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1.
An experiment to measure energetic neutrons and gamma rays in space was launched in the first Indian scientific satellite,Aryobhata, on April 19, 1975. From this experiment, the first measurements in space of the Earth’s albedo fiux of neutrons of energy
between 20 and 500 MeV have been made; the values obtained for two mean geomagnetic vertical cut-off rigidities of 5.6 and
17.0 GV are (6.3±0.4)×10−2 and (1.4±0.3)×10−2 neutrons cm−2 sec−1 respectively. These measurements confirm that protons arising from cosmic ray albedo neutron decay, can adequately account
for the protons in the inner radiation belt. Observations on gamma rays of energy between 0.2 and 24 MeV have enabled the
determination of the total background gamma ray flux in space as a function of latitude. This in turn has permitted useful
information on the diffuse cosmic gamma rays. We have also observed four events that showed sudden increases in the gamma
ray counting rates between 0.2 and 4.0 MeV. Observational details of these events are given. 相似文献
2.
S. V. Rozov V. B. Brudanin A. V. Lubashevskiy S. S. Semikh D. V. Filosofov E. A. Yakushev on behalf of EDELWEISS Collaboration 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(4):464-466
The results from measurements of thermal neutron flux in the EDELWEISS II experiment aimed at the direct detection of WIMPs
(weakly interacting massive particles) by means of cryogenic germanium bolometers are described. Detailed knowledge of the
neutron background is of crucial importance for the experiment, since neutrons with the MeV energy range of scattering seem
to be hard to distinguish from the expected WIMP signal within the bolometers. Monitoring of the thermal neutron flux is performed
using a mobile detection system with a low background proportional 3He counter. The neutron flux measurements were performed both outside and inside the device’s shielding, in the direct proximity
of a cryostat with built-in germanium detectors. The sensitivity of the created thermal neutron detection system is on the
level of 10−9 neutron (cm2 s)−1. 相似文献
3.
A. S. Mikhailenko A. N. Dmitrieva A. A. Petrukhin D. A. Timashkov V. V. Shutenko I. I. Yashin 《Bulletin of the Lebedev Physics Institute》2010,37(6):167-168
The results of the study of the correlation between dynamic atmospheric phenomena and cosmic ray muon flux variations are
presented. The results of the long-term experiment on continuous measurements of spatioangular variations of the muon flux
using the URAGAN muon hodoscope are considered. It was shown that the correlation between weather phenomena and changes in
the angular distribution of the muon flux on the Earth’s surface are observed in 80% of cases, both in the general counting
rate and in the zenith-azimuthal distribution of the muon flux intensity. 相似文献
4.
D. M. Gromushkin V. V. Alekseenko A. A. Petrukhin Yu. V. Stenkin I. I. Yashin 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(3):407-409
The thermal neutron flux near the Earth’s surface has been measured using large unshielded neutron scintillator detectors of a new type, based on ZnS(Ag) and lithium fluoride, enriched with 6Li to 90%. The existence of a gradient of the thermal neutron concentration near the Earth’s surface is shown. 相似文献
5.
I. S. Altarev Yu. V. Borisov A. B. Brandin V. F. Ezhov S. N. Ivanov G. K. Kunstman V. M. Lobashev V. A. Nazarenko V. L. Ryabov A. P. Serebrov R. R. Taldaev 《Physics letters. A》1980,80(5-6):413-416
A liquid hydrogen source of ultra-cold neutrons (UCN) developed for an experimental search for the electric dipole moment of the neutron is described. The results of an investigation of the yield of UCN from gaseous, liquid, and solid hydrogen as a function of temperature are presented. The UCN counting rate obtained at the output of the 6 × 7 cm2 neutron guide tube is 5 × 104 n/s. This counting rate corresponds to a flux of neutrons whose velocity along the axis of the neutron guide tube is below 7 m/s. Preliminary measurements of the UCN yield from liquid and solid deuterium have been carried out. 相似文献
6.
Yu. N. Pokotilovskii 《JETP Letters》1999,69(2):91-96
Small cooling and heating of ultracold neutrons during long storage in traps have been observed in recent experiments. It
is shown that quasielastic neutron scattering due to the diffusive motion of hydrogen at the surface of adsorbed hydrogenous
contaminants on the surface may be a possible cause of the spreading of the energy of ultracold neutrons during long storage
in traps.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 2, 81–86 (25 January 1999)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
7.
V. P. Antonova S. V. Kryukov A. P. Chubenko Yu. V. Shlyugaev A. L. Shepetov 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(6):843-846
Variations in cosmic rays are investigated on the basis of the Tien Shan neutron monitor data. The Earth’s electrical field
during snowfall, rain, and thunderstorm activity is considered as a modulating factor. It is established that the effect of
the electrical field on the monitor data becomes apparent at values exceeding 15–20 kV m−1 in the atmosphere of a thunderstorm. The response is as high as 1.5% for recorded particles with energies lower than 10 GeV. 相似文献
8.
F. F. Karpeshin 《Physics of Atomic Nuclei》2011,74(7):951-957
It is shown that the Strutinsky-Denisov induced polarization mechanism leads to the appearance of the prompt electric dipole
radiation from fission fragments of 235Uby thermal neutrons in the domain of around 5 MeV. The probability of the radiation is at the level of 0.001 per fission,
which is in agreement with experiment. The angular distribution exhibits left-right asymmetry with respect to the direction
of the neutron polarization axis. That means that the emission of gamma quanta at the given angle depends on the neutron polarization.
The asymmetry is at the level of 10−3. The study of this effect will give a direct information about the scission configuration, nuclear viscosity, and dissipation
properties of the collective energy of the surface vibration in fragments with large amplitude. This will give a complete
picture of the process of snapping back the nuclear surface. 相似文献
9.
Summary We report on neutron emission in palladium and titanium electrolitically charged with deuterium. The detection of neutrons
is observed after thermal treatment of the electrode. In the hypothesis that neutrons came from cold fusion processes, we
estimate a fusion rate as high as 1.3·10−21 fusions/deuteron pair/second. 相似文献
10.
The discovery of neutron rich isotopes of the lightest elements on the neutron drip line exhibiting a halo structure has opened
up new vistas in research activities. The novel structural features associated with the halo phenomena have been the subject
for extensive theoretical and experimental investigations in recent times. In this talk, I propose to present a broad overview
of the recent developments in this field, bringing out the striking features which show that a large number oflight nuclei
near the neutron drip line are characterized by a clear separation between a ‘normal’ core nucleus and a loosely bound low
density veil of neutrons. Specifically, the two neutron halos offer a natural premises, from a theoretical standpoint, to
employ three body techniques for studying their detailed structural properties. A considerable part of the talk will be devoted
to report and highlight the results on a number of light halo nuclei such as 11Li, 11Be, 19B and 22C on which we have been carrying out investigations employing a simple but realistic three body model. These three body systems
which have been termed as ‘Borromean’ (i.e while three body systems are bound, the corresponding binary subsystems on the
other hand are unbound) are characterized by large spacial extension and very low separation energy of the neutron. They are,
therefore, ideally suited for exploring the possibility of the existence of Efimov states in two neutron halo nuclei. We have
recently carried out the three body analyses to predict the possibility of the occurrence of such states on which experimental
work at various laboratories is underway. 相似文献
11.
The principles of construction and the results of testing of a system for measuring P-odd asymmetries in nuclear reactions with polarized cold neutrons by the integrated method of recording events at the neutron
polarization switching frequency above the fundamental frequencies of the reactor power fluctuation spectrum are presented.
It is shown experimentally that if the signal under investigation is characterized by the spectral density of power decreasing
with increasing frequency, switching of the equipment at a higher frequency decreases the measuring error. The dependence
of the error of measurements of P-odd asymmetry in the emission of γ quanta in the 10B(n, α)7Li* ⟹ γ ⟹ 7Li(g.s.) reaction on the neutron polarization switching frequency is derived. The system described here is implemented experimentally
for the first time. 相似文献
12.
C. Kikuchi 《辐射效应与固体损伤》2013,168(3-4):249-253
Photoluminescence and electrical resistivity changes in CdS and CdTe produced by thermal neutrons are discussed. The damage is produced principally by the neutron capture reaction 113Cd (n,y) 114Cd. Since the reaction product 114Cd is stable, complications arising from impurity introduction is minimal. The cumulative recoil nuclear recoil energy is about 143 eV, but is not the recoil energy at the time atomic displacement occurs. Thermal and fast neutrons enhance the CdS luminescence band at 7200A in the ratio of 28:1, but the resistivity changes are in the ratio of 40:1 Cd interstitial is suggested as the luminescence center. Hall measurements on n-type CdTe suggest that only Cd defects are produced for low thermal neutron doses. The acceptor introduction rate is about 1.0 to 0.6, compared to 0.098 for CdS. These are in good agreement with the values reported by R. O. Chester. The fast neutron effects in high resistivity CdS reported by Johnson indicate the need for further measurement. 相似文献
13.
S. A. Starodubtsev V. I. Kozlov A. A. Toropov V. A. Mullayarov V. G. Grigor’ev A. V. Moiseev 《JETP Letters》2012,96(3):188-191
The connection of short-term neutron bursts near sea level with the electric and geomagnetic atmospheric fields during thunderstorms in 2009–2011 has been experimentally studied. The data from the cosmic-ray spectrograph named after Kuzmin, an electrostatic fluxmeter, and a three-component fluxgate magnetometer in Yakutsk have been analyzed. It has been shown that short-term (no longer than 4 min) neutron bursts are due to negative lightning discharges. The bursts are detected at the ground level 1–3 km below thunderstorm clouds. In this case, the neutron flux is about 4 × 10−3 cm−2 s−1. The minimum energy of the neutrons that are efficiently detected by the monitor is about 10 MeV. It has been found that short-term neutron bursts are detected when the electric field strength reaches a threshold value of −16 kV/m. 相似文献
14.
The results of experimental measurements of thermal neutrons in 1986–1997 in Pamir, which is one of the most seismoactive regions of the world, are studied. In this period, visible peaks in the thermal neutron flux near the Earth’s surface were found, especially in the periods near the upper and lower transits of the moon during a new moon or full moon, when the tidal gravitational wave reaches its maximum value. Additionally, about 500 earthquakes with m > 4 occurred in the same period of the operation of neutron counters. The time of seismic-wave travel across the given territory was known at a precision of less than 1 min (in some cases). Nevertheless, increases in neutron flux have never been observed during the travel of a seismic wave. Why is this? It appears that the mechanical effect on the Earth’s crust has the same impact with no respect to the cause of this effect; however, this was observed during experiments. This paper studies the reasons for this lack and the probable conditions that are favorable for an increase in terrestrial thermal neutron flux when a seismic wave travels across a territory. 相似文献
15.
To address the problem of the shortage of neutron detectors used in radiation portal monitors(RPMs),caused by the ~3He supply crisis, research on a cadmium-based capture-gated fast neutron detector is presented in this paper. The detector is composed of many 1 cm × 1 cm × 20 cm plastic scintillator cuboids covered by 0.1 mm thick film of cadmium. The detector uses cadmium to absorb thermal neutrons and produce capture γ-rays to indicate the detection of neutrons, and uses plastic scintillator to moderate neutrons and register γ-rays. This design removes the volume competing relationship in traditional ~3He counter-based fast neutron detectors, which hinders enhancement of the neutron detection efficiency. Detection efficiency of 21.66% ± 1.22% has been achieved with a 40.4 cm × 40.4cm × 20 cm overall detector volume. This detector can measure both neutrons and γ-rays simultaneously. A small detector(20.2 cm × 20.2 cm × 20 cm) demonstrated a 3.3 % false alarm rate for a ~(252)Cf source with a neutron yield of 1841 n/s from 50 cm away within 15 s measurement time. It also demonstrated a very low(0.06%) false alarm rate for a 3.21 × 10~5 Bq ~(137)Cs source. This detector offers a potential single-detector replacement for both neutron and the γ-ray detectors in RPM systems. 相似文献
16.
A way of detecting an electromagnetic earthquake precursor is suggested. Detection is carried out with a device composed of
a vertical electrical antenna and a toroidal magnetic antenna located on the Earth’s surface. It is shown that the detector
is the most sensitive to the radiation of an electrical dipole inside the lithosphere that is oriented normally to the Earth’s
surface. Such a pattern allows one to detect electromagnetic precursors by the method suggested. 相似文献
17.
G. A. Bazilevskaya M. B. Krainev V. S. Makhmutov A. K. Svirzhevskaya N. S. Svirzhevsky Yu. L. Stozhkov 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(6):782-785
The minimum between the 23rd and 24th cycles of solar activity was unusually deep and extended. The modulation of cosmic rays
was minimal for the more than 70-year-long period of direct measurements. The data from stratospheric measurements by the
Lebedev Physical Institute suggest that the flux of cosmic rays with more than 100 MeV/nucleon of energy exceeded the highest
ever observed level (May 1965) by almost 12%. However, the ground-based neutron monitors sensitive to relatively high energies
indicated that the flux of cosmic rays increased by less than 3%. This work compares the variations in the cosmic rays over
periods of five minima of solar activity (the 20th to the 24th cycle). It is shown that in late 2008, an extra flux of particles
with energies less than several GeV/nucleon was detected in the Earth’s orbit. A similar (though far smaller in scale) phenomenon
was also observed in 1987 at the same orientation of the Sun’s magnetic field A < 0, but was not observed in epochs where A > 0. 相似文献
18.
G. I. Grigor’ev 《Radiophysics and Quantum Electronics》2006,49(3):174-177
We estimate the influence of internal gravity waves on the radio-wave absorption in the Earth’s atmosphere. It is shown that
the internal gravity waves can lead to significant spatio-temporal variations in the absorption. We conclude that riometric
measurements can be used for the diagnostics of internal gravity waves in the Earth’s atmosphere.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 3, pp. 194–198, March 2006. 相似文献
19.
The results of an experimental work aimed at improving the performance of the CR-39 nuclear track detector for neutron dosimetry
applications are reported. A set of CR-39 plastic detectors was exposed to 252Cf neutron source, which has the emission rate of 0.68 × 108 s−1, and neutron dose equivalent rate 1 m apart from the source is equal to 3.8 mrem/h. The detection of fast neutrons performed
with CR-39 detector foils, subsequent chemical etching and evaluation of the etched tracks by an automatic track counting
system was studied. It is found that the track density increases with the increase of neutron dose and etching time. The track
density in the detector is directly proportional to the neutron fluence producing the recoil tracks, provided the track density
is in the countable range. This fact plays an important role in determining the equivalent dose in the field of neutron dosimetry.
These results are compared with previous work. It is found that our results are in good agreement with their investigations.
相似文献
20.
A. E. Levitin L. I. Gromova L. A. Dremukhina 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(6):812-813
Cosmic ray intensity measurements obtained with the neutron monitors at Thule (geomagnetic latitude, 84.8°) and McMurdo (geomagnetic
latitude, −79.9°) in 2007–2009 were used to test the effect of the magnetic field generated by magnetospheric currents flowing
along geomagnetic field lines in the high latitude region on cosmic ray intensity. The existence of such a relation in a region
where the geomagnetic field lines are virtually radial should revise our concept of the unimpeded access that cosmic ray particles
have to the Earth’s atmosphere. 相似文献