Matrix: a 15 ps resistive interpolation TDC ASIC based on a novel regular structure

This paper presents a 4-channel TDC ASIC with the following features: 15-ps LSB (9.34 ps after calibration), 10-ps jitter, < 4-ps time resolution, up to 10 MHz of sustained input rate per channel, 45 mW of power consumption and very low area (910×215 μm2) in a commercial 180 nm technology. The main contribution of this work is the novel design of the clock interpolation circuitry based on a resistive interpolation mesh circuit (patented), a two-dimensional regular structure with very good properties in terms of power consumption, area and low process variability

FastIC: a fast integrated circuit for the readout of high performance detectors

This work presents the 8-channel FastIC ASIC developed in CMOS 65 nm technology suitable for the readout of positive and negative polarity sensors in high energy physics experiments, Cherenkov detectors and time-of-flight systems. The front-end can be configured to perform analog summation of up to 4 single-ended channels before discrimination in view of improving time resolution when segmenting a SiPM. The outputs encode the time-of-arrival information and linear energy measurement which captures the peak amplitude of the input signal in the 5 µA–25 mA input peak current range. Power consumption of the ASIC is 12 mW/ch with default settings. Measurements of single photon time resolution with a red-light laser source and a HPK SiPM S13360-3050CS are ≈140 ps FWHM

A High Dynamic Range ASIC for Time of Flight PET with monolithic crystals

The HRFlexToT is a 16-channel ASIC for SiPM anode readout designed for Positron Emission Tomography (PET) applications that features high dynamic range (>8 bits), low input impedance, common cathode connection, high speed and low power (~3.5 mW/ch). The ASIC has been manufactured using XFAB 0.18 mm CMOS technology. The main characteristics of the HRFlexToT, compared to its predecessor, are a new energy measurement readout providing a linear Time Over Threshold (ToT) with an extended dynamic range, lower power consumption and better timing response. Initial measurements show a linearity error below 3%. Single Photon Time Resolution (SPTR) measurements performed using a Hamamatsu MPPC S13360-3050CS (3x3 mm2 pixel, 50 umm cell) shows 30% improvement with respect to the previous version of the ASIC, setting this specification in the order of 141 ps FWHM and reducing 3 times power consumption. It is important to highlight that an SPTR of 141 ps FWHM is, according to the best of our knowledge, the best resolution achieved so far for this sensor. Coincidence Time Resolution (CTR) measurements are expected to be performed during 2018

Design and construction of a new detector to measure ultra-low radioactive-isotope contamination of argon

Large liquid argon detectors offer one of the best avenues for the detection of galactic weakly interacting massive particles (WIMPs) via their scattering on atomic nuclei. The liquid argon target allows exquisite discrimination between nuclear and electron recoil signals via pulse-shape discrimination of the scintillation signals. Atmospheric argon (AAr), however, has a naturally occurring radioactive isotope, 39Ar, a β emitter of cosmogenic origin. For large detectors, the atmospheric 39Ar activity poses pile-up concerns. The use of argon extracted from underground wells, deprived of 39Ar, is key to the physics potential of these experiments. The DarkSide-20k dark matter search experiment will operate a dual-phase time projection chamber with 50 tonnes of radio-pure underground argon (UAr), that was shown to be depleted of 39Ar with respect to AAr by a factor larger than 1400. Assessing the 39Ar content of the UAr during extraction is crucial for the success of DarkSide-20k, as well as for future experiments of the Global Argon Dark Matter Collaboration (GADMC). This will be carried out by the DArT in ArDM experiment, a small chamber made with extremely radio-pure materials that will be placed at the centre of the ArDM detector, in the Canfranc Underground Laboratory (LSC) in Spain. The ArDM LAr volume acts as an active veto for background radioactivity, mostly γ-rays from the ArDM detector materials and the surrounding rock. This article describes the DArT in ArDM project, including the chamber design and construction, and reviews the background required to achieve the expected performance of the detector

SiPM-matrix readout of two-phase argon detectors using electroluminescence in the visible and near infrared range

Proportional electroluminescence (EL) in noble gases is used in two-phase detectors for dark matter searches to record (in the gas phase) the ionization signal induced by particle scattering in the liquid phase. The “standard” EL mechanism is considered to be due to noble gas excimer emission in the vacuum ultraviolet (VUV). In addition, there are two alternative mechanisms, producing light in the visible and near infrared (NIR) ranges. The first is due to bremsstrahlung of electrons scattered on neutral atoms (“neutral bremsstrahlung”, NBrS). The second, responsible for electron avalanche scintillation in the NIR at higher electric fields, is due to transitions between excited atomic states. In this work, we have for the first time demonstrated two alternative techniques of the optical readout of two-phase argon detectors, in the visible and NIR range, using a silicon photomultiplier matrix and electroluminescence due to either neutral bremsstrahlung or avalanche scintillation. The amplitude yield and position resolution were measured for these readout techniques, which allowed to assess the detection threshold for electron and nuclear recoils in two-phase argon detectors for dark matter searches. To the best of our knowledge, this is the first practical application of the NBrS effect in detection science

Observation of charmless baryonic decays B(s) 0→p p ¯h+h'-

Decays of B0 and Bs0 mesons to the charmless baryonic final states p p ¯h+h'-, where h and h' each denote a kaon or a pion, are searched for using the LHCb detector. The analysis is based on a sample of proton-proton collision data collected at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb-1 . Four-body charmless baryonic Bs0 decays are observed for the first time. The decays Bs0→p p ¯K+K-, Bs0→p p ¯K±π∓, B0→p p ¯K±π∓ and B0→p p ¯π+π- are observed with a significance greater than 5 standard deviations; evidence at 4.1 standard deviations is found for the B0→p p ¯K+K- decay and an upper limit is set on the branching fraction for Bs0→p p ¯π+π-. Branching fractions in the kinematic region m (p p ¯ )<2850 MeV /c2 are measured relative to the B0→J /ψ (→p p ¯)K*(892 )0 channel

Updated branching fraction measurements of B ( s) 0 → K S 0 h + h ' - decays

The charmless three-body decays B ( s) 0 → K S 0 h + h ' - (where h (') = π, K) are analysed using a sample of pp collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 3 fb-1. The branching fractions are measured relative to that of the B 0 → K S 0 π + π - decay, and are determined to be: B({B}^0\to {K}S^0{K}^{± /π^{∓})}{B({B}^0\to {K}S^0{K}+{π}-)}=0.123± 0.009(stat)± 0.015(syst), B({B}^0\to {K}S^0{K}^{+/K-)}{B({B}^0\to {K}S^0{π}+{π}-)}=0.549± 0.018(stat)± 0.033(syst), B({B}_s^0\to {K}S^0{π}^{+/π-)}{B({B}^0\to {K}S^0{π}+{π}-)}=0.191± 0.027(stat)± 0.031(syst)± 0.011({f}_s/{f}_d), B({B}_s^0\to {K}S^0{K}^{± /π^{∓})}{B({B}^0\to {K}S^0{π}+{π}-)}=1.70± 0.07(stat)± 0.11(syst)± 0.10({f}_s/{f}_d), B({B}_s^0\to {K}S^0{K}^{+/K-)}{B({B}^0\to {K}S^0{π}+{π}-)}\in [0.008-0.051] at 90% confidence level, where f s / f d represents the ratio of hadronisation fractions of the B s 0 and B 0 mesons

Updated search for long-lived particles decaying to jet pairs

A search is presented for long-lived particles with a mass between 25 and 50 GeV/c2 and a lifetime between 2 and 500 ps, using proton-proton collision data corresponding to an integrated luminosity of 2.0 fb^{-1}, collected by the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The particles are assumed to be pair-produced in the decay of a 125 GeV/c2 Standard-Model-like Higgs boson. The experimental signature is a single long-lived particle, identified by a displaced vertex with two associated jets. No excess above background is observed and limits are set on the production cross-section as a function of the mass and lifetime of the long-lived particle

Prompt and nonprompt J/ψ production and nuclear modification in pPb collisions at √{sNN} = 8.16 TeV

The production of J / ψ mesons is studied in proton-lead collisions at the centre-of-mass energy per nucleon pair √{sNN} = 8.16 TeV with the LHCb detector at the LHC. The double differential cross-sections of prompt and nonprompt J / ψ production are measured as a function of the J / ψ transverse momentum and rapidity in the nucleon-nucleon centre-of-mass frame. Forward-to-backward ratios and nuclear modification factors are determined. The results are compared with theoretical calculations based on collinear factorisation using nuclear parton distribution functions, on the colour glass condensate or on coherent energy loss models

DarkSide-50 results and the future liquid argon dark matter program

DarkSide uses a dual-phase Liquid Argon Time Projection Chamber (TPC) to search for WIMP dark matter. The paper will present the latest result on the search for low mass (MWIMP &lt; 20Gev=c2) and high mass (MWIMP &gt; 100Gev=c2) WIMPs from the current experiment, DarkSide-50, running since mid 2015 a 50-kg-active-mass TPC, filled with argon from an underground source. The next stage of the DarkSide program will be a new generation experiment involving a global collaboration from all the current Argon based experiments. DarkSide-20k, is designed as a 20-tonne fiducial mass TPC with SiPM based photosensors, expected to be free of any background for an exposure of &gt;100 ton x years. Like its predecessor DarkSide-20k will be housed at the Gran Sasso (LNGS) underground laboratory, and it is expected to attain a WIMPnucleon cross section exclusion sensitivity of 1047 cm2 for a WIMP mass of 1TeV=c2 in a 5 yr run. A subsequent objective, towards the end of the next decade, will be the construction of the ultimate detector, ARGO, with a 300 t fiducial mass to push the sensitivity to the neutrino floor region for high mass WIMPs. The combination of the three experiments, part of a single family, will cover completely the WIMP hypothesis from 1GeV=c2 to several hundreds of TeV=c2 masses