in a star that is close to its maximum mass. This paper also reviews the history of the Wilson-Mathews-Marronetti controversy and, in an appendix, extends the discussion of tidally induced changes in the central density to rotating stars

Preliminary test of the MONDO project secondary fast and ultrafast neutrons tracker response using protons and MIP particles

Science.gov (United States)

Traini, G.; Battistoni, G.; Giacometti, V.; Gioscio, E.; Marafini, M.; Mirabelli, R.; Pinci, D.; Sarti, A.; Sciubba, A.; Patera, V.

2018-04-01

The risk of developing a second malignant cancer as a late time consequence of undergoing a treatment, is one of the main concerns in particle therapy (PT). Since neutrons can release a significant dose far away from the tumour region, a precise characterisation of their production point, kinetic energy and abundance is eagerly needed. The treatment planning system (TPS) software that predicts the normal tissue toxicity in the target region and the risk of late complications in the whole body is currently based on the poorly known production cross-sections and will greatly benefit from improved precision double differential measurements. The MONDO (MOnitor for Neutron Dose in hadrOntherapy) project aims to build an ultrafast neutron tracker that could be used to characterise the production of secondary neutrons with energies in the 20–400 MeV range. The neutron tracking will proceed via the detection of recoil protons produced in two consecutive (n, p) elastic scattering interactions. The MONDO detector consists of a 10 × 10 × 20 cm3 matrix of thin scintillating fibres, arranged in orthogonally oriented layers. A compact read-out sensor with single photon detection capabilities employing the CMOS SPAD technology has been developed in collaboration with Fondazione Bruno Kessler (FBK). The detector will be completed by the end of 2018. A 4 × 4 × 4.8 cm3 prototype has been built using 250 μ m thick scintillating fibres of squared section and was tested using a proton beam and minimum ionising particles. In this contribution we present the experimental results related to the prototype test performed with a proton beam at the Proton Therapy Centre of the Trento Hospital (PTC) in May 2017. The results are compared with the results of a Monte Carlo simulation performed with the FLUKA software.

Mass-selective Neutron Spectroscopy Beyond the Proton

International Nuclear Information System (INIS)

Krzystyniak, M; Seel, A G; Richards, S E; Gutmann, M J; Fernandez-Alonso, F

2014-01-01

We discuss ongoing methodological developments underpinning the determination of nuclear-momentum distributions from mass-resolved neutron Compton data of lightweight materials. To this end, two systems are considered in detail, namely, lithium hydride (including its deuterated counterpart) and squaric acid, an organic antiferroelectric material containing hydrogen, carbon, and oxygen. Beyond the usual case of the proton, our approach enables direct access to detailed line shape information associated with the underlying nuclear-momentum distributions of both deuterium and lithium. For oxygen and carbon, mean kinetic energies can also be obtained directly from the neutron data, as demonstrated by a detailed analysis of mass- resolved data from squaric acid. From an instrumentation point of view, this work provides a suitable platform for a detailed assessment of existing capabilities and future developments in mass-selective neutron spectroscopy on the VESUVIO spectrometer at ISIS

Measurement of neutron yield by 62 MeV proton beam on a thick Beryllium target

International Nuclear Information System (INIS)

Alba, R; Cosentino, G; Zoppo, A Del; Pietro, A Di; Figuera, P; Finocchiaro, P; Maiolino, C; Santonocito, D; Schillaci, M; Barbagallo, M; Colonna, N; Boccaccio, P; Esposito, J; Celentano, A; Osipenko, M; Ricco, G; Ripani, M; Viberti, C M; Kostyukov, A

2013-01-01

In the framework of research on IVth generation reactors and high intensity neutron sources a low-power prototype neutron amplifier was recently proposed by INFN. It is based on a low-energy, high current proton cyclotron, whose beam, impinging on a thick Beryllium converter, produces a fast neutron spectrum. The world database on the neutron yield from thick Beryllium target in the 70 MeV proton energy domain is rather scarce. The new measurement was performed at LNS, covering a wide angular range from 0 to 150 degrees and an almost complete neutron energy interval. In this contribution the preliminary data are discussed together with the proposed ADS facility.

Comprehensive Measurement of Neutron Yield Produced by 62 MeV Protons on Beryllium Target

International Nuclear Information System (INIS)

Osipenko, M.; Ripani, M.; Ricco, G.; Alba, R.; Schillaci, M.; Cosentino, L.; Del Zoppo, A.; Di Pietro, A.; Figuera, P.; Finocchiaro, P.; Maiolino, C.; Santonocito, D.; Scuderi, V.; Barbagallo, M.; Colonna, N.; Boccaccio, P.; Esposito, J.; Celentano, A.; Viberti, C.M.; Kostyukov, A.

2013-06-01

A low-power prototype of neutron amplifier, based on a 70 MeV, high current proton cyclotron being installed at LNL for the SPES RIB facility, was recently proposed within INFN-E project. This prototype uses a thick Beryllium converter to produce a fast neutron spectrum feeding a sub-critical reactor core. To complete the design of such facility the new measurement of neutron yield from a thick Beryllium target was performed at LNS. This measurement used liquid scintillator detectors to identify produced neutrons by Pulse Shape Discrimination and Time of Flight technique to measure neutron energy in the range 0.5-62 MeV. To extend the covered neutron energy range 3 He detector was used to measure neutrons below 0.5 MeV. The obtained yields were normalized to the charge deposited by the proton beam on the metallic Beryllium target. These techniques allowed to achieve a wide angular coverage from 0 to 150 degrees and to explore almost complete neutron energy interval. (authors)

Proton linac for hospital-based fast neutron therapy and radioisotope production

International Nuclear Information System (INIS)

Lennox, A.J.; Hendrickson, F.R.; Swenson, D.A.; Winje, R.A.; Young, D.E.

1989-09-01

Recent developments in linac technology have led to the design of a hospital-based proton linac for fast neutron therapy. The 180 microamp average current allows beam to be diverted for radioisotope production during treatments while maintaining an acceptable dose rate. During dedicated operation, dose rates greater than 280 neutron rads per minute are achievable at depth, DMAX = 1.6 cm with source to axis distance, SAD = 190 cm. Maximum machine energy is 70 MeV and several intermediate energies are available for optimizing production of isotopes for Positron Emission Tomography and other medical applications. The linac can be used to produce a horizontal or a gantry can be added to the downstream end of the linac for conventional patient positioning. The 70 MeV protons can also be used for proton therapy for ocular melanomas. 17 refs., 1 fig., 1 tab

Activation of 45-MeV proton irradiation and proton-induced neutron irradiation in polymers

International Nuclear Information System (INIS)

Ra, Se-Jin; Kim, Kye-Ryung; Jung, Myung-Hwan; Yang, Tae-Keon

2010-01-01

During beam irradiation experiments with more than a few MeV energetic protons, the sample activation problem can be very severe because it causes many kinds of additional problems for the post-processing of the samples, such as time loss, inconvenience of sample handling, personal radiation safety, etc. The most serious problem is that immediate treatment of the sample is impossible in some experiments, such as nano-particle synthesizing. To solve these problems, we studied why the samples are activated and how the level of the activation can be reduced. It is known that the main reasons of activation are nuclear reactions with elements of the target material by primary protons and secondary produced neutrons. Even though the irradiation conditions are same, the level of the activation can be different depending on the target materials. For the nanoparticle synthesizing experiments, the target materials can be defined as the container and the sample itself. The reduction of the activation from the container is easier than the reduction from the sample. Therefore, we tried to reduce the activation level by changing the container materials. In this paper, the results are displayed for some candidate container materials, such as polymethyl methacrylate, polystyrene, Glass, etc., with 45-MeV and 10-nA proton beams. As a result, PS is the most suitable material for the container because of its relatively low level of the activation by protons. Also the contribution of secondary produced neutrons to the activation is negligible.

The neutron-proton pairing and the moments of inertia of the rare earth even-even nuclei

International Nuclear Information System (INIS)

Calik, A. E.; Deniz, C.; Gerceklioglu, M.

2009-01-01

In this study, the possible effect of the neutron-proton pairing interaction in the heavy nuclei has been investigated in the framework of the BCS model by making a simple approximation. This effect has been searched realistically by calculating the moments of inertia of deformed even-even nuclei. Calculations show that the moments of inertia of rare earth nuclei changed dramatically and approached the experimental values.

SU-E-T-594: Out-Of-Field Neutron and Gamma Dose Estimated Using TLD-600/700 Pairs in the Wobbling Proton Therapy System

International Nuclear Information System (INIS)

Chen, Y; Lin, Y; Chen, H; Tsai, H

2015-01-01

Purpose: Secondary fast neutrons and gamma rays are mainly produced due to the interaction of the primary proton beam with the beam delivery nozzle. These secondary radiation dose to patients and radiation workers are unwanted. The purpose of this study is to estimate the neutron and gamma dose equivalent out of the treatment volume during the wobbling proton therapy system. Methods: Two types of thermoluminescent (TL) dosimeters, TLD-600 ( 6 LiF: Mg, Ti) and TLD-700 ( 7 LiF: Mg, Ti) were used in this study. They were calibrated in the standard neutron and gamma sources at National Standards Laboratory. Annealing procedure is 400°C for 1 hour, 100°C for 2 hours and spontaneously cooling down to the room temperature in a programmable oven. Two-peak method (a kind of glow curve analysis technique) was used to evaluate the TL response corresponding to the neutron and gamma dose. The TLD pairs were placed outside the treatment field at the neutron-gamma mixed field with 190-MeV proton beam produced by the wobbling system through the polyethylene plate phantom. The results of TLD measurement were compared to the Monte Carlo simulation. Results: The initial experiment results of calculated dose equivalents are 0.63, 0.38, 0.21 and 0.13 mSv per Gy outside the field at the distance of 50, 100, 150 and 200 cm. Conclusion: The TLD-600 and TLD-700 pairs are convenient to estimate neutron and gamma dosimetry during proton therapy. However, an accurate and suitable glow curve analysis technique is necessary. During the wobbling system proton therapy, our results showed that the neutron and gamma doses outside the treatment field are noticeable. This study was supported by the grants from the Chang Gung Memorial Hospital (CMRPD1C0682)

SU-E-T-594: Out-Of-Field Neutron and Gamma Dose Estimated Using TLD-600/700 Pairs in the Wobbling Proton Therapy System

Energy Technology Data Exchange (ETDEWEB)

Chen, Y [College of Medicine, Chang Gung University, Linkou, Taoyuan, Taiwan (China); Lin, Y [College of Medicine, Chang Gung University, Linkou, Taoyuan, Taiwan (China); Medical Physics Research Center, Institute for Radiological Research, Chang Gung University / Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan (China); Chen, H [College of Medicine, Chang Gung University, Linkou, Taoyuan, Taiwan (China); Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan (China); Tsai, H [College of Medicine, Chang Gung University, Linkou, Taoyuan, Taiwan (China); Medical Physics Research Center, Institute for Radiological Research, Chang Gung University / Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan (China); Healthy Aging Research Center, Chang Gung University, Linkou, Taoyuan, Taiwan (China)

2015-06-15

Purpose: Secondary fast neutrons and gamma rays are mainly produced due to the interaction of the primary proton beam with the beam delivery nozzle. These secondary radiation dose to patients and radiation workers are unwanted. The purpose of this study is to estimate the neutron and gamma dose equivalent out of the treatment volume during the wobbling proton therapy system. Methods: Two types of thermoluminescent (TL) dosimeters, TLD-600 ({sup 6}LiF: Mg, Ti) and TLD-700 ({sup 7}LiF: Mg, Ti) were used in this study. They were calibrated in the standard neutron and gamma sources at National Standards Laboratory. Annealing procedure is 400°C for 1 hour, 100°C for 2 hours and spontaneously cooling down to the room temperature in a programmable oven. Two-peak method (a kind of glow curve analysis technique) was used to evaluate the TL response corresponding to the neutron and gamma dose. The TLD pairs were placed outside the treatment field at the neutron-gamma mixed field with 190-MeV proton beam produced by the wobbling system through the polyethylene plate phantom. The results of TLD measurement were compared to the Monte Carlo simulation. Results: The initial experiment results of calculated dose equivalents are 0.63, 0.38, 0.21 and 0.13 mSv per Gy outside the field at the distance of 50, 100, 150 and 200 cm. Conclusion: The TLD-600 and TLD-700 pairs are convenient to estimate neutron and gamma dosimetry during proton therapy. However, an accurate and suitable glow curve analysis technique is necessary. During the wobbling system proton therapy, our results showed that the neutron and gamma doses outside the treatment field are noticeable. This study was supported by the grants from the Chang Gung Memorial Hospital (CMRPD1C0682)

Measurement of neutron yield by 62 MeV proton beam on a thick beryllium target

Energy Technology Data Exchange (ETDEWEB)

Osipenko, M., E-mail: osipenko@ge.infn.it [INFN, sezione di Genova, 16146 Genova (Italy); Ripani, M. [INFN, sezione di Genova, 16146 Genova (Italy); Alba, R. [INFN, Laboratori Nazionali del Sud, 95123 Catania (Italy); Ricco, G. [INFN, sezione di Genova, 16146 Genova (Italy); Schillaci, M. [INFN, Laboratori Nazionali del Sud, 95123 Catania (Italy); Barbagallo, M. [INFN, sezione di Bari, 70126 Bari (Italy); Boccaccio, P. [INFN, Laboratori Nazionali di Legnaro, 35020 Legnaro (Italy); Celentano, A. [Dipartimento di Fisica dell' Università di Genova, 16146 Genova (Italy); Colonna, N. [INFN, sezione di Bari, 70126 Bari (Italy); Cosentino, L.; Del Zoppo, A.; Di Pietro, A. [INFN, Laboratori Nazionali del Sud, 95123 Catania (Italy); Esposito, J. [INFN, Laboratori Nazionali di Legnaro, 35020 Legnaro (Italy); Figuera, P.; Finocchiaro, P. [INFN, Laboratori Nazionali del Sud, 95123 Catania (Italy); Kostyukov, A. [Moscow State University, Moscow 119992 (Russian Federation); Maiolino, C.; Santonocito, D.; Scuderi, V. [INFN, Laboratori Nazionali del Sud, 95123 Catania (Italy); Viberti, C.M. [Dipartimento di Fisica dell' Università di Genova, 16146 Genova (Italy)

2013-09-21

The design of a low-power prototype of neutron amplifier recently proposed within the INFN-E project indicated the need for more accurate data on the neutron yield produced by a proton beam with energy of about 70 MeV impinging on a thick beryllium target. Such measurement was performed at the LNS superconducting cyclotron, covering a wide angular range from 0° to 150° and a complete neutron energy interval from thermal to beam energy. Neutrons with energy above 0.5 MeV were measured by liquid scintillators exploiting their time of flight to determine the kinetic energy. For lower energy neutrons, down to thermal energy, a {sup 3}He detector was used. The obtained data are in good agreement with previous measurements at 0° using 66 MeV proton beam, covering neutron energies >10MeV, as well as with measurements at few selected angles using protons of 46, 55 and 113 MeV energy. The present results extend the neutron yield data in the 60–70 MeV beam energy range. A comparison of measured yields to MCNP, FLUKA and Geant4 Monte Carlo simulations was performed.

Quadrupole collectivity in {sup 128}Cd

Energy Technology Data Exchange (ETDEWEB)

Boenig, Esther Sabine

2014-07-07

The regions around shell closures, especially around doubly magic nuclei, are of major interest in nuclear structure physics, as they provide a perfect test for nuclear structure theory. The neutron-rich Cd isotopes in the region of {sup 132}Sn are only two protons away from the shell closure at Z=50 and in close proximity to the N=82 magic number. Nevertheless they show an irregular behaviour regarding the excitation energy of the first excited 2{sup +} state. This is not reproduced by shell model calculations, which is astonishing due to the proximity of the shell closures. In order to shed light on the much discussed region around doubly magic {sup 132}Sn, a Coulomb excitation experiment of {sup 128}Cd has been performed at REX-ISOLDE, CERN. The reduced transition strength B(E2;0{sup +}{sub gs} → 2{sup +}{sub 1}), which is a measure of collectivity, and the spectroscopic quadrupole moment Q{sub s}(2{sup +}{sub 1}) as a measure of deformation could be determined for the first time. The results are shown as the continuation of already measured neutron-rich Cd isotopes and are compared to both beyond mean field and shell model calculations, which give different predictions for these observables.

Skyrme's interaction beyond the mean-field. The DGCM+GOA Hamiltonian of nuclear quadrupole motion

International Nuclear Information System (INIS)

Kluepfel, Peter

2008-01-01

This work focuses on the microscopic description of nuclear collective quadrupole motion within the framework of the dynamic Generator-Coordinate-Method(DGCM)+Gaussian-Overlap-Approximation(GOA). Skyrme-type effective interactions are used as the fundamental many-particle interaction. Starting from a rotational invariant, polynomial and topologic consistent formulation of the GCM+GOA Hamiltonian an interpolation scheme for the collective masses and potential is developed. It allows to define the collective Hamiltonian of fully triaxial collective quadrupole dynamics from a purely axial symmetric configuration space. The substantial gain in performance allows the self-consistent evaluation of the dynamic quadrupole mass within the ATDHF-cranking model. This work presents the first large-scale analysis of quadrupole correlation energies and lowlying collective states within the DGCM+GOA model. Different Skyrme- and pairing interactions are compared from old standards up to more recent parameterizations. After checking the validity of several approximations to the DGCM+GOA model - both on the mean-field and the collective level - we proceed with a detailed investigation of correlation effects along the chains of semi-magic isotopes and isotones. This finally allows to define a set of observables which are hardly affected by collective correlations. Those observables were used for a refit of a Skyrme-type effective interaction which is expected to cure most of the problems of the recent parameterizations. Preparing further work, estimates for the correlated ground state energy are proposed which can be evaluated directly from the mean-field model. (orig.)

Skyrme's interaction beyond the mean-field. The DGCM+GOA Hamiltonian of nuclear quadrupole motion

Energy Technology Data Exchange (ETDEWEB)

Kluepfel, Peter

2008-07-29

This work focuses on the microscopic description of nuclear collective quadrupole motion within the framework of the dynamic Generator-Coordinate-Method(DGCM)+Gaussian-Overlap-Approximation(GOA). Skyrme-type effective interactions are used as the fundamental many-particle interaction. Starting from a rotational invariant, polynomial and topologic consistent formulation of the GCM+GOA Hamiltonian an interpolation scheme for the collective masses and potential is developed. It allows to define the collective Hamiltonian of fully triaxial collective quadrupole dynamics from a purely axial symmetric configuration space. The substantial gain in performance allows the self-consistent evaluation of the dynamic quadrupole mass within the ATDHF-cranking model. This work presents the first large-scale analysis of quadrupole correlation energies and lowlying collective states within the DGCM+GOA model. Different Skyrme- and pairing interactions are compared from old standards up to more recent parameterizations. After checking the validity of several approximations to the DGCM+GOA model - both on the mean-field and the collective level - we proceed with a detailed investigation of correlation effects along the chains of semi-magic isotopes and isotones. This finally allows to define a set of observables which are hardly affected by collective correlations. Those observables were used for a refit of a Skyrme-type effective interaction which is expected to cure most of the problems of the recent parameterizations. Preparing further work, estimates for the correlated ground state energy are proposed which can be evaluated directly from the mean-field model. (orig.)

Study of proton and 2 protons emission from light neutron deficient nuclei around A=20; Etude de l'emission proton et de deux protons dans les noyaux legers deficients en neutrons de la region A=20

Energy Technology Data Exchange (ETDEWEB)

Zerguerras, T

2001-09-01

Proton and two proton emission from light neutron deficient nuclei around A=20 have been studied. A radioactive beam of {sup 18}Ne, {sup 17}F and {sup 20}Mg, produced at the Grand Accelerateur National d'Ions Lourds by fragmentation of a {sup 24}Mg primary beam at 95 MeV/A, bombarded a {sup 9}Be target to form unbound states. Proton(s) and nuclei from the decay were detected respectively in the MUST array and the SPEG spectrometer. From energy and angle measurements, the invariant mass of the decaying nucleus could be reconstructed. Double coincidence events between a proton and {sup 17}F, {sup 16}O, {sup 15}O, {sup 14}O and {sup 18}Ne were registered to obtain excitation energy spectra of {sup 18}Ne, {sup 17}F, {sup 16}F, {sup 15}F et {sup 19}Na. Generally, the masses measures are in agreement with previous experiments. In the case of {sup 18}Ne, excitation energy and angular distributions agree well with the predictions of a break up model calculation. From {sup 17}Ne proton coincidences, a first experimental measurement of the ground state mass excess of {sup 18}Na has been obtained and yields 24,19(0,15)MeV. Two proton emission from {sup 17}Ne and {sup 18}Ne excited states and the {sup 19}Mg ground state was studied through triple coincidences between two proton and {sup 15}O, {sup 16}O and {sup 17}Ne respectively. In the first case, the proton-proton relative angle distribution in the center of mass has been compared with model calculation. Sequential emission from excited states of {sup 17}Ne, above the proton emission threshold, through {sup 16}F is dominant but a {sup 2}He decay channel could not be excluded. No {sup 2}He emission from the 1.288 MeV {sup 17}Ne state, or from the 6.15 MeV {sup 18}Ne state has been observed. Only one coincidence event between {sup 17}Ne and two proton was registered, the value of the one neutron stripping reaction cross section of {sup 20}Mg being much lower than predicted. (author)

Application of the generator coordinate method to neutron-rich Se and Ge isotopes

Directory of Open Access Journals (Sweden)

Higashiyama Koji

2014-03-01

Full Text Available The quantum-number projected generator coordinate method (GCM is applied to the neutron-rich Se and Ge isotopes, where the monopole and quadrupole pairing plus quadrupole-quadrupole interaction is employed as an effective interaction. The energy spectra obtained by the GCM are compared to both the shell model results and the experimental data. The GCM reproduces well the energy levels of high-spin states as well as the low-lying states. The structure of the low-lying collective states is analyzed through the GCM wave functions.

The design of a proton recoil telescope for 14 MeV neutron spectrometry

Energy Technology Data Exchange (ETDEWEB)

Hawkes, N.P.; Bond, D.S.; Croft, S.; Jarvis, O.N. E-mail: onj@jet.uk; Sherwood, A.C

2002-01-01

As part of the design effort for a 14 MeV neutron spectrometer for the Joint European Torus (JET), computer codes were developed to calculate the response of a proton recoil telescope comprising a proton radiator film mounted in front of a proton detector. The codes were used to optimise the geometrical configuration in terms of efficiency and resolution, bearing in mind the constraints imposed by the proposed application as a JET neutron diagnostic for the Deuterium-Tritium phase. A prototype instrument was built according to the optimised design, and tested with monoenergetic 14 MeV neutrons from the Harwell 500 keV Van de Graaff accelerator. The measured energy resolution and absolute efficiency were found to be in acceptable agreement with the calculations. Based on this work, a multi-radiator production version of the spectrometer has now been constructed and successfully deployed at JET.

The design of a proton recoil telescope for 14 MeV neutron spectrometry

International Nuclear Information System (INIS)

Hawkes, N.P.; Bond, D.S.; Croft, S.; Jarvis, O.N.; Sherwood, A.C.

2002-01-01

As part of the design effort for a 14 MeV neutron spectrometer for the Joint European Torus (JET), computer codes were developed to calculate the response of a proton recoil telescope comprising a proton radiator film mounted in front of a proton detector. The codes were used to optimise the geometrical configuration in terms of efficiency and resolution, bearing in mind the constraints imposed by the proposed application as a JET neutron diagnostic for the Deuterium-Tritium phase. A prototype instrument was built according to the optimised design, and tested with monoenergetic 14 MeV neutrons from the Harwell 500 keV Van de Graaff accelerator. The measured energy resolution and absolute efficiency were found to be in acceptable agreement with the calculations. Based on this work, a multi-radiator production version of the spectrometer has now been constructed and successfully deployed at JET

Reaction channel coupling effects for nucleons on 16O: Induced undularity and proton-neutron potential differences

Science.gov (United States)

Keeley, N.; Mackintosh, R. S.

2018-01-01

Background: Precise fitting of scattering observables suggests that the nucleon-nucleus interaction is l dependent. Such l dependence has been shown to be S -matrix equivalent to an undulatory l -independent potential. The undulations include radial regions where the imaginary term is emissive. Purpose: To study the dynamical polarization potential (DPP) generated in proton-16O and neutron-16O interaction potentials by coupling to pickup channels. Undulatory features occurring in these DPPs can be compared with corresponding features of empirical optical model potentials (OMPs). Furthermore, the additional inclusion of coupling to vibrational states of the target will provide evidence for dynamically generated nonlocality. Methods: The fresco code provides the elastic channel S -matrix Sl j for chosen channel couplings. Inversion, Sl j→V (r ) +l .s VSO(r ) , followed by subtraction of the bare potential, yields an l -independent and local representation of the DPP due to the chosen couplings. Results: The DPPs have strongly undulatory features, including radial regions of emissivity. Certain features of empirical DPPs appear, e.g., the full inverted potential has emissive regions. The DPPs for different collective states are additive except near the nuclear center, whereas the collective and reaction channel DPPs are distinctly nonadditive over a considerable radial range, indicating dynamical nonlocality. Substantial differences between the DPPs due to pickup coupling for protons and neutrons occur; these imply a greater difference between proton and neutron OMPs than the standard phenomenological prescription. Conclusions: The onus is on those who object to undularity in the local and l -independent representation of nucleon elastic scattering to show why such undulations do not occur. This work suggests that it is not legitimate to halt model-independent fits to high-quality data at the appearance of undularity.

Relation between proton and neutron asymptotic normalization coefficients for light mirror nuclei and its relevance for nuclear astrophysics)

International Nuclear Information System (INIS)

Timofeyuk, N.K.; Johnson, R.C.; Descouvemont, P.

2005-01-01

In this talk, relation between proton and neutron Asymptotic Normalization Coefficients (ANCs) for light mirror nuclei will be discussed. This relation follows from charge symmetry of nucleon-nucleon interactions and is given by a simple approximate analytical formula which involves proton and neutron separation energies, charges of residual nuclei and the range of their strong interaction with the last nucleon. This relation is valid both for particle-bound mirror nuclear levels and for mirror pairs in which one of the levels is a narrow resonance. In the latter case, the width of this resonance is related to the ANC of its mirror particle-stable analog. Our theoretical study of mirror ANCs for several light nuclei within a framework of microscopic two-, three- and four-cluster models, have shown that the ratio of mirror ANCs changes as predicted by the simple approximate analytical formula. We will also compare the results from our microscopic calculations to the predictions of the single-particle model and discuss mirror symmetry of spectroscopic factors and single-particle ANCs. (author)

Quadrupole interactions of Au in Be and lattice location studies

International Nuclear Information System (INIS)

Perscheid, B.; Gayer, H.W.; Krien, K.; Freitag, K.

1978-01-01

The Moessbauer nucleus 197 Au is used as probe for quadrupole interaction (QI) studies in Be metal. The 77 keV Moessbauer level is populated by the β - decay of 197 Pt and the EC decay of 197 Hg. This fact enabled samples prepared in different ways to be studied. (Auth.)

Current-current interaction picture for proton-proton scattering

International Nuclear Information System (INIS)

Clarke, D.J.; Lo, S.Y.

1979-01-01

The authors propose that color current - color current interaction is reponsible for small angle elastic proton proton scattering at asymptotic energy. Excellent fits are obtained for all data above 12 GeV/c which covers twelve orders of magnitude

Study of proton and 2 protons emission from light neutron deficient nuclei around A=20; Etude de l'emission proton et de deux protons dans les noyaux legers deficients en neutrons de la region A=20

Energy Technology Data Exchange (ETDEWEB)

Zerguerras, T

2001-09-01

Proton and two proton emission from light neutron deficient nuclei around A=20 have been studied. A radioactive beam of {sup 18}Ne, {sup 17}F and {sup 20}Mg, produced at the Grand Accelerateur National d'Ions Lourds by fragmentation of a {sup 24}Mg primary beam at 95 MeV/A, bombarded a {sup 9}Be target to form unbound states. Proton(s) and nuclei from the decay were detected respectively in the MUST array and the SPEG spectrometer. From energy and angle measurements, the invariant mass of the decaying nucleus could be reconstructed. Double coincidence events between a proton and {sup 17}F, {sup 16}O, {sup 15}O, {sup 14}O and {sup 18}Ne were registered to obtain excitation energy spectra of {sup 18}Ne, {sup 17}F, {sup 16}F, {sup 15}F et {sup 19}Na. Generally, the masses measures are in agreement with previous experiments. In the case of {sup 18}Ne, excitation energy and angular distributions agree well with the predictions of a break up model calculation. From {sup 17}Ne proton coincidences, a first experimental measurement of the ground state mass excess of {sup 18}Na has been obtained and yields 24,19(0,15)MeV. Two proton emission from {sup 17}Ne and {sup 18}Ne excited states and the {sup 19}Mg ground state was studied through triple coincidences between two proton and {sup 15}O, {sup 16}O and {sup 17}Ne respectively. In the first case, the proton-proton relative angle distribution in the center of mass has been compared with model calculation. Sequential emission from excited states of {sup 17}Ne, above the proton emission threshold, through {sup 16}F is dominant but a {sup 2}He decay channel could not be excluded. No {sup 2}He emission from the 1.288 MeV {sup 17}Ne state, or from the 6.15 MeV {sup 18}Ne state has been observed. Only one coincidence event between {sup 17}Ne and two proton was registered, the value of the one neutron stripping reaction cross section of {sup 20}Mg being much lower than predicted. (author)

Study of the ratios of neutrino inclusive cross sections on neutron and proton

International Nuclear Information System (INIS)

Francois, T.

1980-01-01

Here is a study of two bubble chamber experiments done at the CERN neutrino beams. The first, using 1 to 10 GeV neutrinos interacting in Gargamelle filled with propane, yields, after an original separation of neutron and proton interactions, to a cross section ratio of 2.07+-0.15 for charged current and 0.74+-0.15 for inelastic neutral current. The secondly using 15 to 200 GeV neutrinos reacting in BEBC filled with neon and implemented with a liquid hydrogen target, yields, by a comparison of both medium, to a cross section ratio of 1.98+-0.19 and to an indication of it increase as a function of the Bjorken x [fr

Proton injection and RF capture in the national spallation neutron source

International Nuclear Information System (INIS)

Luccio, A.U.; Beebe-Wang, J.; Maletic, D.

1997-01-01

The accelerator system for the 1 to 5 MW National Spallation Neutron Source (NSNS) consists of a linac followed by a 1 GeV proton accumulator ring. Since the ring is a very high current machine, the injection and rf capture of the protons is deeply affected by transverse and longitudinal space charge effects. Results of numerical simulation of the process are presented together with considerations on methods and results of space charge treatment in high intensity proton storage rings

An improved permanent magnet quadrupole design with larger good field region for high intensity proton linacs

Energy Technology Data Exchange (ETDEWEB)

Mathew, Jose V., E-mail: josev.mathew@gmail.com; Rao, S.V.L.S.; Krishnagopal, S.; Singh, P.

2013-11-01

The Low Energy High Intensity Proton Accelerator (LEHIPA), being developed at the Bhabha Atomic Research Centre (BARC) will produce a 20 MeV, 30 mA, continuous wave (CW) proton beam. At these low velocities, space-charge forces dominate, and could lead to larger beam sizes and beam halos. Hence in the design of the focusing lattice of the LEHIPA drift tube linac (DTL) using permanent magnet quadrupoles (PMQs), a larger good field region is preferred. Here we study, using the two dimensional (2D) and three dimensional (3D) simulation codes PANDIRA and RADIA, four different types of cylindrical PMQ designs: 16-segment trapezoidal Halbach configuration, bullet-nosed geometry and 8- and 16-segment rectangular geometries. The trapezoidal Halbach geometry is used in a variety of accelerators since it provides very high field gradients in small bores, while the bullet-nosed geometry, which is a combination of the trapezoidal and rectangular designs, is used in some DTLs. This study shows that a larger good field region is possible in the 16-segment rectangular design as compared to the Halbach and bullet-nosed designs, making it more attractive for high-intensity proton linacs. An improvement in good-field region by ∼16% over the Halbach design is obtained in the optimized 16-segment rectangular design, although the field gradient is lower by ∼20%. Tolerance studies show that the rectangular segment PMQ design is substantially less sensitive to the easy axis orientation errors and hence will be a better choice for DTLs. -- Highlights: • An improved permanent magnet quadrupole (PMQ) design with larger good field region is proposed. • We investigate four PMQ designs, including the widely used Halbach and bullet nosed designs. • Analytical calculations are backed by 2D as well as 3D numerical solvers, PANDIRA and RADIA. • The optimized 16 segment rectangular PMQ design is identified to exhibit the largest good field region. • The effect of easy axis orientation

An improved permanent magnet quadrupole design with larger good field region for high intensity proton linacs

International Nuclear Information System (INIS)

Mathew, Jose V.; Rao, S.V.L.S.; Krishnagopal, S.; Singh, P.

2013-01-01

The Low Energy High Intensity Proton Accelerator (LEHIPA), being developed at the Bhabha Atomic Research Centre (BARC) will produce a 20 MeV, 30 mA, continuous wave (CW) proton beam. At these low velocities, space-charge forces dominate, and could lead to larger beam sizes and beam halos. Hence in the design of the focusing lattice of the LEHIPA drift tube linac (DTL) using permanent magnet quadrupoles (PMQs), a larger good field region is preferred. Here we study, using the two dimensional (2D) and three dimensional (3D) simulation codes PANDIRA and RADIA, four different types of cylindrical PMQ designs: 16-segment trapezoidal Halbach configuration, bullet-nosed geometry and 8- and 16-segment rectangular geometries. The trapezoidal Halbach geometry is used in a variety of accelerators since it provides very high field gradients in small bores, while the bullet-nosed geometry, which is a combination of the trapezoidal and rectangular designs, is used in some DTLs. This study shows that a larger good field region is possible in the 16-segment rectangular design as compared to the Halbach and bullet-nosed designs, making it more attractive for high-intensity proton linacs. An improvement in good-field region by ∼16% over the Halbach design is obtained in the optimized 16-segment rectangular design, although the field gradient is lower by ∼20%. Tolerance studies show that the rectangular segment PMQ design is substantially less sensitive to the easy axis orientation errors and hence will be a better choice for DTLs. -- Highlights: • An improved permanent magnet quadrupole (PMQ) design with larger good field region is proposed. • We investigate four PMQ designs, including the widely used Halbach and bullet nosed designs. • Analytical calculations are backed by 2D as well as 3D numerical solvers, PANDIRA and RADIA. • The optimized 16 segment rectangular PMQ design is identified to exhibit the largest good field region. • The effect of easy axis orientation

Probing the pairing interaction through two-neutron transfer reactions

Directory of Open Access Journals (Sweden)

Margueron J.

2012-12-01

Full Text Available The treatment of the pairing interaction in mean-field-based models is addressed. In particular, the possibility to use pair transfers as A tool to better constrain this interaction is discussed. First, pairing inter-actions with various density dependencies (surface/volume mixing are used in the microscopic Hartree-Fock-Bogoliubov + quasiparticle random-phase approximation model to generate the form factors to be used in reaction calculations. Cross sections for (p,t two-neutron transfer reactions are calculated in the one-step zero-range distorted-wave Born approximation for some Tin isotopes and for incident proton energies from 15 to 35 MeV. Three different surface/volume mixings of A zero-range density-dependent pairing interaction are employed in the microscopic calculations and the sensitivity of the cross sections to the different mixings is analyzed. Differences among the three different theoretical predictions are found espacially for the nucleus 136Sn and they are more important at the incident proton energy of 15 MeV. We thus indicate (p,t two-neutron transfer reactions with very neutron-rich Sn isotopes and at proton energies around 15 MeV as good experimental cases where the surface/volume mixing of the pairing interaction may be probed. In the second part of the manuscript, ground-state to ground-state transitions are investigated. Approximations made to estimate two-nucleon transfer probabilities in ground-state to ground-state transitions and the physical interpretation of these probabilities are discussed. Probabilities are often calculated by approximating both ground states of the initial nucleus A and of the final nucleus A±2 by the same quasiparticle vacuum. We analyze two improvements of this approach. First, the effect of using two different ground states with average numbers of particles A and A±2 is quantified. Second, by using projection techniques, the role of particle number restoration is analyzed. Our analysis

Microscopic description of quadrupole collectivity in neutron-rich nuclei across the N = 126 shell closure

Science.gov (United States)

Rodríguez-Guzmán, R.; Robledo, L. M.; Sharma, M. M.

2015-06-01

The quadrupole collectivity in Nd, Sm, Gd, Dy, Er, Yb, Hf and W nuclei with neutron numbers 122 ≤ N ≤ 156 is studied, both at the mean field level and beyond, using the Gogny energy density functional. Besides the robustness of the N = 126 neutron shell closure, it is shown that the onset of static deformations in those isotopic chains with increasing neutron number leads to an enhanced stability and further extends the corresponding two-neutron drip lines far beyond what could be expected from spherical calculations. Independence of the mean-field predictions with respect to the particular version of the Gogny energy density functional employed is demonstrated by comparing results based on the D1S and D1M parameter sets. Correlations beyond mean field are taken into account in the framework of the angular momentum projected generator coordinate method calculation. It is shown that N = 126 remains a robust neutron magic number when dynamical effects are included. The analysis of the collective wave functions, average deformations and excitation energies indicate that, with increasing neutron number, the zero-point quantum corrections lead to dominant prolate configurations in the 0{1/+}, 0{2/+}, 2{1/+} and 2{2/+} states of the studied nuclei. Moreover, those dynamical deformation effects provide an enhanced stability that further supports the mean-field predictions, corroborating a shift of the r-process path to higher neutron numbers. Beyond mean-field calculations provide a smaller shell gap at N = 126 than the mean-field one in good agreement with previous theoretical studies. However, the shell gap still remains strong enough in the two-neutron drip lines.

The Origin of Mass in Neutrons and Protons

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 5. The Origin of Mass in Neutrons and Protons. M N Saha. Classics Volume 3 Issue 5 May 1998 pp 84-96. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/003/05/0084-0096. Author Affiliations.

Spallation study with proton beams around 1 GeV: neutron production

International Nuclear Information System (INIS)

Boudard, A.; Borne, F.; Brochard, F.; Crespin, S.; Drake, D.; Duchazeaubeneix, J.C.; Durand, D.; Durand, J.M.; Frehaut, J.; Hanappe, F.; Kowalski, L.; Lebrun, C.; Lecolley, F.R.; Lecolley, J.F.; Ledoux, X.; Lefebvres, F.; Legrain, R.; Leray, S.; Louvel, M.; Martinez, E.; Meigo, S.I.; Menard, S.; Milleret, G.; Patin, Y.; Petibon, E.; Plouin, F.; Pras, P.; Schapira, J.P.; Stuttge, L.; Terrien, Y.; Thun, J.; Uematsu, M.; Varignon, C.; Volant, C.; Whittal, D.M.; Wlazlo, W.

2000-01-01

Experiments performed at Lab. Nat. SATURNE on neutron produced by spallation from proton beams in the range 0.8 - 1.6 GeV are presented. Experimental data compared with codes show a significant improvement of the recent intra-nuclear cascade (J. Cugnon). This is also true in the same way for the neutron production from thick targets. However the model underestimates the energetic neutrons produced in the backward direction and other quantities as residual nuclei cross sections are not accurately predicted

Neutron transmission benchmark problems for iron and concrete shields in low, intermediate and high energy proton accelerator facilities

Energy Technology Data Exchange (ETDEWEB)

Nakane, Yoshihiro; Sakamoto, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Hayashi, Katsumi [and others

1996-09-01

Benchmark problems were prepared for evaluating the calculation codes and the nuclear data for accelerator shielding design by the Accelerator Shielding Working Group of the Research Committee on Reactor Physics in JAERI. Four benchmark problems: transmission of quasi-monoenergetic neutrons generated by 43 MeV and 68 MeV protons through iron and concrete shields at TIARA of JAERI, neutron fluxes in and around an iron beam stop irradiated by 500 MeV protons at KEK, reaction rate distributions inside a thick concrete shield irradiated by 6.2 GeV protons at LBL, and neutron and hadron fluxes inside an iron beam stop irradiated by 24 GeV protons at CERN are compiled in this document. Calculational configurations and neutron reaction cross section data up to 500 MeV are provided. (author)

Simulation code for the interaction of 14 MeV neutrons on cells

Energy Technology Data Exchange (ETDEWEB)

Nenot, M.L.; Alard, J.P.; Dionet, C.; Arnold, J.; Tchirkov, A.; Meunier, H.; Bodez, V.; Rapp, M.; Verrelle, P

2002-07-01

The structure of the survival curve of melanoma cells irradiated by 14 MeV neutrons displays unusual features at very low dose rate where a marked increase in cell killings at 0.05 Gy is followed by a plateau for survival from 0.1 to 0.32 Gy. In parallel a simulation code was constructed for the interaction of 14 MeV neutrons with cellular cultures. The code describes the interaction of the neutrons with the atomic nuclei of the cellular medium and of the external medium (flask culture and culture medium), and is used to compute the deposited energy into the cell volume. It was found that the large energy transfer events associated with heavy charged recoil can occur and that a large part of the energy deposition events are due to recoil protons emitted from the external medium. It is suggested that such events could partially explain the experimental results. (author)

Nuclear reactions excited by recoil protons on a nuclear reactor

International Nuclear Information System (INIS)

Mukhammedov, S.; Khaydarov, A.; Barsukova, E.G.

2006-01-01

The nuclear reactions excited by recoil protons and of the detection possibility of the various chemical elements with the use of these secondary nucleus reactions were investigated. The recoil protons are produced on a nuclear reactor in the result of (n, p) inelastic and elastic scattering interaction of fast neutrons with nuclei of hydrogen. It is well known that the share of fast neutrons in energetic spectrum of reactor's neutrons in comparison with the share of thermal neutrons is small. . Consequently, the share of recoil protons produced in the result of fast neutron interaction with nuclei of light elements, capable to cause the nuclear reactions, is also small, des, due to Coulomb barrier of nuclei the recoil protons can cause the nuclear reactions only on nuclei of light and some middle elements. Our studies show that observable yields have radio nuclides excited in the result of nuclear reactions on Li, B, O, V and Cu. Our experimental results have demonstrated that the proton activation analysis based on the application of secondary nuclear reactions is useful technique to determine large contents of various light and medium chemical elements. Detection limits for studied chemical elements are estimated better than 10 ppm

Quadrupole interaction studies of Hg in Sb

International Nuclear Information System (INIS)

Soares, J.C.; Krien, K.; Herzog, P.; Folle, H.R.; Freitag, K.; Reuschenbach, F.; Reuschenbach, M.; Trzcinski, R.

1978-01-01

Time differential perturbed angular correlation and nuclear orientation studies of the electric quadrupole interaction for Hg in Sb have been performed. The effective field gradients at room temperature and below 0.05K have been derived. These two values are no indication for an anomalous temperature dependence of the effective field gradient for Hg in Sb. The value of the electric field gradient fits well into the systematics for Hg in other hosts. It is shown that the electronic enhancements of the field gradients are correlated to the valence of the impurities and are rather insensitive to the host properties. (orig./HPOE) [de

Consistent analysis of collective level structure and neutron interaction data for 12C in the framework of the soft-rotator model

International Nuclear Information System (INIS)

Sukhovitskii, E.Sh.; Porodzinskii, Yu.V.; Iwamoto, Osamu; Chiba, Satoshi.

1997-09-01

A systematic analysis of nuclear structure and neutron interaction data for 12 C was carried out in the framework of the soft-rotator model. The model was firstly applied to analyze the low-lying collective level structure of the 12 C nucleus, which turned out to be very successful. The intrinsic wave function obtained in such an analysis was then used to construct the coupling potentials in the coupled-channels formalism to calculate the neutron total and scattering cross sections. The quadrupole deformation parameter obtained in the present analysis was 0.164, which was much smaller in the absolute sense than the value used in the symmetric-rotator, vibrator model employed frequently in the past, i.e., ≅0.6. When averaged over the β-vibration function, however, the present result yields an effective quadrupole strength of about the same scale as the previous studies due to softness of the 12 C wave function with respect to β 2 degree of freedom. The soft-rotator model was found to be very successful in reproducing both the structure and neutron scattering data consistently for the first time in this mass region. (author)

Secondary neutron doses received by patients of different ages during intracranial proton therapy treatments

International Nuclear Information System (INIS)

Sayah, R.

2012-01-01

Proton therapy is an advanced radiation therapy technique that allows delivering high doses to the tumor while saving the healthy surrounding tissues due to the protons' ballistic properties. However, secondary particles, especially neutrons, are created during protons' nuclear reactions in the beam-line and the treatment room components, as well as inside the patient. Those secondary neutrons lead to unwanted dose deposition to the healthy tissues located at distance from the target, which may increase the secondary cancer risks to the patients, especially the pediatric ones. The aim of this work was to calculate the neutron secondary doses received by patients of different ages treated at the Institut Curie-centre de Protontherapie d'Orsay (ICPO) for intracranial tumors, using a 178 MeV proton beam. The treatments are undertaken at the new ICPO room equipped with an IBA gantry. The treatment room and the beam-line components, as well as the proton source were modeled using the Monte Carlo code MCNPX. The obtained model was then validated by a series of comparisons between model calculations and experimental measurements. The comparisons concerned: a) depth and lateral proton dose distributions in a water phantom, b) neutron spectrometry at one position in the treatment room, c) ambient dose equivalents at different positions in the treatment room and d) secondary absorbed doses inside a physical anthropomorphic phantom. A general good agreement was found between calculations and measurements, thus our model was considered as validated. The University of Florida hybrid voxelized phantoms of different ages were introduced into the MCNPX validated model, and secondary neutron doses were calculated to many of these phantoms' organs. The calculated doses were found to decrease as the organ's distance to the treatment field increases and as the patient's age increases. The secondary doses received by a one year-old patient may be two times higher than the doses

An assessment of the secondary neutron dose in the passive scattering proton beam facility of the national cancer center

Energy Technology Data Exchange (ETDEWEB)

Han, Sang Eun [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Cho, Gyuseong [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Lee, Se Byeong [Proton Therapy Center, National Cancer Center, Goyang (Korea, Republic of)

2017-06-15

The purpose of this study is to assess the additional neutron effective dose during passive scattering proton therapy. Monte Carlo code (Monte Carlo N-Particle 6) simulation was conducted based on a precise modeling of the National Cancer Center's proton therapy facility. A three-dimensional neutron effective dose profile of the interior of the treatment room was acquired via a computer simulation of the 217.8-MeV proton beam. Measurements were taken with a 3He neutron detector to support the simulation results, which were lower than the simulation results by 16% on average. The secondary photon dose was about 0.8% of the neutron dose. The dominant neutron source was deduced based on flux calculation. The secondary neutron effective dose per proton absorbed dose ranged from 4.942 ± 0.031 mSv/Gy at the end of the field to 0.324 ± 0.006 mSv/Gy at 150 cm in axial distance.

On the idea of low-energy nuclear reactions in metallic lattices by producing neutrons from protons capturing "heavy" electrons

Science.gov (United States)

Tennfors, Einar

2013-02-01

The present article is a critical comment on Widom and Larsens speculations concerning low-energy nuclear reactions (LENR) based on spontaneous collective motion of protons in a room temperature metallic hydride lattice producing oscillating electric fields that renormalize the electron self-energy, adding significantly to the effective electron mass and enabling production of low-energy neutrons. The frequency and mean proton displacement estimated on the basis of neutron scattering from protons in palladium and applied to the Widom and Larsens model of the proton oscillations yield an electron mass enhancement less than one percent, far below the threshold for the proposed neutron production and even farther below the mass enhancement obtained by Widom and Larsen assuming a high charge density. Neutrons are not stopped by the Coulomb barrier, but the energy required for the neutron production is not low.

Study on bulk shielding for a spallation neutron source facility in the high-intensity proton accelerator project

CERN Document Server

Maekawa, F; Takada, H; Teshigawara, M; Watanabe, N

2002-01-01

Under the JAERI-KEK High-Intensity Proton Accelerator Project, a spallation neutron source driven by a 3 GeV-1 MW proton beam is planed to be constructed in a main part of the Materials and Life Science Facility. This report describes results of a study on bulk shielding performance of a biological shield for the spallation neutron source by means of a Monte Carlo calculation method, that is important in terms of radiation safety and cost reduction. A shielding configuration was determined as a reference case by considering preliminary studies and interaction with other components, then shielding thickness that was required to achieve a target dose rate of 1 mu Sv/h was derived. Effects of calculation conditions such as shielding materials and dimensions on the shielding performance was investigated by changing those parameters. By taking all the results and design margins into account, a shielding configuration that was identified as the most appropriate was finally determined as follows. An iron shield regi...

Structural activation calculations due to proton beam loss in the APT accelerator design

International Nuclear Information System (INIS)

Lee, S. K.; Beard, C. A.; Wilson, W. B.; Daemen, L. L.; Liska, D. J.; Waters, L. S.; Adams, M. L.

1995-01-01

For the new, high-power accelerators currently being designed, the amount of activation of the accelerator structure has become an important issue. To quantify this activation, a methodology was utilized that coupled transport and depletion codes to obtain dose rate estimates at several locations near the accelerator. This research focused on the 20 and 100 MeV sections of the Bridge-Coupled Drift Tube Linear Accelerator. The peak dose rate was found to be approximately 6 mR/hr in the 100 MeV section near the quadrupoles at a 25-cm radius for an assumed beam loss of 1 nA/m. It was determined that the activation was dominated by the proton interactions and subsequent spallation product generation, as opposed to the presence of the generated neutrons. The worst contributors were the spallation products created by proton bombardment of iron, and the worst component was the beam pipe, which consists mostly of iron. No definitive conclusions about the feasibility of hands-on maintenance can be determined, as the design is still not finalized

Structural activation calculations due to proton beam loss in the APT accelerator design

International Nuclear Information System (INIS)

Lee, S.K.; Beard, C.A.; Wilson, W.B.; Daemen, L.L.; Liska, D.J.; Waters, L.S.; Adams, M.L.

1994-01-01

For the new, high-power accelerators currently being designed, the amount of activation of the accelerator structure has become an important issue. To quantify this activation, a methodology was utilized that coupled transport and depletion codes to obtain dose rate estimates at several locations near the accelerator. This research focused on the 20 and 100 MeV sections of the Bridge-Coupled Drift Tube Linear Accelerator. The peak dose rate was found to be approximately 6 mR/hr in the 100 MeV section near the quadrupoles at a 25-cm radius for an assumed beam loss of 1 nA/m. It was determined that the activation was dominated by the proton interactions and subsequent spallation product generation, as opposed to the presence of the generated neutrons. The worst contributors were the spallation products created by proton bombardment of iron, and the worst component was the beam pipe, which consists mostly of iron. No definitive conclusions about the feasibility of hands-on maintenance can be determined, as the design is still not finalized

A new target concept for proton accelerator driven boron neutron capture therapy applications

International Nuclear Information System (INIS)

Powell, J.R.; Ludewig, H.; Todosow, M.; Reich, M.

1998-01-01

A new target concept termed Discs Incorporating Sector Configured Orbiting Sources (DISCOS), is proposed for spallation applications, including BNCT (Boron Neutron Capture Therapy). In the BNCT application a proton beam impacts a sequence of ultra thin lithium DISCOS targets to generate neutrons by the 7 Li(p,n) 7 Be reaction. The proton beam loses only a few keV of its ∼MeV energy as it passes through a given target, and is re-accelerated to its initial energy, by a DC electric field between the targets

Research on anisotropy of fusion-produced protons and neutrons emission from high-current plasma-focus discharges

Energy Technology Data Exchange (ETDEWEB)

Malinowski, K., E-mail: karol.malinowski@ncbj.gov.pl; Sadowski, M. J.; Szydlowski, A. [National Centre for Nuclear Research (NCBJ), 05-400 Otwock (Poland); Institute of Plasma Physics and Laser Microfusion (IFPiLM), 01-497 Warsaw (Poland); Skladnik-Sadowska, E.; Czaus, K.; Kwiatkowski, R.; Zaloga, D. [National Centre for Nuclear Research (NCBJ), 05-400 Otwock (Poland); Paduch, M.; Zielinska, E. [Institute of Plasma Physics and Laser Microfusion (IFPiLM), 01-497 Warsaw (Poland)

2015-01-15

The paper concerns fast protons and neutrons from D-D fusion reactions in a Plasma-Focus-1000U facility. Measurements were performed with nuclear-track detectors arranged in “sandwiches” of an Al-foil and two PM-355 detectors separated by a polyethylene-plate. The Al-foil eliminated all primary deuterons, but was penetrable for fast fusion protons. The foil and first PM-355 detector were penetrable for fast neutrons, which were converted into recoil-protons in the polyethylene and recorded in the second PM-355 detector. The “sandwiches” were irradiated by discharges of comparable neutron-yields. Analyses of etched tracks and computer simulations of the fusion-products behavior in the detectors were performed.

Fast neutron spectroscopy by gas proton-recoil methods at the light water reactor pressure vessel simulator

International Nuclear Information System (INIS)

Rogers, J.W.

1980-10-01

Fast neutron spectrum measurements were made in a Light Water Reactor (LWR) Pressure Vessel Simulator (PVS) to provide neutron spectral definition required to appropriately perform and interpret neutron dosimetry measurements related to fast neutron damage in LWR-PV steels. Proton-recoil proportional counter methods using hydrogen and methane gas-filled detectors were applied to obtain the proton spectra from which the neutron spectra were derived. Cylindrical and spherical geometry detectors were used to cover the neutron energy range between 50 keV and 2 MeV. Results show that the neutron spectra shift in energy distribution toward lower energy between the front and back of a PVS. The relative neutron flux densities increase in this energy range with increasing thickness of the steel. Neutron spectrum fine structure shapes and changes are observed. These results should assist in the generation of more accurate effective cross sections and fluences for use in LWR-PV fast neutron dosimetry and materials damage analyses

1/N expansion in the interacting boson model. II. The neutron-proton degree of freedon

International Nuclear Information System (INIS)

Kuyucak, S.; Morrison, I.

1989-01-01

The 1/N expansion method is used to study the neutron-proton degree of freedom in a general boson model. Employing a standard IBM-2 hamiltonian, analytic expressions for energies and electromagnetic transition rates are derived both for the symmetric and mixed-symmetry states. A formalism for F-spin analysis is developed. Effects of the g-boson and F-spin breaking in various quantities are discussed. The method is not restricted to dynamic symmetries and allows for explicit breaking of the F-spin symmetry. Thus, the formulae derived here should be useful for systematic analysis of deformed nuclei in realistic situations. 42 refs., 13 figs

Neutron-proton elastic scattering between 200 and 500 MeV

International Nuclear Information System (INIS)

Clough, A.S.; Gibson, D.R.; Axen, D.

1979-01-01

Measurements over an extensive angular range of the Dsub(t) and P parameters in free neutron-proton elastic scattering at laboratory energies of 220, 325, 425 and 495 MeV are reported. Experimental and analytical details are given. (author)

Comparison of Out-Of-Field Neutron Equivalent Doses in Scanning Carbon and Proton Therapies for Cranial Fields

DEFF Research Database (Denmark)

Athar, B.; Henker, K.; Jäkel, O.

2010-01-01

Purpose: The purpose of this analysis is to compare the secondary neutron lateral doses from scanning carbon and proton beam therapies. Method and Materials: We simulated secondary neutron doses for out-of-field organs in an 11-year old male patient. Scanned carbon and proton beams were simulated...

Fast neutron dosimetry for radioprotection near large accelerators. Application to the proton synchrotron Saturne; Dosimetrie des neutrons rapides en vue de la radioprotection aupres des grands accelerateurs. Application au synchrotron a protons Saturne

Energy Technology Data Exchange (ETDEWEB)

Tardy-Joubert, P

1963-07-01

Methods are described that are used for the measurement of a neutron flux, and of the corresponding energy flux and dose absorbed. The methods are checked experimentally by the use of neutron sources of known energy distribution. The conditions of use of a proportional counter for recoil protons are described. The experimental results obtained with the synchrotron SATURNE at Saclay are described. (author) [French] L'auteur presente les methodes utilisables pour la mesure d'un flux de neutrons, du flux d'energie et de la dose absorbee correspondants. Les methodes sont verifiees experimentalement au moyen de sources de neutrons de spectre connu. Les conditions d'emploi d'un compteur proportionnel a protons de recul sont definies. Les resultats experimentaux obtenus aupres du synchrotron Saturne de Saclay sont presentes. (auteur)

Implementation of $ab$ $initio$ perturbed angular correlation observables for analysis of fluctuating quadrupole interactions

CERN Document Server

Barbosa, Marcelo

A review about the nuclear properties, namely the nuclear moments (magnetic dipole moment and electric quadrupole moment) and their interaction with electromagnetic fields external to the nucleus (hyperfine interactions), as well as the angular distribution of radiation produced by $\\gamma$-decay, is presented. A detailed description about the theory of Perturbed Angular Correlations was done, including the comparison between $\\gamma-\\gamma$- correlations and $e^{-}- \\gamma$ correlations. For dynamic nuclear interactions, an introduction to the theory of stochastic states in PAC was performed. We focused on ab-initio implementation of observables for analyzing fluctuating quadrupole hyperfine interactions on time dependent perturbed angular correlations experiments. The development of computacional codes solving the full problem, adapted to fit data obtained on single crystals or polycrystals for two-state transient fields with any axial symmetry and orientation was the main purpose of this work. The final pa...

Current status of accelerator-based boron neutron capture therapy

International Nuclear Information System (INIS)

Kreiner, A. J.; Bergueiro, J.; Di Paolo, H.; Castell, W.; Vento, V. Thatar; Cartelli, D.; Kesque, J.M.; Valda, A.A.; Ilardo, J.C.; Baldo, M.; Erhardt, J.; Debray, M.E.; Somacal, H.R.; Estrada, L.; Sandin, J.C. Suarez; Igarzabal, M.; Huck, H.; Padulo, J.; Minsky, D.M.

2011-01-01

The direct use of proton and heavy ion beams for radiotherapy is a well established cancer treatment modality, which is becoming increasingly widespread due to its clear advantages over conventional photon-based treatments. This strategy is suitable when the tumor is spatially well localized. Also the use of neutrons has a long tradition. Here Boron Neutron Capture Therapy (BNCT) stands out, though on a much smaller scale, being a second-generation promising alternative for tumors which are diffuse and infiltrating. On this sector, so far only nuclear reactors have been used as neutron sources. In this paper we describe the current situation worldwide as far as the use of accelerator-based neutron sources for BNCT is concerned (so-called Accelerator-Based (AB)-BNCT). In particular we discuss the present status of an ongoing project to develop a folded Tandem-ElectroStatic-Quadrupole (TESQ) accelerator at the Atomic Energy Commission of Argentina. The project goal is a machine capable of delivering 30 mA of 2.4 MeV protons to be used in conjunction with a neutron production target based on the 7 Li(p,n) 7 Be reaction. These are the specifications needed to produce sufficiently intense and clean epithermal neutron beams to perform BNCT for deep-seated tumors in less than an hour. (author)

Shape of 44Ar: Onset of deformation in neutron-rich nuclei near 48Ca

International Nuclear Information System (INIS)

Zielinska, M.; Goergen, A.; Clement, E.; Korten, W.; Dossat, C.; Ljungvall, J.; Obertelli, A.; Theisen, Ch.; Delaroche, J.-P.; Girod, M.; Buerger, A.; Catford, W.; Iwanicki, J.; Napiorkowski, P. J.; Srebrny, J.; Wrzosek, K.; Libert, J.; PiePtak, D.; Rodriguez-Guzman, R.; Sletten, G.

2009-01-01

The development of deformation and shape coexistence in the vicinity of doubly magic 48 Ca, related to the weakening of the N=28 shell closure, was addressed in a low-energy Coulomb excitation experiment using a radioactive 44 Ar beam from the SPIRAL facility at GANIL. The 2 1 + and 2 2 + states in 44 Ar were excited on 208 Pb and 109 Ag targets at two different beam energies. B(E2) values between all observed states and the spectroscopic quadrupole moment of the 2 1 + state were extracted from the differential Coulomb excitation cross sections, indicating a prolate shape of the 44 Ar nucleus and giving evidence of an onset of deformation already two protons and two neutrons away from doubly magic 48 Ca. New Hartree-Fock-Bogoliubov based configuration mixing calculations have been performed with the Gogny D1S interaction for 44 Ar and neighboring nuclei using two different approaches: the angular momentum projected generator coordinate method considering axial quadrupole deformations and a five-dimensional approach including the triaxial degree of freedom. The experimental values and new calculations are furthermore compared to shell-model calculations and to relativistic mean-field calculations. The new results give insight into the weakening of the N=28 shell closure and the development of deformation in this neutron-rich region of the nuclear chart.

Deep-inelastic electroproduction of neutrons in the proton fragmentation region

International Nuclear Information System (INIS)

Kopeliovich, B.; Povh, B.; Potashnikova, I.

1996-01-01

Experiments at HERA looking for deep-inelastic electroproduction of neutrons in the proton fragmentation region are in process. They are aimed to measure the pion structure function at small Bjorken x. The important condition for such a study is to establish under what kinematical conditions the dominance of the pion-pole graph in the process is guaranteed. We analyse other sources of the leading neutron, in order to figure out the kinematical region where the one-pion exchange dominates. (orig.)

Effect of neutron and proton radiations on magnetization of biotite

CERN Document Server

Abdurakhimov, A U; Sharipov, S M; Yugaj, V P; Granovskij, A B; Radkovskaya, A A

2002-01-01

One analyzes curves of field dependence of magnetization of biotite measured in the initial state under 4.2 K temperature subsequent to irradiation of 14 MeV energy and 1.2 x 10 sup 1 sup 3 cm sup - sup 2 dose neutrons and by 3 MeV energy and 2.2 x 10 sup 1 sup 4 cm sup - sup 2 dose protons, as well as, subsequent to annealing under 1000 deg temperature during 15 min. Irradiation by neutrons and protons was determined to result in increase of magneto-ordered phase content in biotite and, thus, in increase of magnetization of specimen. It is accounted for by formation of oxides in melt radiation thermal peaks and by freezing of high-temperature phase states corresponding to magnetite or solid solution of magnetite and hematite there. Thermal treatment does not change content of magneto-ordered phase in specimens

Static quadrupole moment of the Kπ = 14+ isomer in 176W

International Nuclear Information System (INIS)

Ionescu-Bujor, M.; Iordachescu, A.; Bucurescu, D.; Brandolini, F.; Lenzi, S. M.; Pavan, P.; Rossi Alvarez, C.; Marginean, N.; Medina, N.H.; Ribas, R.V.; De Poli, M.; Napoli, D. R.; Podolyak, Zs.; Ur, C. A.

2001-01-01

The investigation of high-K isomeric states in the deformed nuclei of the A∼180 region has found renewed interest in recent years. Much experimental and theoretical work was devoted to understand the mechanisms which govern their decay to lower-lying states, particularly the anomalous strong decays to low-K states. Other questions of great importance are the quenching of the pairing correlations and the shape polarization effects in the high-seniority multi-quasiparticle excitations. Our interest focused on the 41 ns K π =14 + 3746 keV isomeric state with anomalous decay in 176 W. On the basis of a precise g-factor measurement we assigned to this isomer a pure four-quasiparticle configuration, composed by two protons in the 7/2 + [404] and 9/2 - [514] orbitals and two neutrons in the 7/2 + [633] and 5/2 - [512] orbitals. In the present work the measurement of its static quadrupole moment has been performed. Prior to our experiment, static quadrupole moments have been measured only for three high-K isomeric states of seniority ≥ 4 in the A∼180 region: 16 + in 178 Hf, 35/2 - in 179 W and 25 + in 182 Os. A deformation very similar to that of the ground state has been deduced for the 16 + isomer in 178 Hf, while for the high-K isomers in 179 W and 182 Os significantly smaller deformations were reported. The quadrupole interaction of the 14 + isomeric state in 176 W has been investigated in the electric field gradient (EFG) of the polycrystalline lattice of metallic Tl by applying the time-differential perturbed angular distribution method. For W impurities in Tl host the EFG strength and its temperature dependence have been recently reported. The isomer was populated in the 164 Dy( 16 O,4n) 176 W reaction using a 83 MeV 16 O pulsed beam (pulse width 1.5 ns, repetition period 800 ns) delivered by the XTU-Tandem of Laboratori Nazionali di Legnaro. The target consisted of 0.5 mg/cm 2 metallic 164 Dy on thick Tl backing in which both the recoiling 176 W nuclei and

Garvey-Kelson mass relations and n-p interaction

International Nuclear Information System (INIS)

Gao Zaochun; Meng Jie; Chen Yongshou

2001-01-01

Two Garvey-Kelson mass relations are found to be directly related to the n-p interaction. In the case of the same nuclear core, the neutron-proton interaction energy between two neutrons and one proton ε 2n-1p is experimentally found to be close to that between one neutron and two protons ε 1n-2p , which is equivalent to the first Garvey-Kelson mass relation. The sum of ε 2n-1p and ε 1n-2p is close to the n-p interaction energy between two neutrons and two protons ε 2n-2p , which leads to the second Garvey-Kelson mass relation. An explanation of these two n-p interaction relations is presented. It is shown that both of these mass relations hold more accurately when the core is an even-even core

Neutron protein crystallography hydrogen protons and hydration in bio-macromolecules

CERN Document Server

Niimura, Nobuo

2011-01-01

This text is dedicated to the emerging field of neutron protein crystallography (NPC). It covers all of the practical aspects of NPC and demonstrates how NPC can explore protein features such as hydrogen bonds, protonation and deprotonation of amino acid residues, and hydration structures.

Parametric Model for Astrophysical Proton-Proton Interactions and Applications

Energy Technology Data Exchange (ETDEWEB)

Karlsson, Niklas [KTH Royal Institute of Technology, Stockholm (Sweden)

2007-01-01

Observations of gamma-rays have been made from celestial sources such as active galaxies, gamma-ray bursts and supernova remnants as well as the Galactic ridge. The study of gamma rays can provide information about production mechanisms and cosmic-ray acceleration. In the high-energy regime, one of the dominant mechanisms for gamma-ray production is the decay of neutral pions produced in interactions of ultra-relativistic cosmic-ray nuclei and interstellar matter. Presented here is a parametric model for calculations of inclusive cross sections and transverse momentum distributions for secondary particles--gamma rays, e^±, v_e, $\\bar{v}$_e, v_μ and $\\bar{μ}$_e--produced in proton-proton interactions. This parametric model is derived on the proton-proton interaction model proposed by Kamae et al.; it includes the diffraction dissociation process, Feynman-scaling violation and the logarithmically rising inelastic proton-proton cross section. To improve fidelity to experimental data for lower energies, two baryon resonance excitation processes were added; one representing the Δ(1232) and the other multiple resonances with masses around 1600 MeV/c². The model predicts the power-law spectral index for all secondary particle to be about 0.05 lower in absolute value than that of the incident proton and their inclusive cross sections to be larger than those predicted by previous models based on the Feynman-scaling hypothesis. The applications of the presented model in astrophysics are plentiful. It has been implemented into the Galprop code to calculate the contribution due to pion decays in the Galactic plane. The model has also been used to estimate the cosmic-ray flux in the Large Magellanic Cloud based on HI, CO and gamma-ray observations. The transverse momentum distributions enable calculations when the proton distribution is anisotropic. It is shown that the gamma-ray spectrum and flux due to a

Skyrme's interaction beyond the mean-field. The DGCM+GOA Hamiltonian of nuclear quadrupole motion

Energy Technology Data Exchange (ETDEWEB)

Kluepfel, Peter

2008-07-29

This work focuses on the microscopic description of nuclear collective quadrupole motion within the framework of the dynamic Generator-Coordinate-Method(DGCM)+Gaussian-Overlap-Approximation(GOA). Skyrme-type effective interactions are used as the fundamental many-particle interaction. Starting from a rotational invariant, polynomial and topologic consistent formulation of the GCM+GOA Hamiltonian an interpolation scheme for the collective masses and potential is developed. It allows to define the collective Hamiltonian of fully triaxial collective quadrupole dynamics from a purely axial symmetric configuration space. The substantial gain in performance allows the self-consistent evaluation of the dynamic quadrupole mass within the ATDHF-cranking model. This work presents the first large-scale analysis of quadrupole correlation energies and lowlying collective states within the DGCM+GOA model. Different Skyrme- and pairing interactions are compared from old standards up to more recent parameterizations. After checking the validity of several approximations to the DGCM+GOA model - both on the mean-field and the collective level - we proceed with a detailed investigation of correlation effects along the chains of semi-magic isotopes and isotones. This finally allows to define a set of observables which are hardly affected by collective correlations. Those observables were used for a refit of a Skyrme-type effective interaction which is expected to cure most of the problems of the recent parameterizations. Preparing further work, estimates for the correlated ground state energy are proposed which can be evaluated directly from the mean-field model. (orig.)

An analytical model of leakage neutron equivalent dose for passively-scattered proton radiotherapy and validation with measurements.

Science.gov (United States)

Schneider, Christopher; Newhauser, Wayne; Farah, Jad

2015-05-18

Exposure to stray neutrons increases the risk of second cancer development after proton therapy. Previously reported analytical models of this exposure were difficult to configure and had not been investigated below 100 MeV proton energy. The purposes of this study were to test an analytical model of neutron equivalent dose per therapeutic absorbed dose  at 75 MeV and to improve the model by reducing the number of configuration parameters and making it continuous in proton energy from 100 to 250 MeV. To develop the analytical model, we used previously published H/D values in water from Monte Carlo simulations of a general-purpose beamline for proton energies from 100 to 250 MeV. We also configured and tested the model on in-air neutron equivalent doses measured for a 75 MeV ocular beamline. Predicted H/D values from the analytical model and Monte Carlo agreed well from 100 to 250 MeV (10% average difference). Predicted H/D values from the analytical model also agreed well with measurements at 75 MeV (15% average difference). The results indicate that analytical models can give fast, reliable calculations of neutron exposure after proton therapy. This ability is absent in treatment planning systems but vital to second cancer risk estimation.

Long-Range Electrostatics-Induced Two-Proton Transfer Captured by Neutron Crystallography in an Enzyme Catalytic Site.

Science.gov (United States)

Gerlits, Oksana; Wymore, Troy; Das, Amit; Shen, Chen-Hsiang; Parks, Jerry M; Smith, Jeremy C; Weiss, Kevin L; Keen, David A; Blakeley, Matthew P; Louis, John M; Langan, Paul; Weber, Irene T; Kovalevsky, Andrey

2016-04-11

Neutron crystallography was used to directly locate two protons before and after a pH-induced two-proton transfer between catalytic aspartic acid residues and the hydroxy group of the bound clinical drug darunavir, located in the catalytic site of enzyme HIV-1 protease. The two-proton transfer is triggered by electrostatic effects arising from protonation state changes of surface residues far from the active site. The mechanism and pH effect are supported by quantum mechanics/molecular mechanics (QM/MM) calculations. The low-pH proton configuration in the catalytic site is deemed critical for the catalytic action of this enzyme and may apply more generally to other aspartic proteases. Neutrons therefore represent a superb probe to obtain structural details for proton transfer reactions in biological systems at a truly atomic level. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetohydrodynamics of neutron star interiors

International Nuclear Information System (INIS)

Easson, I.; Pethick, C.J.

1979-01-01

Magnetohydrodynamic equations for the charged particles in the fluid interior of a neutron star are derived from the Landau-Boltzmann kinetic equations. It is assumed that the protons are normal and the neutrons are superfluid. The dissipative processes associated with the weak interactions are shown to be negligible except in very hot neutron stars; we neglect them here. Among the topics discussed are: the influence of the neutron-proton nuclear force (Fermi liquid corrections) on the magnetohydrodynamics; the effects of the magnetic field on the pressure, viscosity, and heat conductivity tensors; the plasma equation of state; and the form of the generalized Ohm's law

An accelerated beam-plasma neutron/proton source and early application of a fusion plasma

International Nuclear Information System (INIS)

Ohnishi, M.; Yoshikawa, K.; Yamamoto, Y.; Hoshino, C.; Masuda, K.; Miley, G.; Jurczyk, B.; Stubbers, R.; Gu, Y.

1999-01-01

We measured the number of the neutrons and protons produced by D-D reactions in an accelerated beam-plasma fusion and curried out the numerical simulations. The linear dependence of the neutron yield on a discharge current indicates that the fusion reactions occur between the background gas and the fast particles. i.e. charge exchanged neutrals and accelerated ions. The neutron yield divided by (fusion cross section x ion current x neutral gas pressure) still possesses the dependence of the 1.2 power of discharge voltage. which shows the fusion reactions are affected by the electrostatic potential built-up in the center. The measured proton birth profiles suggest the existence of a double potential well, which is supported by the numerical simulations. (author)

On the properties of nuclear matter with an excess of neutrons, spin-up neutrons and spin-up protons using effective nucleon-nucleon potential

International Nuclear Information System (INIS)

Hassan, M.Y.; Ramadan, S.

1978-01-01

The binding energy of nuclear matter with an excess of neutrons, with spin-up neutrons and spin-up protons (characterized by the corresponding parameters αsub(tau)=(N-Z)/A, αsub(n)=(N(up)-N(down))/A, and αsub(p)=(Z(up)-Z(down))/A) contains three symmetry energies: the isospin symmetry energy epsilon sub(tau), the spin symmetry energy epsilon sub(sigma) and the spin-isospin symmetry energy epsilon sub(sigma tau). These energies are calculated using velocity-dependent effective potential of s-wave interaction, which was developed by Dzhibuti and Mamasakhlisov. The spin, isospin and spin-isospin dependent parts of the single-particle potential in nuclear matter are also calculated using the same effective nucleon-nucleon potentials. The spin-spin part of the optical model potential is estimated. (author)

Spin-isospin excitation of 3He with three-proton final state

Science.gov (United States)

Ishikawa, Souichi

2018-01-01

Spin-isospin excitation of the {}^3He nucleus by a proton-induced charge exchange reaction, {}^3He(p,n)ppp, at forward neutron scattering angle is studied in a plane wave impulse approximation (PWIA). In PWIA, cross sections of the reaction are written in terms of proton-neutron scattering amplitudes and response functions of the transition from {}3He to the three-proton state by spin-isospin transition operators. The response functions are calculated with realistic nucleon-nucleon potential models using a Faddeev three-body method. Calculated cross sections agree with available experimental data in substance. Possible effects arising from the uncertainty of proton-neutron amplitudes and three-nucleon interactions in the three-proton system are examined.

Electron cloud instabilities in the Proton Storage Ring and Spallation Neutron Source

Directory of Open Access Journals (Sweden)

M. Blaskiewicz

2003-01-01

Full Text Available Electron cloud instabilities in the Los Alamos Proton Storage Ring and those foreseen for the Oak Ridge Spallation Neutron Source are examined theoretically, numerically, and experimentally.

Double Polarized Neutron-Proton Scattering and Meson-Exchange Nucleon-Nucleon Potential Models

International Nuclear Information System (INIS)

Raichle, B.W.; Gould, C.R.; Haase, D.G.; Seely, M.L.; Walston, J.R.; Tornow, W.; Wilburn, W.S.; Raichle, B.W.; Gould, C.R.; Haase, D.G.; Seely, M.L.; Walston, J.R.; Tornow, W.; Wilburn, W.S.; Penttilae, S.I.; Hoffmann, G.W.

1999-01-01

We report on polarized beam - polarized target measurements of the spin-dependent neutron-proton total cross-section differences in longitudinal and transverse geometries (Δσ L and Δσ T , respectively) between E n =5 and 20MeV. Single-parameter phase-shift analyses were performed to extract the phase-shift mixing parameter var-epsilon 1 , which characterizes the strength of the nucleon-nucleon tensor interaction at low energies. Consistent with the trend of previous determinations at E n =25 and 50MeV, our values for var-epsilon 1 imply a stronger tensor force than predicted by meson-exchange nucleon-nucleon potential models and nucleon-nucleon phase-shift analyses. copyright 1999 The American Physical Society

The team responsible for testing and measuring the LHC insertion quadrupoles

CERN Multimedia

Patrice Loïez

2003-01-01

The LHC main magnet system includes about 600 superconducting quadrupoles for beam focusing. Superconducting Matching Quadrupole Magnets (MQMs) are just one of several varieties of quadrupole; they will be installed in the accelerator´s eight ´insertion zones´, four of which are also experimental areas, where the beams will intersect to produce proton-proton collisions. The first MQM, built by the UK firm Tesla Engineering, has passed its acceptance tests. The team responsible for the tests is pictured here with the 3.5-metre-long magnet. Photo 01: Bottom row, left to right, Michäel Ky, Antoine Dias Goncalves, Gilles Rittaud, Yannick Riva; middle row, left to right, Vladimir Bretin, Noël Dalexandro, Bert Lust, Patrick Viret; top row, left to right, Christian Giloux, Ranko Ostojic, Walter Venturini Delsolaro, Lassaâd Gharsallah.

NMR study of electric quadrupole interactions in GdCo2

International Nuclear Information System (INIS)

Barata, A.C.; Guimaraes, A.P.

1984-01-01

Quadrupole oscillations have been observed with 59 Co pulsed NMR in the intermetallic compound GdCo 2 . From theses oscillations the nuclear electric quadrupoles interaction (EQI) has been studied as a function of temperature in the range 4K-312K. The value measured at 4K, ν sub(Q)=672 +-3 KHz, is the largest so far reported for the cobalt EQI in the RCo 2 intermetallics. The EQI decreases with increasing temperature, reaching 432 +- 10 KHz at 312K. The amplitude of the oscillations tends to decrease with temperature, being also dependent on the easy direction of magnetization of the compound. Thus, above 200K, as the direction of magnetization changes, large oscillations are again visible in the satellite line; the main line shows no oscillations in this range. The observed temperature dependence of the EQI is roughly linear, as found in other transition metal systems. (Author) [pt

Radiation-induced conductivity of doped silicon in response to photon, proton and neutron irradiation

International Nuclear Information System (INIS)

Kishimoto, N.; Amekura, H.; Plaksin, O.A.; Stepanov, V.A.

2000-01-01

The opto-electronic performance of semiconductors during reactor operation is restricted by radiation-induced conductivity (RIC) and the synergistic effects of neutrons/ions and photons. The RICs of Si due to photons, protons and pulsed neutrons have been evaluated, aiming at radiation correlation. Protons of 17 MeV with an ionizing dose rate of 10 3 Gy/s and/or photons (hν=1.3 eV) were used to irradiate impurity-doped Si (2x10 16 B atoms/cm 3 ) at 300 and 200 K. Proton-induced RIC (p-RIC) and photoconductivity (PC) were intermittently detected in an accelerator device. Neutron-induced RIC (n-RIC) was measured for the same Si in a pulsed fast-fission reactor, BARS-6, with a 70-μs pulse of 2x10 12 n/cm 2 (E>0.01 MeV) and a dose rate of up to 6x10 5 Gy/s. The neutron irradiation showed a saturation tendency in the flux dependence at 300 K due to the strong electronic excitation. Normalization of the electronic excitation, including the pulsed regime, gave a fair agreement among the different radiation environments. Detailed comparison among PC, p-RIC and n-RIC is discussed in terms of radiation correlation including the in-pile condition

High energy nuclear data evaluations for neutron-, proton-, and photon-induced reactions at KAERI

International Nuclear Information System (INIS)

Lee, Young Ouk; Chang, Jong Hwa; Kim, Doo Hwan; Lee, Jeong Yeon; Han, Yinlu; Sukhovitski, Efrem Sh.

2001-01-01

The Korea Atomic Energy Research Institute (KAERI) is building high energy neutron-, proton-, and photon-induced nuclear data libraries for energies up to hundreds MeV in response to nuclear data needs from various R and Ds and applications. The librares provide nuclear data needed for the accelerator-driven transmutation of nuclear waste and radiation transport simulations of cancer radiotherapy. The neutron library currently has 10 isotopes such as C-12, N-14, O-16, Al-27, Si-28, Ca-40, Fe-56, Ni-58, Zr-90, Sn-120, and Pb-208 for energies from 20 up to 400 MeV. The proton nuclear data were evaluated in a consistent manner with the neutron case, using the same nuclear model parameters. In addition to the same isotopes included in the neutron library, the proton library has 70 extra isotopes of 24 elements ranging from nitrogen to lead up to 150 MeV for which the evaluations are focused on the medical and activation analyses applications. The photonuclear data library has been built along with international collaboration by participating in the IAEA's Coordinated Research Project (CRP) which ended last year. Currently the KAERI photonuclear library includes 143 isotopes of 39 elements

Spectral flux of the p-7Li(C Q-M neutron source measured by proton recoil telescope

Directory of Open Access Journals (Sweden)

Simakov S.P.

2010-10-01

Full Text Available The cyclotron-based fast neutron source at NPI produces mono-energetic neutron fields up to 35 MeV neutron energy using the p + 7Li(carbon backing reactions. To be applied for activation cross-section measurements, not only the intensity of neutron peak, but also the contribution of low-energy continuum in the spectra must be well determined. Simulations of the spectral flux from present source at a position of irradiated samples were performed using CYRIC TOF-data validated in the present work against LA150h by calculations with the transport Monte Carlo code MCNPX. Simulated spectra were tested by absolute measurements using a proton-recoil telescope technique. The recoil-proton spectrometer consisted of a shielded scattering chamber with polyethylene and carbon radiators and the ΔE1-ΔE2-E telescope of silicon-surface detectors located to the neutron beam axis at 45° in the laboratory system. Si-detectors were handled by usual data acquisition system. Dead-time – and pulse-overlap losses of events were determined from the count rate of pulse generator registered during duty cycle of accelerator operation. The proton beam charge and data were taken in the list mode for later replay and analysis. The calculations for 7Li(p,n and 12C(p,n reactions reasonably reproduce CYRIC TOF neutron source spectra. The influence of neutron source set-up (proton beam dimensions, 7Li-foil, carbon stopper, cooling medium, target support/chamber and the geometry-arrangement of irradiated sample on the spectral flux is discussed in details.

Equivalence of the spherical and deformed shell-model approach to intruder states

International Nuclear Information System (INIS)

Heyde, K.; Coster, C. de; Ryckebusch, J.; Waroquier, M.

1989-01-01

We point out that the description of intruder states, incorporating particle-hole (p-h) excitation across a closed shell in the spherical shell model or a description starting from the Nilsson model are equivalent. We furthermore indicate that the major part of the nucleon-nucleon interaction, responsible for the low excitation energy of intruder states comes as a two-body proton-neutron quadrupole interaction in the spherical shell model. In the deformed shell model, quadrupole binding energy is gained mainly through the one-body part of the potential. (orig.)

Gamow-Teller strength distributions in 76Ge, 76,82Se, and 90,92Zr by the deformed proton-neutron QRPA

Science.gov (United States)

Ha, Eunja; Cheoun, Myung-Ki

2015-02-01

The deformed proton-neutron quasiparticle random phase approximation (QRPA) has been developed and applied to evaluate Gamow-Teller (GT) transition strength distributions, including high-lying excited states. The data of high-lying excited states are recently available beyond one or two nucleon threshold by charge exchange reactions using hundreds of MeV projectiles. Our calculations started with single-particle states calculated using a deformed, axially symmetric Woods-Saxon potential. The neutron-neutron and proton-proton pairing correlations are explicitly taken into account at the deformed Bardeen-Cooper-Schriffer theory. Additionally, the ground state correlations and two-particle and two-hole mixing states were included in the deformed QRPA. In this work, we used a realistic two-body interaction, given by the Brueckner G-matrix based on the CD Bonn potential to reduce the ambiguity on the nucleon-nucleon interactions inside nuclei. We applied our formalism to the GT transition strengths for 76Ge, 76,82Se, and 90,92Zr, and compared the results with the available experimental data. The GT strength distributions were sensitive to the deformation parameter as well as its sign, i.e., oblate or prolate. The Ikeda sum rule, which is usually thought to be satisfied under the one-body current approximation, regardless of nucleon models, was used to test our numerical calculations and shown to be satisfied without introducing the quenching factor, if high-lying GT excited states were properly taken into account. Most of the GT strength distributions of the nuclei considered in this work have the high-lying GT excited states beyond one-nucleon threshold, which are shown to be consistent with the available experimental data.

Neutron-proton analyzing power at 12 MeV and charged πNN coupling constant

International Nuclear Information System (INIS)

Braun, R.T.; Tornow, W.; Gonzalez Trotter, D.E.; Howell, C.R.; Machleidt, R.; Roper, C.D.; Salinas, F.; Setze, H.R.; Walter, R.L.

1995-01-01

Recent reanalysis of scattering data by the Nijmegen group has led to new values for the πNN coupling constants, g 2 πdegree /4π and g 2 π± /4π, about 6% smaller than the previously accepted values. The impact of this finding is far reaching. Since the neutron-proton A y (θ) is dominated at low energies by the one-pion-exchange mechanism, accurate np data should provide unique information as to the magnitude of g 2 π± /4π. Using a new experimental setup consisting of a shielded neutron source, a five-pair neutron detector array, a n- 4 He polarimeter, and an intense polarized source with fast spin-flipping capability, we have measured a 15 point angular distribution of the neutron-proton A y (θ) at and incident neutron energy of 12 MeV to a statistical accuracy of 5x10 -4 . We will discuss the data taking procedures, the analysis, and the corrections applied to the data. Preliminary results will be presented

The neutron total cross-section measurement of 56Fe and 57Fe by using Japan Proton Accelerator Research Complex facility

International Nuclear Information System (INIS)

Kim, Eun Ae; Shvetsov, Valery; Cho, Moo Hyun; Won, Nam Kung; Kim, Kwang Soo; Yang, Sung Chul; Lee, Man Woo; Kim, Guin Yun; Yi, Kyoung Rak; Choi, Hong Yub; Ro, Tae Ik; Mizumoto, Motoharu; Katabuchi, Tatsuya; Igashira, Masayuki

2012-01-01

The measurement of neutron cross section using Time-Of-Flight (TOF) method gives significant information for the nuclear data research. In the present work, the neutron total cross section of 56 Fe and 57 Fe has been measured in the energy range between 10 eV and 100 keV by using the neutron beam produced from 3-GeV proton synchrotron accelerator. The 3-GeV proton synchrotron accelerator is located at Japan Proton Accelerator Research Complex (J-PARC) facility in Tokai village. In this study, the neutron total cross section data measured by 6 Li glass scintillator detector was compared with the evaluated values of ENDF/B-VII.0

On unfolding counting-rate spectra of recoil-proton neutron detectors

International Nuclear Information System (INIS)

Yeivin, Yehuda

1983-01-01

This note proposes a possible scheme for unfolding recoil-proton neutron detector data, in which at first the undistorted proton source spectrum is derived. The main argument in favour of this scheme is that, compared with the conventional scheme, it necessitates somewhat weaker assumptions with respect to the unknown spectrum above the detector's upper energy cutoff, and would therefore be more reliable. We also demonstrate a simple, elementary proof of the wall effect correction for spherical detectors, and, in order to gain insight of the potential merits of the proposed unfolding scheme, illustrate our main argument by considering a hypothetic linear range-energy relation, in which case complete unfolding becomes possible with no assumptions at all on the proton spectrum above the cutoff energy. (author)

Calibration of the proton detector used for the neutron life time experiment τSPECT

Energy Technology Data Exchange (ETDEWEB)

Ross, Kim; Haack, Jan; Heil, Werner; Karch, Jan [Johannes Gutenberg-Universitaet Mainz (Germany); Beck, Marcus [Johannes Gutenberg-Universitaet Mainz (Germany); Helmholtz-Institut Mainz (Germany)

2016-07-01

In order to measure the lifetime of free neutrons, a decay curve will be measured by detecting the decay products proton and electron. Their energies range up to 750 eV (protons) respectively 780 keV (electrons). The protons are accelerated onto 15 keV, in order to pass the dead layer of the detector and to be distinguishable from electronic noise. For the measurement a silicon drift detector is used which needs to be calibrated. This is achieved with a {sup 133}Ba source mounted on three source holders of different materials in a vacuum chamber. Thus not only four of the characteristic lines of the {sup 133}Ba source were measured but also the characteristic lines of the three source holders which yield four more calibration lines in the area of the proton energy in the spectrum. We report the implementation and results of the calibration of the silicon drift detector used for the neutron lifetime measurement τSPECT.

Applications of proton and deuteron accelerators

Energy Technology Data Exchange (ETDEWEB)

Todd, A.M.M. (Grumman Corporate Research Center, Princeton, NJ (United States))

1993-06-01

Applications of positive and negative hydrogen and deuterium ion accelerators beyond basic research are increasing. Large scale proposed national laboratory/industrial projects include the Accelerator Production of Tritium (APT) which will utilize protons, and the International Fusion Material Irradiation Facility (IFMIF) which will accelerate a deuteron beam into a lithium target. At the small scale end, radio-frequency quadrupole (RFQ) accelerator based systems have been built for neutron activation analysis and for applications such as explosive detection. At an intermediate scale, the Loma Linda proton therapy accelerator is now successfully treating a full schedule of patients, and more than half a dozen such hospital based units are under active study world-wide. At this same scale, there are also several ongoing negative ion, military accelerator projects which include the Continuous Wave Deuterium Demonstrator (CWDD) and the Neutral Particle Beam Space Experiment (NPBSE). These respective deuterium and hydrogen accelerators, which have not been previously described, are the focus of this paper. (orig.)

Radiation shielding for 250 MeV protons

International Nuclear Information System (INIS)

Awschalom, M.

1987-01-01

This paper is targetted at personnel who have the responsibility of designing the radiation shielding against neutron fluences created when protons interact with matter. Shielding of walls and roofs are discussed, as well as neutron dose leakage through labyrinths. Experimental data on neutron flux attenuation are considered, as well as some calculations using the intranuclear cascade calculations and parameterizations

All systems go for LHC quadrupoles

CERN Multimedia

2003-01-01

The series fabrication of the Main Quadrupole cold masses for the LHC has begun with the delivery of the first unit on February 12th. The superconducting dipole magnets required to bend the proton beams around the LHC are often in the news. Less famous, perhaps, but equally important are the 360 main quadrupole (MQ) magnets, which will perform the principal focusing around the 27 km ring. CERN and CEA-Saclay began collaborating on the development and prototyping of these magnets in 1989. This resulted in five highly successful quadrupole units - also known as short straight sections - one of which was integrated for testing in String 1, and two others of the final design in String 2. Once the tests had confirmed the validity of the design and realization, the fabrication of the 360 cold masses had to be transferred to industry. After highly competitive tendering, the German firm ACCEL Instruments was entrusted both with the construction of the quadrupole magnets themselves, and with their assembly into the co...

Measured and calculated neutron yields for 100 MeV protons on thick targets of Pb and Li

International Nuclear Information System (INIS)

Jones, R.T.; Lone, M.A.; Okazaki, A.

1983-01-01

The neutron yield per proton from thick targets of lead and lithium irradiated with 100 MeV protons has been measured and calculated. The water bath method was used to measure the neutron production, and a Faraday cup for the beam current determination. Measured yields are 0.343 +- 0.021 for lead and 0.123 +- 0.007 for lithium. Corresponding yields calculated with the nucleon-meson transport code NMTC are 0.363 +- 0.002 and 0.160 +- 0.001. Measured and calculated thermal neutron distributions in the water bath are also compared

Neutron-proton matrix element ratios of 21+ states in 58,60,62,64Ni

International Nuclear Information System (INIS)

Antalik, R.

1989-01-01

The neutron-proton matrix element ratios (η) for 2 1 + states of even Ni isotopes are investigated within the framework of the shell model quasiparticle random-phase approximation. The special attention is devoted to the dependence of η ratios on the radial neutron and proton ground-state density-distribution differences (Δ np ). This dependence is found to be about 0.5Δ np . The theoretical η ratios are 14-23% greater than the hydrodynamical limit. The theoretical Δ np dependence of η ratios enable us to understand the empirical η ratio results. 20 refs.; 2 figs.; 2 tabs

Measurement of the spin dependent structure functions of proton and neutron

International Nuclear Information System (INIS)

Rith, K.

1989-01-01

Recent results from the EMC experiment on the spin dependent structure function g 1 p (x) of the proton are discussed. They suggest that the nucleon spin does not originate from quark spins but rather from angular orbital momentum and gluon contributions. A proposed experiment at HERA is presented which will allow a very accurate measurement of the spin dependent structure functions and their integrals of both proton and neutron and a precise test of the Bjorken sum rule. (orig.)

An Analytical Model of Leakage Neutron Equivalent Dose for Passively-Scattered Proton Radiotherapy and Validation with Measurements

International Nuclear Information System (INIS)

Schneider, Christopher; Newhauser, Wayne; Farah, Jad

2015-01-01

Exposure to stray neutrons increases the risk of second cancer development after proton therapy. Previously reported analytical models of this exposure were difficult to configure and had not been investigated below 100 MeV proton energy. The purposes of this study were to test an analytical model of neutron equivalent dose per therapeutic absorbed dose (H/D) at 75 MeV and to improve the model by reducing the number of configuration parameters and making it continuous in proton energy from 100 to 250 MeV. To develop the analytical model, we used previously published H/D values in water from Monte Carlo simulations of a general-purpose beamline for proton energies from 100 to 250 MeV. We also configured and tested the model on in-air neutron equivalent doses measured for a 75 MeV ocular beamline. Predicted H/D values from the analytical model and Monte Carlo agreed well from 100 to 250 MeV (10% average difference). Predicted H/D values from the analytical model also agreed well with measurements at 75 MeV (15% average difference). The results indicate that analytical models can give fast, reliable calculations of neutron exposure after proton therapy. This ability is absent in treatment planning systems but vital to second cancer risk estimation

An Analytical Model of Leakage Neutron Equivalent Dose for Passively-Scattered Proton Radiotherapy and Validation with Measurements

Energy Technology Data Exchange (ETDEWEB)

Schneider, Christopher; Newhauser, Wayne, E-mail: newhauser@lsu.edu [Department of Physics and Astronomy, Louisiana State University and Agricultural and Mechanical College, 202 Nicholson Hall, Baton Rouge, LA 70803 (United States); Mary Bird Perkins Cancer Center, 4950 Essen Lane, Baton Rouge, LA 70809 (United States); Farah, Jad [Institut de Radioprotection et de Sûreté Nucléaire, Service de Dosimétrie Externe, BP-17, 92262 Fontenay-aux-Roses (France)

2015-05-18

Exposure to stray neutrons increases the risk of second cancer development after proton therapy. Previously reported analytical models of this exposure were difficult to configure and had not been investigated below 100 MeV proton energy. The purposes of this study were to test an analytical model of neutron equivalent dose per therapeutic absorbed dose (H/D) at 75 MeV and to improve the model by reducing the number of configuration parameters and making it continuous in proton energy from 100 to 250 MeV. To develop the analytical model, we used previously published H/D values in water from Monte Carlo simulations of a general-purpose beamline for proton energies from 100 to 250 MeV. We also configured and tested the model on in-air neutron equivalent doses measured for a 75 MeV ocular beamline. Predicted H/D values from the analytical model and Monte Carlo agreed well from 100 to 250 MeV (10% average difference). Predicted H/D values from the analytical model also agreed well with measurements at 75 MeV (15% average difference). The results indicate that analytical models can give fast, reliable calculations of neutron exposure after proton therapy. This ability is absent in treatment planning systems but vital to second cancer risk estimation.

Dynamical effects in proton breakup from exotic nuclei

International Nuclear Information System (INIS)

Bonaccorso, Angela; Kumar, Ravinder

2012-01-01

This contribution discusses dynamical effects in proton breakup from a weakly bound state in an exotic nucleus on a heavy target. The Coulomb interactions between the proton and the core and the proton and the target are treated to all orders, including also the full multipole expansion of the Coulomb potential. The dynamics of proton Coulomb breakup is compared to that of an equivalent neutron of larger binding energy in order to elucidate the differences with the well understood neutron breakup mechanism. A number of experimentally measurable observables such as parallel momentum distributions, proton angular distributions and total breakup cross sections can be calculated. With respect to nuclear breakup it is found that a proton behaves exactly as a neutron of larger binding energy. The extra “effective energy” is due to the combined core-target Coulomb barrier. In Coulomb breakup we distinguish the effect of the core-target Coulomb potential (called recoil effect), with respect to which the proton behaves again as a more bound neutron, from the direct proton-target Coulomb potential. The latter gives cross sections about an order of magnitude larger than the recoil term. The two effects give rise to complicated interferences in the parallel momentum distributions. They are instead easily separable in the proton angular distributions which are therefore suggested as a very useful observable for future experimental studies.

Determination of the Jet Neutron Rate and Fusion Power using the Magnetic Proton Recoil Neutron Spectrometer

Energy Technology Data Exchange (ETDEWEB)

Sjoestrand, Henrik

2003-01-01

In this thesis a new independent method has been developed to enable precise measurements of neutron yields and rates from fusion plasmas and thereby determining the fusion power and fusion energy. The new method, together with the associated diagnostics, can provide information of great importance to present and future high fusion yield experiments, such as the Joint European Torus (JET) tokamak and the International Thermonuclear Experiment Reactor (ITER). The method has been applied to data from high fusion rate experiments from the tritium campaign at JET. By using the count-rate from the Magnetic Proton Recoil (MPR) neutron spectrometer the number of neutrons in the spectrometer's line of sight has been calculated. To be able to do this, all relevant factors between the plasma and the instrument have been evaluated. The number of neutrons in the MPR line of sight has been related to the total number of produced neutrons in the plasma by using information on the neutron emission profile. The achieved results have been compared with other JET neutron diagnostic data and the agreement is shown to be very good.

Three-dimensional charge dispersion curves from interactions of 11--29 GeV protons with uranium

International Nuclear Information System (INIS)

Yu, Y.

1980-01-01

Experimental nuclear charge dispersion curves from interactions of 11--29 Gev protons with 238 U have been used in the construction of three-dimensional charge dispersion curves. They show the yield variation with mass number A. Neutron-deficient products are distributed over the entire mass range with a peak at A near 87, while the yield of neutron-excessive products is distributed only in the relatively narrow mass region between A=70 and A=150 and has a maximum around A=115. An isobaric yield curve has been obtained by summing up each of the charge dispersion curves and shows a peak, rather than the flat top, in the mass region A=80 to 140 reported previously. The mass yield curves of neutron-excessive and neutron-deficient products are obtained by a decomposition of the charge dispersion curve with two Gaussians, and the mechanism of formation is suggested

SU-E-T-521: Investigation of the Uncertainties Involved in Secondary Neutron/gamma Production in Geant4/MCNP6 Monte Carlo Codes for Proton Therapy Application

International Nuclear Information System (INIS)

Mirzakhanian, L; Enger, S; Giusti, V

2015-01-01

Purpose: A major concern in proton therapy is the production of secondary neutrons causing secondary cancers, especially in young adults and children. Most utilized Monte Carlo codes in proton therapy are Geant4 and MCNP. However, the default versions of Geant4 and MCNP6 do not have suitable cross sections or physical models to properly handle secondary particle production in proton energy ranges used for therapy. In this study, default versions of Geant4 and MCNP6 were modified to better handle production of secondaries by adding the TENDL-2012 cross-section library. Methods: In-water proton depth-dose was measured at the “The Svedberg Laboratory” in Uppsala (Sweden). The proton beam was mono-energetic with mean energy of 178.25±0.2 MeV. The measurement set-up was simulated by Geant4 version 10.00 (default and modified version) and MCNP6. Proton depth-dose, primary and secondary particle fluence and neutron equivalent dose were calculated. In case of Geant4, the secondary particle fluence was filtered by all the physics processes to identify the main process responsible for the difference between the default and modified version. Results: The proton depth-dose curves and primary proton fluence show a good agreement between both Geant4 versions and MCNP6. With respect to the modified version, default Geant4 underestimates the production of secondary neutrons while overestimates that of gammas. The “ProtonInElastic” process was identified as the main responsible process for the difference between the two versions. MCNP6 shows higher neutron production and lower gamma production than both Geant4 versions. Conclusion: Despite the good agreement on the proton depth dose curve and primary proton fluence, there is a significant discrepancy on secondary neutron production between MCNP6 and both versions of Geant4. Further studies are thus in order to find the possible cause of this discrepancy or more accurate cross-sections/models to handle the nuclear

Influence of i13/2 proton and j15/2 neutron intruding orbitals on the behaviour of 190 mass region superdeformed nuclei

International Nuclear Information System (INIS)

Duprat, J.

1995-01-01

This work concerns the study of the nuclear superdeformation phenomenon in the A = 190 mass region. The superdeformed (SD) states in 193 Tl, 194 Tl 195 Tl were produced via heavy-ion induced reactions and studied with the EUROGAM gamma multidetector array. The analysis of high-multiplicity events allowed the study of the magnetic properties of the SD states in these nuclei. For the first time, the g-factor of a proton orbital in a SD nucleus in the A = 190 mass region has been extracted. This measurement indicates that the two known bands in 195 Tl-SD are built on the i 13/2 proton intruder orbital. A new SD band has been found in this isotope: it is the first SD band built on an excited proton state found in the A = 190 region. Finally an interaction between two pairs of bands has been established in 194 Tl; this interaction indicate the crossing of two neutron orbitals above the N = 112 gap. The magnetic properties of the states of the SD bands in 194 Tl reveals that these bands are built on configurations in which the single proton and neutron intrinsic spins are aligned. Comparison between different SD bands in the Thallium isotopes shows the prominent role of the i 13/2 proton and the j 15/2 neutron intruder orbitals in the smooth increase of the dynamical moment of inertia as a function of the rotational frequency. In addition, this work reports on the first observation of a SD rotational band produced in a (HI, αxn) reaction channel. The study of the maximum spin reached by the SD bands indicates both a competition between alpha emission and fission of the compound nucleus, and the limitation due to the fission process in the population of the SD nuclei in the A = 190 region. (author). 120 refs., 112 figs., 22 tabs., 2 ann

Evaluation of neutron- and proton-induced cross sections of {sup 27}Al up to 2 GeV

Energy Technology Data Exchange (ETDEWEB)

Lee, Young-Ouk; Chang, Jonghwa [Korea Atomic Energy Research Institute, Yusung, Taejon (Korea, Republic of); Fukahori, Tokio; Chiba, Satoshi

1999-03-01

We have evaluated neutron and proton nuclear data of {sup 27}Al for energies up to 2 GeV. The best set of optical model parameters were obtained above 20 MeV for neutron and above reaction threshold for proton up to 250 MeV with the phenomenological potential forms proposed by Chiba. The transmission coefficients for neutron and proton derived from the optical models are fed into the GNASH code system to calculate angle-energy correlated emission spectra for light ejectiles and gamma rays. For energies above 250 MeV and below 2 GeV, the total, reaction and elastic scattering cross sections were evaluated by an empirical fit and recent systematics. Emitted nucleon and pion were estimated by use of QMD + SDM (Quantum Molecular Dynamics + Statistical Decay Model). (author)

Irradiations of human melanoma cells by 14 MeV neutrons; survival curves interpretation; physical simulation of neutrons interactions in the cellular medium

International Nuclear Information System (INIS)

Bodez, Veronique

2000-01-01

14 MeV neutrons are used to irradiate human melanoma cells in order to study survival curves at low dose and low dose rate. We have simulated with the MCNP code, transport of neutrons through the experimental setup to evaluate the contamination of the primary beam by gamma and electrons, for the feasibility of our experiments. We have shown a rapid decrease of the survival curve in the first cGy followed by a plateau for doses up to 30 cGy; after we observed an exponential decrease. This results are observed for the first time, for neutrons at low dose rate (5 cGy/h). In parallel with this experimental point, we have developed a simulation code which permitted the study of neutrons interactions with the cellular medium for individual cells defined as in our experimental conditions. We show that most of the energy is deposited by protons from neutron interactions with external medium, and by heavy ions for interactions into the cell. On the other hand the code gives a good order of magnitude of the dose rate, compared to the experimental values given by silicon diodes. The first results show that we can, using a theory based on induced repair of cells, give an interpretation of the observed experimental plateau. We can give an estimation of the radial distribution of dose for the tracks of charged ions, we show the possibility of calculate interaction cross sections with cellular organelles. Such a work gives interesting perspectives for the future in radiobiology, radiotherapy or radioprotection. (author) [fr

Gravitational radiation quadrupole formula is valid for gravitationally interacting systems

International Nuclear Information System (INIS)

Walker, M.; Will, C.M.

1980-01-01

An argument is presented for the validity of the quadrupole formula for gravitational radiation energy loss in the far field of nearly Newtonian (e.g., binary stellar) systems. This argument differs from earlier ones in that it determines beforehand the formal accuracy of approximation required to describe gravitationally self-interacting systems, uses the corresponding approximate equation of motion explicitly, and evaluate the appropriate asymptotic quantities by matching along the correct space-time light cones

Impact Parameter Dependence of the Double Neutron/Proton Ratio of Nucleon Emissions in Isotopic Reaction Systems

International Nuclear Information System (INIS)

Xun-Chao, Zhang; Gao-Chan, Yong; Bao-An, Li; Lie-Wen, Chen

2009-01-01

Within the transport model IBUU04, we investigate the double neutron/proton ratio of free nucleons taken from two reaction systems using two Sn isotopes at a beam energy of 50 MeV/nucleon and with impact parameters 2 fm, 4 fm and 8 fm, respectively. It is found that the double neutron/proton ratio from peripheral collisions is more sensitive to the density dependence of the symmetry energy than those from mid-central and central collisions. (nuclear physics)

Spin, quadrupole moment, and deformation of the magnetic-rotational band head in Pb193

Science.gov (United States)

Balabanski, D. L.; Ionescu-Bujor, M.; Iordachescu, A.; Bazzacco, D.; Brandolini, F.; Bucurescu, D.; Chmel, S.; Danchev, M.; de Poli, M.; Georgiev, G.; Haas, H.; Hübel, H.; Marginean, N.; Menegazzo, R.; Neyens, G.; Pavan, P.; Rossi Alvarez, C.; Ur, C. A.; Vyvey, K.; Frauendorf, S.

2011-01-01

The spectroscopic quadrupole moment of the T1/2=9.4(5) ns isomer in Pb193 at an excitation energy Eex=(2585+x) keV is measured by the time-differential perturbed angular distribution method as |Qs|=2.6(3) e b. Spin and parity Iπ=27/2- are assigned to it based on angular distribution measurements. This state is the band head of a magnetic-rotational band, described by the 1i13/2 subshell with the (3s1/2-21h9/21i13/2)11- proton excitation. The pairing-plus-quadrupole tilted-axis cranking calculations reproduce the measured quadrupole moment with a moderate oblate deformation ɛ2=-0.11, similar to that of the 11-proton intruder states, which nuclei in the region. This is the first direct measurement of a quadrupole moment and thus of the deformation of a magnetic-rotational band head.

EXPERIMENTAL ANALYSES OF SPALLATION NEUTRONS GENERATED BY 100 MEV PROTONS AT THE KYOTO UNIVERSITY CRITICAL ASSEMBLY

Directory of Open Access Journals (Sweden)

CHEOL HO PYEON

2013-02-01

Full Text Available Neutron spectrum analyses of spallation neutrons are conducted in the accelerator-driven system (ADS facility at the Kyoto University Critical Assembly (KUCA. High-energy protons (100 MeV obtained from the fixed field alternating gradient accelerator are injected onto a tungsten target, whereby the spallation neutrons are generated. For neutronic characteristics of spallation neutrons, the reaction rates and the continuous energy distribution of spallation neutrons are measured by the foil activation method and by an organic liquid scintillator, respectively. Numerical calculations are executed by MCNPX with JENDL/HE-2007 and ENDF/B-VI libraries to evaluate the reaction rates of activation foils (bismuth and indium set at the target and the continuous energy distribution of spallation neutrons set in front of the target. For the reaction rates by the foil activation method, the C/E values between the experiments and the calculations are found around a relative difference of 10%, except for some reactions. For continuous energy distribution by the organic liquid scintillator, the spallation neutrons are observed up to 45 MeV. From these results, the neutron spectrum information on the spallation neutrons generated at the target are attained successfully in injecting 100 MeV protons onto the tungsten target.

The comparison of microstructure and nanocluster evolution in proton and neutron irradiated Fe–9%Cr ODS steel to 3 dpa at 500 °C

Energy Technology Data Exchange (ETDEWEB)

Swenson, M.J., E-mail: matthewswenson1@u.boisestate.edu; Wharry, J.P.

2015-12-15

A model Fe–9%Cr oxide dispersion strengthened (ODS) steel was irradiated with protons or neutrons to a dose of 3 displacements per atom (dpa) at a temperature of 500 °C, enabling a direct comparison of ion to neutron irradiation effects at otherwise fixed irradiation conditions. The irradiated microstructures were characterized using transmission electron microscopy and atom probe tomography including cluster analysis. Both proton and neutron irradiations produced a comparable void and dislocation loop microstructure. However, the irradiation response of the Ti–Y–O oxide nanoclusters varied. Oxides remained stable under proton irradiation, but exhibited dissolution and an increase in Y:Ti composition ratio under neutron irradiation. Both proton and neutron irradiation also induced varying extents of Si, Ni, and Mn clustering at existing oxide nanoclusters. Protons are able to reproduce the void and loop microstructure of neutron irradiation carried out to the same dose and temperature. However, since nanocluster evolution is controlled by both diffusion and ballistic impacts, protons are rendered unable to reproduce the nanocluster evolution of neutron irradiation at the same dose and temperature. - Highlights: • Fe–9% Cr ODS was irradiated with protons and neutrons to 3 dpa at 500 °C. • Dislocation loop size and density were similar upon proton and neutron irradiation. • Oxide nanocluster size and density decreased more with neutron irradiation. • Oxide Y:Ti ratio increased from 0.54 to 0.97 upon neutron irradiation. • Irradiation induced enrichment of Si, Mn, and Ni at oxide locations.

Study of the deuteron break-up with protons and neutrons

International Nuclear Information System (INIS)

Kumpf, H.; Moeller, K.; Moesner, J.; Schmidt, G.

1977-06-01

A review is given on the present situation and the results obtained in the experimental and theoretical investigation of the break-up of deuterons by protons and neutrons at bombarding energies up to 50 MeV. The nonrelativistic three-particle kinematics, experimental techniques and the basic theoretical equations for three particle scattering are described and the most important experimental results of the last years are discussed together with theoretical interpretation. It is shown that the reaction mechanism of the N-d break-up is well understood and that one can extract two-particle low energy scattering parameters (e.g., the n-n scattering length) with good accuracy. But despite of a relatively good agreement between experimental spectra and theoretical calculations (except polarisation measurements) no reliable quantitative information on the off-shell behaviour of the two-particle interaction and on three-body forces can be obtained at present. (author)

Intermediate energy proton scattering from 10B

International Nuclear Information System (INIS)

Lewis, P.R.; Shute, G.G.; Spicer, R.S.; Henderson, R.S.

1990-01-01

Differential cross sections have been measured for 200 MeV proton scattering from 10 B. Data for six low lying natural parity levels below 6 MeV excitation energy are presented. Distorted wave analysis using a density dependent nucleon-nucleon interaction has assessed model spectroscopies of these excited states. The significance of the contribution from quadrupole scattering to the elastic cross section is discussed. 49 refs., 5 tabs., 21 figs

Influence of i{sub 13/2} proton and j{sub 15/2} neutron intruding orbitals on the behaviour of 190 mass region superdeformed nuclei; Influence des orbitales intruses proton i{sub 13/2} et neutron j{sub 15/2} sur le comportement des noyaux superdeformes de la region de masse 190

Energy Technology Data Exchange (ETDEWEB)

Duprat, J

1995-01-01

This work concerns the study of the nuclear superdeformation phenomenon in the A = 190 mass region. The superdeformed (SD) states in {sup 193}Tl, {sup 194}Tl {sup 195}Tl were produced via heavy-ion induced reactions and studied with the EUROGAM gamma multidetector array. The analysis of high-multiplicity events allowed the study of the magnetic properties of the SD states in these nuclei. For the first time, the g-factor of a proton orbital in a SD nucleus in the A = 190 mass region has been extracted. This measurement indicates that the two known bands in {sup 195}Tl-SD are built on the i{sub 13/2} proton intruder orbital. A new SD band has been found in this isotope: it is the first SD band built on an excited proton state found in the A = 190 region. Finally an interaction between two pairs of bands has been established in {sup 194}Tl; this interaction indicate the crossing of two neutron orbitals above the N = 112 gap. The magnetic properties of the states of the SD bands in {sup 194}Tl reveals that these bands are built on configurations in which the single proton and neutron intrinsic spins are aligned. Comparison between different SD bands in the Thallium isotopes shows the prominent role of the i{sub 13/2} proton and the j{sub 15/2} neutron intruder orbitals in the smooth increase of the dynamical moment of inertia as a function of the rotational frequency. In addition, this work reports on the first observation of a SD rotational band produced in a (HI, {alpha}xn) reaction channel. The study of the maximum spin reached by the SD bands indicates both a competition between alpha emission and fission of the compound nucleus, and the limitation due to the fission process in the population of the SD nuclei in the A = 190 region. (author). 120 refs., 112 figs., 22 tabs., 2 ann.

ISABELLE: a proposal for construction of a proton--proton storage accelerator facility

International Nuclear Information System (INIS)

1976-05-01

The construction of an Intersecting Storage Accelerator Facility (ISA or ISABELLE) at Brookhaven National Laboratory is proposed. ISABELLE will permit the exploration of proton-proton collisions at center-of-mass energies continuously variable from 60 to 400 GeV and with luminosities of 10 32 to 10 33 cm -2 sec -1 over the entire range. An overview of the physics potential of this machine is given, covering the production of charged and neutral intermediate vector bosons, the hadron production at high transverse momentum, searches for new, massive particles, and the energy dependence of the strong interactions. The facility consists of two interlaced rings of superconducting magnets in a common tunnel about 3 km in circumference. The proton beams will collide at eight intersection regions where particle detectors will be arranged for studying the collision processes. Protons of approximately 30 GeV from the AGS will be accumulated to obtain the design current of 10A prior to acceleration to final energy. The design and performance of existing full-size superconducting dipoles and quadrupoles is described. The conceptual design of the accelerator systems and the conventional structures and buildings is presented. A preliminary cost estimate and construction schedule are given. Possible future options such as proton-antiproton, proton-deuteron and electron-proton collisions are discussed

Estimate of neutron secondary doses received by patients in proton therapy: cases of ophthalmologic treatments

International Nuclear Information System (INIS)

Martinetti, F.

2009-12-01

This research thesis aims at assessing doses due to secondary neutrons and received by the organs of a patient which are located outside of the treatment field. The study focused on ophthalmological treatments performed at the Orsay proton therapy centre. A 75 eV beam line model has first been developed with the MCNPX Monte Carlo code. Several experimental validations of this model have been performed: proton dose distribution in a water phantom, ambient equivalent dose due to secondary neutrons and neutron spectra in the treatment room, and doses deposited by secondary neutrons in an anthropomorphous phantom. Simulations and measurements are in correct agreement. Then, a numeric assessment of secondary doses received by the patient's organs has been performed by using a MIRD-type mathematical phantom. These doses have been computed for several organs: the non-treated eye, the brain, the thyroid, and other parts of the body situated either in the front part of the body (the one directly exposed to neutrons generated in the treatment line) or deeper and further from the treatment field

Electron, proton, neutron as spheroidical particles

International Nuclear Information System (INIS)

Bagge, E.R.

1993-01-01

It is shown that it is possible to describe the electron and the proton at rest within the framework of Dirac's relativistic theory of particles as electro-magnetic stable, spheroidal particles like balloons with very thin envelopes. Their properties, especially their spins and their magnetic momenta, are exactly those, which have been measured at first and later on derived by Dirac. In this picture the neutron plays the role of a system of two concentric and synchronically rotating balloons with a small distance between them at a positive energetic minimum of balance at 1.26 MeV. The magnetic moment of this particle has a negative sign and is of the correct size. (orig.)

Dose conversion coefficients for high-energy photons, electrons, neutrons and protons

CERN Document Server

Sakamoto, Y; Sato, O; Tanaka, S I; Tsuda, S; Yamaguchi, Y; Yoshizawa, N

2003-01-01

In the International Commission on Radiological Protection (ICRP) 1990 Recommendations, radiation weighting factors were introduced in the place of quality factors, the tissue weighting factors were revised, and effective doses and equivalent doses of each tissues and organs were defined as the protection quantities. Dose conversion coefficients for photons, electrons and neutrons based on new ICRP recommendations were cited in the ICRP Publication 74, but the energy ranges of theses data were limited and there are no data for high energy radiations produced in accelerator facilities. For the purpose of designing the high intensity proton accelerator facilities at JAERI, the dose evaluation code system of high energy radiations based on the HERMES code was developed and the dose conversion coefficients of effective dose were evaluated for photons, neutrons and protons up to 10 GeV, and electrons up to 100 GeV. The dose conversion coefficients of effective dose equivalent were also evaluated using quality fact...

Nano-scale chemical evolution in a proton-and neutron-irradiated Zr alloy

Energy Technology Data Exchange (ETDEWEB)

Harte, Allan, E-mail: allan.harte@manchester.ac.uk [The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Topping, M.; Frankel, P. [The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Jädernäs, D. [Studsvik Nuclear AB, SE 611 82, Nyköping (Sweden); Romero, J. [Westinghouse Electric Company, Columbia, SC (United States); Hallstadius, L. [Westinghouse Electric Sweden AB, SE 72163 Västerås (Sweden); Darby, E.C. [Rolls Royce Plc., Nuclear Materials, Derby (United Kingdom); Preuss, M. [The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom)

2017-04-15

Proton-and neutron-irradiated Zircaloy-2 are compared in terms of the nano-scale chemical evolution within second phase particles (SPPs) Zr(Fe,Cr){sub 2} and Zr{sub 2}(Fe,Ni). This is accomplished through ultra-high spatial resolution scanning transmission electron microscopy and the use of energy-dispersive X-ray spectroscopic methods. Fe-depletion is observed from both SPP types after irradiation with both irradiative species, but is heterogeneous in the case of Zr(Fe,Cr){sub 2}, predominantly from the edge region, and homogeneously in the case of Zr{sub 2}(Fe,Ni). Further, there is evidence of a delay in the dissolution of the Zr{sub 2}(Fe,Ni) SPP with respect to the Zr(Fe,Cr){sub 2}. As such, SPP dissolution results in matrix supersaturation with solute under both irradiative species and proton irradiation is considered well suited to emulate the effects of neutron irradiation in this context. The mechanisms of solute redistribution processes from SPPs and the consequences for irradiation-induced growth phenomena are discussed. - Highlights: •Protons emulate the effects of neutron irradiation in the evolution of chemistry and morphology of second phase particles. •Detailed energy-dispersive X-ray spectroscopy reveals heterogeneity in Zr-Fe-Cr SPPs both before and after irradiation. •Zr-Fe-Ni SPPs are delayed in irradiation-induced dissolution due to their better self-solubility with respect to Zr-Fe-Cr.

Type-I superconductivity and neutron star precession

International Nuclear Information System (INIS)

Sedrakian, Armen

2005-01-01

Type-I proton superconducting cores of neutron stars break up in a magnetic field into alternating domains of superconducting and normal fluids. We examine two channels of superfluid-normal fluid friction where (i) rotational vortices are decoupled from the nonsuperconducting domains and the interaction is due to the strong force between protons and neutrons; (ii) the nonsuperconducting domains are dynamically coupled to the vortices and the vortex motion generates transverse electric fields within them, causing electronic current flow and Ohmic dissipation. The obtained dissipation coefficients are consistent with the Eulerian precession of neutron stars

Influence of differences in the proton and neutron distributions on nuclear fusion and fission; Infuence de la difference entre les distributions de protons et de neutrons dans le noyau sur les processus de fusion et de fission

Energy Technology Data Exchange (ETDEWEB)

Dobrowolski, A

2006-04-15

This thesis work is centred on some essential ingredients of a theoretical description of the reaction dynamics of the nuclear fusion and fission process, such as the interaction potential between projectile and target nuclei for fusion and the deformation energy landscape in a multidimensional space for the fission process. We have in particular evaluated the importance of the difference between the neutron and proton density distributions on these 2 processes. The fusion potential between the two interacting nuclei is obtained through the nucleon densities, determined in a self-consistent way through semiclassical density variational calculations for a given effective nucleon-nucleon effective interaction of the Skyrme type. These fusion barriers can then be used in a Langevin formalism to evaluation fusion cross sections. For the fission process it turns out to be essential to allow for the large variety of shapes which appear between the nuclear ground state and the the scission configuration. We show that a shape parametrisation taking into account elongation, as well as possible neck formation, left-right asymmetry and non-axiality allows a precise description of this phenomena in the framework of the macroscopic-microscopic approach. We are thus able to enrich the expression of the liquid-drop type energy through a term which describes the variation of the nuclear energy due to a deformation difference between the proton and neutron distribution. The resulting reduction of the fission barriers is only of the order of one MeV but this can easily cause a change in the fission cross-section by an order of magnitude and thus plays a capital role for the stability of super-heavy of exotic nuclei. (author)

Neutron-proton mass difference in a baryonic medium and the Nolen-Schiffer anomaly

International Nuclear Information System (INIS)

Fiolhais, M.; Christov, C.; Neuber, T.; Bergmann, M.; Goeke, K.

1991-01-01

The neutron-proton mass difference ΔM np = M n - M p in a baryonic medium is evaluated in the framework of the Nambu-Jona-Lasinio model. It is demonstrated that ΔM np (ρ) increases with increasing medium density, ρ, a trend being opposite to the one required to explain the Nolen-Schiffer anomaly as suggested by Henley and Krein. In the same conceptual framework the quantity M n (ρ n ) - M p (ρ p ) is evaluated which takes into account that the valence orbits of the proton and the neutron are different. The calculations show that this quantity goes into the right direction, but the effect is an order of magnitude larger than needed to explain the Nolen-Schiffer anomaly. (orig.)

Neutron elastic scattering at very small angles

CERN Multimedia

2002-01-01

This experiment will measure neutron-proton elastic scattering at very small angles and hence very small four-momentum transfer, |t|. The range of |t| depends on the incident neutron momentum of the events but the geometrical acceptance will cover the angular range 0.025 < $\\Theta_{lab}$ < 1.9 mrad. The higher figure could be extended to 8.4 mrad by changing the geometry of the experiment in a later phase. \\\\ \\\\ The neutron beam will be highly collimated and will be derived from a 400 GeV external proton beam of up to $4 \\times 10^{10}$ protons per pulse in the SPS North Area Hall 1. The hydrogen target will be gaseous, operating at 40 atm. pressure and acts as a multiwire proportional chamber to detect the recoil protons. The forward neutron will be detected and located by interaction in a neutron vertex detector and its energy measured by a conventional steel plate calorimeter. \\\\ \\\\ The experiment will cover the angular region of nucleon-nucleon scattering which is dominated by Coulomb scattering ...

RMF+BCS description of some traditional neutron magic isotones

International Nuclear Information System (INIS)

Saxena, G.; Singh, D.; Kaushik, M.

2014-01-01

The traditional neutron magic nuclei with N = 8, 20, 28, 50, 82 and 126, and those with neutron sub-magic number N = 40 are investigated within the relativistic mean-field plus BCS (RMF+BCS) approach. The results indicate appearance of new proton magic numbers as well as the disappearance of conventional magic numbers for nuclei with extreme isospin values. The calculated energies and densities do not indicate any tendency for the proton halo formations in any of the proton rich isotones due to Coulomb interaction and different single particle spectra. However, the potential barrier provided by the Coulomb interaction and that due to the centrifugal force may cause a long delay in the actual decay of proton rich nucleus resulting in the extended drip line. (authors)

A new Recoil Proton Telescope for energy and fluence measurement of fast neutron fields

Energy Technology Data Exchange (ETDEWEB)

Lebreton, Lena; Bachaalany, Mario [IRSN / LMDN (Institut de Radioprotection et de Surete nucleaire / Laboratoire de Metrologie et de dosimetrie des neutrons), Cadarache Bat.159, 13115 Saint Paul-lez-Durance, (France); Husson, Daniel; Higueret, Stephane [IPHC / RaMsEs (Institut Pluridisciplinaire Hubert Curien / Radioprotection et Mesures Environnementales), 23 rue du loess - BP28, 67037 Strasbourg cedex 2, (France)

2015-07-01

The spectrometer ATHENA (Accurate Telescope for High Energy Neutron metrology Applications), is being developed at the IRSN / LMDN (Institut de Radioprotection et de Surete nucleaire / Laboratoire de Metrologie et de dosimetrie des neutrons) and aims at characterizing energy and fluence of fast neutron fields. The detector is a Recoil Proton Telescope and measures neutron fields in the range of 5 to 20 MeV. This telescope is intended to become a primary standard for both energy and fluence measurements. The neutron detection is achieved by a polyethylene radiator for n-p conversion, three 50{sub m} thick silicon sensors that use CMOS technology for the proton tracking and a 3 mm thick silicon diode to measure the residual proton energy. This first prototype used CMOS sensors called MIMOSTAR, initially developed for heavy ion physics. The use of CMOS sensors and silicon diode increases the intrinsic efficiency of the detector by a factor of ten compared with conventional designs. The first prototype has already been done and was a successful study giving the results it offered in terms of energy and fluence measurements. For mono energetic beams going from 5 to 19 MeV, the telescope offered an energy resolution between 5 and 11% and fluence difference going from 5 to 7% compared to other home standards. A second and final prototype of the detector is being designed. It will hold upgraded CMOS sensors called FastPixN. These CMOS sensors are supposed to run 400 times faster than the older version and therefore give the telescope the ability to support neutron flux in the order of 107 to 108cm{sup 2}:s{sup 1}. The first prototypes results showed that a 50 m pixel size is enough for a precise scattering angle reconstruction. Simulations using MCNPX and GEANT4 are already in place for further improvements. A DeltaE diode will replace the third CMOS sensor and will be installed right before the silicon diode for a better recoil proton selection. The final prototype with

Neutron to proton ratios of quasiprojectile and midrapidity emission in the 58Ni+58Ni reaction at 52 MeV/nucleon

International Nuclear Information System (INIS)

Theriault, D.; Vallee, A.; Gingras, L.; Larochelle, Y.; Roy, R.; April, A.; Beaulieu, L.; Grenier, F.; Lemieux, F.; Moisan, J.; St-Pierre, C.; Turbide, S.; Samri, M.; Borderie, B.; Rivet, M. F.; Bougault, R.; Colin, J.; Cussol, D.; Durand, D.; Lecolley, J.F.

2005-01-01

By combining data from a charged particle 58 Ni+ 58 Ni experiment at 52 MeV/nucleon with an 36 Ar+ 58 Ni experiment at 50 MeV/nucleon for which free neutrons have been detected, an increase in the neutron to proton ratio of the whole nuclear material at midrapidity has been experimentally observed in the reaction 58 Ni+ 58 Ni at 52 MeV/nucleon. The neutron-to-proton ratio of the quasi-projectile emission is analyzed for the same reactions and is seen to decrease below the ratio of the initial system. Those observations suggest that an asymmetric exchange of neutrons and protons between the quasiprojectile and the midrapidity region exists

Comparing of γ-ray, proton and neutron radiation effects on optoelectronics for space

International Nuclear Information System (INIS)

Yu Qingkui; Tang Min; Meng Meng; Li Pengwei; Wen Ping; Li Haian; Tang Jiesen; Wang Sixin; Song Yamei

2014-01-01

We performed irradiation test on optoelectronics with γ-rays, proton and neutron. The electrical measurements were performed pre and after irradiation. The degradations induced by each radiation source was compared. (authors)

An epithermal neutron source for BNCT based on an ESQ-accelerator

International Nuclear Information System (INIS)

Ludewigt, B.A.; Chu, W.T.; Donahue, R.J.; Kwan, J.; Phillips, T.L.; Reginato, L.L.; Wells, R.P.

1997-07-01

An accelerator-based BNCT facility is under development at the Lawrence Berkeley National Laboratory. Neutrons will be produced via the 7 Li(p,n) reaction at proton energies of about 2.5 MeV with subsequent moderation and filtering for shaping epithermal neutron beams for BNCT. Moderator, filter, and shielding assemblies have been modeled using MCNP. Head-phantom dose distributions have been calculated using the treatment planning software BNCT RTPE. The simulation studies have shown that a proton beam current of ∼ 20 mA is required to deliver high quality brain treatments in about 40 minutes. The results also indicate that significantly higher doses can be delivered to deep-seated tumors in comparison to the Brookhaven Medical Research Reactor beam. An electrostatic quadrupole (ESQ) accelerator is ideally suited to provide the high beam currents desired. A novel power supply utilizing the air-coupled transformer concept is under development. It will enable the ESQ-accelerator to deliver proton beam currents exceeding 50 mA. A lithium target has been designed which consists of a thin layer of lithium on an aluminum backing. Closely spaced, narrow coolant passages cut into the aluminum allow the removal of a 50kW heat-load by convective water cooling. The system under development is suitable for hospital installation and has the potential for providing neutron beams superior to reactor sources

Neutron-proton scattering experiments and phase analyses for the n-p system in the energy range from 17 to 50 MeV

International Nuclear Information System (INIS)

Krupp, H.

1986-01-01

In the framework of the study of the nucleon-nucleon interaction neutron-proton scattering experiments were performed at the neutron collimator POLKA of the Karlsruhe cyclotron. Neutrons were produced by the source reaction D(d,n)X in the energy range between 17 and 50 MeV. Measured were the differential cross section, the analyzing power, and the spin correlation coefficient of the elastic n-p scattering. By means of the new data the knowledge of the isospin T=0 scattering phases could be improved. It is for the first time possible to determine the scattering phases for T=1 independently from n-p and p-p data with comparable accuracy. (orig./HSI) [de

Development and manufacturing of a Nb$_{3}$Sn quadrupole magnet Model at CEA/Saclay for TESLA Interaction Region

CERN Document Server

Durante, Maria; Fratini, M; Leboeuf, D; Segreti, M; Védrine, Pierre; 10.1109/TASC.2004.829129

2004-01-01

One possible application of Nb/sub 3/Sn, whose superconducting properties far exceed those of NbTi, is the fabrication of short and powerful quadrupole magnets for the interaction regions of large particle accelerators. In some projects, as in the future linear collider TESLA, the quadrupole magnets are inside the detector solenoid and must operate in its background field. This situation gives singular Lorentz force distribution in the ends of the magnet. To learn about Nb/sub 3/Sn technology, evaluate fabrication techniques and test the interaction with a solenoidal field, DAPNIA /SACM at CEA/Saclay has started the manufacturing of a 1-m-long, 56- mm-single-aperture quadrupole magnet model. The model relies on the same coil geometry as the LHC arc quadrupole magnets, but has no iron yoke. It will produce a nominal field gradient of 211 T/m at 11,870 A. The coils are wound from Rutherford-type cables insulated with glass fiber tape, before being heat-treated and vacuum-impregnated with epoxy resin. Laminated,...

Elastic neutron-proton differential cross section at 647 MeV

International Nuclear Information System (INIS)

Evans, M.L.

1979-04-01

The differential cross section for n-p elastic scattering in the angular range 51 0 was measured with high statistical accuracy using the 647 MeV monoenergetic neutron beam of the Los Alamos Meson Physics Facility. A proton recoil magnetic spectrometer was used for momentum analysis of the charge exchange protons from the reaction n+p→p+n. Absolute normalization of the cross section was established to within 7% using existing cross section data for the reaction p+p→π + +d. The results differ significantly from previous Dubna and PPA cross sections but agree well with recent Saclay data except at extreme backward angles. 41 references

Coherence features of the spin-aligned neutron-proton pair coupling scheme

International Nuclear Information System (INIS)

Qi, C; Blomqvist, J; Bäck, T; Cederwall, B; Johnson, A; Liotta, R J; Wyss, R

2012-01-01

The seniority scheme has been shown to be extremely useful for the classification of nuclear states in semi-magic nuclei. The neutron-proton (np) correlation breaks the seniority symmetry in a major way. As a result, the corresponding wave function is a mixture of many components with different seniority quantum numbers. In this paper, we show that the np interaction may favor a new kind of coupling in N=Z nuclei, i.e. the so-called isoscalar spin-aligned np pair mode. Shell model calculations reveal that the ground and low-lying yrast states of the N=Z nuclei 92 Pd and 96 Cd may be mainly built upon such spin-aligned np pairs, each carrying the maximum angular momentum J=9 allowed by the shell 0 g 9/2 which is dominant in this nuclear region.

Experimental and Simulated Characterization of a Beam Shaping Assembly for Accelerator- Based Boron Neutron Capture Therapy (AB-BNCT)

International Nuclear Information System (INIS)

Burlon, Alejandro A.; Valda, Alejandro A.; Girola, Santiago; Minsky, Daniel M.; Kreiner, Andres J.

2010-01-01

In the frame of the construction of a Tandem Electrostatic Quadrupole Accelerator facility devoted to the Accelerator-Based Boron Neutron Capture Therapy, a Beam Shaping Assembly has been characterized by means of Monte-Carlo simulations and measurements. The neutrons were generated via the 7 Li(p, n) 7 Be reaction by irradiating a thick LiF target with a 2.3 MeV proton beam delivered by the TANDAR accelerator at CNEA. The emerging neutron flux was measured by means of activation foils while the beam quality and directionality was evaluated by means of Monte Carlo simulations. The parameters show compliance with those suggested by IAEA. Finally, an improvement adding a beam collimator has been evaluated.

Unified description of neutron-, proton- and photon-induced fission cross sections in intermediate energy region

International Nuclear Information System (INIS)

Fukahori, Tokio; Iwamoto, Osamu; Chiba, Satoshi

2003-01-01

For an accelerator-driven nuclear waste transmutation system, it is very important to estimate sub-criticality of core system for feasibility and design study of the system. The fission cross section in the intermediate energy range has an important role. A program FISCAL has been developed to calculate neutron-, proton- and photon-induced fission cross sections in the energy region from several tens of MeV to 3 GeV. FISCAL adopts the systematics considering experimental data for Ag- 243 Am. It is found that unified description of neutron-, proton- and photon-induced fission cross sections is available. (author)

Consequences of Relativistic Neutron Outflow beyond the Accretion Disks of Active Galaxies

Science.gov (United States)

Ekejiuba, I. E.; Okeke, P. N.

1993-05-01

Three channels of relativistic electron injection in the jets of extragalactic radio sources (EGRSs) are discussed. With the assumption that an active galactic nucleus (AGN) is powered by a spinning supermassive black hole of mass ~ 10(8) M_⊙ which sits at the center of the nucleus and ingests matter and energy through an accretion disk, a model for extracting relativistic neutrons from the AGN is forged. In this model, the inelastic proton--proton and proton--photon interactions within the accretion disk, of relativistic protons with background thermal protons and photons, respectively, produce copious amounts of relativistic neutrons. These neutrons travel ballistically for ~ 10(3gamma_n ) seconds and escape from the disk before they decay. The secondary particles produced from the neutron decays then interact with the ambient magnetic field and/or other particles to produce the radio emissions observed in the jets of EGRSs. IEE acknowledges the support of the World Bank and the Federal University of Technology, Yola, Nigeria as well as the hospitality of Georgia State University.

Proton ejection project for Saturne; Projet d'ejection des protons de saturne

Energy Technology Data Exchange (ETDEWEB)

Bronca, G; Gendreau, G

1959-07-01

The reasons for choosing the ejection system are given. The characteristics required for the ejected beam are followed by a description of the ejection process, in chronological order from the viewpoint of the protons: movement of the particles, taking into account the various elements which make up the system (internal magnet, external magnet, quadrupoles, ejection correction coils, thin and thick cables,...) and specification of these elements. Then follows an estimation of the delay in manufacture and the cost of the project. Finally, the characteristics of the magnets and quadrupoles are listed in an appendix. (author) [French] On donne d'abord les raisons du choix du systeme d'ejection, puis le principe. Apres les caracteristiques requises pour le faisceau ejecte, on decrit le processus d'ejection selon l'ordre chronologique vu par les protons: mouvement des particules compte tenu des divers elements composant le systeme (aimant interne, aimant externe, quadrupoles, enroulements correcteurs ejection, cibles mince et epaisse,. ..) et cahier de charge de ces elements. On estime, ensuite les delais de realisation et le cout du projet. Enfin, un resume des caracteristiques des aimants et quadrupoles est donne en appendice. (auteur)

Transport calculation of medium-energy protons and neutrons by Monte Carlo method

International Nuclear Information System (INIS)

Ban, Syuuichi; Hirayama, Hideo; Katoh, Kazuaki.

1978-09-01

A Monte Carlo transport code, ARIES, has been developed for protons and neutrons at medium energy (25 -- 500 MeV). Nuclear data provided by R.G. Alsmiller, Jr. were used for the calculation. To simulate the cascade development in the medium, each generation was represented by a single weighted particle and an average number of emitted particles was used as the weight. Neutron fluxes were stored by the collisions density method. The cutoff energy was set to 25 MeV. Neutrons below the cutoff were stored to be used as the source for the low energy neutron transport calculation upon the discrete ordinates method. Then transport calculations were performed for both low energy neutrons (thermal -- 25 MeV) and secondary gamma-rays. Energy spectra of emitted neutrons were calculated and compared with those of published experimental and calculated results. The agreement was good for the incident particles of energy between 100 and 500 MeV. (author)

Some Results of the Research Work on the Biological Effect of Neutrons and Protons; Quelques Resultats des Etudes sur les Effets Biologiques des Neutrons et des Protons; Nekotorye itogi izucheniya biologicheskogo dejstviya nejtronov i protonov; Algunos Resultados del Estudio de los Efectos Biologicos de los Neutrones y Protones

Energy Technology Data Exchange (ETDEWEB)

Moskalev, Ju. I. [Institut Biofiziki AMN SSSR, SSSR (Russian Federation)

1964-03-15

The author correlates and analyses the experimental data obtained over the past two or three years regarding the biological effects of neutrons and high-energy protons, and shows that it is a matter of prime concern for present-day radiobiology to investigate the relative biological effectiveness of the various types of radiation under various irradiation conditions and the reasons for the qualitative differences in their effect on the animal organism. Attention is drawn to the need for more research into the combined effect of various types of radiation and other agents. Specific examples are cited to demonstrate the main progress achieved in studying the prophylaxis of radiation injury induced by neutrons or high-energy protons and to show the contribution such research can make towards understanding the specific way in which various types of radiation act. (author) [French] L'auteur generalise les resultats des recherches experimentales qui ont ete faites au cours des deux ou trois dernieres annees sur les effets biologiques des neutrons et protons de haute energie. Il montre qu'une des taches importantes de la radiobiologie moderne est d'etudier a la fois l'efficacite biologique relative des divers types de rayonnements dans des conditions d'irradiation differentes et les differences qualitatives que presente leur action sur l'organisme vivant. Le memoire souligne qu'il est indispensable de developper les recherches sur l'effet combine des divers facteurs: rayonnements et autres. En partant d'exemples concrets, l'auteur expose les principaux resultats des recherches-sur la prophylaxie des radiolesions provoquees par les neutrons et les protons de haute energie; il montre egalement a quel point ces travaux sont necessaires pour mieux comprendre le caractere specifique de l'e ffet des divers types de rayonnements. (author) [Spanish] En esta memoria se generalizan los resultados de los estudios experimentales efectuados en los ultimos dos o tres anos en materia de

Impact parameter analysis of proton-proton elastic and inelastic interactions at 360 GeV/c

International Nuclear Information System (INIS)

Banerjee, S.; Ragavan, R.; Bailly, J

1987-01-01

Data obtained with the European Hybrid Spectrometer on the proton-proton elastic scattering at 360 GeV/c are presented. The differential cross sections of elastic and inelastic pp-interactions are studied as a function of the impact parameter. The results are compared to those obtained at other energies. They are interpreted in the framework of a simple geometrical Monte-Carlo model of inelastic collisions considering protons as composite particles having a definite effective radius with valence quarks inside. The shape of the inelastic overlap function is well reproduced for both pp- and π + p-interactions. The effective radii of the proton and pion as well as of the valence quarks are estimated for inelastic interactions. The model calculations indicate an increase of the effective radii both of protons and valence quarks and an increase of the proton opacity with increasing energy

90 deg.Neutron emission from high energy protons and lead ions on a thin lead target

CERN Document Server

Agosteo, S; Foglio-Para, A; Mitaroff, W A; Silari, Marco; Ulrici, L

2002-01-01

The neutron emission from a relatively thin lead target bombarded by beams of high energy protons/pions and lead ions was measured at CERN in one of the secondary beam lines of the Super Proton Synchrotron for radiation protection and shielding calculations. Measurements were performed with three different beams: sup 2 sup 0 sup 8 Pb sup 8 sup 2 sup + lead ions at 40 GeV/c per nucleon and 158 GeV/c per nucleon, and 40 GeV/c mixed protons/pions. The neutron yield and spectral fluence per incident ion on target were measured at 90 deg.with respect to beam direction. Monte-Carlo simulations with the FLUKA code were performed for the case of protons and pions and the results found in good agreement with the experimental data. A comparison between simulations and experiment for protons, pions and lead ions have shown that--for such high energy heavy ion beams--a reasonable estimate can be carried out by scaling the result of a Monte-Carlo calculation for protons by the projectile mass number to the power of 0.80-0...

Neutron and proton densities and the symmetry energy

International Nuclear Information System (INIS)

Bodmer, A.R.; Usmani, Q.N.

2003-01-01

The neutron/proton distributions in nuclei, in particular, the n-p difference, are considered in a 'macroscopic' Thomas-Fermi approach. The density dependence F(ρ) of the symmetry-energy density, where ρ is the total density, drives this difference in the absence of Coulomb and density-gradient contributions when we obtain an explicit solution for the difference in terms of F. If F is constant then the n-p difference and, in particular, the difference δR between the neutron and proton rms radii are zero. The Coulomb energy and gradient terms are treated variationally. The latter make only a small contribution to the n-p difference, and this is then effectively determined by F. The Coulomb energy reduces δR. Switching off the Coulomb contribution to the n-p difference then gives the maximum δR for a given F. Our numerical results are for 208 Pb. We consider a wide range of F; for these, both δR and the ratio χ of the surface to volume symmetry-energy coefficient depend, approximately, only on an integral involving F -1 . For δR < or approx. 0.45 fm this dependence is one valued and approximately linear for small δR, and this integral is then effectively determined by δR. There is a strong correlation between δR and χ, allowing an approximate determination of χ from δR. δR has a maximum of congruent with 0.65 fm

Quadrupole moments of hadrons

International Nuclear Information System (INIS)

Krivoruchenko, M.I.

1985-01-01

In chiral bag model an expression is obtained for the quark wave functions with account of color and pion interaction of quarks. The quadrupole moments of nonstrange hadrons are calculated. Quadrupole moment of nucleon isobar is found to be Q(Δ)=-6.3x10 -28 esub(Δ)(cm)sup(2). Fredictions of the chiral bag model are in strong disagreement with the non-relativistic quark model

Elementary design of a 30 TeV on 30 TeV proton antiproton collider

International Nuclear Information System (INIS)

Kondo, Takahiko

1984-01-01

A crude conceptual design was made for a 30TeV on 30TeV antiproton-proton collider. The choice of energy and antiproton-proton (instead of PP) are somewhat arbitrary. The basic parameters of the main ring are listed in a table; the bending radius, ring radius and circumference are 11.1km, 14.4km, and 90.6km, respectively; 7680 dipole magnets with maximum field of 9 Tesla; 1280 quadrupole magnets with maximum gradient of 200Tesla/m. The development of high-field, low-heat loss dipoles and quadrupoles are essential, together with the consideration for their mass production method. On the other hand, the possibility of obtaining antiproton-proton luminosity exceeding 10 32 /cm 2 sec is suggested without any fundamental limitation. With such high luminosity, however, it should be pointed out that particle detectors must face their limitation due to extremely high rate, high multiplicity interaction, requiring large steps of detector research and development efforts. (Aoki, K.)

Spin filtering neutrons with a proton target dynamically polarized using photo-excited triplet states

International Nuclear Information System (INIS)

Haag, M.; Brandt, B. van den; Eichhorn, T.R.; Hautle, P.; Wenckebach, W.Th.

2012-01-01

In a test of principle a neutron spin filter has been built, which is based on dynamic nuclear polarization (DNP) using photo-excited triplet states. This DNP method has advantages over classical concepts as the requirements for cryogenic equipment and magnets are much relaxed: the spin filter is operated in a field of 0.3 T at a temperature of about 100 K and has performed reliably over periods of several weeks. The neutron beam was also used to analyze the polarization of the target employed as a spin filter. We obtained an independent measurement of the proton spin polarization of ∼0.13 in good agreement with the value determined with NMR. Moreover, the neutron beam was used to measure the proton spin polarization as a function of position in the naphthalene sample. The polarization was found to be homogeneous, even at low laser power, in contradiction to existing models describing the photo-excitation process.

Proton-proton elastic scattering measurements at COSY

Energy Technology Data Exchange (ETDEWEB)

Bagdasarian, Zara [Forschungszentrum Juelich, Juelich (Germany); Tbilisi State University, Tbilisi (Georgia); Collaboration: ANKE-Collaboration

2014-07-01

To construct the reliable phase shift analysis (PSA) that can successfully describe the nucleon-nucleon (NN) interaction it is necessary to measure variety of experimental observables for both proton-proton (pp) and neutron-proton (np) elastic scattering. The polarized beams and targets at COSY-ANKE facility allow a substantial contribution to the existing database. The experiment was carried out in April 2013 at ANKE using a transversely polarized proton beam incident on an unpolarized hydrogen cluster target. Six beam energies of T{sub p}=0.8,1.6,1.8,2.0,2.2,2.4 GeV were used. The aim of this talk is to present the preliminary results for the analyzing power (A{sub y}) for the pp elastic scattering in the so-far unexplored 5 <θ{sub cm}<30 angular range. Our measurements are also compared to the world data and current partial wave solutions.

High energy proton simulation of 14-MeV neutron damage in Al2O3

International Nuclear Information System (INIS)

Muir, D.W.; Bunch, J.M.

1975-01-01

High-energy protons are a potentially useful tool for simulating the radiation damage produced by 14-MeV neutrons in CTR materials. A comparison is given of calculations and measurements of the relative damage effectiveness of these two types of radiation in single-crystal Al 2 O 3 . The experiments make use of the prominent absorption band at 206 nm as an index to lattice damage, on the assumption that peak absorption is proportional to the concentration of lattice vacancies. The induced absorption is measured for incident proton energies ranging from 5 to 15 MeV and for 14-MeV neutrons. Recoil-energy spectra are calculated for elastic and inelastic scattering using published angular distributions. Recoil-energy spectra also are calculated for the secondary alpha particles and 12 C nuclei produced by (p,p'α) reactions on 16 O. The recoil spectra are converted to damage-energy spectra and then integrated to yield the damage-energy cross section at each proton energy and for 14 MeV neutrons. A comparison of the calculations with experimental results suggests that damage energy, at least at high energies, is a reasonable criterion for estimating this type of radiation damage. (auth)

The neutron total cross-section measurement of {sup 56}Fe and {sup 57}Fe by using Japan Proton Accelerator Research Complex facility

Energy Technology Data Exchange (ETDEWEB)

Kim, Eun Ae; Shvetsov, Valery; Cho, Moo Hyun [Pohang University of Science and Technology, Pohang (Korea, Republic of); Won, Nam Kung [Pohang Accelerator Laboratory, Pohang (Korea, Republic of); Kim, Kwang Soo; Yang, Sung Chul; Lee, Man Woo; Kim, Guin Yun [Kyungpook National University, Daegu (Korea, Republic of); Yi, Kyoung Rak; Choi, Hong Yub; Ro, Tae Ik [Dong-A University, Pusan (Korea, Republic of); Mizumoto, Motoharu; Katabuchi, Tatsuya; Igashira, Masayuki [Tokyo Institute of Technology, Tokyo (Japan)

2012-05-15

The measurement of neutron cross section using Time-Of-Flight (TOF) method gives significant information for the nuclear data research. In the present work, the neutron total cross section of {sup 56}Fe and {sup 57}Fe has been measured in the energy range between 10 eV and 100 keV by using the neutron beam produced from 3-GeV proton synchrotron accelerator. The 3-GeV proton synchrotron accelerator is located at Japan Proton Accelerator Research Complex (J-PARC) facility in Tokai village. In this study, the neutron total cross section data measured by {sup 6}Li glass scintillator detector was compared with the evaluated values of ENDF/B-VII.0

A proposed experiment for studying the direct neutron-neutron interaction

International Nuclear Information System (INIS)

Hassan Fikry, A.R.; Maayouf, R.M.A.

1979-01-01

An experiment for studying the direct neutron-neutron interaction is suggested. The experiment is based on the combined use of an accelerator, e.g., an electron linear accelerator, together with a mobile pulsed reactor; or using a pulsed beam reactor together with a mobile neutron generator

Design and field measurement of the BEPC-II interaction region dual-aperture quadrupoles

International Nuclear Information System (INIS)

Yin, Z.S.; Wu, Y.Z.; Zhang, J.F.; Chen, W.; Li, Y.J.; Li, L.; Hou, R.; Yin, B.G.; Sun, X.J.; Ren, F.L.; Wang, F.A.; Chen, F.S.; Yu, C.H.; Chen, C.

2007-01-01

With the Beijing Electron Positron Collider upgrade project (BEPC-II), two dual-aperture septum-style quadrupole magnets are used in the interaction region for the final focusing of the electron and positron beams. The BEPC-II lattice design calls for the same high quality integral quadrupole field and large good field region in both apertures for each magnet. Two-dimensional contour optimization and pole-end chamfer iteration are used to minimize the systematic harmonic errors. Unexpected non-systematic errors induced by the unsymmetrical structure and the manufacturing errors are compensated with the pole-end shimming. Magnet measurements with rotating coils are performed to guide and confirm the magnet design. This paper discusses the design consideration, optimizing procedure and measurement results of these dual-aperture magnets

A measurement of ΔσL(np), the difference between neutron-proton total cross sections in pure longitudinal spin states

International Nuclear Information System (INIS)

Beddo, M.E.

1990-10-01

A measurement off Δσ L (np), the difference between neutron-proton total cross sections in pure longitudinal spin states, is described. The results will help determine the isospin-zero (I = 0) scattering amplitudes, which are not well known above laboratory energies of 500 MeV, whereas the isospin-one (I = 1) amplitudes are fairly well-determined to 1 GeV. Data points were taken at the Los Alamos Meson Physics Facility (LAMPF) at Los Alamos, New Mexico, for five neutron beam energies: 484, 568, 634,720 and 788 MeV; they are the first in this energy range. Polarized neutrons were produced by charge-exchange of polarized protons on a liquid deuterium target (LD 2 ). Large-volume neutron counters detected the neutrons that passed through a polarized proton target. The counters subtended a range of solid angles large enough to allow extrapolation of the scattered neutrons to 0 degree. Two modifications to the LAMPF accelerator system which were made for this work are described. They included a ''beam buncher,'' which modified the normal rf-time structure of the proton beam and allowed for the selection of peak-energy neutrons by time-of-flight means, and a computerized beam steering program, which reduced systematic effects due to beam motion at the LD 2 target. The experimental values of Δσ L (np) are found to be consistent with other np data, including preliminary data from SIN and Saclay, but not with some results from Argonne which used a polarized proton beam and a polarized deuteron target. The I = 0 component was extracted from Δσ L (np) using existing pp data (I = 1), with the unexpected result that Δσ L (I = 0) was found to be essentially identical in shape to Δσ L (I = 1). The significance of this is not yet understood

Celerity, pulse and wavelength of De broglie for a nucleon (proton or neutron), according to its kinetic energy. - Formulas and curves; Vitesse, impulsion et longueur d'onde de de broglie d'un nucleon (proton ou neutron), en fonction de son energie cinetique. - Formules et courbes

Energy Technology Data Exchange (ETDEWEB)

Rogozmski, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1952-07-01

The celerity curves, pulse and wavelength of De Broglie for a nucleon (proton or neutron) have been calculated and traced accordingly to its kinetic energy. (M.B.) [French] Les courbes de vitesses, d mpulsion et de longueur d nde de Broglie d n nucleon (proton ou neutron) ont ete calcule et trace en fonction de son energie cinetique. (M.B.)

Neutrino interactions, proton production and a nuclear effect

International Nuclear Information System (INIS)

Guy, J.; Allport, P.P.; Cooper-Sarkar, A.; Sansum, R.A.; Venus, W.; Berggren, M.; Morrison, D.R.O.; Parker, M.A.; Wachsmuth, H.; Clayton, E.F.; Mobayyen, M.M.; Hulth, P.O.; Katz, U.; Wittek, W.; Marage, P.; Sacton, J.; Matsinos, E.; Simopoulou, E.; Myatt, G.; Neveu, M.; Apeldoorn, G.W. van

1989-01-01

Neutrino interactions are classified by the presence or absence of protons with momentum below 600 MeV/c at the interaction vertex. Interactions producing protons have softer x distributions for hydrogen and deuterium targets as well as for neon. In contrast to a recent claim, the effect is therefore not directly related to any nuclear effect in neon. (orig.)

Neutrino interactions, proton production and a nuclear effect

Science.gov (United States)

Guy, J.; Allport, P. P.; Berggren, M.; Clayton, E. F.; Cooper-Sarkar, A.; Hulth, P. O.; Jones, G. T.; Katz, U.; Marage, P.; Matsinos, E.; Mobayyen, M. M.; Morrison, D. R. O.; Myatt, G.; Neveu, M.; O'Neale, S.; Parker, M. A.; Sacton, J.; Sansum, R. A.; Simopoulou, E.; van Apeldoorn, G. W.; Varvell, K.; Venus, W.; Wachsmuth, H.; Wittek, W.

1989-10-01

Neutrino interactions are classified by the presence or absence of protons with momentum below 600 MeV/c at the interaction vertex. Interactions producing protons have softer x distributions for hydrogen and deuterium targets as well as for neon. In contrast to a recent claim, the effect is therefore not directly related to any nuclear effect in neon.

Installation and performance of the Budapest-Hamburg proton microprobe

International Nuclear Information System (INIS)

Kovacs, I.; Kocsonya, A.; Kostka, P.; Szokefalvi-Nagy, Z.; Schrang, K.; Krueger, A.; Niecke, M.

2005-01-01

A new scanning proton microprobe has been installed at the 5 MV Van de Graaff accelerator of the KFKI Research Institute for Particle and Nuclear Physics. It is the energy-upgraded version of the Hamburg proton microprobe dismantled in 2001. The probe forming system includes a pair of focusing quadrupoles and an additional quadrupole pair in front of it, which is applied to increase the proton beam divergence. The average probe size at 2.5 MeV proton energy is 2.2 μm x 1.1 μm. The test results on stability and the preliminary experiments on cement corrosion and fish otoliths are also presented

Double-photoionization of helium including quadrupole radiation effects

Energy Technology Data Exchange (ETDEWEB)

Colgan, James [Los Alamos National Laboratory; Ludlow, J A [AUBURN UNIV; Lee, Teck - Ghee [AUBURN UNIV; Pindzola, M S [AUBURN UNIV; Robicheaux, F [AUBURN UNIV

2009-01-01

Non-perturbative time-dependent close-coupling calculations are carried out for the double photoionization of helium including both dipole and quadrupole radiation effects. At a photon energy of 800 eV, accessible at CUlTent synchrotron light sources, the quadrupole interaction contributes around 6% to the total integral double photoionization cross section. The pure quadrupole single energy differential cross section shows a local maxima at equal energy sharing, as opposed to the minimum found in the pure dipole single energy differential cross section. The sum of the pure dipole and pure quadrupole single energy differentials is insensitive to non-dipole effects at 800 eV. However, the triple differential cross section at equal energy sharing of the two ejected electrons shows strong non-dipole effects due to the quadrupole interaction that may be experimentally observable.

Detecting neutrons by forward recoil protons at the Energy & Transmutation facility: Detector development and calibration with 14.1-MeV neutrons

Science.gov (United States)

Afanasev, S.; Vishnevskiy, A.; Vishnevskiy, D.; Rogachev, A.; Tyutyunnikov, S.

2017-05-01

As part of the Energy & Transmutation project, we are developing a detector for neutrons with energies in the 10-100 MeV range emitted from the target irradiated by a charged-particle beam. The neutron is detected by measuring the time-of-flight and total kinetic energy of the forward-going recoil proton [1] knocked out at a small angle from a thin layer of plastic scintillator, which has to be selected against an intense background created by γ quanta, scattered neutrons, and charged particles. On the other hand, neutron energy has to be measured over the full range with no extra tuning of the detector operation regime. Initial measurements with a source of 14.1-MeV neutrons are reported.

Analysing power for neutron-proton scattering at 14.1 MeV

International Nuclear Information System (INIS)

Brock, J.E.; Chisholm, A.; Duder, J.C.; Garrett, R.; Poletti, J.L.

1981-01-01

The analysing power Asub(y)(theta) for neutron-proton scattering has been measured at 14.1 MeV for c.m. angles between 50 0 and 157 0 . A polarized neutron beam was produced by the reaction 3 H(d,n) 4 He at 110 keV, using polarized deuterons from an atomic beam polarized ion source. Liquid and plastic scintillators were used for proton targets and the scattered particles were detected in an array of platic scintillators. Use of the associated alpha technique, multi-parameter recording of events and off-line computer treatment led to very low backgrounds. The results differ significantly from the predictions of the phase-shift analyses of Yale IV, Livermore X and Arndt et al. We find, however, excellent agreement with the predictions of the Paris potential of Lacombe et al. Existing n-p analysing power results up to 30 MeV are surveyed and found to be consistent. An attempt was made to look for an isospin splitting of the triplet P-wave phase shifts. (orig.)

Proton-proton bremsstrahlung

International Nuclear Information System (INIS)

Fearing, H.W.

1990-01-01

We summarize some of the information about the nucleon-nucleon force which has been obtained by comparing recent calculations of proton-proton bremsstrahlung with cross section and analyzing power data from the new TRIUMF bremsstrahlung experiment. Some comments are made as to how these results can be extended to neutron-proton bremsstrahlung. (Author) 17 refs., 6 figs

PENTrack-a simulation tool for ultracold neutrons, protons, and electrons in complex electromagnetic fields and geometries

Science.gov (United States)

Schreyer, W.; Kikawa, T.; Losekamm, M. J.; Paul, S.; Picker, R.

2017-06-01

Modern precision experiments trapping low-energy particles require detailed simulations of particle trajectories and spin precession to determine systematic measurement limitations and apparatus deficiencies. We developed PENTrack, a tool that allows to simulate trajectories of ultracold neutrons and their decay products-protons and electrons-and the precession of their spins in complex geometries and electromagnetic fields. The interaction of ultracold neutrons with matter is implemented with the Fermi-potential formalism and diffuse scattering using Lambert and microroughness models. The results of several benchmark simulations agree with STARucn v1.2, uncovered several flaws in Geant4 v10.2.2, and agree with experimental data. Experiment geometry and electromagnetic fields can be imported from commercial computer-aided-design and finite-element software. All simulation parameters are defined in simple text files allowing quick changes. The simulation code is written in C++ and is freely available at github.com/wschreyer/PENTrack.git.

Coulomb excitation of neutron-rich $^{134-136}$Sn isotopes

CERN Multimedia

We propose to study excited states in the isotopes $^{134,136}$Sn by $\\gamma$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to investigate the evolution of quadrupole collectivity beyond the magic shell closure at N = 82 by the determination of B(E2) values and electric quadrupole moments $\\mathcal{Q}_2$. Recent shell-model calculations using realistic interactions predict possible enhanced collectivity in neutron-rich regions. Evidence for this could be obtained by this experiment. Furthermore, the currently unknown excitation energies of the 2$^+_{1}$ and 4$^+_{1}$ states in $^{136}$Sn will be measured for the first time.

Neutron matter, neutron pairing, and neutron drops based on chiral effective field theory interactions

Energy Technology Data Exchange (ETDEWEB)

Krueger, Thomas

2016-10-19

The physics of neutron-rich systems is of great interest in nuclear and astrophysics. Precise knowledge of the properties of neutron-rich nuclei is crucial for understanding the synthesis of heavy elements. Infinite neutron matter determines properties of neutron stars, a final stage of heavy stars after a core-collapse supernova. It also provides a unique theoretical laboratory for nuclear forces. Strong interactions are determined by quantum chromodynamics (QCD). However, QCD is non-perturbative at low energies and one presently cannot directly calculate nuclear forces from it. Chiral effective field theory circumvents these problems and connects the symmetries of QCD to nuclear interactions. It naturally and systematically includes many-nucleon forces and gives access to uncertainty estimates. We use chiral interactions throughout all calculation in this thesis. Neutron stars are very extreme objects. The densities in their interior greatly exceed those in nuclei. The exact composition and properties of neutron stars is still unclear but they consist mainly of neutrons. One can explore neutron stars theoretically with calculations of neutron matter. In the inner core of neutron stars exist very high densities and thus maybe exotic phases of matter. To investigate whether there exists a phase transition to such phases even at moderate densities we study the chiral condensate in neutron matter, the order parameter of chiral symmetry breaking, and find no evidence for a phase transition at nuclear densities. We also calculate the more extreme system of spin-polarised neutron matter. With this we address the question whether there exists such a polarised phase in neutron stars and also provide a benchmark system for lattice QCD. We find spin-polarised neutron matter to be an almost non-interacting Fermi gas. To understand the cooling of neutron stars neutron pairing is of great importance. Due to the high densities especially triplet pairing is of interest. We

X-rays from neutron stars

International Nuclear Information System (INIS)

Boerner, G.

1979-08-01

The basic theoretical in the models of regularly pulsating X-ray sources are discussed, and put in relation to the observations. The topics covered include physics of the magnetosphere of an accreting neutron star, hydrodynamics of the accretion column, physical processes close to the surface of the neutron star such as proton-electron collisions, photon-electron interactions. (orig.)

The thin-foil magnetic proton recoil neutron spectrometer MPRu at JET

International Nuclear Information System (INIS)

Andersson Sunden, E.; Sjoestrand, H.; Conroy, S.; Ericsson, G.; Gatu Johnson, M.; Giacomelli, L.; Hellesen, C.; Hjalmarsson, A.; Ronchi, E.; Weiszflog, M.; Kaellne, J.; Gorini, G.; Tardocchi, M.; Combo, A.; Cruz, N.; Batista, A.; Pereira, R.; Fortuna, R.; Sousa, J.; Popovichev, S.

2009-01-01

Neutrons are produced in fusion energy experiments with both deuterium (D) and deuterium-tritium (DT) plasmas. Neutron spectroscopy is a valuable tool in the study of the underlying fuel ion populations. The magnetic proton recoil neutron spectrometer, originally installed at JET in 1996 for 14-MeV neutron measurements, has been upgraded, with the main aim of improving its signal-to-background ratio (S/B), making measurements of the 2.5-MeV neutron emission in D plasmas possible. The upgrade includes a new focal-plane detector, based on the phoswich technique and consequently less sensitive to background, and a new custom-designed digital data acquisition system based on transient recorder cards. Results from JET show that the upgraded MPRu can measure 2.5-MeV neutrons with S/B=5, an improvement by a factor of 50 compared with the original MPR. S/B of 2.8x10 4 in future DT experiments is estimated. The performance of the MPRu is exemplified with results from recent D plasma operations at JET, concerning both measurements with Ohmic, ion cyclotron resonance (ICRH) and neutral beam injection (NBI) plasma heating, as well as measurements of tritium burn-up neutrons. The upgraded instrument allows for 2.5-MeV neutron emission and deuterium ion temperature measurements in plasmas with low levels of tritium, a feature necessary for the ITER experiment.

Quasiparticle Interactions in Neutron Matter for Applications in Neutron Stars

Science.gov (United States)

Wambach, J.; Anisworth, T. L.; Pines, D.

1993-01-01

A microscopic model for the quaisiparticle interaction in neutron matter is presented. Both particle-particle (pp) and particle-hole (ph) correlation are are included. The pp correlations are treated in semi-empirical way, while ph correlations are incorporated by solving coupled two-body equations for the particle hole interaction and the scattering amplitude on the Fermi sphere. The resulting integral equations self-consistently sum the ph reducible diagrams. Antisymmetry is kept at all stages and hence the forward-scattering sum rules are obeyed. Results for Landau parameters and transport coefficients in a density regime representing the crust of a neutron star are presented. We also estimate the S-1 gap parameter for neutron superfluidity and comment briefly on neutron-star implications.

A new version of DWPI (inelastic pion-nucleus scattering) to incorporate microscopic form factors and differing proton and neutron radii

International Nuclear Information System (INIS)

Funsten, H.O.

1979-01-01

This is a modification of the Eisenstein-Miller program for calculation of collective inelastic pion-nucleus differential cross sections using free π-N scattering amplitudes. This revision permits the additional use of microscopic (shell model) proton and neutron form factors. It also incorporates separate proton and neutron radii for the nuclear density rho(r) generating the distorted wave optical potential. (Auth.)

Systematic analysis of neutron yields from thick targets bombarded by heavy ions and protons with moving source model

Energy Technology Data Exchange (ETDEWEB)

Kato, Takashi; Kurosawa, Tadahiro; Nakamura, Takashi E-mail: nakamura@cyric.tohoku.ac.jp

2002-03-21

A simple phenomenological analysis using the moving source model has been performed on the neutron energy spectra produced by bombarding thick targets with high energy heavy ions which have been systematically measured at the Heavy-Ion Medical Accelerator (HIMAC) facility (located in Chiba, Japan) of the National Institute of Radiological Sciences (NIRS). For the bombardment of both heavy ions and protons in the energy region of 100-500 MeV per nucleon, the moving source model incorporating the knock-on process could be generally successful in reproducing the measured neutron spectra within a factor of two margin of accuracy. This phenomenological analytical equation is expressed having several parameters as functions of atomic number Z{sub p}, mass number A{sub p}, energy per nucleon E{sub p} for projectile, and atomic number Z{sub T}, mass number A{sub T} for target. By inputting these basic data for projectile and target into this equation we can easily estimate the secondary neutron energy spectra at an emission angle of 0-90 deg. for bombardment with heavy ions and protons in the aforementioned energy region. This method will be quite useful to estimate the neutron source term in the neutron shielding design of high energy proton and heavy ion accelerators.

Neutron roton pairing effect on some even ven rare-earth proton-rich nuclei

International Nuclear Information System (INIS)

Mokhtari, D.

2004-01-01

The neutron roton pairing effect on some even ven rare-earth proton-rich nuclei is studied. It is taken into account, in the isovector case, within the framework of the generalized Bogoliubov-Valatin transformation, using Woods-Saxon single-particle energies. (author)

Validation of Neutrons in Geant4 Using TARC Data - production, interaction and transportation

CERN Document Server

Howard, A

2007-01-01

The TARC (Transmutation by Adiabatic Resonance Crossing) experiment has been simulated with the Geant4 toolkit. The experiment measured neutron production from 2.5 GeV/c and 3.5 GeV/c protons incident on high purity lead. The Geant4 simulation utilised either the Bertini or Binary nuclear cascade models together with the low energy neutron HP extension. The neutron time-energy correlation and relative fluence spectrum is compared between data and simulation. A thin target comparison was undertaken for incident protons of energy 800-1600 MeV and for pre-compound evaporation and nuclear de-excitation in the energy range 24-52 MeV.

Microscopic analysis of proton elastic scattering in the range 80-200 MeV

International Nuclear Information System (INIS)

Dietrich, F.S.; Petrovich, F.

1983-01-01

A systematic comparison is made of differential cross-section and analyzing-power data on 12 C, 28 Si, 40 Ca, 90 Zr, and 208 Pb at 80-200 MeV with calculations based on the single-step folding-model approach to the optical potential. In these calculations, proton densities have been inferred from electron scattering results, with neutron densities either the same as for protons ( 12 C, 28 Si, 40 Ca) or with a small neutron skin consistent with 800-MeV proton scattering results ( 80 Zr, 208 Pb). The effective two-body interactions that have been used are the Love-Franey t-matrix, a density-dependent interaction based on the Paris potential (calculated by von Geramb), and finally the Brieva-Rook density-dependent central interaction used with the spin-orbit part of the Love-Franey interaction