[en] In this contribution, we present ALDO2, a multi-function, adjustable, low dropout linear regulator designed in onsemi I3T80 0.35 μm HV CMOS technology for use in HEP detectors that adopt SiPMs/MPPCs. The chip features four independent regulators, two low voltage channels (max 3.3 V) used to filter and stabilize the power supply of front-end chips, one with 0.6 A output and one with 20 mA output, and two HV channels (max 70 V), specifically designed to provide the bias voltage to arrays of SiPMs up to a current of 45 mA per channel. Each regulator can be independently shut down and is protected for over-currents and over-temperature. The HV regulators also implement a circuit to monitor the bias current of the SiPM arrays, allowing to perform I-V curves and thus to fine-tune the working point of the SiPM arrays during the detector lifetime. The chip adopts radiation hardening techniques and has been fully qualified up to a TID of 20 Mrad, a 1-MeV-equivalent neutron fluence of 1015 cm−2, and with heavy ions up to 40 MeV cm2 mg−1 LET and 1010 cm−2 cumulative fluence. The chip will be installed in two CMS detectors in the HL-LHC phase, the Barrel Timing Detector (BTL) and the High Granularity Calorimeter (HGCAL).

[en] The LHCb experiment will be upgraded during the second LHC long shutdown (years 2019–2020) to operate at higher luminosity. The new triggerless architecture of LHCb requires data from the entire detector to be read out at 40 MHz. The basic element of the front-end electronics of the Ring Imaging Cherenkov (RICH) detector upgrade is the 'Elementary Cell' (EC), a readout system for multianode photomultiplier tubes designed to minimise parasitic capacitance at the anodes, to obtain a fast readout with low noise and low crosstalk. At the heart of the EC is the CLARO, an 8 channel, low power and radiation hard front-end ASIC designed in 0.35 μm CMOS technology. Each channel compares the charge signals from the photomultiplier anodes with a programmable threshold, and gives a digital pulse at the output when the threshold is exceeded. Baseline recovery occurs in less than 25 ns for typical single photon signals. In the LHCb RICH upgrade environment, the chips will have to withstand radiation up to a total ionising dose of 2 kGy (200 krad) and neutron and hadron fluences up to 03×1¹² cm⁻² and following irradiation, the chips have been shown to tolerate such doses with a margin of safety.

[en] Fast charge sensitive preamplifiers were built using commercial current feedback operational amplifiers for fast read out of charge pulses from a photomultiplier tube. Current feedback opamps prove to be particularly well suited for this application where the charge from the detector is large, of the order of one million electrons, and high timing resolution is required. A proper circuit arrangement allows very fast signals, with rise times down to one nanosecond, while keeping the amplifier stable. After a review of current feedback circuit topology and stability constraints, we provide a 'recipe' to build stable and very fast charge sensitive preamplifiers from any current feedback opamp by adding just a few external components. The noise performance of the circuit topology has been evaluated and is reported in terms of equivalent noise charge.

[en] High impedance connecting links and cables are modeled at low frequency in terms of their impedance to ground and to neigbouring connecting links. The impedance is usually considered to be the parallel combination of a resistance and a capacitance. While this model is adequate at moderate and low frequency, it proved to be not satisfactory at very low frequency, in the fractions of Hz range. Deep characterization was carried out on some samples down to 10 μHz, showing that an additional contribution to capacitance can emerge. A model was developed to explain and account for this additional contribution.

[en] In order to study where the binding site of cholinergic agents is in the sequence of the α-subunit of nicotinic acetylcholine receptor (AChR), we have synthetized 3 peptides with an aminoacid sequence corresponding to the following sequences of the α-subunit of Torpedo californica AChR: 125-143, 158-167, [Lys] 188-201. For binding studies the peptides were immobilized on Sepharose 4B. Only the peptide [Lys] 188-201 binds ¹²⁵I-α-bungarotoxin (α-Bgtx) with K_d of 1.03μM. The binding of ¹²⁵I-α-Bgtx to the peptide is reduced by 85% after reduction of the S-S bridge present between 192-193 cysteines indicating that an intact disulfide bond is important for toxin binding. The ¹²⁵I-α-Bgtx binding is inhibited by curare, decamethonium, hexamethonium but not by carbamylcholine and Naja naja siamensis α-toxin and P15 toxin. All these data provide direct evidence that the sequence 188-201 of the α-subunit of AChR binds α-Bgtx and that this binding has a pharmacological profile similar to that of nicotinic acetylcholine receptor. 16 refs. (Author)

[en] The characterization of the single photon response of the Hamamatsu R7600 multi-anode photomultiplier tube (MaPMT) is presented, in view of a possible application in Ring Imaging Cherenkov (RICH) detectors and high rate single photon counting applications in general. For most of the measurements the main source of single photons was a commercial blue LED biased with a small current of a few nA. The spectra obtained with this source match those obtained with Cherenkov light from a PbF₂ crystal illuminated with a ²²Na gamma source, confirming that the test signals are single photons. Dark current and cross-talk were measured at the single photoelectron level. The single photon response of the PMT was also studied as a function of the bias ratio between dynodes. The sensitivity to magnetic field up to 30 G and the effectiveness of three magnetic shields with different geometries were evaluated. Gain loss due to aging was also studied up to 2000 hours of operation at high counting rate.

[en] The H12700 is a novel 64-channel 52 × 52 mm"2 square Multi-Anode PhotoMultiplier Tube (MaPMT) produced by Hamamatsu. Its characteristics make this device suitable for high energy physics applications, such as in Ring Imaging Cherenkov (RICH) detectors. Hamamatsu provides the H12700 tube with an embedded socket connecting the anodes to the output pins and including an active voltage divider. A second device version, the R12699, is also available and differs from the former by the absence of the socket. This paper describes a complete characterization of both models, starting from the standard operating parameters (single photon spectra, average gain, anode uniformity and dark current value), investigating in detail the cross-talk effect among neighbouring pixels and considering the behaviour in critical environment conditions, such as in presence of a static magnetic field up to 100 Gauss, at different operating temperatures and after long exposure to intense light

[en] Measuring low noise of electronic devices with a spectrum analyzer requires particular care as the instrument could add significant contributions. A Low Noise Amplifier, LNA, is therefore necessary to be connected between the source to be measured and the instrument, to mitigate its effect at the LNA input. In the present work we suggest a technique for the implementation of the LNA that allows to optimize both low frequency noise and white noise, obtaining outstanding performance in a very broad frequency range

[en] An ASIC named CLARO-CMOS was designed for fast photon counting with MaPMTs, MCPs and SiPMs. The prototype was realized in a .35 μm CMOS technology and has four channels, each with a fast amplifier and a discriminator. The main features of the design are the high speed of operation and the low power dissipation, below 1 mW per channel. This paper focuses on the use of the CLARO for SiPM readout. The ASIC was tested with several SiPMs of various sizes, connected to the input of the chip both directly and through a coaxial cable about one meter long. In the latter case the ASIC is still fully functional although the speed of response is affected by the cable capacitance. The threshold could be set just above the single photoelectron level, and with 1 ×1 mm² SiPMs the discrete photoelectron peaks could be well resolved.

[en] Bolometric experiments searching for rare events usually require an extremely low radioactive background to prevent spurious signals from mimicking those of interest, spoiling the sensitivity of the apparatus. In such contexts, radioactive sources cannot be used to produce a known signal to calibrate the measured energy spectrum during data taking. In this paper we present an instrument designed to generate ultra-stable and very precise calibrating pulses, which can be used to stabilize the response of bolometers during data taking. The instrument is characterized by the presence of multi-outputs, a completely programmable pulse width and amplitude and a dedicated daisy-chained optical trigger line. It can be fully controlled and monitored remotely via CAN bus protocol. An energy resolution of the order of 20 eV FWHM at 1 MeV (2 eV FWHM at 10 keV) and a thermal stability of the order of 0.1 ppm/^oC have been achieved. The device can also provide an adjustable power to compensate the low frequency thermal fluctuations that typically occur in cryogenic experiments.