Over almost three decades the TAUP conference has seen a remarkable momentum gain in direct dark matter search. An important accelerator were first indications for a modulating signal rate in the ...DAMA/NaI experiment (today DAMA/LIBRA) reported in 1997. Today the presence of an annual modulation observed by DAMA, which matches in period and phase the expectation for dark matter, is doubtless and supported at > 9σ confidence. Despite the positive evidence from the DAMA experiment the underlying nature of dark matter is still considered an open and fundamental question of nowadays particle physics. No other direct dark matter search experiment could confirm the DAMA claim up to now; moreover, numerous null-results are in clear contradiction with DAMA under so-called standard assumptions for the dark matter halo and the interaction mechanism of dark with ordinary matter. As both bear a dependence on the target material, resolving this controversial situation will convincingly only be possible with an experiment using sodium iodide (NaI) as target, just like DAMA. COSINUS aims to even go a step further by combining NaI with a novel detection approach. DAMA and all other NaI experiments solely measure the scintillation light created by a particle interaction in the NaI crystal. COSINUS aims to operate NaI as a cryogenic calorimeter reading scintillation light and phonon/heat signal. Two distinct advantages arise from this approach, a substantially lower energy threshold for nuclear recoils and particle identification on an event-by-event basis. These key benefits will allow COSINUS to clarify a possible nuclear recoil origin of the DAMA signal with comparatively little exposure of O(100kg days) and, thereby, answer a long-standing question of particle physics. Today COSINUS is in R&D phase; in this contribution we show results from the 2nd prototype, albeit the first one of the final foreseen detector design. The key finding of this measurement is that pure, undoped NaI is a truly excellent scintillator at low temperatures: We measure 13.1% of the total deposited energy in the NaI crystal in the form of scintillation light (in the light detector).
Next generation calorimetric experiments for the search of rare events rely on the detection of tiny amounts of light (of the order of 20 optical photons) to discriminate and reduce background ...sources and improve sensitivity. Calorimetric detectors are the simplest solution for photon detection at cryogenic (mK) temperatures. The development of silicon based light detectors with enhanced performance thanks to the use of the Neganov–Luke effect is described. The aim of this research line is the production of high performance detectors with industrial-grade reproducibility and reliability.
The Cryogenic Observatory for SIgnals seen in Next-generation Underground Searches (COSINUS) project aims to provide a model-independent cross-check of the long-standing DAMA/LIBRA claim on the ...observation of dark matter by using the same target material, but in a different experimental approach. Operating sodium iodide (NaI) scintillating crystals as low-temperature scintillating calorimeters has the distinct advantage of providing a lower energy threshold for nuclear recoil events as expected from dark matter particle interactions combined with particle discrimination. The dual readout of phonon and light allows us to provide background rejection on an event-by-event basis, a unique feature in comparison with other NaI-based dark matter searches. The manuscript discusses in detail the COSINUS detector concept and presents the results and performance parameters from our second prototype detector.
The CLARO8 chip has been designed for single-photon counting in the upgraded RICH detector of the LHCb experiment at CERN. The chip has 8 channels with 5ns peaking time and a recovery time better ...than 25ns. Each channel is made of a charge amplifier with 2-bit settable attenuation, plus a comparator with a 6-bit settable threshold, and the configuration register is protected against Single Event Upsets by triple modular redundancy. In order to ensure stable operation of the upgraded RICH detectors over the expected lifetime of the experiment after the upgrade, the performance of the CLARO8 in high radiation fields has been assessed. These chips will be exposed, during the whole upgrade running phase, to a total ionizing dose of 200krad, a neutron fluence of 3×1012 1MeVneq/cm2 and a high energy hadrons fluence of 1.2×1012cm−2. Systematic irradiation campaigns have been performed using ions, protons and mixed-field high-energy hadron beams. This paper describes the radiation hardness campaign of the CLARO8 chips and the main results of its extensive characterisation.
The CLARO-CMOS is a prototype ASIC that allows fast photon counting with 5 ns peaking time, a recovery time to baseline smaller than 25 ns, and a power consumption of less than 1 mW per channel. This ...chip is capable of single-photon counting with multi-anode photomultipliers and finds applications also in the read-out of silicon photomultipliers and microchannel plates. The prototype is realized in AMS 0.35 micron CMOS technology. In the LHCb RICH environment, assuming 10 years of operation at the nominal luminosity expected after the upgrade in Long Shutdown 2 (LS2), the ASIC must withstand a total fluence of about 610 super(12) 1 MeV n sub(eq)/cm super(2)neq/cm2 and a total ionizing dose of 400 krad. A systematic evaluation of the radiation effects on the CLARO-CMOS performance is therefore crucial to ensure long term stability of the electronics front-end. The results of multi-step irradiation tests with neutrons and X-rays up to the fluence of 10 super(14) cm super(-2) and a dose of 4 Mrad, respectively, are presented, including measurement of single event effects during irradiation and chip performance evaluation before and after each irradiation step.
The characterization of the new Hamamatsu R11265-103-M64 multi-anode photomultiplier tube is presented. The sample available in our laboratory was tested and in particular the response to single ...photon was extensively studied. The gain, the anode uniformity and the dark current were measured. The tube behaviour in a longitudinal magnetic field up to 100 G was studied and the gain loss due to the ageing was quantified. The characteristics and performance of the photomultiplier tube make the R11265-103-M64 particularly tailored for an application in high energy physics experiments, such as in the LHCb Ring Imaging Cherenkov (RICH) detector at LHC.
A new approach was developed for the design of front-end circuits for semiconductor radiation detectors. The readout scheme is a charge sensitive amplifier, split between a very front-end stage ...(input transistor, feedback resistor and capacitor) located close to the detector and a remote second stage located far from the detector. The element of novelty, with respect to similar configurations, is the fact that the connecting links between the very front-end and the second stage are made with transmission lines. As a result, wide bandwidth and closed-loop stability are maintained even if the distance between the very front-end and the second stage is much larger than usual, up to tens of meters. The circuit was named GeFRO for Germanium front-end, and was tested with a BEGe detector from Canberra. Timing resolutions of 20 ns (open loop) and 185 ns (closed loop with 60 ° phase margin) were obtained with 10 m long cables between the very front-end and the second stage. The noise of the circuit after a 10 μs Gaussian shaping was close to 160 e - RMS with an input capacitance of 26 pF.
The COSINUS (Cryogenic Observatory for SIgnals seen in Next-generation Underground Searches) project aims to provide a model independent cross-check of the long-standing DAMA/LIBRA claim on the ...observation of dark matter, by using the same target material (NaI) with a different experimental approach. The use of sodium iodide (NaI) crystals, operated at cryogenic temperature as scintillating calorimeters, provides both a low energy threshold for nuclear recoil events as expected from dark matter particle interactions, and the possibility to perform particle discrimination. Indeed, the dual read-out of phonon and light allows to perform signal-to-background discrimination on an event-by-event basis, a unique feature in comparison to other NaI-based dark matter searches. In this paper we will discuss in detail the COSINUS detector concept and we will present the performances of our first prototypes together with the results of the first measurements.
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