Low-noise, low drift, high precision linear bipolar (±10 V) voltage supply/reference for cryogenic front-end apparatus

A very simple linear bipolar (±10 V) voltage supply/reference (VS/R) featuring very low noise has been implemented. The noise is about 1 μVpp in a 0.1–10 Hz bandwidth, becoming, for the −10 V supply only, 1.3 μVpp at 1.5 A. The VS/R is based on commercial devices and has been designed to face the stringent requirement of very low drift systems. It features very good line regulation, less than 10 mV over 10 V at 1.5 A supply current, and very low drift, between 3 and 8 ppm/°C; it also shows large power supply rejection ratio (PSRR), >120 dB. The VS/R presented includes also safety circuits, to protect itself and the electronic equipment to be supplied in an actual experimental condition. It is protected against inversion of polarity and against under and over voltage at its inputs, and has a foldback current limiting circuit which shuts down the whole system if the current absorption lasts for some time. These protecting circuits acts on both outputs (±10 V), to maintain always the symmetry. From an analysis made on the data extracted from the measured noise spectra, it was possible to measure the dynamic output impedance, found mainly inductive, with a value of the order of 1 mH. The dc PSRR has been improved by about 20 dB with respect to the performances of the devices used, thanks to a very simple circuit solution

Room temperature differential voltage sensitive preamplifier for large mass bolometric detectors

The present version of the very front-end preampli"er which readouts an array of 20 large mass TeO 2 bolometric detectors is reported. It operates at room temperature and has low series and parallel noise. The thermal drift has been maintained at negligible levels thanks to a correcting circuit especially designed for this purpose. ( 2000 Elsevier Science B.V. All rights reserved

Characterization of the Hamamatsu R11265-103-M64 multi-anode photomultiplier tube

The aim of this paper is to fully characterize the new multi-anode photomultiplier tube R11265-103-M64, produced by Hamamatsu. Its high effective active area (77%), its pixel size, the low dark signal rate and the capability to detect single photon signals make this tube suitable for an application in high energy physics, such as for RICH detectors. Four tubes and two different bias voltage dividers have been tested. The results of a standard characterization of the gain and the anode uniformity, the dark signal rate, the cross-talk and the device behaviour as a function of temperature have been studied. The behaviour of the tube is studied in a longitudinal magnetic field up to 100 Gauss. Shields made of a high permeability material are also investigated. The deterioration of the device performance due to long time operation at intense light exposure is studied. A quantitative analysis of the variation of the gain and the dark signals rate due to the aging is described.Comment: 22 page

Cryogenic light detectors with enhanced performance for rare events physics

We have developed and tested a new way of coupling bolometric light detectors to scintillating crystal bolometers based upon simply resting the light detector on the crystal surface, held in position only by gravity. This straightforward mounting results in three important improvements: (1) it decreases the amount of non-active materials needed to assemble the detector, (2) it substantially increases the light collection efficiency by minimizing the light losses induced by the mounting structure, and (3) it enhances the thermal signal induced in the light detector thanks to the extremely weak thermal link to the thermal bath. We tested this new technique with a 16 cm$^2$ Ge light detector with thermistor readout sitting on the surface of a large TeO$_2$ bolometer. The light collection efficiency was increased by greater than 50\% compared to previously tested alternative mountings. We obtained a baseline energy resolution on the light detector of 20~eV RMS that, together with increased light collection, enabled us to obtain the best $\alpha$ vs $\beta/\gamma$ discrimination ever obtained with massive TeO$_2$ crystals. At the same time we achieved rise and decay times of 0.8 and 1.6 ms, respectively. This superb performance meets all of the requirements for the CUPID (CUORE Upgrade with Particle IDentification) experiment, which is a 1-ton scintillating bolometer follow up to CUORE.Comment: 6 pages, 4 figure

A very simple method to measure the input capacitance and the input current of transistors

Abstract We describe a method to measure the gate capacitance and the gate current of transistors at any temperature and at any operating condition. Discrimination between the total input capacitance and transfer reverse capacitance (gate to drain capacitance) is also possible with high accuracy. With this data the optimization of the signal to noise ratio and power dissipation can be achieved in the design of the front-end electronics for nuclear applications