Challenges for dark matter direct search with SiPMs

Liquid xenon and liquid argon detectors are leading the direct dark matter search and are expected to be the candidate technology for the forthcoming generation of ultra-sensitive large-mass detectors. At present, the scintillation light detection in those experiments is based on ultra-pure low-noise photo-multipliers. To overcome the issues in terms of the extreme radio-purity, costs, and technological feasibility of the future dark matter experiments, the novel SiPM-based photo-detector modules look promising candidates, capable of replacing the present light detection technology. However, the intrinsic features of SiPMs may limit the present expectations. In particular, interfering phenomena, especially related to the optical correlated noise, can degrade the energy and pulse shape resolutions. As a consequence, the projected sensitivity of the future detectors has to be reconsidered accordingly.Comment: 10 pages, 8 figure

Challenges for dark matter direct search with SiPMs

Liquid xenon and liquid argon detectors are leading the direct dark matter search and are expected to be the candidate technology for the forthcoming generation of ultra-sensitive large-mass detectors. At present, scintillation light detection in those experiments is based on ultra-pure low-noise photo-multipliers. To overcome the issues in terms of the extreme radio-purity, costs, and technological feasibility of the future dark matter experiments, the novel silicon photomultiplier (SiPM)-based photodetector modules seem to be promising candidates, capable of replacing the present light detection technology. However, the intrinsic features of SiPMs may limit the present expectations. In particular, interfering phenomena, especially related to the optical correlated noise, can degrade the energy and pulse shape resolutions. As a consequence, the projected sensitivity of the future detectors has to be reconsidered accordingly

Cryogenic Characterization of FBK HD Near-UV Sensitive SiPMs

We report on the characterization of near-ultraviolet high density silicon photomultiplier (\SiPM) developed at Fondazione Bruno Kessler (\FBK) at cryogenic temperature. A dedicated setup was built to measure the primary dark noise and correlated noise of the \SiPMs\ between 40 and 300~K. Moreover, an analysis program and data acquisition system were developed to allow the precise characterization of these parameters, some of which can vary up to 7 orders of magnitude between room temperature and 40~K. We demonstrate that it is possible to operate the \FBK\ near-ultraviolet high density \SiPMs\ at temperatures lower than 100~K with a dark rate below 0.01 cps/mm$^2$ and total correlated noise probability below 35\% at an over-voltage of 6~V. These results are relevant for the development of future cryogenic particle detectors using \SiPMs\ as photosensors

Development of a very low-noise cryogenic pre-amplifier for large-area SiPM devices

Silicon Photomultipliers (SiPMs) are an excellent candidate for the development of large-area light sensors. Large SiPM-based detectors require low-noise pre-amplifiers to maximize the signal coupling between the sensor and the readout electronics. This article reports on the development of a low-noise transimpedance amplifier sensitive to single-photon signals at cryogenic temperature. The amplifier is used to readout a 1 cm$^{2}$ SiPM with a signal to noise ratio in excess of 40

Borexino : geo-neutrino measurement at Gran Sasso, Italy

Geo-neutrinos, electron anti-neutrinos produced in beta-decays of naturally occurring radioactive isotopes in the Earth, are a unique direct probe of our planet's interior. After a brief introduction of the geo-neutrinos' properties and of the main aims of their study, we discuss the features of a detector which has recently provided breakthrough achievements in the field, Borexino, a massive, calorimetric liquid scintillator detector installed at the underground Gran Sasso Laboratory. With its unprecedented radiopurity levels achieved in the core of the detection medium, it is the only experiment in operation able to study in real time solar neutrino interactions in the challenging sub-MeV energy region. Its superior technical properties allowed Borexino also to provide a clean detection of terrestrial neutrinos. Therefore, the description of the characteristics of the detected geo-neutrino signal and of the corresponding geological implications are the main core of the discussion contained in this work

Identifying a recombinant alkyldihydroxyacetonephosphate synthase suited for crystallographic studies

Alkyldihydroxyacetonephosphate is the building block for the biosynthesis of ether phospholipids, which are essential components of eukaryotic cell membranes and are involved in a variety of signaling processes. The metabolite is synthesized by alkyldihydroxyacetonephosphate synthase (ADPS), a peroxisomal flavoenzyme. Deficiency in ADPS activity causes rhizomelic chondrodysplasia punctata type 3, a very severe genetic disease. ADPS is unusual in that it uses a typical redox cofactor such as FAD to catalyze a non-redox reaction. With the goal of undertaking a structural investigation of the enzyme, we have characterized recombinant ADPS from different sources: Cavia porcellus, Drosophila melanogaster, Homo sapiens, Archaeoglobus fulgidus, and Dictyostelium discoideum. The protein from D. discoideum was found to be the best candidate for structural studies. We describe a protocol for expression and purification of large amounts of pure and stable enzyme in its holo (FAD-bound) form. A search of deletion mutants identified a protein variant that forms crystals diffracting up to 2A resolution

Measurement of CNGS Muon Neutrinos Speed with Borexino: INRIM and ROA Contribution

This paper describes the contribution given by the INRIM “Time and Frequency Laboratory” and the ROA “Time Department” to the Borexino cooperation in the experiments for the accurate measurement of the CNGS (CERN neutrinos to Gran Sasso) muon neutrinos speed. We briefly report about the design, installation, and performance of a new system called High Precision Timing Facility (HPTF), intended as a GPS-based timing facility with a calibrated time-link to the CERN GPS receiver and with continual real time monitoring of the fiber link time delay to the underground laboratory. Details about the INRIM/ROA contribution will be presented, reporting the calibration of the CERN-LNGS GPS time link, as well as the calibration of the HPTF internal delays. This system, specifically designed for the Borexino experiments, has also been made available to other LNGS experiments (namely, LVD and Icarus) and has been used to measure the muon neutrino speed in May 2012, during a special short bunch run of the CNGS beam

Development of a Novel Single-Channel, 24 cm 2

We report on the realization of a novel SiPM-based, cryogenic photosensor with an active area of 24 cm$^2$ that operates as a single-channel analog detector. The device is capable of single photon counting with a signal to noise ratio better than 13, a dark rate lower than $10^{-2}$ cps/mm$^2$ and an overall photon detection efficiency significantly larger than traditional photomultiplier tubes. This development makes SiPM-based photosensors strong candidates for the next generation of dark matter and neutrino detectors, which will require multiple square meters of photosensitive area, low levels of intrinsic radioactivity and a limited number of detector channels

Development of a Novel Single-Channel, 24 cm(2), SiPM-Based, Cryogenic Photodetector

We report on the realization of a novel silicon photomultiplier (SiPM)-based, cryogenic photosensor with an active area of 24 cm(2) that operates as a single-channel analog detector. The device is capable of single-photon counting with a signal-to-noise ratio better than 13, a dark rate lower than 10(-2) Hz/mm(2), and an overall photon detection efficiency significantly larger than traditional photomultiplier tubes. This development makes SiPM-based photosensors strong candidates for the next generation of dark matter and neutrino detectors, which will require multiple square meters of photosensitive area, low levels of intrinsic radioactivity, and a limited number of detector channels