Claudio Gotti

CLARO-CMOS, a very low power ASIC for fast photon counting with pixellated photodetectors

The CLARO-CMOS is an application specific integrated circuit (ASIC) designed for fast photon counting with pixellated photodetectors such as multi-anode photomultiplier tubes (Ma- PMT), micro-channel plates (MCP), and silicon photomultipliers (SiPM). The first prototype has four channels, each with a charge sensitive amplifier with settable gain and a discriminator with settable threshold, providing fast hit information for each channel independently. The design was realized in a long-established, stable and inexpensive 0.35mm CMOS technology, and provides outstanding performance in terms of speed and power dissipation. The prototype consumes less than 1 mW per channel at low rate, and less than 2 mW at an event rate of 10 MHz per channel. The recovery time after each pulse is less than 25 ns for input signals within a factor of 10 above threshold. Input referred RMS noise is about 7.7 ke (1.2 fC) with an input capacitance of 3.3 pF. With this value of input capacitance a timing resolution down to 10 ps RMS was measured for pulser signals of a few million electrons, corresponding to the single photon response for these detectors.

A fast and low noise charge sensitive preamplifier in 90 nm CMOS technology

A fast charge sensitive preamplifier was designed and built in a 90 nm CMOS technology. The work is part of the R&D effort towards the read out of pixel or small strip sensors in next generation HEP experiments. The preamplifier features outstanding noise performance given its wide bandwidth, with a ENC (equivalent noise charge) of about 350 electrons RMS with a detector of 1 pF capacitance. With proper filtering, the ENC drops to less than 200 electrons RMS. Power consumption is 5 mW for one channel, and the closed loop bandwith is about 180 MHz, for a risetime down to 2 ns in the fastest operation mode. Thanks to some freedom left to the user in setting the open loop gain, detectors with larger source capacitance can be read out without significant loss in bandwidth, being the rise time still 5.5 ns for a 5.6 pF detector. The output can drive a 50 ? terminated transmission line.

Characterization of the Hamamatsu H12700A-03 and R12699-03 multi-anode photomultiplier tubes

The H12700 is a novel 64-channel 52

Crosstalk Study of the Single-Photon Response of a Flat-Panel PMT for the RICH Upgrade at LHCb

\times

CLARO-CMOS, an ASIC for single photon counting with Ma-PMTs, MCPs and SiPMs

52 mm

A new approach to the readout of cryogenic ionization detectors: GeFRO

^2

Current feedback operational amplifiers as fast charge sensitive preamplifiers for photomultiplier read out

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.

Aging and time resolution measurements for the Hamamatsu R7600 multi-anode photomultiplier tube

The ring imaging Cherenkov (RICH) detector at LHCb is now read out by hybrid photon detectors. In view of its upgrade, a possible option is the adoption of the flat-panel photon multiplier tube (PMT). An important issue for good reconstruction of the Cherenkov rings is a negligible level of crosstalk. We have experimentally studied the crosstalk from the 16 × 16-pixels Hamamatsu H9500 PMT. Results have shown that, for the single-photon response, the statistics tied to the small number of electrons generated at the first dynode of the PMT chain (a few units) leads to a number of crosstalk signals that are a small fraction of the fired pixel. With the H9500, in a Cherenkov ring, only one or two pixels are expected to generate crosstalk. As a consequence, crosstalk cannot be considered a limit in the use of the H9500 for the upgrade of the RICH at LHCb.

GeFRO, a new front-end approach for the phase II of the GERDA experiment

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.

Characterization of a Hamamatsu R7600 multi-anode photomultiplier tube with single photon signals

We present a novel approach to the readout of ionization detectors. The solution allows to minimize the number of components and the space occupation close to the detector. This way a minimal impact is added on the radioactive background in those experiments where very low signal rates are expected, such as GERDA and MAJORANA. The circuit consists in a JFET transistor and a remote second stage. The DC feedback path is closed using a diode. Two signal cables are only necessary for biasing and readout.We present GeFRO (Germanium FROntend) a novel approach to the readout of ionization detectors. The circuit allows to minimize the number of components and the space occupation close to the detector. This way a minimal impact is added on the radioactive background in those experiments where very low signal rates are expected, such as GERDA and MAJORANA. The circuit consists of a JFET transistor and a remote second stage. The DC feedback path is closed using a diode. Only two signal cables are necessary for biasing and readout.