共查询到20条相似文献,搜索用时 15 毫秒
1.
A high-pressure parallel-grid gas scintillation proportional counter for high-energy X-ray astronomy
F. Celi R. di Raffaele G. Gerardi G. Manzo O. Mistretta S. Re L. Scarsi 《Il Nuovo Cimento C》1984,7(6):559-567
Summary We present preliminary results on a new detector for X-ray astronomy sensitive in the energy range from 3 to 120 keV. The
detector can be implemented either as a narrow-field instrument (∼1 degree field of view) or as wide field camera (30×30 degree
field of view). This detector with its large area, good energy resolution and background rejection represents a valid option
to the present generation of instruments for high-energy X-ray astronomy.
Paper presented at the 2° Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 29 May–2 June 1984. 相似文献
2.
T. Peitzmann 《Zeitschrift fur Physik C Particles and Fields》1992,54(4):559-564
The role of the combinatorial background of photon pairs in the analysis of correlations of neutral pions is investigated. The influence of four-particle effects in the Bose-Einstein enhancement is studied within a simulation. The HBT effect can be observed even in a high multiplicity environment, if the source size is not too large. A new method for neutral pion interferometry is introduced, which would allow also the measurement of large sources in high statistics experiments. 相似文献
3.
The absorbed dose as a function of lineal energy was measured at the CERN-EC Reference-field Facility (CERF) using a 512-channel tissue equivalent proportional counter (TEPC), and neutron dose equivalent response evaluated. Although there are some differences, the measured dose equivalent is in agreement with that measured by the 16-channel HANDI tissue equivalent counter. Comparison of TEPC measurements with those made by a silicon solid-state detector for low linear energy transfer particles produced by the same beam, is presented. The measurements show that about 4% of dose equivalent is delivered by particles heavier than protons generated in the conducting tissue equivalent plastic. 相似文献
4.
A study was undertaken to investigate the effect of a high pressure gas environment on the laser welding mechanism. This was specifically related to high power CO2 lasers in the power range between 1.2 and 5 kW. A small high pressure chamber rated up to 150 bar was utilized for the trials. Successful laser welding was completed up to a pressure of 50 bar in the pressurized helium environment. The chamber was modified to incorporate a high pressure transmissive zinc selenide window and internal focusing optics. The initial welds exhibited wide and shallow profiles indicating a loss of keyhole penetration welding. By filming the welding action the problem was found to be the formation of a plasma approximately an order of magnitude larger than in normal atmospheric conditions. The solution was to implement a gas jet system and to use a higher power laser. The resulting welds in terms of penetration and quality were significantly improved. 相似文献
5.
A new detector for CEMS has been built and optimized with respect to the statistical quality of spectra obtained. The optimization has been performed by measuring Mößbauer and pulse height spectra at in- and off-resonance. Single channel analyzer settings were calculated by a new optimization routine. A comparison of different detector designs has been performed using the statistical utility rate of spectra obtained from a stainless steel foil. A procedure for determining optimal operating parameters for ICEMS gas flow proportional counters is proposed. 相似文献
6.
P. S. Antsiferov 《Technical Physics》1998,43(5):596-597
A procedure is described for choosing the optimum pulse amplitude interval for a proportional counter when the useful signal
level is comparable with the natural background level. It is shown that the optimum interval for counter pulses having a Gaussian
amplitude distribution function corresponds to 1.4σ. The application of the procedure is demonstrated in a test example with processing of the iron K
α x-ray spectrum.
Zh. Tekh. Fiz. 68, 126–127 (May 1998) 相似文献
7.
The use of He-filled proportional counters for CEMS studies with57Fe is very attractive because of their high efficiency. Stability problems at low temperature have been solved by using an
electronic feed back which controls the anode voltage to keep the gas gain constant. Long term stable operation has been achieved
between 370 K and 50 K. The potential of the counter is demonstrated on epitaxial and amorphous magnetic thin films. 相似文献
8.
9.
Abdurashitov D. N. Berlev A. I. Likhovid N. A. Lokhov A. V. Tkachev I. I. Yants V. E. 《Physics of Atomic Nuclei》2015,78(2):268-280
Physics of Atomic Nuclei - An experiment aimed at searches for an admixture of a sterile neutrino whosemass is 1 to 8 keV via detecting electrons from tritium decay in a proportional counter is... 相似文献
10.
D. C. Cook 《Hyperfine Interactions》1986,29(1-4):1463-1466
A gas flow proportional counter has been constructed for operation between 100K and 400K without the need for an evacuated
cryostat. The detector is temperature controlled and may be used for detecting conversion electrons or X-rays. Six different
gases, pure He, He/1%CH4, He/5%CH4, He/10%CH4, He/5%Co, and Ar/5%CH4 have been investigated in order to obtain maximum efficiency and reliability of operation. At room temperature and above,
all gases are suitable. At low temperatures, He/5%Co is the most suitable for electron detection, For X-ray detection, Ar/5%CH4 is suitable over the entire temperature range. 相似文献
11.
An algorithm to extract the multiplicity and the higher moments of a multiplicity distribution from the measured counting rates of multiple coincidences is described. In the statistical averaging process a direct transformation to the central moments is performed which results in a well converging procedure to obtain the moments. Important aspects of error analysis and of numerics are outlined. The generality of the formalism allows applications beyond nuclear physics. Guidelines for optimizing an experimental set-up are given. 相似文献
12.
13.
Gavrilyuk Yu. M. Gangapshev A. M. Kazalov V. V. Kuzminov V. V. Panasenko S. I. Ratkevich S. S. Tekueva D. A. Yakimenko S. P. 《Physics of Atomic Nuclei》2015,78(13):1563-1566
Physics of Atomic Nuclei - An experimental technique for searching for the 2K capture in 124Xe with a large low-background copper proportional counter is described. Such an experiment is conducted... 相似文献
14.
I. Alikhanov 《The European Physical Journal C - Particles and Fields》2010,65(1-2):269-273
A solution to the problem of parton distributions in a gas of photons with blackbody spectrum is proposed. The cosmic microwave background radiation is considered as a particular case. The survival probability of ultra-high energy neutrinos traveling through this radiation is calculated. 相似文献
15.
When applying numerical simulation to physical problems it is important to be able to clearly understand the quality that can be reached and the uncertainty associated with the modelling. In this paper we will deal with the Monte Carlo simulation of neutron coincidence and multiplicity counters. These instruments are intensively used in nuclear safeguards for the measurement and verification of the mass of fissile materials in nuclear installations. Their numerical simulation, either for detector design or for numerical calibration, is now used more and more frequently as support to inspections.Several benchmark exercises have been organised in order to assess the capabilities of Monte Carlo simulation to correctly predict realistic practical cases in neutron coincidence and multiplicity counting. Nevertheless most of them allowed reaching conclusions only on the overall uncertainties associated to the modelling through the comparison between calculated and measured integral data.In this paper we aim to analyse more deeply the sources of these uncertainties, separating the different possible causes and analysing parametrically the individual factors. We will include influencing factors deriving from the physical model of the detector, of the acquisition electronics, of the sample and from the nuclear data. The final total uncertainties are consistent with the results of the integral benchmarks. 相似文献
16.
为了减少Am-Li中子本底对高浓铀部件质量主动多重性测量的影响,对大空腔探测系统(NPLNMC)Am-Li中子本底的优化屏蔽进行了模拟研究,提出了一个基于高密度聚乙烯为中子屏蔽体的优化方案。通过对比模拟结果与屏蔽前实验测量结果,发现屏蔽使Am-Li中子本底探测效率明显降低,从原来的15.77%降为屏蔽后的1.94%,大约降低了87.7%;而屏蔽对裂变中子计数的影响却相对较小,只比屏蔽前降低约2.4%。本底中子计数的降低明显提高了系统对铀部件质量测量的灵敏度,在3000s测量时间内,其质量测量下限从原来的大约6.4kg下降到屏蔽后的2.6kg;同时,屏蔽后的NPL-NMC系统在相同测量条件下,铀部件质量测量准确性提高50%以上。 相似文献
17.
为了减少Am-Li中子本底对高浓铀部件质量主动多重性测量的影响,对大空腔探测系统(NPL-NMC)Am-Li中子本底的优化屏蔽进行了模拟研究,提出了一个基于高密度聚乙烯为中子屏蔽体的优化方案。通过对比模拟结果与屏蔽前实验测量结果,发现屏蔽使Am-Li中子本底探测效率明显降低,从原来的15.77%降为屏蔽后的1.94%,大约降低了87.7%;而屏蔽对裂变中子计数的影响却相对较小,只比屏蔽前降低约2.4%。本底中子计数的降低明显提高了系统对铀部件质量测量的灵敏度,在3000 s测量时间内,其质量测量下限从原来的大约6.4 kg下降到屏蔽后的2.6 kg;同时,屏蔽后的NPL-NMC系统在相同测量条件下,铀部件质量测量准确性提高50%以上。 相似文献
18.
A boron-lined proportional counter (BLPC) with a count rate limit close to the multi-wire proportional counter was manufactured to measure the mixed field around reactors. After measurement with a standard Am-Be neutron source (activity: 100 mCi), the results show that the operating voltage of the BLPC is 800 V, the plateau length is 100 V and the slope is 13.2%/100 V. The width and rise time of the output pulse of the BLPC are 1.26 μs and 370 ns, respectively. When the BLPC works at a count rate of 1.0×105 count/s, the pulse pile-up probability of the BLPC is 3.6%. A clear peak can be seen in the pulse height spectrum of the BLPC. and the performances illustrate that a BLPC working in pulse mode can serve as a source range detector of reactors. 相似文献
19.
O. Andersen R. Bauer G.B. Hagemann M.L. Halbert B. Herskind M. Neiman H. Oeschler H. Ryde 《Nuclear Physics A》1978,295(1):163-188
Reactions between 18O and 16O ions, with energies well above the Coulomb barrier, and 148, 150Nd target nuclei were used to study the cascades of γ-rays in the residual nuclei 161, 162Er. A multi-counter setup was used in which the γ-rays were detected by a Ge(Li) counter coupled in coincidence with up to 9 NaI(Tl) counters. The γ-multiplicity has been studied for γ-rays cascading through states above and along the yrast line. Higher moments of the multiplicity distributions (shape parameters) were deduced from the data. These moments allow the construction of the spin distribution for the entry states. The difference between these spin distributions from reactions induced by 16O and 18O ions was studied. Also the fusion cross section was measured for the two systems as a function of bombarding energy and compared to the multiplicity results at two different excitation energies (Ex = 49.5 and 56.2 MeV). A subtraction technique has been applied in the data analysis with the intention to study the decay of a selected part of the high-spin region, and the results show besides the 4n channel an unexpected large contribution of the 5n channel from this region. The sidefeeding patterns of the multiplicity distributions are extracted and show a significant difference for the 16O and 18O induced reactions, especially at the lowest bombarding energies. The results are compared with statistical model calculations. 相似文献
20.
The technique and results of a precise measurement of the 14C beta spectrum in the energy range 10–160 keV by using a wall-less proportional counter are presented. The results of analysis and the inclusion of possible factors that distort the spectrum in the calculation of the detector response function are reported. Considerable deviations from the distribution expected for an allowed transition are found. 相似文献