Calculated Production of High-Energy Neutrons by 800-MeV Protons

2009 ◽  
pp. 3-3-9
Author(s):  
AI Hawari ◽  
AS Kumar ◽  
LR Greenwood
Keyword(s):  
High Energy ◽  
Mev Protons

SPALLATION YIELDS FROM HIGH ENERGY PROTON BOMBARDMENT OF HEAVY ELEMENTS

1957 ◽  
Vol 35 (1) ◽  
pp. 21-37 ◽  
Author(s):  
J. D. Jackson
Keyword(s):  
Cross Sections ◽  
High Energy ◽  
Heavy Elements ◽  
Collective Effects ◽  
Comparison With Experiment ◽  
Energy Proton ◽  
Stringent Test ◽  
Neutron Evaporation ◽  
Nuclear Processes ◽  
Mev Protons

The Monte Carlo calculations of McManus and Sharp (unpublished) for the prompt nuclear processes occurring upon bombardment of heavy elements by 400 Mev. protons are combined with a description of the subsequent neutron evaporation to determine spallation cross sections for comparison with experiment. The model employed is a schematic one which suppresses the detailed characteristics of individual nuclei, but gives the over-all behavior to be expected. Many-particle and collective effects such as alpha particle emission and fission are ignored. The computed cross sections are presented in a variety of different graphical forms which illustrate quantitatively the qualitative picture of high energy reactions first given by Serber (1947). The calculations are in general agreement with existing data when fission is not an important effect, but the agreement does not imply a very stringent test of the various features of the model.

Measurements of Displacement Cross Section of Tungsten under 389-MeV Proton Irradiation and Thermal Damage Recovery

2021 ◽  
Vol 1024 ◽  
pp. 95-101
Author(s):  
Yosuke Iwamoto ◽  
Makoto Yoshida ◽  
Hiroki Matsuda ◽  
Shin Ichiro Meigo ◽  
Daiki Satoh ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Thermal Conduction ◽  
Thermal Damage ◽  
Proton Irradiation ◽  
High Energy ◽  
Wire Sample ◽  
Energy Proton ◽  
Measured Displacement ◽  
Mev Protons

For validating the number of displacements per atom (dpa) for tungsten under high-energy proton irradiation, we measured displacement cross sections related to defect-induced electrical resistivity changes in a tungsten wire sample under irradiation with 389-MeV protons under 10 K. The Gifford–McMahon cryocooler was used to cool the sample using a conductive coolant via thermal conduction plates of oxygen-free high-conductivity copper and electrical insulation sheets of aluminum nitride ceramic. In this experiment, the displacement cross section was 1612 ± 371 b for tungsten at 389 MeV. A comparison of the experimental displacement cross sections of tungsten with the calculated results obtained using Norgett–Robinson–Torrens (NRT) dpa and athermal recombination-corrected (arc) dpa cross sections indicates that arc-dpa was in better agreement with the experimental data than NRT-dpa; this is similar to the displacement cross sections of copper. From the measurements of damage recovery of the accumulated defects in tungsten through isochronal annealing, which is related to the defect concentration of the sample, approximately 20% of the damage was recovered at 60 K. This trend was similar to those observed in other experimental results for reactor neutrons.

Strain in Epitaxial GaAs on CaF2/Si(111)

1989 ◽  
Vol 160 ◽  
Author(s):  
L.J. Schowalter ◽  
J.E. Ayers ◽  
S.K. Ghandhi ◽  
Shin Hashimoto ◽  
W.M. Gibson ◽  
...  
Keyword(s):  
Layer Structure ◽  
High Energy ◽  
Buffer Layers ◽  
Epitaxial Layers ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
Ion Channeling ◽  
Gaas Films ◽  
Mev Protons ◽  
Good Agreement

AbstractEpitaxial layers of (111) GaAs of approximately 1 µm thickness were grown on epitaxial CaF2 buffer layers which were either 140 or 380 nm thick on Si(111) substrates. The best nucleation temperature for the GaAs on CaF2/Si(111) we have observed was 620 °C. This resulted in high quality GaAs films which exhibited channeling minimum yields of 4%. The density of threading dislocations in the GaAs layers was observed by TEM to be ~108 cm-2. Double-crystal x-ray diffraction measurements showed that the strain (ε┴.) was less than 2.2×10-4 in both sets of GaAs samples. Ion channeling, however, revealed a large tetragonal strain of 3.5×10-3 (ε┴ = 1.7×10-3) in the thinner (140 nm) CaF2 buffer layers. By doing ion channeling with high energy (2.5 MeV) protons, it was possible to determine strain more accurately. Using this technique, we were able to set an upper limit for the tetragonal strain of 2.5×10-4 in both the GaAs (which implies ε┴ < 8×10-5 and CaF2 (ε┴ < 1.5×10-4) layers for the thicker (380 nm) CaF2 buffer layer structure. These results are in good agreement with the strain predicted from previous strain measurements of CaF2 epitaxial layers on Si.

scholarly journals Enhanced efficiency of femtosecond laser-driven proton generation from a two-species target with heavy atoms

2016 ◽  
Vol 34 (2) ◽  
pp. 294-298 ◽  
Author(s):  
J. Domański ◽  
J. Badziak ◽  
S. Jabłoński
Keyword(s):  
Proton Beam ◽  
Proton Energy ◽  
High Energy ◽  
Two Dimensional ◽  
Particle In Cell ◽  
Heavy Atoms ◽  
Fs Laser ◽  
The Mean ◽  
Proton Generation ◽  
Mev Protons

AbstractUsing two-dimensional particle-in-cell simulations, the properties of a proton beam generated from a thin erbium hydride target irradiated by a 25 fs laser pulse of intensity ranging from 1020 to 1021 W/cm2 are investigated and compared with the features of a proton beam produced from a hydrocarbon (CH) target. It is shown that in case of using the hydride target the mean proton energy and the number of high-energy (>10 MeV) protons as well as the peak proton pulse intensity can be higher by a factor ~10 than the ones obtained from the CH target.

scholarly journals Response of Human HTB140 Melanoma Cells to Conventional Radiation and Hadrons

2011 ◽  
pp. S129-S135 ◽  
Author(s):  
A. RISTIĆ-FIRA ◽  
D. TODOROVIĆ ◽  
J. ŽAKULA ◽  
O. KETA ◽  
P. CIRRONE ◽  
...  
Keyword(s):  
Bragg Peak ◽  
High Energy ◽  
Melanoma Cells ◽  
Cellular Radio ◽  
Conventional Radiotherapy ◽  
Conventional Radiation ◽  
Γ Rays ◽  
The Common ◽  
Mev Protons ◽  
Spread Out Bragg Peak

Conventional radiotherapy with X- and γ-rays is one of the common and effective treatments of cancer. High energy hadrons, i.e., charged particles like protons and 12C ions, due to their specific physics and radiobiological advantages are increasingly used. In this study, effectiveness of different radiation types is evaluated on the radio-resistant human HTB140 melanoma cells. The cells were irradiated with -rays, the 62 MeV protons at the Bragg peak and in the middle of the spread-out Bragg peak (SOBP), as well as with the 62 MeV/u 12C ions. The doses ranged from 2 to 24 Gy. Cell survival and proliferation were assessed 7 days after irradiation, whereas apoptosis was evaluated after 48 h. The acquired results confirmed the high radio-resistance of cells, showing better effectiveness of protons than γ-rays. The best efficiency was obtained with 12C ions due to higher linear energy transfer. All analyzed radiation qualities reduced cell proliferation. The highest proliferation was detected for 12C ions because of their large killing capacity followed by small induction of reparable lesions. This enabled unharmed cells to preserve proliferative activity. Irradiations with protons and 12C ions revealed similar moderate pro-apoptotic ability that is in agreement with the level of cellular radio-resistance.

The biological action of high energy (500 Mev) protons

1964 ◽  
Vol 55 (5) ◽  
pp. 542-545 ◽  
Author(s):  
Yu. I. Moskalev ◽  
I. K. Petrovich
Keyword(s):  
High Energy ◽  
Biological Action ◽  
Mev Protons

Observation of the High-Energy Octupole Giant Resonance with 800-MeV Protons

1980 ◽  
Vol 45 (4) ◽  
pp. 239-242 ◽  
Author(s):  
T. A. Carey ◽  
W. D. Cornelius ◽  
N. J. DiGiacomo ◽  
J. M. Moss ◽  
G. S. Adams ◽  
...  
Keyword(s):  
Giant Resonance ◽  
High Energy ◽  
Mev Protons

HIGH ENERGY PROTON PIXE [HEPP]

1993 ◽  
Vol 03 (03) ◽  
pp. 187-214 ◽  
Author(s):  
J.S.C. McKEE
Keyword(s):  
Review Paper ◽  
Analytical Techniques ◽  
High Energy ◽  
Low Energy ◽  
X Ray ◽  
Energy Proton ◽  
History Of ◽  
History Of Analysis ◽  
Compare And Contrast ◽  
Mev Protons

Studies of particle induced X-ray emission (PIXE) have been widespread and detailed in recent years and despite the fact that most data obtained are from low energy 1–3 MeV experiments, the value of higher energy proton work with its emphasis on K X-ray emission has become more marked as time has progressed. The purpose of this review paper is to outline the history of analysis using high energy protons and to compare and contrast the results obtained with those from lower energy analysis using more firmly established analytical techniques. The work described will concentrate exclusively on proton induced processes and will attempt to outline the rationale for selecting an energy, greater than 20 and up to 70 MeV protons for initiating particles. The relative ease and accuracy of the measurements obtained will be addressed. Clearly such X-ray studies should be seen as complementing low energy work in many instances rather than competing directly with them. However, it will be demonstrated that above a Z value of approximately 20, K X-ray analysis using high energy protons is the only way to go in this type of analysis.

scholarly journals Neutron Spectrum

2021 ◽  
pp. 125-156
Author(s):  
Cheol Ho Pyeon
Keyword(s):  
Neutron Spectrum ◽  
High Energy ◽  
Reactor Physics ◽  
The Core ◽  
Foil Activation ◽  
Fission Neutrons ◽  
Spallation Neutrons ◽  
Core Characteristics ◽  
Mev Protons ◽  
Fast Neutron Spectrum

AbstractThe subcritical multiplication factor is considered an important index for recognizing, in the core, the number of fission neutrons induced by an external neutron source. In this study, the influences of different external neutron sources on core characteristics are carefully monitored. Here, the high-energy neutrons generated by the neutron yield at the location of the target are attained by the injection of 100 MeV protons onto these targets. In actual ADS cores, liquid Pb–Bi has been selected as a material for the target that generates spallation neutrons and for the coolant in fast neutron spectrum cores. The neutron spectrum information is acquired by the foil activation method in the 235U-fueled and Pb–Bi-zoned fuel region of the core, modeling the Pb–Bi coolant core locally around the central region. The neutron spectrum is considered an important parameter for recognizing information on neutron energy at the target. Also, the neutron spectrum evaluated by reliable methodologies could contribute to the accurate prediction of reactor physics parameters in the core through numerical simulations of desired precision. In the present chapter, experimental analyses of high-energy neutrons over 20 MeV are conducted after adequate preparation of experimental settings.

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