In this paper we investigate di-atomic molecules embedded in ice crystals under strain. In this environment coherent vibrations of many OH-bonds may be generated by one WIMP collision. The detection ...of such multiple-photon signals may provide a signature of a 100 GeV/c2 WIMP. To do a proper lab test of “WIMP-induced” multi-photon emission is very difficult. We suggest that Ice Cube make a search for multi-photon events, and investigate whether the rate of such events exhibits yearly modulation.
We believe that the Dark Matter (DM) search should be expanded into the domain of detectors sensitive to molecular excitations, and so that we should create detectors which are more sensitive to ...collisions with very light WIMPs. In this paper we investigate in detail diatomic molecules, such as fused silica material with large OH-molecule content, and water molecules. Presently, we do not have suitable low-cost IR detectors to observe single photons, however some OH-molecular excitations extend to visible and UV wavelengths and can be measured by bialkali photocathodes. There are many other chemical substances with diatomic molecules, or more complex oil molecules, which could be also investigated. This idea invites searches in experiments having large target volumes of such materials coupled to a large array of single-photon detectors with bialkali or infrared-sensitive photocathodes.
Detector examples discussed: MRPCs, MCP-PMTs, Diamond detectors, SiPMTs, Low and high gain Avalanche diodes (LGADs) and Micromegas. We specifically discuss issues such as single pixel vs. multi-pixel ...tests, small test vs. large physics system results and hidden problems people usually do not want to talk about.
PID techniques: Alternatives to RICH methods Va’vra, J.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2017, Letnik:
876, Številka:
C
Journal Article
Recenzirano
Odprti dostop
In this review article we discuss new updates on PID techniques, other than the Cherenkov method. In particular, we discuss recent efforts to develop high resolution timing, placing an emphasis on ...small scale test results.
DIRC: Internally reflecting imaging Cherenkov detectors Ratcliff, B.; Va’vra, J.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2020, Letnik:
970, Številka:
C
Journal Article
Recenzirano
Odprti dostop
In this article we review a distinctive type of Cherenkov ring imaging device generically called a DIRC detector. DIRC is an acronym for “Detection of Internally Reflected Cherenkov (Light)”. We ...briefly discuss how these devices were first motivated and conceived, describe their basic operating principles, their early prototypes, and fabrication R&D. We then describe the BaBar DIRC at SLAC, as the first full scale implementation of this detector type for a major physics experiment. Further R&D at SLAC that was motivated to enable operations at the very high rates of SuperB factories led to the Focusing DIRC concept and prototype that will next be described. We then review a wide range of further developments now underway using variants on the DIRC theme, including the TOP counter at Belle-II; a number of FDIRC designs for GLUEX, PANDA barrel and endcap; and the LHCb TORCH.
Design and performance of the focusing DIRC detector Dey, B.; Borsato, M.; Arnaud, N. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2015, Letnik:
775, Številka:
C
Journal Article
Recenzirano
Odprti dostop
We present the final results from a novel Cherenkov imaging detector called the Focusing DIRC (FDIRC). This detector was designed as a full-scale prototype of the particle identification system for ...the SuperB experiment 1, and comprises 1/12 of the SuperB barrel azimuthal coverage, with partial photodetector and electronics implementation. The prototype was tested in the SLAC Cosmic Ray Telescope which provided 3D tracking of cosmic muons with an angular resolution of ~1.5mrad, a position resolution of 4–5mm, a start time resolution of 70ps, and muon tracks above ~2GeV tagged using an iron range stack. The fused silica focusing photon camera was coupled to a full-size BaBar DIRC bar box and was read out, over part of the full coverage, by 12 Hamamatsu H8500 multi-anode photomultipliers (MaPMTs) providing 768 pixels. We used waveform digitizing electronics to read out the MaPMTs. We give a detailed description of our data analysis methods and point out limitations on the present performance. We present results that demonstrate some basic performance characteristics of this design, including (a) single photon Cherenkov angle resolutions with and without chromatic corrections, (b) signal-to-noise (S/N) ratio between the Cherenkov peak and background, which primarily consists of ambiguities of the possible photon paths from emission along the track to a given pixel, (c) dTOP=TOPmeasured – TOPexpected resolutions (with TOP being the photon Time-of-Propagation in fused silica), and (d) performance of the detector in the presence of high-rate backgrounds.
Physics and chemistry of aging – early developments Va’vra, J
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2003, Letnik:
515, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The aging phenomena are very complex physical and chemical processes. The author attempts to qualitatively discuss various physical processes contributing to aging. A satisfactory quantitative ...explanation is not presently available. In this sense, little progress has been made since the 1986 LBL Aging Workshop. However, what was accomplished during the past decade is a heightened awareness from the research and management sides to pay more attention to this problem, and as a result a number of aging tests have increased in quantity and quality. These efforts will undoubtedly yield some new results in the future. Examples in this paper are mainly from a “pre-LHC and pre-HERA-B era of aging,” where the total charge doses are limited to much less than 1
C/cm.
At present there is an effort to reconcile the results of the DAMA experiment with those from other Dark Matter experiments such as CoGeNT, CRESST, CDMS, and all LXe experiments. The author suggests ...a new model describing the Dark Matter signal as the result of collisions of very light (1-to-few GeV/c2) WIMPs with hydrogen, and compares it with currently accepted models of collisions with heavy nuclei (Na, Ge or Xe). The hydrogen target would come from H-contamination of NaI(Tl), Ge and CaWO4 crystals. Initial tuning indicates that one can explain the modulation amplitude of DAMA and CoGeNT with this model, assuming a WIMP-proton cross section between 10−33 and 10−32 cm2. This paper should be considered to be a new idea which will need substantial new experimental input from all involved experiments.
Optical properties of RICH detectors Va’vra, J.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2014, Letnik:
766
Journal Article
Recenzirano
Odprti dostop
In this review article super(1) we discuss the optical components in RICH detectors. In particular we mention transmission and refraction index in gases, liquids, solids, optical glues, matching gels ...and aerogel. We mention a few examples of mirror reflectivity in UV and visible region. We also discuss radiation damage, radio-luminescence, yellowing from light exposure, optical distortions in materials, and scintillation.
PDF
