39 research outputs found
The Successful Operation of Hole-type Gaseous Detectors at Cryogenic Temperatures
We have demonstrated that hole-type gaseous detectors, GEMs and capillary
plates, can operate up to 77 K. For example, a single capillary plate can
operate at gains of above 10E3 in the entire temperature interval between 300
until 77 K. The same capillary plate combined with CsI photocathodes could
operate perfectly well at gains (depending on gas mixtures) of 100-1000.
Obtained results may open new fields of applications for capillary plates as
detectors of UV light and charge particles at cryogenic temperatures: noble
liquid TPCs, WIMP detectors or LXe scintillating calorimeters and cryogenic
PETs.Comment: Presented at the IEEE Nuclear Science Symposium, Roma, 200
Study of capillary-based gaseous detectors
We have studied gain vs. voltage characteristics and position resolutions of
multistep capillary plates (two or three capillary plates operating in a
cascade), as well as capillary plates operating in a mode when the main
amplification occurs between plates or between the capillary plate and the
readout plate (parallel plate amplification mode). Results of these studies
demonstrated that in the parallel-plate amplification mode one can reach both
high gains (>100000) and good position resolutions (~100 micro meter) even with
a single step arrangement. It offers a compact amplification structure, which
can be used in many applications. For example, in preliminary tests we
succeeded to combine it with a photocathode and use it as a position sensitive
gaseous photomultiplier. CsI coated capillary plates could also be used as a
high position resolution and high rate X-ray converter.Comment: Presented at the NSS IEEE 2003 conference in Portland, submitted to
TN
A Study of the Operation of Especially Designed Photosensitive Gaseous Detectors at Cryogenic Temperatures
In some experiments and applications there is need for large-area
photosensitive detectors to operate at cryogenic temperatures. Nowadays, vacuum
PMs are usually used for this purpose. We have developed special designs of
planar photosensitive gaseous detectors able to operate at cryogenic
temperatures. Such detectors are much cheaper PMs and are almost insensitive to
magnetic fields. Results of systematic measurements of their quantum
efficiencies, the maximum achievable gains and long-term stabilities will be
presented. The successful operation of these detectors open realistic
possibilities in replacing PMs by photosensitive gaseous detectors in some
applications dealing with cryogenic liquids; for example in experiments using
noble liquid TPCs or noble liquid scintillating calorimeters.Comment: Submitted to the Nuclear Instruments and Method
A High Position Resolution X-ray Detector: an Edge on Illuminated Capillary Plate Combined with a Gas Amplification Structure
We have developed and successfully tested a prototype of a new type of high
position resolution hybrid X-ray detector. It contains a thin wall lead glass
capillary plate converter of X-rays combined with a microgap parallel-plate
avalanche chamber filled with gas at 1 atm. The operation of these converters
was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident
angles varying from 0-90 degree. The detection efficiency, depending on the
geometry, photon energy, incident angle and the mode of operation, was between
5-30 percent in a single step mode and up to 50 percent in a multi-layered
combination. Depending on the capillary geometry, the position resolution
achieved was between 0.050-0.250 mm in digital form and was practically
independent of the photon energy or gas mixture. The usual lead glass capillary
plates operated without noticeable charging up effects at counting rates of 50
Hz/mm2, and hydrogen treated capillaries up to 10E5 Hz/mm2. The developed
detector may open new possibilities for medical imaging, for example in
mammography, portal imaging, radiography (including security devices),
crystallography and many other applications.Comment: Presented at the IEEE Nuclear Science Symposium, Roma, Octber 200
The development of gaseous detectors with solid photocathodes for low temperature
There are several applications and fundamental research areas which require
the detection of VUV light at cryogenic temperatures. For these applications we
have developed and successfully tested special designs of gaseous detectors
with solid photocathodes able to operate at low temperatures: sealed gaseous
detectors with MgF2 windows and windowless detectors. We have experimentally
demonstrated, that both primary and secondary (due to the avalanche
multiplication inside liquids) scintillation lights could be recorded by
photosensitive gaseous detectors. The results of this work may allow one to
significantly improve the operation of some noble liquid gas TPCs.Comment: Presented at the X Vienna Conference on Instumentation, Vienna,
February 200
The Development and Study of High-Position Resolution (50 micron) RPCs for Imaging X-rays and UV photons
Nowadays, commonly used Resistive Plate Chambers (RPCs) have counting rate
capabilities of ~10E4Hz/cm2 and position resolutions of ~1cm. We have developed
small prototypes of RPCs (5x5 and 10x10cm2) having rate capabilities of up to
10E7Hz/cm2 and position resolutions of 50 micron("on line" without application
of any treatment method like "center of gravity"). The breakthrough in
achieving extraordinary rate and position resolutions was only possible after
solving several serious problems: RPC cleaning and assembling technology,
aging, spurious pulses and afterpulses, discharges in the amplification gap and
along the spacers. High-rate, high-position resolution RPCs can find a wide
range of applications in many different fields, for example in medical imaging.
RPCs with the cathodes coated by CsI photosensitive layer can detect
ultraviolet photons with a position resolution that is better than ~30 micron.
Such detectors can also be used in many applications, for example in the focal
plane of high resolution vacuum spectrographs or as image scanners.Comment: 6 pages, 5 figures, other comment
Photosensitive Gaseous Detectors for Cryogenic Temperature Applications
There are several proposals and projects today for building LXe Time
Projection Chambers (TPCs) for dark matter search. An important element of
these TPCs are the photomultipliers operating either inside LXe or in vapors
above the liquid.
We have recently demonstrated that photosensitive gaseous detectors (wire
type and hole-type) can operate perfectly well until temperatures of LN2. In
this paper results of systematic studies of operation of the photosensitive
version of these detectors (combined with reflective or semi-transparent CsI
photocathodes) in the temperature interval of 300-150 K are presented. In
particular, it was demonstrated that both sealed and flushed by a gas detectors
could operate at a quite stable fashion in a year/time scale. Obtained results,
in particular the long-term stability of photosensitive gaseous detectors,
strongly indicate that they can be cheap and simple alternatives to
photomultipliers or avalanche solid-state detectors in LXe TPC applications.Comment: Submitted to the Proceedings of the PSD-7 Conf. in Liverpool, U
Evaluation of various planar gaseous detectors with CsI photocathodes for the detection of primary scintillation light from noble gases
Noble gases and liquids are excellent scintillators and this opens a unique opportunity to directly detect the primary scintillation light produced in these media by photons or particles. This signal can be used for several purposes, for example as a start signal for TPCs or for particles identification. Usually photomultipliers (PMs) are used for the detection of the scintillation light. In our previous work we have demonstrated that costly PMs could be replaced by gaseous detectors with CsI photocathodes . Such detectors have the same quantum efficiency as the best PMs but at the same time are cheap, simple and have high position and time resolutions. The aim of this work is to evaluate various planar type gaseous detectors with CsI photocahodes in order to choose the best one for the detection of the primary scintillation light from noble gases and liquids