In the present report, we summarize our experience in the development of high-resolution position sensitive gas detectors for medicine and synchrotron radiation experiments at Budker Institute of ...Nuclear Physics for the last years. We have designed several versions of Multistrip Ionisation Chambers with a channel pitch varying from 0.4 down to 0.1
mm. The high quantum efficiency
(
>
65
%
)
of these detectors allow its application in high quality diagnostic imaging. The detector with 0.1
mm strip pitch and 20
atm pressure of Xe demonstrates the best possible DQE and spatial resolution for gaseous detectors in a wide range of X-ray energies. Additionally, the initial results of feasibility study of the detector for beam position monitoring for Heavy Ion Therapy System are presented too.
The ratio of the electron and muon widths of the J/ psi J/ psi meson has been measured using direct J/ psi J/ psi decays in the KEDR experiment at the VEPP-4M electron-positron collider. The result ...Gamma e+e-(J/ psi )/ Gamma mu + mu -(J/ psi )=1.0022 plus or minus 0.0044 plus or minus 0.0048(0.65%) is in good agreement with the lepton universality. The experience collected during this analysis will be used for J/ psi J/ psi lepton width determination with up to 1% accuracy.
Some specific features of scanners with parallel scanning are considered. It is shown that such apparatuses are able to decrease the radiation dose down to the level comparable with the level of ...day-night natural background. Some fields of applications of the low-dose devices are considered, especially those where the radiation dose is one of the determining factors, such as the prophylactic examination of the chest organs, radiographic studies of children, examination of women with pregnancy pathology, etc.
Measurement of parameters Anashin, V V; Aulchenko, V M; Baldin, E M ...
Physics letters. B,
05/2012, Letnik:
711, Številka:
3-4
Journal Article
Recenzirano
We report the final results of a study of the psi ( 3770 ) meson using a data sample collected with the KEDR detector at the VEPP-4M electron-positron collider. The data analysis takes into account ...interference between the resonant and nonresonant D D macr production, where the latter is related to the nonresonant part of the energy-dependent form factor F D . The vector dominance approach and several empirical parameterizations have been tried for the nonresonant F D N R ( s ) . Our results for the mass and total width of psi ( 3770 ) are M = 3779.2 - 1.7 + 1.8 - 0.7 + 0.5 - 0.3 + 0.3 MeV , Gamma = 24.9 - 4.0 + 4.6 - 0.6 + 0.5 - 0.9 + 0.2 MeV , where the first, second and third uncertainties are statistical, systematic and model, respectively. For the electron partial width two possible solutions have been found: ( 1 ) Gamma e e = 154 - 58 + 79 - 9 + 17 - 25 + 13 eV , ( 2 ) Gamma e e = 414 - 80 + 72 - 26 + 24 - 10 + 90 eV . Our statistics are insufficient to prefer one solution to another. The Solution (2) mitigates the problem of non- D D macr decays but is disfavored by potential models. It is shown that taking into account the resonance-continuum interference in the near-threshold region affects resonance parameters, thus the results presented cannot be directly compared with the corresponding PDG values obtained ignoring this effect.
A high-precision determination of the main parameters of the psi ( 2 S ) resonance has been performed with the KEDR detector at the VEPP-4M e + e - collider in three scans of the psi ( 2 S ) - psi ( ...3770 ) energy range. Fitting the energy dependence of the multihadron cross section in the vicinity of the psi ( 2 S ) we obtained the mass value M = 3686.114 plus or minus 0.007 plus or minus 0.011 - 0.012 + 0.002 MeV and the product of the electron partial width by the branching fraction into hadrons Gamma e e B h = 2.233 plus or minus 0.015 plus or minus 0.037 plus or minus 0.020 keV . The first and second uncertainties are statistical and systematic, respectively. The third uncertainty quoted is an estimate of the model dependence of the result due to assumptions on the interference effects in the cross section of the single-photon e + e - annihilation to hadrons explicitly considered in this work. Implicitly, the same assumptions were employed to obtain the charmonium leptonic width and the absolute branching fractions in many experiments. Using the result presented and the world average values of the electron and hadron branching fractions, one obtains the electron partial width and the total width of the psi ( 2 S ) : Gamma e e = 2.282 plus or minus 0.015 plus or minus 0.038 plus or minus 0.021 keV , Gamma = 296 plus or minus 2 plus or minus 8 plus or minus 3 keV . These results are consistent with and more than two times more precise than any of the previous experiments.
GaAs detectors for medical imaging Ayzenshtat, G.I.; Babichev, E.A.; Baru, S.E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2003, Letnik:
509, Številka:
1-3
Journal Article
Recenzirano
X-ray detectors for use with a scanning radiographic device have been developed based on the technique of compensated semi-insulating GaAs. The main detector feature is a linear current–voltage ...characteristic due to the use of Ohmic contacts. The detector consists of two identical detectors connected to power supplies with different polarities in order to minimize the detector leakage current.
Testing of the detectors has been carried out at the Budker Institute of Nuclear Physics. The detector was used with the digital X-ray apparatus “LDRD SIBERIA–N”. The detector parameters have been studied, looking at the dependence with radiation dose, with the applied bias voltage and with the gamma photon energy, using photons in the range of 60–120keV. Images of a test-object were obtained with a resolution of 1.4 line pairs per mm for a detector with 400μm pitch and 2.8 line pairs per mm for a detector with 200μm pitch.
The new effective detector for digital scanning radiography Babichev, E.A.; Baru, S.E.; Groshev, V.R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2003, Letnik:
513, Številka:
1
Journal Article
Recenzirano
The new effective one-dimensional detector for digital scanning radiography is presented. The progress in the design of low-noise electronics allowed the Multistrip Ionization Chamber to be used as ...the X-ray detector. The detector has been designed for use in the Low-dose Digital Radiographic Device “Siberia” instead of a multiwire proportional chamber. The working gas is Xe under 12
atm pressure. The main detector parameters are as follows: total number of channels, −1024; channel size, −0.4×0.4
mm
2; space resolution, −1.25
lp/mm; contrast sensitivity, −1%; dynamic range, −480; surface dose for chest image, −3 to 5
mR.
The security system of personal radiographic inspection for detection of explosive materials and plastic weapons was developed in BINP recently. Basic system parameters are: maximum scanning height—
...2000
mm
, image width—
800
mm
, number of detector channels—768, channel size—
1.05×1
mm
, charge collecting time for one line—2,
5
ms
, scanning speed—
40
cm/s
, maximum scanning time—
5
s
, radiation dose per one inspection
<5
μSv
. The detector is a multichannel ionization Xe chamber. The image of inspected person will appear on the display just after scanning. The pilot sample of this system was put into operation in March, 2003.b
Low-dose digital radiographic device “Siberia” based on a multistrip ionization chamber was developed in Budker Institute of Nuclear Physics. Originally, the detector was filled with Xe gas under
10
...bar
pressure, however, the latest study showed that Kr filled detector at
20
bar
has higher signal-to-noise ratio (SNR) than Xe one. The main factor affecting SNR is amplitude fluctuation of detected signal. Kr has lower value of K-shell binding energy and less K-shell fluorescence yield than Xe gas. It leads to less distortion of registered X-ray spectra and better energy localization. As a result the detector has better channel shape and higher DQE value.
Status of the KEDR drift chamber Baru, S.E; Blinov, A.E; Blinov, V.E ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2002, Letnik:
494, Številka:
1
Journal Article
Recenzirano
The
1
m
long and
1
m
outer diameter chamber consists of 42 layers. The chamber is based on a jet type cells with drift distance of
30
mm
. The measurements of the spatial and d
E/d
x resolution were ...performed with DME gas with the cosmic particles. The resolution averaged over the drift distance is equal to
110
μm
while d
E/d
x resolution is 8.2%.
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