Eric Hazen

IMB-3: a large water Cherenkov detector for nucleon decay and neutrino interactions

Abstract The IMB experiment, a large water Cherenkov detector which began data collection in September 1982, has undergone several upgrades to improve light collection, on-line processing power, data throughput and buffering, calibration, and operating efficiency. The current device, known as IMB-3, enjoys a factor of four light collection advantage over its precursor. Since May 1986, it has been used to search for such diverse phenomena as nucleon decay, dark matter, neutrino oscillation, and magnetic monopoles, and to study stellar collapse and cosmic rays. Due to its large size and long exposure time IMB presents unique challenges. The design and operation of the IMB-3 detector are described in detail.

ATLAS Muon Drift Tube Electronics

This paper describes the electronics used for the ATLAS monitored drift tube (MDT) chambers. These chambers are the main component of the precision tracking system in the ATLAS muon spectrometer. The MDT detector system consists of 1,150 chambers containing a total of 354,000 drift tubes. It is capable of measuring the sagitta o f muon tracks to an accuracy of 60 μm, which corresponds to a momentum accuracy of about 10% at pT = 1 TeV. The design and perfor- mance of the MDT readout electronics as well as the electronics for controlling, monitoring and powering the detector will be discussed. These electronics have been extensively tested under sim- ulated running conditions and have undergone radiation testing certifying them for more than 10 years of LHC operation. They are now installed on the ATLAS detector and are operating during cosmic ray commissioning runs.

Calibration of a digital hadron calorimeter with muons

The calibration procedure of a finely granulated digital hadron calorimeter with Resistive Plate Chambers as active elements is described. Results obtained with a stack of nine layers exposed to muons from the Fermilab test beam are presented.The calibration procedure of a finely granulated digital hadron calorimeter with Resistive Plate Chambers as the active elements is described. Results obtained with a stack of nine layers exposed to muons from the Fermilab test beam are presented.

On-chamber readout system for the ATLAS MDT muon spectrometer

The ATLAS MDT Muon Spectrometer is a system of approximately 380 000 pressurized cylindrical drift tubes of 3 cm diameter and up to 6 m in length. These monitored drift tubes (MDTs) are precision glued to form superlayers, which in turn are assembled into precision chambers of up to 432 tubes each. Each chamber is equipped with a set of mezzanine cards containing analog and digital readout circuitry sufficient to read out 24 MDTs per card. Up to 18 of these cards are connected to an on-chamber DAQ element referred to as a chamber service module (CSM). The CSM multiplexes data from the mezzanine cards and outputs this data on an optical fiber which is received by the off-chamber DAQ system. Thus, the chamber forms a highly self-contained unit with DC power in and a single optical fiber out. The MDTs, due to their length, require a terminating resistor at their far end to prevent reflections. The readout system has been designed so that thermal noise from this resistor remains the dominant noise source of the system. This level of noise performance has been achieved and maintained in large scale on-chamber tests.

The performance of photomultipliers exposed to helium

Abstract We report results of a study to determine how the performance of photomultipliers is affected by exposure to He. In our tests we monitor two 5 in. diameter EMI hemispherical photomultipliers while they are operated in He environments. Initially we observed He + afterpulses, at an approximately constant delay relative to the primary anode pulse. As the He gas pressure in the tubes increases however, strings of pulses typical of Townsend discharges occur. For the glass composition and geometry of the photomultipliers used in our tests, the internal gas concentration as a function of exposure to He is calculated using Ficks law for the permeation of solids by gases. The He permeation constant for the photomultiplier glass is obtained from a semiempirical formula developed by Altemose. We calculate the internal He concentration resulting from the He exposure which is observed to cause the regular occurrence of discharges and find that it is consistent with that required for production of discharges in the Townsend model. Guidelines are presented for using our results to estimate lifetimes of photomultipliers of different geometries and glass types when operated in He environments.

A new readout system for “Digital Hadron Calorimetry” for the International Linear Collider

A new detector concept called digital calorimetry is being developed for the International Linear Collider to achieve unprecedented jet energy resolution. Instead of traditional tower geometry and energy summation from many sampling layers, the new approach detects energy deposition in 1 cm2 cells on each sampling layer using discriminators. Jets are reconstructed using hit patterns from each layer, combined with information from inner tracking and the electromagnetic calorimeter. Detector R&D is in progress, and we are building a readout system for a 400,000 channel prototype detector to demonstrate this concept. The readout system uses a 64-channel custom integrated circuit called DCAL to record hits from each cell and apply a global timestamp. The chips mount directly on sophisticated front-end boards that are not only an integral part of the charge collection of the detector chambers, but also incorporate digital signal transmission, clock and control, and power and ground. The readout of data is serial, multiplexed into high-speed serial streams and sent to a back-end VME system for time-sorting and higher-level triggering. The system can be operated with an external trigger or be self-triggered, and can produce trigger signals from the front-end chips. We have built a vertical slice of the readout system, and are using it for tests of Resistive Plate Chambers (RPCs) and Gas Electron Multipliers (GEMs) in a test beam at Fermilab. This represents the first stage in building a 400,000 channel system for reading out the cubic meter prototype detector as part of the CALICE collaboration. The components of the system are described, and preliminary system performance is reported.

Calibration of the IMB detector

The IMB detector (named after its founding institutions: University of California, Irvine, the University of Michigan and Brookhaven National Laboratory) collected data on a wide range of phenomena for over eight years. It was the first and the largest of the ring imaging water Cherenkov detectors. The detector consisted of 8000 metric tons of ultra-pure water instrumented with 2048 photomultiplier tubes (PMTs). The PMTs were placed on the roof, floor, and walls of the detector in a lattice of approximately 1 m spacing. It made measurements of contained events that ranged in energy from 15 MeV up to 1.5 GeV. This paper describes the calibration of the IMB detector. This procedure was accurate and stable over a wide range of physical variables. It was used with little change throughout the entire eight-year lifetime of the experiment. The IMB calibration is a model for future large-scale detectors that employ the water Cherenkov technique.

A new multihit digital TDC implemented in a gallium arsenide ASIC

A monolithic multi-hit digital TDC (time-to-digital converter) has been developed for the DUMAND II experiment. This TDC has a 27 channel pipelined architecture, with a 1ns least count. An overview of the performance requirements and implementation in a GaAs gate array is described here. >

A fast TDC for the CPLEAR experiment at CERN

Abstract A fast time-to-digital converter, FTDC, based on a time-to-voltage converter and a fast successive-approximation ADC, is described. Results of tests of 64 FTDC cards within the experiments data acquisition system are presented. Circuit design techniques useful to future applications are discussed.

Glass-panel 6 Li neutron detector

We report on the development of a neutron detector utilizing solid enriched lithium, which has substantial neutron detection efficiency. The detector employs large, thin sheets of lithium in a gas-filled multi-wire proportional chamber (MWPC). Using low-cost design methods, readout electronics, and a small fraction of the already available enriched lithium available from Y-12/Oak Ridge National Laboratory, the amount of 3He equivalent detection capability for nuclear non-proliferation activities can be greatly increased.