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The Cryogenic Dark Matter Search (CDMS II) experiment aims to detect dark matter particles that elastically scatter from nuclei in semiconductor detectors. The resulting nuclear-recoil energy depositions are detected by ionization and phonon sensors. Neutrons produce a similar spectrum of low-energy nuclear recoils in such detectors, while most other backgrounds produce electron recoils. The absolute energy scale for nuclear recoils is necessary to interpret results correctly. The energy scale can be determined in CDMS II silicon detectors using neutrons incident from a broad-spectrum $^{252}$Cf source, taking advantage of a prominent resonance in the neutron elastic scattering cross section of silicon at a recoil (neutron) energy near 20 (182) keV. Results indicate that the phonon collection efficiency for nuclear recoils is $4.8^{+0.7}_{-0.9}$% lower than for electron recoils of the same energy. Comparisons of the ionization signals for nuclear recoils to those measured previously by other groups at higher electric fields indicate that the ionization collection efficiency for CDMS II silicon detectors operated at $\sim$4 V/cm is consistent with 100% for nuclear recoils below 20 keV and gradually decreases for larger energies to $\sim$75% at 100 keV. The impact of these measurements on previously published CDMS II silicon results is small., Comment: 22 pages, 17 figures, 1 table, 1 appendix

The use of Silicon Photo-Multipliers (SiPMs) as photon detectors in Positron Emission Tomography (PET) modules offers significant advantages over conventional light sensors, including application in a magnetic field, better resolution and easier operation. Different types of SiPMs have been tested: Photonique, 2.1×2.1 mm 2 , Hamamatsu 3×3 mm 2 and STMicroelectronics 3.5×3.5 mm 2 . Dark noise, surface sensitivity, photon detection efficiency and linearity at low light intensities have been measured. A LYSO crystal was coupled to a SiPM to test the performance as a photon detector for PET. We will present the results of the measurements for different samples and types.

Silicon photomultipliers, whose main advantage over conventional photomultiplier tubes is the operation in high magnetic fields, have been considered as position sensitive, single photon detectors in a proximity focusing RICH with aerogel radiator. A module, consisting of 64 (8×8) Hamamatsu MPPC S10362-11-100P silicon photomultipliers, has been constructed and tested with Cherenkov photons emitted in an aerogel radiator by 120 GeV/c pions from the CERN T4-H6 beam. In order to increase the efficiency, i.e. the effective surface on which light is detected, the potential of using light guides has been investigated.

A module, consisting of 64 ( = 8 × 8 ) Hamamatsu MPPC S10362-11-100P silicon photomultipliers, has been constructed and tested as a position sensitive detector of Cherenkov photons. In order to increase the efficiency, i.e. the effective surface over which Cherenkov light is collected, we have manufactured and tested suitable light guides. In addition to the increase in efficiency, it is shown that such light guides considerably improve the signal-to-noise ratio. The results of our measurements indicate that the performance of such a Cherenkov counter with aerogel radiator could meet the requirements of particle identification at the foreseen upgraded Belle detector.

Silicon Photomultipliers (SiPMs) are attractive photon detectors for Ring Imaging Cherenkov (RICH) counters inside large magnetic spectrometers due to their insensitivity to magnetic fields. We have investigated the possibilities offered by these new photon detectors in a cosmic ray test set-up. Cherenkov photons emitted by cosmic ray particles in an aerogel radiator have been detected with silicon photomultipliers for the first time. Estimates and tests show how light concentrators may improve the detection efficiency, thus showing promise for a SiPM based RICH detector. The optimum shape for these light guides is investigated.

We have constructed and tested a module, consisting of 64 (= 8×8) Hamamatsu MPPC S10362-11-100P silicon photomultipliers, for position sensitive detection of Cherenkov photons. Suitable light concentrators were produced to increase the efficiency and to improve the signal to noise ratio. The results of our measurements indicate that the performance of such a Cherenkov counter with aerogel radiator could meet the requirements of particle identification at the foreseen upgraded Belle detector.

The use of Silicon Photomultipliers (SiPMs) as photon detectors in Positron Emission Tomography (PET) modules offers significant advantages over conventional light sensors, including application in a magnetic field, better resolution and easier operation. Two PET modules have been constructed by coupling 4 × 4 arrays of LYSO sctintillation crystals of area 4.2 × 4.2 mm2 and length 20 mm to SiPMs. Two types of SiPM have been tested: the Hamamatsu S10931-100P and Photonique PCB-PET07 of active surface areas 3 × 3 mm2 and 2.1 × 2.1 mm2 respectively. The energy resolutions, signal pulse properties and energy response of the arrays are presented in view of arrangement into a larger module. Additionally, the surface sensitivity and time resolutions of smaller 1 × 1 mm2 SiPMs from the same manufacturers have been analysed.

Multi-channel MCP-PMTs are considered as position sensitive detectors of single Cherenkov photons for the upgrade of particle identification systems at B-factories, where magnetic field tolerant sensors are required. They also exhibit excellent timing properties. In the case of proximity focusing RICH detector this allows to measure the time-of-flight employing the Cherenkov light produced in the sensor window. To reduce the number of electronic channels with high precision timing capabilities, the output of the second MCP stage (MCP signal) can be used to provide the timing information for the whole sensor. In this work we report on the timing properties of MCP signal.

A novel photon detector, the Silicon Photomultiplier (SiPM), has been tested in proximity focusing Ring Imaging Cherenkov (RICH) counters that were exposed to cosmic-ray particles in Ljubljana, and a 2 GeV electron beam at the KEK research facility. This type of RICH detector is a candidate for the particle identification detector upgrade of the BELLE detector at the KEK B-factory, for which the use of SiPMs, microchannel plate photomultiplier tubes or hybrid avalanche photodetectors, rather than traditional Photomultiplier Tubes (PMTs) is essential due to the presence of high magnetic fields. In both experiments, SiPMs are found to compare favourably with PMTs, with higher photon detection rates per unit area. Through the use of hemispherical and truncated pyramid light guides to concentrate photons onto the active surface area, the light yield increases significantly. An estimate of the contribution to dark noise from false coincidences between SiPMs in an array is also presented., to appear in Proc. 11th Topical Seminar on Innovative Particle and Radiation Detectors, 1-4 October 2008, Siena, Italy; Nucl. Phys. B Proc. Suppl., in press; 5 pages, 6 figures

The present work investigates the potential of silicon photomultipliers as position sensitive detectors of single photons in a ring imaging Cherenkov counter. The main advantage of silicon photomultipliers is their insensitivity to high magnetic fields, so they can be used inside large magnetic spectrometers. A module, consisting of 64 (=8x8) Hamamatsu MPPC S10362-11-100P silicon photomultipliers, has been constructed and tested with Cherenkov photons emitted in an aerogel radiator by 120 GeV/c pions from the CERN T4-H6 beam. In order to increase the efficiency, i.e. the effective surface on which light is detected, we have made and tested pyramidal light concentrators. The results of these tests indicate that a RICH counter based on silicon photomultipliers is feasible.

A novel photon detector, the Silicon Photomultiplier (SiPM), has been tested in view of a photosensitive device for Positron Emission Tomography (PET), which is one of the most important non-invasive methods for in-depth and in vivo imaging of tissue. Such a device offers advantages over existing ones, including application in a magnetic field, better resolution and easier operation. Two PET modules have been constructed by coupling an array of Hamamatsu 3 mm×3 mm Multi-pixel photon Counters (MPPCs) and Photonique 2.2 mm×2.2 mm Solid-state Photomultipliers (SSPMs) to LYSO scintillation crystals. The results of studies of the two module prototypes are presented.

The first measurements of the muon-induced neutron flux at the Boulby Underground Laboratory are presented. The experiment was carried out with an 0.73 tonne liquid scintillation detector that also served as an anticoincidence system for the ZEPLIN-II direct dark matter search. The experimental method exploited the delayed coincidences between high-energy muon signals and gamma-rays from radiative neutron capture on hydrogen or other elements. The muon-induced neutron rate, defined as the average number of detected neutr ons per detected muon, was measured as 0.079± 0.003 (stat.) neutrons/muon using neutron-capture signals above 0.55 MeV in a time window of 40-190 μs after the muon trigger. Accurate Monte Carlo simulations of the neutron production, transport and detection in a precisely modeled laboratory and experimental setup using the GEANT4 toolkit gave a result 1.8 times higher than the measured value. The difference greatly exceeds all statistical and systematic uncertainties. As the vast majority of neutrons detected in the current setup were produced in lead we evaluated from our measurements the neutron yield in lead as (1.31± 0.06)× 10 3 neutrons/muon/(g/cm 2 ) for a mean muon energy of about 260 GeV.