High-precision Detector Research Articles

High-precision analogue peak detector for X-ray imaging applications

A new analogue high-precision peak detector is presented. Owing to its very low power consumption the circuit is particularly well suited for photon energy detection in multichannel receiver integrated circuits used in nuclear medicine.

Test alert service against very large SEP Events

The Aragats Solar Environment Center provides real time monitoring of different components of secondary cosmic ray fluxes. We plan to use this information to establish an early warning alert system against extreme, very large solar particle events with hard spectra, dangerous for satellite electronics and for the crew of the Space Station. Neutron monitors operating at altitude 2000 and 3200 m are continuously gathering data to detect possible abrupt variations of the particle count rates. Additional high precision detectors measuring muon and electron fluxes, along with directional information are under construction on Mt. Aragats. Registered ground level enhancements, in neutron and muon fluxes along with correlations between different species of secondary cosmic rays are analyzed to reveal possible correlations with expected times of arrival of dangerous solar energetic particles.

Aragats space-environmental centre: status and SEP forecasting possibilities

The Aragats Space Environment Center in Armenia provides real-time monitoring of cosmic particle fluxes. Neutron monitors operating at altitudes of 2000 m and 3200 m on Mt Aragats continuously gather data to detect possible abrupt enhancement of the count rates. Additional high precision detectors, measuring muon and electron fluxes, along with directional information have been put in operation on Mt Aragats in the summer of 2002. We plan to use this information to establish an early warning system against extreme solar energetic particle (SEP) events which pose danger to the satellite electronics and the space station crew. Solar ion and proton fluxes as measured by space-borne sensors on ACE and GOES satellites are used to derive expected arrival times of highest energy ions at 1 AU. The peaks in the time series detected by Aragats neutron monitors, coincided with these times, demonstrate the possibility of early detection of SEP events using the ground-based detectors.

A detector for the TESLA project

An overview of the detectors foreseen for the European e + e − Linear Collider (TESLA) is presented. The requirements from the Physics program imply high precision detectors. The detector concepts and the expected detector performance are illustrated.

Investigations of weak couplings measuring angular correlations in μ-capture: impact of nuclear models

The angular correlations were investigated measuring with high-precision HPGe detectors γ-lines following the ordinary muon capture (OMC) on 28Si and 16O. The Doppler-broadened shapes of these lines are sensitive to the weak couplings as well as to the nuclear matrix elements (NME) of OMC transitions.

THE ZEUS MICROVERTEX DETECTOR

A new silicon microvertex detector (MVD) will be installed in the ZEUS experiment during the 2000 HERA luminosity upgrade. Such a high precision detector will improve the global tracking system and allow to identity events with secondary vertices originating from the decays of long-lived states. It will be placed in the proximity to the beam pipe to surround the interaction region. The barrel part is a 60 cm long cylinder consisting of three double layers of single-sided silicon detectors, the forward part is made of four double shaped layers, called wheels, extending 42 cm along the beam. A test beam has been setup in order to characterize the performance of the detector modules and readout electronics (i.e. track position resolution, signal to noise ratio, detection efficiency). The detector layout and some selected test beam results are presented.

The digital readout system for the CMS electromagnetic calorimeter

The CMS Electromagnetic Calorimeter is a high-precision detector demanding innovative solutions in order to cope with the high dynamic range and the extreme high resolution of the detector as well as with the harsh environment created by the high level of radiation and the 4 T magnetic field. The readout system is partly placed within the detector and partly in the adjacent counting room. As the on-detector electronics must cope with the harsh environment the use of standard components is excluded for this part of the system. This paper describes the solutions adopted for the high-precision analogue stages, the A–D conversion, the optical transfer of the raw data from the on-detector part to the so-called Upper Level Readout, placed in the counting room, and the functionality of the latter. The ECAL is instrumental in providing information to the first-level trigger process and the generation of this information will be described. Also, the problem of reducing the raw data volume (6×10 12 bytes/s) to a level that can be handled by the central DAQ system (10 5 bytes/s) without degrading the physics performance will be discussed.

Charge-coupled devices as particle tracking detectors

Following a few years after the invention of the charge-coupled device (CCD) in 1970, the discovery of charmed particles established the need for very high precision (few μm) detectors for tracking high energy charged particles. This review describes the work which has evolved over the past 20 years from these disconnected events, both as regards the application of increasingly refined CCDs to particle tracking (in particular as vertex detectors for identifying heavy flavor quarks and tau leptons), and also the advances in CCD detector design stimulated by these requirements. The lessons learned in this work should provide guidance for the construction of large arrays of CCDs or active pixel devices in the future in a number of areas of science and technology.

Precision microvertex detectors

The current status and future perspectives of the development of high-precision microvertex detectors are reviewed. A description is given of the characteristics, operating principles, and methods of signal readout from microvertex detectors designed on the basis of semiconductor technology and fiber-optics light-guide techniques. The parameters of the best known microvertex detectors used in fixed-target and collider experiments are given in tables. The specialized processors used for fast calculation of the impact parameter and selection of events containing decay vertices are discussed.

A CDMA communication detector with robust near-far resistance using paralleled array processors

The code division multiple access (CDMA) scheme has become very popular due to high efficiency for spectrum usage and robust jamming resistance. However, the inherent near-far problem is an impediment. Though deliberate power control algorithms can partially handle this problem, the cost is high. Under the assumption of synchronous symbols and white Gaussian noise, a neural-network-based detector with robust near-far resistance is presented. By proper mapping and applying a hardware annealing technique, compact realization of high precision detectors is possible.

Testing quantum mechanics in the neutral kaon system at a φ-factory

In this paper the possibility of performing a Bell-type test of quantum mechanics in the neutral kaon system at a φ-factory is discussed. It is shown that a Bell inequality can be formulated for this system using a formalism based on a kaon quasispin picture and taking into account CP violation. Tiny violations of this inequality by quantum mechanics could be experimentally tested at a high luminosity φ-factory, by exploiting either coherent K S - K L regeneration in a thin regenerator, or single kaon quasispin oscillations in vacuum. The high precision detector of an experiment at a φ-factory, addressing direct CP violation in neutral kaon decays, could successfully perform such a test.

Results of a thyroid monitoring survey carried out on workers exposed to 125I in São Paulo, Brazil.

The thyroids of 30 workers performing routine 125I labelling in several laboratories of the city of São Paulo have been monitored about once every 2-3 mo from November 1985 to October 1986. Twenty-five of them presented a significant radioactivity (in our detection system greater than 62 Bq), but none reached the maximum permissible thyroid burden. The maximum measured thyroid contamination is 24 kBq (650 nCi). The uptakes were determined by comparison with a standard curve obtained by placing various calibrated standard sources of 125I in a thyroid neck phantom. The paper also describes the set up of quality controlled counting conditions, with high sensitivity, precision, accuracy and stable detector efficiency, by adaptation of an old equipment to this purpose. Calculated 125I effective half-lives for five individuals ranged between 31.7 and 47.0 d, the average being 39.4 +/- 6.1 d.

Use of Charge-Coupled Devices as High Precision Detectors

We describe here the readout system and performance for the two charge-coupled devices being used in the NA32 charm production experiment on the SPS at CERN by the ACCMOR Collaboration.