scholarly journals Profiling of proton beams by fluence scanners

2021 ◽  
Vol 61 (2) ◽  
Author(s):  
L. Deveikis ◽  
J.V. Vaitkus ◽  
T. Čeponis ◽  
M. Gaspariūnas ◽  
V. Kovalevskij ◽  
...  
Keyword(s):  
Proton Beam ◽  
Carrier Lifetime ◽  
Diagnostic Procedures ◽  
Particle Beams ◽  
Proton Beams ◽  
Profiling Techniques ◽  
Radiation Induced ◽  
Induced Defects ◽  
Mev Protons

Profiling of particle beams is one of the most important diagnostic procedures for operating any kind of accelerator. In this work, the proton beam profilers, based on fluence measurements performed by recording the changes of carrier lifetime in Si material and scintillation intensity of thin GaN layers, caused by radiation induced defects and emission centres, are presented. The beams of penetrative (26 GeV/c) and stopped (1.6 MeV) protons have been examined. It is shown that the penetrative particle regime should be employed to appropriately record 2D fluence distribution profiles. It is also illustrated that the presented profiling techniques can be applied for scanning of other charged (namely, pions) and neutral (neutrons) particle beams.

Studies of Defects in ZnO by Positron Annihilation

1995 ◽  
Vol 378 ◽  
Author(s):  
Werner Puff ◽  
Sebastian Brunner ◽  
Peter Mascher ◽  
Adam G. Balogh
Keyword(s):  
Positron Annihilation ◽  
Colour Change ◽  
Doppler Broadening ◽  
Positron Annihilation Lifetime ◽  
Dark Orange ◽  
Radiation Induced ◽  
Induced Defects ◽  
Annealing Experiments ◽  
Mev Protons ◽  
Yellowish White

AbstractIn order to investigate the basic properties of radiation-induced defects in ZnO crystals, positron annihilation lifetime and Doppler-broadening measurements were performed on crystals sinterd for 18 hours at 1200 °C and irradiated with 3 MeV protons at 223 K. The irradiation induced a colour change of the specimens from the original yellowish-white to dark orange or even brown. Isochronal annealing experiments showed three annealing stages, centred at about 150 °C, 500 – 550 °C, and 750 °C, respectively. These stages are related to the annealing of variously sized vacancy complexes.

Microstructural Evolution of Radiation Induced Defects In ZnO During Isochronal Annealing

1998 ◽  
Vol 540 ◽  
Author(s):  
S. Brunner ◽  
W. Puff ◽  
P. Mascher ◽  
A.G. Balogh
Keyword(s):  
Room Temperature ◽  
Proton Irradiation ◽  
Positron Lifetime ◽  
Thermal Evolution ◽  
Isochronal Annealing ◽  
Doppler Broadening ◽  
Thermal Dependence ◽  
Radiation Induced ◽  
Induced Defects ◽  
Mev Protons

AbstractIn this study we discuss the microstructural changes after electron and proton irradiation and the thermal evolution of the radiation induced defects during isochronal annealing. The nominally undoped samples were irradiated either with 3 MeV protons to a fluence of 1.2× 1018 p/cm2 or with 1 MeV electrons to a fluence of 1×1018 e/cm2. The investigation was performed with positron lifetime and Doppler-broadening measurements. The measurements were done at room temperature and in some cases down to 10 K to investigate the thermal dependence of the trapping characteristics of the positrons.

Vacancy-Type Defects in Electron and Proton Irradiated II- VI Compounds

1996 ◽  
Vol 439 ◽  
Author(s):  
S. Brunner ◽  
W. Puff ◽  
P. Mascher ◽  
A. G. Balogh ◽  
H. Baumann
Keyword(s):  
Positron Annihilation ◽  
Proton Irradiation ◽  
Basic Properties ◽  
Radiation Induced ◽  
Induced Defects ◽  
Mev Protons

AbstractIn this contribution, we present a study aimed at investigating the basic properties of radiation induced defects in ZnS and ZnO and the influence of the atmosphere on the annealing characteristics of the defects. Positron annihilation experiments (both lifetime and Dopplerbroadening measurements) were performed on both single- and polycrystalline samples, irradiated with 3 MeV protons or 1 MeV electrons. For ZnS it was found that both electron and proton irradiation caused significant changes in the positron annihilation characteristics. The annealing of proton irradiated ZnS in air leads to significant oxidation and eventual transformation into ZnO.

Analysis of Proton Induced Defects in Cu(In,Ga)Se2 Thin-Film Solar Cells

2005 ◽  
Vol 865 ◽  
Author(s):  
Shirou Kawakita ◽  
Mitsuru Imaizumi ◽  
Koichi Kibe ◽  
Shinichi Yoda ◽  
Takeshi Ohshima ◽  
...  
Keyword(s):  
Solar Cells ◽  
Spectral Response ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Minority Carrier Diffusion Length ◽  
Defect Annealing ◽  
Radiation Induced ◽  
Cigs Solar Cells ◽  
Induced Defects ◽  
Mev Protons

AbstractWe investigated radiation-induced defects in CIGS solar cells with a solar-cell simulator to analyze the spectral response of the irradiated cells. The damage constant of the minority-carrier diffusion length of the cells irradiated with 1 MeV protons was determined to be 3.5 ×10-5. This analysis led to the relation between the defect introduction rate and proton energy, and was obtained using the same method, as was the defect annealing rate. This result agreed well with that estimated from an analysis of changes in short-circuit current degradation.

Chemical Effects Induced by Low-Energy Particle Beams in Fluorozirconate Glasses

1989 ◽  
Vol 152 ◽  
Author(s):  
Giovanni Marletta ◽  
Monica Ferraris
Keyword(s):  
Glass Network ◽  
Low Energy ◽  
Energy Particle ◽  
Progressive Reduction ◽  
Particle Beams ◽  
Fluorozirconate Glasses ◽  
Chemical Effects ◽  
Radiation Induced ◽  
Chemical States ◽  
Induced Defects

ABSTRACTThe modification of the chemical structure of fluorozirconate glasses (ZBLAN) with Ar ion and atom beams of low energy (2–10 key) has been studied in comparison with the damage produced in the starting polycrystalline ZrF4 and BaF2. A variety of reduced chemical states of Zr is produced in ZrF4 as well as in ZBLAN glasses, including metallic Zr0 state. A strong enhancement of the amount of the metallic Zr formed under irradiation is observed in ZBLAN, while it is present only as trace in the irradiated pure ZrF4 samples. The reported effect is tentatively attributed to the presence of Ba ions in the glass network which could prompt the self-trapping of radiation-induced defects at the Zr sites, involving their progressive reduction

Vacancy-Type Defects in Electron and Proton Irradiated II- VI Compounds

1996 ◽  
Vol 438 ◽  
Author(s):  
S. Brunner ◽  
W. Puff ◽  
P. Mascher ◽  
A. G. Balogh ◽  
H. Baumann
Keyword(s):  
Positron Annihilation ◽  
Proton Irradiation ◽  
Basic Properties ◽  
Radiation Induced ◽  
Induced Defects ◽  
Mev Protons

AbstractIn this contribution, we present a study aimed at investigating the basic properties of radiation induced defects in ZnS and ZnO and the influence of the atmosphere on the annealing characteristics of the defects. Positron annihilation experiments (both lifetime and Dopplerbroadening measurements) were performed on both single- and polycrystalline samples, irradiated with 3 MeV protons or 1 MeV electrons. For ZnS it was found that both electron and proton irradiation caused significant changes in the positron annihilation characteristics. The annealing of proton irradiated ZnS in air leads to significant oxidation and eventual transformation into ZnO.

Vacancy-Type Defects in Electron and Proton Irradiated II-VI Compounds

1998 ◽  
Vol 510 ◽  
Author(s):  
S. Brunner ◽  
W. Puff ◽  
P. Mascher ◽  
A.G. Balogh
Keyword(s):  
Band Gap ◽  
Proton Irradiation ◽  
Positron Lifetime ◽  
Wide Band ◽  
Compound Semiconductors ◽  
Doppler Broadening ◽  
Wide Band Gap ◽  
Radiation Induced ◽  
Induced Defects ◽  
Mev Protons

AbstractIn this contribution we present a study aimed at comparing results of positron-lifetime and Doppler-broadening measurements on the wide-band-gap compound semiconductors ZnS, ZnSe, and ZnTe. To investigate the basic properties of intrinsic and radiation induced defects the samples were irradiated either with 3 MeV protons or 1 MeV electrons. The isochronal annealing was performed in an Ar atmosphere. It was found that electron and proton irradiation cause different changes in the positron annihilation characteristics. Several annealing stages were observed, related to the annealing of variously sized vacancy complexes.

Xenon ion irradiation of superconducting YBa2Cu3O7 thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 92-93
Author(s):  
H. Watanabe ◽  
B. Kabius ◽  
B. Roas ◽  
K. Urban
Keyword(s):  
Defect Formation ◽  
Ion Irradiation ◽  
High Resolution Electron Microscopy ◽  
Structural Disorder ◽  
Flux Lines ◽  
Pinning Effect ◽  
Magnetic Flux Lines ◽  
Resolution Electron ◽  
Radiation Induced ◽  
Induced Defects

Recently it was reported that the critical current density(Jc) of YBa2Cu2O7, in the presence of magnetic field, is enhanced by ion irradiation. The enhancement is thought to be due to the pinning of the magnetic flux lines by radiation-induced defects or by structural disorder. The aim of the present study was to understand the fundamental mechanisms of the defect formation in association with the pinning effect in YBa2Cu3O7 by means of high-resolution electron microscopy(HRTEM).The YBa2Cu3O7 specimens were prepared by laser ablation in an insitu process. During deposition, a substrate temperature and oxygen atmosphere were kept at about 1073 K and 0.4 mbar, respectively. In this way high quality epitaxially films can be obtained with the caxis parallel to the <100 > SrTiO3 substrate normal. The specimens were irradiated at a temperature of 77 K with 173 MeV Xe ions up to a dose of 3.0 × 1016 m−2.

EXAFS STUDY ON RADIATION INDUCED DEFECTS

1986 ◽  
Vol 47 (C8) ◽  
pp. C8-1045-C8-1048
Author(s):  
T. BOLZE ◽  
J. PEISL
Keyword(s):  
Radiation Induced ◽  
Exafs Study ◽  
Induced Defects

Evaluation and treatment of children with radiation-induced cerebral vasculopathy

2019 ◽  
Vol 24 (6) ◽  
pp. 680-688
Author(s):  
David S. Hersh ◽  
Kenneth Moore ◽  
Vincent Nguyen ◽  
Lucas Elijovich ◽  
Asim F. Choudhri ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Proton Beam ◽  
Tumor Imaging ◽  
Clinic Visit ◽  
Surgical Patient ◽  
Beam Radiation ◽  
Proton Beam Radiotherapy ◽  
Cranial Radiation ◽  
Delayed Complication ◽  
Radiation Induced

OBJECTIVEStenoocclusive cerebral vasculopathy is an infrequent delayed complication of ionizing radiation. It has been well described with photon-based radiation therapy but less so following proton-beam radiotherapy. The authors report their recent institutional experience in evaluating and treating children with radiation-induced cerebral vasculopathy.METHODSEligible patients were age 21 years or younger who had a history of cranial radiation and subsequently developed vascular narrowing detected by MR arteriography that was significant enough to warrant cerebral angiography, with or without ischemic symptoms. The study period was January 2011 to March 2019.RESULTSThirty-one patients met the study inclusion criteria. Their median age was 12 years, and 18 (58%) were male. Proton-beam radiation therapy was used in 20 patients (64.5%) and photon-based radiation therapy was used in 11 patients (35.5%). Patients were most commonly referred for workup as a result of incidental findings on surveillance tumor imaging (n = 23; 74.2%). Proton-beam patients had a shorter median time from radiotherapy to catheter angiography (24.1 months [IQR 16.8–35.4 months]) than patients who underwent photon-based radiation therapy (48.2 months [IQR 26.6–61.1 months]; p = 0.04). Eighteen hemispheres were revascularized in 15 patients. One surgical patient suffered a contralateral hemispheric infarct 2 weeks after revascularization; no child treated medically (aspirin) has had a stroke to date. The median follow-up duration was 29.2 months (IQR 21.8–54.0 months) from the date of the first catheter angiogram to last clinic visit.CONCLUSIONSAll children who receive cranial radiation therapy from any source, particularly if the parasellar region was involved and the child was young at the time of treatment, require close surveillance for the development of vasculopathy. A structured and detailed evaluation is necessary to determine optimal treatment.

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