Absolute Calibration of Photoelectric Diodes

1975 ◽  
Vol 19 ◽  
pp. 597-606 ◽  
Author(s):  
R. H. Day ◽  
E. J. T. Burns

Photoelectric diodes with aluminum photocathod.es have been calibrated in the energy range from 0.1 keV to 1 keV with a multielement Henke X-ray tube system using regenerative monochromatic filters. The calibration is performed at six energies: (1) Be - (0.109 keV) , (2) C - Kα (0.277 keV), (3) Ti – Lα1, 2 (0.452 keV) , (4) Fe – Lα1, 2 (0.705 keV), (5) Cu – Lα1, 2 (0.930 keV), and (6) Al – Kαl, 2 (1.487 keV). Several different 99.9%, (1000 series) aluminum foils were calibrated for use as cathodes. In addition, the average energy per electron ion pair, W, has been measured for methane at these same energies.

1987 ◽  
Vol 42 (10) ◽  
pp. 1051-1053
Author(s):  
H. W. Morsi ◽  
H. Röhr ◽  
U. Schumacher

A large-area (10 x 30 cm2) X -ray source for relative and absolute calibration of double-crystal monochromators for plasma soft X -ray spectroscopy was developed. For a voltage of 20 kV and a current of 1 mA uniform and reproducible emission is achieved at a level of about 30 mW /(m2 · sr) for Kx, line emission in the photon energy range from 1 keV to about 8 keV, while the Lx line emission increases with photon energy from 10 to 20 m W/(m2 · sr).


The average energy per ion pair, W , for the ionization of helium by 1 to 6 MeV α -particles is calculated using the Born approximation, the number of ion pairs produced by secondary, tertiary, etc., electrons being calculated from an integral equation which is solved numeric­ally. The calculated W is nearly constant over this energy range, with average W = 41∙1 eV. This agrees well with the value, W = 42∙7 eV, measured recently by Jesse & Sadauskis for 5∙3 MeV α -particles in helium, and supports their suggestion that the earlier measured values of W for α -particles in helium may have been spuriously low owing to the presence of small amounts of other gases.


1987 ◽  
Vol 48 (C9) ◽  
pp. C8-669-C8-672 ◽  
Author(s):  
S. SINGH ◽  
S. KUMAR ◽  
D. MEHTA ◽  
M. L. GARG ◽  
N. SINGH ◽  
...  
Keyword(s):  

2020 ◽  
pp. 8-12
Author(s):  
Alexandr V. Oborin ◽  
Anna Y. Villevalde ◽  
Sergey G. Trofimchuk

The results of development of the national primary standard of air kerma, air kerma rate, exposure, exposure rate and energy flux for X-rays and gamma radiation GET 8-2011 in 2019 are presented according to the recommendations of the ICRU Report No. 90 “Key Data for Ionizing-Radiation Dosimetry: Measurement Standards and Applications”. The following changes are made to the equations for the units determination with the standard: in the field of X-rays, new correction coefficients of the free-air ionization chambers are introduced and the relative standard uncertainty of the average energy to create an ion pair in air is changed; in the field of gamma radiation, the product of the average energy to create an ion pair in air and the electron stopping-power graphite to air ratio for the cavity ionization chambers is changed. More accurate values of the units reproduced by GET 8-2019 are obtained and new metrological characteristics of the standard are stated.


Author(s):  
Josef Hormes ◽  
Wantana Klysubun ◽  
Jost Göttert ◽  
Henning Lichtenberg ◽  
Alexey Maximenko ◽  
...  
Keyword(s):  

2020 ◽  
Vol 92 (10) ◽  
pp. 1627-1641
Author(s):  
Guangguo Wang ◽  
Yongquan Zhou ◽  
He Lin ◽  
Zhuanfang Jing ◽  
Hongyan Liu ◽  
...  

AbstractThe structure of aq. sodium acetate solution (CH3COONa, NaOAc) was studied by X-ray scattering and density function theory (DFT). For the first hydrated layer of Na+, coordination number (CN) between Na+ and O(W, I) decreases from 5.02 ± 0.85 at 0.976 mol/L to 3.62 ± 1.21 at 4.453 mol/L. The hydration of carbonyl oxygen (OC) and hydroxyl oxygen (OOC) of CH3COO− were investigated separately and the OC shows a stronger hydration bonds comparing with OOC. With concentrations increasing, the hydration shell structures of CH3COO− are not affected by the presence of large number of ions, each CH3COO− group binds about 6.23 ± 2.01 to 7.35 ± 1.73 water molecules, which indicates a relatively strong interaction between CH3COO− and water molecules. The larger uncertainty of the CN of Na+ and OC(OOC) reflects the relative looseness of Na-OC and Na-OOC ion pairs in aq. NaOAc solutions, even at the highest concentration (4.453 mol/L), suggesting the lack of contact ion pair (CIP) formation. In aq. NaOAc solutions, the so called “structure breaking” property of Na+ and CH3COO− become effective only for the second hydration sphere of bulk water. The DFT calculations of CH3COONa (H2O)n=5–7 clusters suggest that the solvent-shared ion pair (SIP) structures appear at n = 6 and become dominant at n = 7, which is well consistent with the result from X-ray scattering.


2002 ◽  
Vol 17 (12n13) ◽  
pp. 1799-1808 ◽  
Author(s):  
MARCO TAVANI

Gamma-ray astrophysics in the energy range between 30 MeV and 30 GeV is in desperate need of arcminute angular resolution and source monitoring capability. The AGILE Mission planned to be operational in 2004-2006 will be the only space mission entirely dedicated to gamma-ray astrophysics above 30 MeV. The main characteristics of AGILE are the simultaneous X-ray and gamma-ray imaging capability (reaching arcminute resolution) and excellent gamma-ray timing (10-100 microseconds). AGILE scientific program will emphasize a quick response to gamma-ray transients and multiwavelength studies of gamma-ray sources.


1997 ◽  
Vol 82 (2) ◽  
pp. 871-877 ◽  
Author(s):  
A. Pansky ◽  
A. Breskin ◽  
R. Chechik
Keyword(s):  
Ion Pair ◽  
X Ray ◽  
The Mean ◽  

1976 ◽  
Vol 47 (12) ◽  
pp. 1475-1478 ◽  
Author(s):  
L. S. Birks ◽  
J. W. Sandelin ◽  
C. M. Dozier
Keyword(s):  

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