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  • 1
    Electronic Resource
    Electronic Resource
    The CRESST dark matter search (2000)
    Springer
    Physics of atomic nuclei 63 (2000), S. 1242-1248 
    Details
    ISSN: 1063-7788
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We discuss the short-and long-term perspectives of the CRESST (Cryogenic Rare Event Search using Superconducting Thermometers) project and present the current status of the experiment and new results concerning detector development. In the search for elementary particle dark matter, CRESST is presently the most advanced deep underground, low-background, cryogenic facility. The basic technique involved is to search for WIMPs (Weakly Interacting Massive Particles) by the measurement of nonthermal phonons, as created by WIMP-induced nuclear recoils. Combined with our newly developed method for the simultaneous measurement of scintillation light, strong background discrimination is possible, resulting in a substantial increase in WIMP detection sensitivity. This will allow a test of the reported positive evidence for a WIMP signal by the DAMA Collaboration in the near future. In the long term, the present CRESST setup permits the installation of a detector mass up to 100 kg. In contrast to other projects, CRESST technology allows the employment of a large variety of detection materials. This offers a powerful tool in establishing a WIMP signal and in investigating WIMP properties in the event of a positive signal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.855777
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  • 2
    Electronic Resource
    Electronic Resource
    Feasibility of a detector for nuclear radiation based on superconducting grains (1987)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 1471-1476 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We studied the sensitivity of a radiation detector based on metastable superconducting grains. Radiation is detected by the phase transition from the superconducting to the normal-conducting state of a grain induced by energy absorption. Metastable states of tin and cadmium grains were tested. The phase boundary of a large sample of grains was found to be broadened due to variations of the phase diagrams of single grains. Therefore, the use of superconductors with a low critical temperature Tc and an operation temperature close to Tc seems advisable to increase the sensitivity of the detector. For Cd grains a sensitivity normalized to the grain volume of 12 eV/μm3 was achieved for the detection of γ rays. These grains showed an instability in the superconducting to normal-conducting phase transition for temperatures below 350 mK.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139383
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  • 3
    Electronic Resource
    Electronic Resource
    Nonequilibrium phonon detectors (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 1791-1804 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Many experiments in nuclear and particle physics would benefit from a device capable of detecting nonionizing events with a low energy threshold. We report on experimental tests of a low-temperature detector based on the registration of nonequilibrium phonons. The device is composed of a silicon single crystal with superconducting tunnel junctions (Al/Al2O3/Al) evaporated onto its surface. In first experiments a 20×10×3 mm3 crystal at an operating temperature of T = 0.37 K was tested with 5.5-MeV α particles. Pulse-height analysis and the timing of pulses in different junctions is shown to yield position and energy resolution. An energy threshold of 250 keV was estimated for absorption anywhere in the crystal. A position resolution of 0.6 mm was determined over a sensitive length of 10 mm. Though phonon focusing effects were registered in the vicinity of the [001] direction, scattered and reflected phonons dominate the signals in the general case. The experimental results are discussed in terms of ballistic and quasidiffuse phonon propagation. To improve the energy threshold, the operating temperature was lowered to 60 mK in order to increase junction sensitivity and a weak thermal coupling of the absorber to the heat bath was introduced to force phonons to leave the crystal via the detecting junctions. Si crystals of up to 20×20×10 mm3 size were used in these second experiments. With a 4 cm3 crystal a threshold of 270 keV was obtained. The performance in these experiments at 60 mK, however, was limited by exceptionally high values of the normal conducting junction resistances. With a reasonable value of this parameter it should be possible to realize an energy threshold of 1 keV with absorbers of a volume of several cm3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347233
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  • 4
    Electronic Resource
    Electronic Resource
    Energy resolution of 12 eV at 5.9 keV from Al-superconducting tunnel junction detectors (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 1425-1429 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An energy resolution of ΔE=12 eV [full width at half maximum (FWHM)] has been measured for the 55Mn Kα1 line (E=5.9 keV) using a superconducting lead absorber (90×90×1.3 μm3) readout by a single aluminum superconducting tunnel junction (100×100 μm2). The total detector area has been illuminated, while a slit mask of 150 μm width was used to partially shadow the detector leads and substrate area from impinging x rays. The total electronic noise contribution was measured as ΔEelec=4 eV (FWHM). The superconducting tunnel junction is located on a Si3N4 membrane of thickness 0.3 μm, the lead absorber is separated from the superconducting tunnel junction's top layer by a thin layer of natural aluminum oxide. No deviations from linear energy response were observed in the energy range between E=1.74 keV and E=6.49 keV. The same resolution was obtained for a single aluminum superconducting tunnel junction, where the influence of substrate events was suppressed by a metallic buffer layer between tunnel junction and substrate. The escape of recombination phonons into the substrate causes small nonlinearities in the tunnel junction's energy response. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1331332
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  • 5
    Electronic Resource
    Electronic Resource
    Search for the electron-positron decay of axions and axionlike particles at a nuclear power reactor at Bugey (1995)
    Springer
    The European physical journal 68 (1995), S. 221-227 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A search for the decay of isoscalar penetrating particles into ane + e-pair has been performed at the nuclear power reactor Bugey 5, situated close to Lyon (France). The detector set-up, consisting of an arrangement of large-area multiwire proportional chambers, and the data analysis are described. No excess of decay events over background has been observed. For standard axions, therefrom, stringent upper limits for the branching ratio 〈Γ a /Γ M γ , averaged over the entire reactor gamma spectrum of magnetic multipolarity, have been obtained. Analysis in terms of the decay χ→e ++e − of a more general axionlike boson χ yields new constraints for the decay constantf χ which enhance existing laboratory limits considerably.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01566670
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  • 6
    Electronic Resource
    Electronic Resource
    Lamb-shift measurement in hydrogenlike Sulfur (1984)
    Springer
    The European physical journal 318 (1984), S. 7-11 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The 2S 1/2-2P 1/2 Lamb-shift in hydrogenlike Sulfur was measured with a field quench technique. A high velocity beam of S15+-ions (v/c=0.086) prepared in the metastable 2S 1/2 state crosses a homogeneous magnetic field of about 1.8 Tesla. The strong electric field of 4·107 V/m in the rest frame of the ions mixes the longlived 2S 1/2-state (τ=7.18 nsec) with the short lived 2P 1/2-state (τ=2.4·10−5 ns). From the measured lifetime of the thus quenched 2S 1/2-state a Lamb-shift value of 25.14±0.24 THz is derived and compared with theoretical predictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02117208
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  • 7
    Electronic Resource
    Electronic Resource
    Neutron activation analysis of ultrapure water in a 500 ml silicon single crystal irradiation flask (1998)
    Springer
    Journal of radioanalytical and nuclear chemistry 234 (1998), S. 37-41 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Trace element analysis of ultrapure liquids requires the avoidance of contamination not only during preparation but also during irradiation of the sample. Double subboiling distilled water activated within flasks made out of synthetic quartz shows a significant correlation between irradiation time, quality of the flasks and the determined trace element concentration. The resulting falsification of the analysis and limitation of sensitivity seems to be caused by diffusion-like processes during irradiation. Even though single crystal FZ-silicon is rather brittle, it has been possible to fabricate a 500 ml irradiation flask out of this extremely pure material. The flask as well as its application in the analysis of double subboiling distilled water are discussed in the article.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02389744
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  • 8
    Electronic Resource
    Electronic Resource
    Ultra-sensitive determination of K, Th, U and other trace impurities in liquid organic scintillators by NAA (1998)
    Springer
    Journal of radioanalytical and nuclear chemistry 234 (1998), S. 43-49 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We present a NAA method to determine ultratraces of K, Th, U and other trace impurities in liquid organic scintillators, which are known as ultrapure detector materials for neutrino or dark matter experiments. A combined optimization of relevant factors for sensitive NAA has been realized, leading to a sensitivity for U down to 10−16g/g. Samples of 250 ml have been irradiated up to 120 h at a thermal neutron flux of 5–8·1012·n·cm−2·s−1. Acidic extraction, wet ashing and TBP-extraction are used for radiochemical separations. Finally, coincidence techniques are applied for increased sensitivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02389745
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