Radiochemical investigation of high-energy spallation reactions resulting from the bombardment of separated copper isotopes with 660-mev protons

1958 ◽  
Vol 6 (4) ◽  
pp. 419-424
Author(s):  
A. N. Murin ◽  
I. A. Yutlandov
Keyword(s):  
High Energy ◽  
Copper Isotopes ◽  
Spallation Reactions ◽  
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The Monte Carlo calculations of McManus and Sharp (unpublished) for the prompt nuclear processes occurring upon bombardment of heavy elements by 400 Mev.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.

Identification of 26-minute Zr-84

1983 ◽  
Vol 61 (4) ◽  
pp. 754-756 ◽  
Author(s):  
Seiichi Shibata ◽  
Paul J. Karol
Keyword(s):  
Cross Sections ◽  
Half Life ◽  
Production Cross ◽  
Isotopic Distribution ◽  
Absolute Abundance ◽  
Spallation Reactions ◽  
Relative Production ◽  
Γ Ray ◽  
The Absolute ◽  
Mev Protons

An unknown γ-ray of energy 112.5 keV was found in zirconium fractions chemically extracted from isotopically enriched molybdenum targets bombarded with 500 and 800 MeV protons. All evidence suggests that the γ-ray is identifiable with the decay of 84Zr to 84Y. A half-life of 25.7 ± 0.5 min was obtained for 84Zr, which is considerably longer than previously reported half-lives. The absolute abundance of the 112.5 keV γ-ray was also determined. Relative production cross sections for 84Zr were calculated using these results and were consistent with the values interpolated from isotopic distribution curves for spallation reactions.

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.

123I production from radioxenon formed in spallation reactions by 660 MeV protons for medical research

1980 ◽  
Vol 31 (3) ◽  
pp. 163-167 ◽  
Author(s):  
M. Adilbish ◽  
V.G. Chumin ◽  
V.A. Khalkin ◽  
O. Knotek ◽  
M.Ja. Kuznetsova ◽  
...  
Keyword(s):  
Medical Research ◽  
Spallation Reactions ◽  
Mev Protons

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.

scholarly journals New Beryllium results in halo stars from Keck/HIRES spectra

2009 ◽  
Vol 5 (S268) ◽  
pp. 231-236
Author(s):  
Ann Merchant Boesgaard ◽  
Jeffrey A. Rich ◽  
Emily M. Levesque ◽  
Brendan P. Bowler
Keyword(s):  
Galactic Halo ◽  
Massive Stars ◽  
High Energy ◽  
High Signal ◽  
Signal To Noise ◽  
Interstellar Gas ◽  
Halo Stars ◽  
Spallation Reactions ◽  
Blue Straggler ◽  
The Galaxy

AbstractWe have obtained high-resolution, high signal-to-noise Keck spectra to determine Be abundances in over 100 stars in the Galactic halo. The stellar metallicities range from [Fe/H] = −0.50 to −3.50. Using this large sample, we have examined the trends of Be with Fe and Be with O. We find a real dispersion in Be at a given [O/H] that indicates that Be may not be a good cosmochronometer. Our results indicate that the dominant production mechanism for Be changes as the Galaxy ages. In the early eras of the Galaxy, when massive stars become supernovae, Be is produced from the acceleration of energetic CNO atoms which bombard protons in the vicinity of supernovae. Later spallation reactions occur as high energy protons bombard CNO atoms in the interstellar gas. The change occurs near [Fe/H] = −2.2. We have found that Be is deficient in Li-deficient halo stars, which favors the blue straggler analog hypothesis.

Sign in / Sign up

Export Citation Format

Share Document