Design and construction of a Cherenkov imager for charge measurement of nuclear cosmic rays

A proximity focusing Cherenkov imager called CHERCAM, has been built for the charge measurement of nuclear cosmic rays with the CREAM instrument. It consists of a silica aerogel radiator plane across from a detector plane equipped with 1,600 1" diameter photomultipliers. The two planes are separated by a ring expansion gap. The Cherenkov light yield is proportional to the charge squared of the incident particle. The expected relative light collection accuracy is in the few percents range. It leads to an expected single element separation over the range of nuclear charge Z of main interest 1 < Z < 26. CHERCAM is designed to fly with the CREAM balloon experiment. The design of the instrument and the implemented technical solutions allowing its safe operation in high altitude conditions (radiations, low pressure, cold) are presented.Comment: 24 pages, 19 figure

MATE, a single front-end ASIC for silicon strip, Si(Li) and CsI detectors

MATE (Must ASIC for Time and Energy) will process signals delivered from the hodoscope MUST2. The hodoscope consists of six large area telescopes (100 cm²), each made up of a double sided Si strip detector followed by a Si(Li) and Csi crystal. MATE has sixteen channels and can deliver three types of analogue information per channel; time of flight and energy loss of the detected particle; value of leakage DC current per channel. MATE also gives a trigger logical signal corresponding to the cross over of an adjustable threshold value. The analogue information is transmitted as differential current through twisted pair to the acquisition system based on VXI-C. The slow control is assured via the I2C industrial protocol. The first version of MATE for Si(strip) is available. An update of MATE will allow it to be used for the Si(Li) and Csi detectors. MATE is a novel R&D project for nuclear physics which includes both energy and time measurements with good resolution and high energy dynamic range

Front-end multi-channel PMT-associated readout chip for hodoscope application

International audienceThe system development requires a dedicated multi-channel readout ASIC (Application Specific Integrated Circuit) to be associated with the MaPMTs. Each channel should have very low input impedance to avoid electrical crosstalk between adjacent channels and to minimize effects of detector and wiring capacitances (Cd + Cw). Crosstalk between channels may degrade position resolution, while these capacitances may degrade both frequency and noise performances. Each channel should also provide two separated outputs corresponding respectively to high-speed signal-event detection and low-noise signal-charge quantification at low counting rate. This paper presents a readout chip for this purpose. It has been designed in a 0.35µm SiGe BiCMOS process (AMS). This process allows the use of RF and large-transconductance bipolar components, which is useful for the design of wide-band, low-impedance and low-noise circuits with improved performances

Electronics for the CREAM calorimeter and hodoscopes

The electronics used for the CREAM calorimeter trigger and signal readout are based on 80 (32-channel) VA32-HDR2/TA32C chips digitized by 80 (12-bit) LTC1400 ADCs. The hodoscope electronics use 144 (16-channel) CR-1.4A chips digitized by 72 (16-bit) MAX1133 ADCs. The basic characteristics, such as noise level, dynamic range, linearity, and gain of both systems were measured in the laboratory. The results confirm that the design goals of the CREAM experiment could be achieved

TDC Chip and Readout Driver Developments for COMPASS and LHC-Experiments

A new TDC-chip is under development for the COMPASS experiment at CERN. The ASIC, which exploits the 0.6 micrometer CMOS sea-of-gate technology, will allow high resolution time measurements with digitization of 75 ps, and an unprecedented degree of flexibility accompanied by high rate capability and low power consumption. Preliminary specifications of this new TDC chip are presented. Furthermore a FPGA based readout-driver and buffer-module as an interface between the front-end of the COMPASS detector systems and an optical S-LINK is in development. The same module serves also as remote fan-out for the COMPASS trigger distribution and time synchronization system. This readout-driver monitors the trigger and data flow to and from front-ends. In addition, a specific data buffer structure and sophisticated data flow control is used to pursue local pre-event building. At start-up the module controls all necessary front-end initializations.Comment: 5 pages, 4 figure

Development, Characterization, and Analysis of Silicon Microstrip Detector Modules for the CBM Silicon Tracking System

The future Facility for Antiproton and Ion Research (FAIR) at GSI, Germany, will enable scientists to create tiny droplets of cosmic matter in the laboratory—matter subject to extreme conditions usually found in the interior of stars or during stellar collisions. The Compressed Baryonic Matter (CBM) experiment at FAIR aims to explore the quantum chromodynamics (QCD) phase diagram at high densities and moderate temperatures. By colliding heavy ions at relativistic beam energies, the conditions inside these supermassive objects can be recreated for an exceptionally short amount of time. The CBM detector is a fixed-target multi-purpose detector designed for measuring hadrons, electrons and muons in elementary nucleon and heavy-ion collisions over the full FAIR beam energy range delivered by the SIS100 synchrotron. One of the core detectors of CBM is the Silicon Tracking System (STS), responsible for measuring the momentum and tracks of up to 700 charged particles produced in a central nucleus-nucleus collisions. Due to the required momentum resolution, the material budget of the STS must be minimized. Therefore, the readout electronics and the cooling and mechanical infrastructure are placed out of the detector acceptance. The double-sided silicon microstrip sensors are connected to the self-triggering frontend electronics using low-mass flexible microcables with a length of up to 50 cm. The main goal of this thesis was to develop a high-density interconnection technology based on copper microcables. We developed a low-mass double-layered copper microcable at the edge of modern fabrication technology. Based on the copper microcable, we developed a novel high-density interconnection technology, comprising fine-grain solder paste printing on the microcable and gold stud bumping on the die. The gold stud--solder technology combines a high automation capability with good mechanical and electrical properties, making it an interesting technology also for future detector systems. Building on the gold stud--solder technology, a fully customized bonder machine was developed and constructed in hardware and software. Its main purpose is the realization of the challenging interconnection between the microcable and the sensor. Key components of the machine are four step motors with a sub-micron step resolution, a dual-camera pattern recognition system, a heatable, temperature-controlled bond head and sensor plate, as well as tailor-made mechanical supports for the STS detector modules. With the help of this bonder machine, a full-scale STS detector module in the copper technology was built. The noise performance of the copper module was evaluated in a bias voltage scan. Very low noise levels were observed. Measurements of the absolute value of the signal with a radioactive source allowed us to estimate the signal-to-noise ratio of the module. The results of these measurements give us confidence that STS modules based on the copper technology can achieve a satisfying performance comparable to the modules built in the aluminium technology. Another essential component of the STS detector module is the frontend electronics chip. During this work, the version 2.1 of the STS-XYTER readout ASIC was extensively characterized. Noise discrepancies between odd and even channels and increasingly higher noise towards the higher channel numbers had been observed in the predecessor chip. Our measurements of the STS-XYTER2.1 verified that both issues were successfully resolved. Furthermore, the noise behavior of the ASIC with respect to input load capacitance was studied. This is essential to parametrize expected noise levels for the many kinds of detector modules employed in the STS, to which the measured noise levels can then be compared. Measurements of the noise levels as a function of shaping time showed that the overall noise level is practically independent of shaper peaking time. Radiation tests with 50 MeV protons were performed with copper microcables connected to the ASIC in a non-powered state. No indications of damage to the chip and interconnects could be observed. Finally, a complete STS detector module in aluminium technology was subjected to a pencil-like monochromatic beam of 2.7 GeV/c protons at the Cooling Synchrotron at the research center Jülich. Several essential performance criteria of the detector module were evaluated. The best coincidence between the STS and the reference fiber hodoscopes was established based on time information. An excellent time resolution of a few nanoseconds could be demonstrated. Based on the best coincidence, the spatial resolution of the full system was determined to be a few hundred microns. This is in line with expectations, as the resolution is limited by the fiber hodoscope resolution. Charge distributions of 1-strip clusters showed a clear separation between the noise and the proton signal peak, with a signal-to-noise ratio above 20 for the p-- and n-side. The charge collection efficiency of the module was estimated to be $96 \%$. The COSY beamtime enabled a first-time evaluation of the full analysis software chain with real data and the evaluation of the full electronic readout chain of STS. The experience gained at COSY is immensely helpful for commissioning and data analysis in more complex beam environments such as mCBM, where a subsample of the CBM detectors is exposed to the particles created in a heavy-ion collision in run-time scenarios closely resembling the final CBM environment

MARTA: A high-energy cosmic-ray detector concept with high-accuracy muon measurement

A new concept for the direct measurement of muons in air showers is presented. The concept is based on resistive plate chambers (RPCs), which can directly measure muons with very good space and time resolution. The muon detector is shielded by placing it under another detector able to absorb and measure the electromagnetic component of the showers such as a water-Cherenkov detector, commonly used in air shower arrays. The combination of the two detectors in a single, compact detector unit provides a unique measurement that opens rich possibilities in the study of air showers.Comment: 11 page