The assessment of the ecological quality of surface water bodies has a long tradition and has become even more important over the last decade. Unfortunately the thorough sampling of the faunistic ...quality components is too seldom accompanied by an equally detailed analysis of the hydromorphological structures which form the basis of the aquatic ecosystems. This has led to sophisticated faunistic evaluations based on crude assumptions. The TRiSHa method (Typology of Riverbed Structures and Habitats) was specifically designed to correct this current lopsidedness. It is a hydromorphological mapping method that complements the state of the art hydrobiological methods like PERLODES and thus can provide the missing detailed information about the structural characteristics of riverbeds, which form the basis for the faunistic evaluations. TRiSHa provides a strong focus on the scale of the microhabitats, which are most relevant for the species of the macrozoobenthos, an often used ecological quality indicator. The method is easy to apply, scales well for (wadeable) river stretches of different sizes and is, due to its inductive habitat classification system, fully expandable. It is well suited for a wide range of scientific and water management topics like the high resolution analysis of riverbed structures, their heterogeneity and diversity as well as the spatial and temporal dynamic of individual parameters or whole river stretches. This paper presents the TRiSHa method in detail and exemplifies potential scientific applications through two showcase examples.
The AMS-02 TRD for the international space station Hauler, F.; Bartoloni, A.; Becker, U. ...
IEEE transactions on nuclear science,
2004-Aug., 2004-08-00, 20040801, Letnik:
51, Številka:
4
Journal Article
Recenzirano
The Alpha Magnetic Spectrometer (AMS-02) is an experiment which will be mounted on the international space station (ISS) to measure primary cosmic ray spectra in space. A key element is the ...transition radiation detector (TRD) to extract an e/sup +/ or p/sup -/ signal reducing the p/sup +/ or e/sup -/ background by a rejection factor 10/sup 2/--10/sup 3/ in an energy range from 10 to 300 GeV. This will be used in combination with an electromagnetic calorimeter to provide overall p/sup +/ rejection of 10/sup 6/ at 90% e/sup +/ efficiency. The detector consists of 20 layers of 6 mm diameter straw tubes alternating with 20 mm layers of polyethylene/polypropylene fleece radiator. The tubes are filled with a 4:1 mixture of Xe:CO/sub 2/ at 1 bar absolute pressure from a recirculating gas system designed to operate >3 years in space. There are in total 5248 straw tubes which are read out by a custom-made DAQ system in less than 80 /spl mu/s. The electronics must be low in power consumption and sustain the stringent requirements of operation in space. The construction of the detector and its electronics is presented in this paper.
CMOS monolithic active pixel sensors (MAPS) constitute a novel technique for position sensitive charged particle detectors. Their development is driven by the requirements of vertex detectors for ...future high-energy and nuclear physics experiments as well as by those of biomedical applications, namely highly granular dosimetry. The radiation hardness of MAPS-detectors is subject to intensive studies. Their resistance against up to ∼10
12
n
eq/cm
2 was demonstrated M. Deveaux, G. Claus, G. Deptuch,W. Dulinski, Y. Gornushkin, M. Winter, Nucl. Instr. and Meth. A 512 (2003) 71–76. On the other hand, only poor data are available so far about their resistance against ionising doses. This paper summarises the results of radiation hardness studies on two different MAPS-detectors up to a dose of 1
MRad.
For TeV energy superconducting linear accelerator (TESLA), it is foreseen to measure the beam profile with so-called wire scanners. A thin carbon fiber is moved through the beam and the number of ...scattered secondary particles is measured in correlation to the position of the wire. From this, a beam profile can be calculated as an average over many bunches of the beam. With strip detectors made from diamond, the beam profile can be measured online for single bunches. With two perpendicular arrays of strips on the front and the back side of the detector, the beam profile can also be measured in the X and Y direction. If fast electronics are used and the bunches are not too short, even a longitudinal profile in the Z direction can be obtained. We successfully tested a diamond detector in a heavy ion beam with bunches of up to 3/spl middot/10/sup 10/ O/sup 6+/ ions and in a beam of 10/sup 10/ electrons in bunches with a length of 300 /spl mu/m, as planned for TESLA. The fluence of 10/sup 15/ e/sup -//cm/sup 2/ or more by one of the bunches foreseen for TESLA corresponds to the irradiation a vertex detector receives during ten years of large hadron collider. The results of our measurements will be presented and discussed.
There are two key approaches in our CERN RD 39 Collaboration efforts to obtain ultra-radiation-hard Si detectors: (1) use of the charge/current injection to manipulate the detector internal electric ...field in such a way that it can be depleted at a modest bias voltage at cryogenic temperature range (⩽150
K), and (2) freezing out of the trapping centers that affects the CCE at cryogenic temperatures lower than that of the liquid nitrogen (LN
2) temperature.
In our first approach, we have developed the advanced radiation hard detectors using charge or current injection, the current injected diodes (CID). In a CID, the electric field is controlled by injected current, which is limited by the space charge, yielding a nearly uniform electric field in the detector, independent of the radiation fluence. In our second approach, we have developed models of radiation-induced trapping levels and the physics of their freezing out at cryogenic temperatures.
The SUCIMA collaboration has been developing instruments and methods for real-time, high granularity imaging of extended electron sources. In particular, dosimetry of intravascular brachytherapy
β
...sources has been intensively studied, together with monitoring of hadrontherapy beams by imaging of secondary electrons emitted by a non-disruptive target. The paper reports the latest results on absolute dosimetry with a large-area silicon strip detectors and on beam monitoring with a hybrid pad sensor.
An algorithm for calculating the Lorentz angle in silicon detectors Bartsch, V.; de Boer, W.; Bol, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2003, Letnik:
497, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Future experiments will use silicon sensors in the harsh radiation environment of the Large Hadron Collider and high magnetic fields. The drift direction of the charge carriers is affected by the ...Lorentz force due to the high magnetic field. Also the resulting radiation damage changes the properties of the drift.
In this paper measurements of the Lorentz angle of electrons and holes before and after irradiation are reviewed and compared with a simple algorithm to compute the Lorentz angle.
The recovery of the charge collection efficiency (CCE) at low temperatures, the so-called ”Lazarus effect”, was studied in Si detectors irradiated by fast reactor neutrons, by protons of medium and ...high energy, by pions and by gamma-rays. The experimental results show that the Lazarus effect is observed: (a) after all types of irradiation; (b) before and after space charge sign inversion; (c) only in detectors that are biased at voltages resulting in partial depletion at room temperature. The experimental temperature dependence of the CCE for proton-irradiated detectors shows non-monotonic behaviour with a maximum at a temperature defined as the CCE recovery temperature. The model of the effect for proton-irradiated detectors agrees well with that developed earlier for detectors irradiated by neutrons. The same midgap acceptor-type and donor-type levels are responsible for the Lazarus effect in detectors irradiated by neutrons and by protons. A new, abnormal “zigzag”-shaped temperature dependence of the CCE was observed for detectors irradiated by all particles (neutrons, protons and pions) and by an ultra-high dose of γ-rays, when operating at low bias voltages. This effect is explained in the framework of the double-peak electric field distribution model for heavily irradiated detectors. The redistribution of the space charge region depth between the depleted regions adjacent to p+ and n+ contacts is responsible for the “zigzag”- shaped curves. It is shown that the CCE recovery temperature increases with reverse bias in all detectors, regardless of the type of radiation.
The charge collection efficiency (CCE) of heavily irradiated silicon diode detectors was investigated at temperatures between 77 and 200
K. The CCE was found to depend on the radiation dose, bias ...voltage value and history, temperature, and bias current generated by light. The detector irradiated to the highest fluence 2×10
15
n/cm
2 yields a MIP signal of at least 15000
e
− both at 250
V forward bias voltage, and at 250
V reverse bias voltage in the presence of a light-generated current. The “Lazarus effect” was thus shown to extend to fluences at least ten times higher than was previously studied.
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