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1.
K. Vetter 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):265-269
Gamma-ray tracking in a closed array of highly segmented HPGe detectors is a new concept for the detection of γ-radiation.
Each of the interacting γ-rays is identified and separated by measuring the energies and positions of individual interactions
and by applying tracking algorithms to reconstruct the scattering sequences, even if many γ-rays hit the array at the same
time. The three-dimensional position and the energy of interactions are determined by using two-dimensionally segmented Ge
detectors along with pulse-shape analysis of the signals. Such a detector will have new and much improved capabilities compared
to current γ-ray spectrometer. One implementation of this concept, called GRETA (Gamma-Ray Energy Tracking Array), is currently
being under development at LBNL.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: kvetter@lbl.gov 相似文献
2.
Various noise sources limit the sensitivity of current interferometric gravitational wave detectors, including seismic noise,
thermal noise of the optical components and suspension elements and photon shot noise. Plans are in place for a suite of hardware
upgrades which should increase the sensitivity of these detectors by reducing the various noise sources. With these designs
for 2nd generation detectors mature, techniques for further improvement of detector sensitivity by a factor of approximately
10 are under study. A particular challenge is the reduction of the thermal noise associated with the interferometer mirrors
and their suspensions. We review the current status of research on thermal noise in interferometric gravitational wave detectors.
Aspects of possible techniques for use in future ‘3rd generation detectors’ such as cryogenics and diffractive optics are
discussed. 相似文献
3.
Valentin N. Rudenko 《Czechoslovak Journal of Physics》2002,52(7):821-837
We discuss the problem of of detection the gravitational radiation which could be produced by relativistic objects in the
Universe. After a brief sketch of the detector world net the attention is concentrated on present programs of search for conceivable
signals expected in the frame of modern astrophysics. It is concluded that the probability of succeeding with the modern generation
of gravitational detectors, sensitive to the metric perturbation on the order of 10−21, is low. One of the ways to increase the probability is a search for “astro-gravity correlations” where a gravitational detector
noise background is analysed referring to the data of gamma-ray and neutrino detectors.
Author dedicates this article to Prof. Jiří Bičák’s 60th birthday. 相似文献
4.
V. I. Dashkevich V. A. Orlovich A. P. Shkadarevich 《Journal of Applied Spectroscopy》2010,77(3):349-356
It has been shown that the generation of the 1st Stokes component (λ = 1.538 μm) in an Nd:KGW laser with a passive V:YAG Q Q -switch is multimodal and its dynamics have a complex spatio-temporal character. The SRS-generation features the impact excitation
manifested as the formation of a high-intensity peak at the beginning of the pulse, the peak position relative to the subsequent
part of the pulse depending on the radius of curvature of the end cavity mirror. The SRS-conversion of the fundamental laser
radiation (λ = 1.351 μm) starts in the central region of the Nd:KGW-element and then spreads towards its boundaries. The total
integral SRS-pulse of duration 15–25 ns represents an envelope of shorter (1–2 ns) time-shifted pulses generated by separate
local areas of the active medium cross-section. The multimode character of generation results in gradual damage to the V:YAG
Q Q -switch at the attained SRS-radiation energy of 8–14 mJ. 相似文献
5.
For over 27 years, SCD has been manufacturing and developing a wide range of high performance infrared detectors, designed
to operate in either the mid-wave (MWIR) or the long-wave (LWIR) atmospheric windows. These detectors have been integrated
successfully into many different types of system including missile seekers, time delay integration scanning systems, hand-held
cameras, missile warning systems and many others. SCD’s technology for the MWIR wavelength range is based on its well established
2D arrays of InSb photodiodes. The arrays are flip-chip bonded to SCD’s analogue or digital signal processors, all of which
have been designed in-house. The 2D focal plane array (FPA) detectors have a format of 320×256 elements for a 30-μm pitch
and 480×384 or 640×512 elements for a 20-μm pitch. Typical operating temperatures are around 77–85 K. Five years ago SCD began
to develop a new generation of MWIR detectors based on the epitaxial growth of antimonide based compound semiconductors (ABCS).
This ABCS technology allows band-gap engineering of the detection material which enables higher operating temperatures and
multi-spectral detection. This year SCD presented its first prototype FPA from this program, an InAlSb based detector operating
at a temperature of 100 K. By the end of this year SCD will introduce the first prototype MWIR detector with a 640×512 element
format and a pitch of 15 μm. For the LWIR wavelength range SCD manufactures both linear Hg1−xCdxTe (MCT) detectors with a line of 250 elements and time delay and integration (TDI) detectors with formats of 288×4 and 480×6.
Recently, SCD has demonstrated its first prototype uncooled detector which is based on VOx technology and which has a format of 384×288 elements, a pitch of 25 μm, and a typical NETD of 50 mK at F/1. In this paper,
we describe the present technologies and products of SCD and the future evolution of our detectors for the MWIR and LWIR detection.
The paper presented there appears in Infrared Photoelectronics, edited by Antoni Rogalski, Eustace L. Dereniak, Fiodor F. Sizov, Proc. SPIE Vol. 5957, 59570S (2005). 相似文献
6.
Time Differential gamma–gamma Perturbed Angular Correlation spectroscopy has traditionally been done using scintillation detectors
along with constant–fraction discriminators, spectroscopy amplifiers, single channel analyzers, and time to amplitude detectors.
We describe a new generation spectrometer where these electronics are replaced by high speed digital transient recorders that
record the output from each scintillation detector. The energy and time-of-arrival of gamma rays in any detector can be determined
accurately. Many experimental difficulties related to electronics are eliminated; the number of detectors can be increased
with no increase in complexity of the apparatus; coincidences among any two detectors are measurable; and coincidences separated
by as little as a ns are detectable in principle within one detector. All energies are collected, and energy windows are imposed
by software filtering, permitting both high energy resolution and high data-gathering power. 相似文献
7.
Summary The present observational and instrumental status of hard-X-ray astronomy ((10÷200) keV) is discussed. The relevance of observations
in this energy range is stressed and a few examples of unsolved observational problems in galactic and in extragalactic astronomy
are discussed. In these examples we focus on the possibility to solve the problems with observations using detectors of the
current generation. In this framework, the performances of the most sensitive hard-X-ray detectors are discussed with particular
emphasis on the control of systematic errors. Quite simple but unavoidable considerations on limits of the present generation
of hard-X-ray detectors (supported by results of simple simulations) lead to the conclusion that a decisive breakthrough can
be achieved only using optics with a sufficiently good concentration power. In particular we discuss the feasibility of hard-X-ray
telescopes (with a concentration power ≫1), using either grazing incidence or Bragg diffraction. The use of concentrators
in this energy band can also make feasible polarimetric measures of a substantial sample of X-ray sources, up to now severely
limited by the very low detection efficiency of the devices used in polarimetry.
Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990. 相似文献
8.
Johann M. Heuser Walter F.J. Muller Peter Senger Christian Muntz Joachim Stroth 《Czechoslovak Journal of Physics》2005,55(12):1649-1653
The Compressed Baryonic Matter (CBM) experiment is a fixed-target heavy-ion experiment planned at GSI's future international
Facility for Antiproton and Ion Research (FAIR). CBM will study strongly interacting matter at high baryon densities where
the QCD phase diagram is poorly known. The experiment applies a detector concept new to heavy-ion physics: All charged particles
as well as secondary vertices from heavy-flavor decays are exclusively reconstructed in a high-performance silicon tracking
system. It will be installed in a magnetic dipole field between the target and further detection systems for particle identification
and calorimetry. High track densities and high collision rates require the application of most advanced silicon detectors.
The technological challenges include high position resolution in thinnest possible pixel and microstrip sensors, combined
with extreme radiation hardness, fast self-triggered readout and ultra low-mass mechanical supports. The article outlines
the physics and detector concept of CBM and discusses the performance requirements of the silicon tracker and the beginning
R&D.
for the CBM collaboration
Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”,
Budapest, Hungary, 4–9 August 2005. 相似文献
9.
K. M. Belotsky D. Fargion M. Yu. Khlopov R. V. Konoplich 《Physics of Atomic Nuclei》2008,71(1):147-161
Primordial heavy neutrinos of the fourth generation might explain different astrophysical puzzles. The simplest fourth-neutrino
scenario is consistent with known fourth-neutrino physics, cosmic ray antimatter, cosmic gamma fluxes, and positive signals
in underground detectors for a very narrow neutrino mass window (46–47 GeV). However, accounting for the constraint of underground
experiment CDMS prohibits solution of cosmic-ray puzzles in this scenario. We have analyzed extended heavy-neutrino models
related to the clumpiness of neutrino density, new interactions in heavy-neutrino annihilation, neutrino asymmetry, and neutrino
decay. We found that, in these models, the cosmic-ray imprint may fit the positive underground signals in DAMA/Nal experiment
in the entire mass range 46–70 GeV allowed from uncertainties of electroweak parameters, while satisfaction of the CDMS constraint
reduces the mass range to around 50 GeV, where all data can come to consent in the framework of the considered hypothesis.
The text was submitted by the authors in English. 相似文献
10.
J.?Piotrowski J.?Pawluczyk A.?Piotrowski W.?Gawron M.?Romanis K.?K?os 《Opto-Electronics Review》2010,18(3):318-327
The history, status, and recent progress in the middle and long wavelength Hg1−xCdxTe infrared detectors operating at near room temperatures are reviewed. Thermal generation of charge carriers in narrow gap
semiconductor is a major limitation or sensitivity. Cooling is a straightforward way to suppress thermal generation of charge
carriers and reduce related noise. However, at the same time, cooling requirements make infrared systems bulky, heavy, and
inconvenient in use. A number of concepts to improve performance of photodetectors operating at near room temperatures have
been proposed and implemented. Recent considerations of the fundamental detector mechanisms suggest that near perfect detection
can be achieved without the need for cryogenic cooling. This paper, to a large degree, is based on the research, development,
and commercialization of uncooled HgCdTe detectors in Poland. The devices have been based on 3D-variable band gap and doping
level structures that integrate optical, detection and electric functions in a monolithic chip. The device architecture is
optimized for the best compromise between requirements of high quantum efficiency, efficient and fast collection of photogenerated
charge carriers, minimized thermal generation, reduced parasitic impedances, wide linear range, wide acceptance angles and
other device features. Recent refinements in the devices design and technology have lead to sensitivities close to the background
radiation noise limit, extension of useful spectral range to > 16 μm wavelength and picosecond range response times. The devices
have found numerous applications in various optoelectronic systems. Among them there are fast scan FTIR spectrometers developed
under MEMFIS project. 相似文献
11.
12.
A. Rogalski 《Opto-Electronics Review》2006,14(1):84-98
Hitherto, two families of multielement infrared (IR) detectors are used for principal military and civilian infrared applications;
one is used for scanning systems (first generation) and the other is used for staring systems (second generation). Third generation
systems are being developed nowadays. In the common understanding, third generation IR systems provide enhanced capabilities
like larger number of pixels, higher frame rates, better thermal resolution as well as multicolour functionality and other
on-chip functions.
In the paper, issues associated with the development and exploitation of materials used in fabrication of third generation
infrared photon detectors are discussed. In this class of detectors two main competitors, HgCdTe photodiodes and quantum well
IR photoconductors (QWIPs) are considered. The performance figures of merit of state-of-the-art HgCdTe and QWIP focal plane
arrays (FPAs) are similar because the main limitations come from the readout circuits. However, the metallurgical issues of
the epitaxial layers such as uniformity and number of defected elements are the serious problems in the case of long wavelength
infrared (LWIR) and very LWIR (VLWIR) HgCdTe FPAs. It is predicted that superlattice based InAs/GaInSb system grown on GaSb
substrate seems to be an attractive to HgCdTe with good spatial uniformity and an ability to span cutoff wavelength from 3
to 25 μm. 相似文献
13.
A. Casaburi M. Ejrnaes F. Mattioli A. Gaggero R. Leoni N. Martucciello S. Pagano M. Ohkubo R. Cristiano 《Journal of nanoparticle research》2011,13(11):6121-6131
The recent progress in the nanofabrication of superconducting films opens the road toward detectors with highly improved performances.
This is the case for superconducting nano-striplines where the thickness and the width are pushed down to the extreme limits
to realize detectors with unprecedented sensitivity and ultra fast response time. In this way quantum detectors for single
photons at telecommunication wavelengths and for macromolecules such as proteins can be realized. As is often the case in
applied nanotechnology, it is a challenge to make devices with the necessary macroscopic dimensions that are needed to interface
present technologies, while maintaining the performance improvements. For nano-stripline detectors, both the fast temporal
response and the device sensitivity is generally degraded when the area is increased. Here, we present how such detectors
can be scaled up to macroscopic dimensions without losing the performance of the nano-structured active elements by using
an innovative configuration. In order to realize ultrathin superconducting film the nano-layer is growth with a careful setup
of the deposition technique which guarantees high quality and thickness uniformity at the nano-scale size. The active nano-strips
are defined with the state-of-the-art electron beam nanolithography to achieve a highly uniform linewidth. We present working
detectors based on nano-strips with thicknesses 9–40 nm and widths of 100–1000 nm which exhibit unprecedented speed and area
coverage (40 × 40 μm2 for single photon detectors and 1 × 1 mm2 for single molecule detectors) based on niobium nitride thus enabling practical use of this nanotechnology. 相似文献
14.
Shen Shuifa Fang Keming Gu Jiahui Liu Qingcheng Xu Furong 《The European Physical Journal A - Hadrons and Nuclei》2007,32(2):149-158
The decay of 95Ru has been investigated by means of γ-ray spectroscopy. The 95Ru nuclei were produced by the reaction 92Mo( α, n) 95Ru at a beam energy of 17MeV. High-purity Ge detectors have been used singly and in coincidence to study γ-rays in the decay of 95Ru to 95Tc. 132 γ-rays are reported, among them, energies and intensities for 127 transitions have been determined. A decay scheme of 95Ru with 31 levels is proposed which accommodates 127 of these transitions. Spins and parities for three new levels are proposed
from calculated log ft values, measured γ-ray branching ratios, and in-beam experiment results of the daughter nucleus 95Tc. Combining with the high-spin states observed by in-beam γ-ray spectroscopy of previous decay works, the structure of the excited states of 95Tc is discussed in the framework of the projected shell model. 相似文献
15.
V. V. Siksin 《Bulletin of the Lebedev Physics Institute》2020,47(1):33-35
It is urgent to use a “warm liquid” TMS in large massive calorimeters (with a volume of several hundred liters). This direction in modern nuclear physics is referred to as “non-accelerator” experiments with low-background detectors. Such experiments are associated with the solution of most important problems to understand the Universe structure and search for new particles. These are the well-known problems for searching “dark matter” in the form of new weakly interacting particles, i.e., wimps, observations of coherent scattering of reactor neutrinos. Using this experiment, the standard model of electroweak interactions can be tested. The fully developed fabrication technology of large amounts of “warm liquid” ТМS (in collaboration with the State Research Institute of Chemistry and Technology of Organoelement Compounds) makes it possible to perform such experiments. 相似文献
16.
H. Ejiri 《The European physical journal. Special topics》2008,162(1):171-180
Neutrino-less double beta decays (0νββ) are sensitive and realistic probes for studying the Majorana nature of neutrinos (ν), the ν-mass spectrum, the absolute ν-mass scale, the Majorana CP phases and other fundamental properties of neutrinos and weak interactions. Current 0νββ experiments, which use detectors with the mass sensitivity of the order of 300 meV, study the ν-mass in that mass region. Future experiments with higher sensitivities of the orders of 100meV and 30 meV, using different
nuclei and methods (calorimetric, spectroscopic), are indispensable for establishing 0νββ in the quasi degenerate and the inverted hierarchy mass regions. R&D for ultra-high sensitivity detectors are encouraged
for studying the normal hierarchy mass region. Theoretical and experimental studies for evaluating nuclear matrix elements
are important for extracting the sensible ν-mass from the 0νββ rate. Charge exchange reactions by means of nuclear, electromagnetic and ν probes provide valuable data which are used to evaluate the nuclear matrix elenments. International collaborations for 0νββ experiments and for the matrix elements are crucial for next generation 0νββ studies. 相似文献
17.
P Mukherjee 《Pramana》2001,57(1):5-9
Experimental studies of nuclear excitations have been an important subject from the earliest days when the institute was established.
The construction of 4 MeV proton cyclotron was mainly aimed to achieve this goal. Early experiments in nuclear spectroscopy
were done with radioactive nuclei with the help of beta and gamma ray spectrometers. Small NaI(Tl) detectors were used for
gamma-gamma coincidence, angular correlation and life time measurements. The excited states nuclear magnetic moments were
measured in perturbed gamma-gamma angular correlation experiments. A high transmission magnetic beta ray spectrometer was
used to measure internal conversion coefficients and beta-gamma coincidence studies. A large number of significant contributions
were made during 1950–59 using these facilities. Proton beam in the cyclotron was made available in the late 1950’s and together
with 14 MeV neutrons obtained from a C-W generator a large number of short-lived nuclei were investigated during 1960’s and
1970’s. The introduction of high resolution Ge gamma detectors and the improved electronics helped to extend the spectroscopic
work which include on-line (p
7
p′γ) and (p
7
nγ) reaction studies. Nuclear spectroscopic studies entered a new phase in the 1980’s with the availability of 40–80 MeV alpha
beam from the variable energy cyclotron at VECC, Calcutta. A number of experimental groups were formed in the institute to
study nuclear level schemes with (α
7
xnγ) reactions. Initially only two unsuppressed Ge detectors were used for coincidence studies. Later in 1989 five Ge detectors
with a large six segmented NaI(Tl) multiplicitysum detector system were successfully used to select various channels in (α
7
xnγ) reactions. From 1990 to date a variety of medium energy heavy ions were made available from the BARC-TIFR Pelletron and
the Nuclear Science Centre Pelletron. The state of the art gamma detector arrays in these centres enabled the Saha Institute
groups to undertake more sophisticated experiments. Front line nuclear spectroscopy works are now being done and new informations
are obtained for a large number of nuclei over a wide mass range. Currently Saha Institute is building a multi-element gamma
heavy ion neutron array detector (MEGHNAD), which will have six high efficiency clover Ge detector together with charged particle
ball and other accessories. The system is expected to be usable in 2002 and will be used in experiments using high energy
heavy ions from VECC. 相似文献
18.
《Il Nuovo Cimento C》1991,14(2):171-193
Summary The data recorded with the neutrino detectors at Mont Blanc, Kamioka, Baksan and with the gravitational-wave detectors in
Maryland and Rome have been analysed searching for correlations associated with SN 1987 A, without presuming or excluding
hypotheses for correlations due to neutrinos and gravitational waves. The statistical analysis has been based on a previous
analysis that showed a correlation among Maryland, Rome and Mont Blanc with a probability to be accidental less than 10−5. Independent correlations are found during a period of one or two hours, around the Mont Blanc 5ν burst (2h 52 min 36 s UT),
among the various sets of data: Mont Blanc-Baksan with a probability to be accidental of the order ofp∼4·10−3, Mont Blanc-Kamioka withp∼4·10−3, Maryland-Rome-Kamioka withp∼5·10−4, Maryland-Rome-Baksan withp∼5·10−2. It is remarkable that the events from all the neutrino detectors follow the signals from the g.w. detectors by a time of
the order of 1/2 or 1 s. At present we will not give a physical interpretation of the observed correlations which have strong
statistical significance.
Professor Edoardo Amaldi died on December 5, 1989. 相似文献
19.
Anita Topkar S. Praveenkumar Bharti Aggarwal S. K. Kataria M. D. Ghodgaonkar 《Pramana》2007,69(6):1085-1088
A specific research and development program has been carried out by BARC in India to develop the technology for large area
silicon strip detectors for application in nuclear and high energy physics experiments. These strip detectors will be used
as pre-shower detector in the CMS experiment at LHC, CERN for π
0/λ rejection. The fabrication technology to produce silicon strip detectors with very good uniformity over a large area of ∼40
cm2, low leakage currents of the order of 10 nA/cm2 per strip and high breakdown voltage of >500 V has been developed by BARC. The production of detectors is already under way
to deliver 1000 detector modules for the CMS and 90% production is completed. In this paper, research and development work
carried out to develop the detector fabrication technology is briefly described. The performance of the silicon strip detectors
produced in India is presented. The present status of the detector technology is discussed.
相似文献
20.
G. Pizzella 《Il Nuovo Cimento C》1992,15(6):931-941
Summary A review of the correlations between gravitational-wave detectors and particle detectors during SN1987A is given. The correlation
between the Maryland and Rome g.w. detectors with the Mont Blanc neutrino detector is illustrated. This correlation extends
during a period of one or two hours centred at 2∶45 UT of 23 February 1987, with the ?neutrino? signals delayed by (1.1±0.5)
s and with a probability of the order of 10−5 to be accidental. Using the data obtained with the Kamiokande and IMB detectors, with the same statistical choices and procedures
for the data analysis used previously, the above result is confirmed with a probability of the order of 10−3 or 10−4 that the additional correlation be accidental.
Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990. 相似文献