J. Jochum

Limits on WIMP dark matter using sapphire cryogenic detectors

Abstract Data taken by CRESST with a cryogenic detector system based on 262 g sapphire crystals has been used to place limits on WIMP dark matter in the Galactic Halo. The experiment was especially sensitive for low-mass WIMPs with spin-dependent cross sections and improves on existing limits in this region.

A large-scale low-background liquid scintillation detector: the counting test facility at Gran Sasso

A 4.8 m3 unsegmented liquid scintillation detector at the underground Laboratori Nazionali del Gran Sasso has shown the feasibility of multi-ton low-background detectors operating to energies as low as 250 keV. Detector construction and the handling of large volumes of liquid scintillator to minimize the background are described. The scintillator, 1.5 g PPO/L-pseudocumene, is held in a flexible nylon vessel shielded by 1000 t of purified water. The active detector volume is viewed by 100 photomultipliers, which measure time and charge for each event, from which energy, position and pulse shape are deduced. On-line purification of the scintillator by water extraction, vacuum distillation and nitrogen stripping removed radioactive impurities. Upper limits were established of < 10−7 Bq/kg-scintillator for events with energies 250 keV < E < 800 keV, and < 10−9 Bq/kg-scintillator due to the decay products of uranium and thorium. The isotopic abundance of 14C12C in the scintillator was shown to be approximately 10−18 by extending the energy window of the detector to 25–250 keV. The 14C abundance and uranium and thorium levels in the CTF are compatible with the Borexino Solar Neutrino Experiment.

Quasiparticle trapping in a superconductive detector system exhibiting high energy and position resolution

Abstract A new superconductive detector system employing quasiparticle trapping from a separate absorber into two superconducting tunnel junctions is investigated. The energy resolution for the 55Mn-Kα-energy (5.89 keV) is 60 eV (FWHM) and the position resolution was determined to be better than 5 μ over a sensitive length of 450 μm. A quasiparticle rejection efficiency of better than 99.6% was measured for a thick superconducting lead barrier between two superconducting tin absorbers.

Measurement of the 14C abundance in a low-background liquid scintillator

Abstract The 14 C/ 12 C ratio in 4.8 m 3 of high-purity liquid scintillator was measured at (1.94±0.09)×10 −18 , the lowest 14 C abundance ever measured. At this level the spectroscopy of low-energy solar neutrinos, in particular a measurement of the 7 Be neutrino flux, will not be obstructed by the 14 C β decay intrinsic to a liquid scintillator detector. A comprehensive study of the deviation of the shape of the 14 C β spectrum from the allowed statistical shape reveals consistent results with recent observations and calculations. Possible origins of the 14 C in the liquid scintillator are discussed.

Detection of the naturalαdecay of tungsten

The natural

Energy resolution of 12 eV at 5.9 keV from Al-superconducting tunnel junction detectors

ensuremath{alpha}

Development of superconducting tunnel junction detectors for high-resolution X-ray spectroscopy

-decay of

Status of the CRESST Dark Matter Search

^{180}mathrm{W}

High-resolution x-ray spectrometry using iridium–gold phase transition thermometers

has been unambiguously detected for the first time. The

X-ray detectors with Ta/Al/AlxOy/Al hetero tunnel junctions

ensuremath{alpha}