Scintillation from liquid rare gases has a fast decay component with a high photon yield which is comparable to that of NaI(Tl), although the wavelength is in the vacuum ultraviolet. On the basis of these properties, many investigators have tried to realize liquid rare gas scintillation detector. In particular, liquid Xe is expected to be an excellent detector medium for γ-rays because of its fast response, its large atomic number, and high density. However, it is very difficult to achieve sufficient light collection as scintillator, because the light emission are in vacuum ultraviolet. Recently, some groups have reported liquid Xe/Kr homogeneous scintillation calorimeters for high-energy γ-rays using reflectors method, but their energy resolution was not as high as expected. In this situation it seems that the realization of liquid rare gas detectors may not be easy. In this paper, we review the physical properties of scintillation from liquid rare gas, the scintillation yields, the decay time constants and attenuation lengths. We summarize the results obtained with liquid rare gas scintillation detector. The present status of development of liquid Kr/Xe homogeneous scintillation calorimeters by using reflected light is described. A new device which observes only direct light is proposed as high-energy γ-ray detector or homogeneous electromagnetic shower calorimeters for γ-rays.

Present status of liquid rare gas scintillation detectors and their new application to gamma-ray calorimeters

The KEDR detector is a universal magnetic detector designed for studying the c- and b-quarks and two-photon physics, and is employed at the VEPP-4M e
 +
 e
 − collider. A specific feature of the experiment is the measurement of absolute beam energy using two methods: the resonant depolarization and the faster but less precise Compton backscattering of laser photons. This allowed a large series of measurements to be performed, in which the accuracy of determination of such fundamental parameters of particles as mass and total and leptonic widths was improved.

The KEDR detector

The UV scintillation light in liquid xenon has been observed using silicon drift photodiodes. Measurements were carried out in a rectangular light cell of dimentions 7.4 × 7.4 × 60 cm3 using 5 GeV electrons. The photodiodes and the preamplifiers were immersed in the liquid. A high quantum efficiency for 175 nm UV light has been measured. The scintillation light yield is found to be (1.5 ± 0.6) × 104 photons per MeV of energy deposited in liquid xenon. A light attenuation lenght of ≈ 40 cm has been measured.

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Observation of the UV scintillation light from high energy electron showers in liquid xenon

A historical view on the R&D for liquid rare gas detectors starting from 1948 up to now is presented with some comments on their applications to future experiments.

/pdf/a-historical-view-on-the-r-d-for-liquid-rare-gas-detectors-hmnssm6pd8.pdf

A historical view on the R&D for liquid rare gas detectors

A description of the liquid krypton calorimeter for the KEDR detector and experimental results on energy and position resolution obtained with prototypes are presented.

Liquid krypton calorimeter for KEDR detector

Effects determining the energy and spatial resolution of a calorimeter based on liquid krypton have been studied. With cathode strips of 10 mm a spatial resolution of 0.4 mm has been obtained in a cosmic rays test. The energy resolution of the calorimeter (0.4 ton of krypton) has been measured with positrons, achieving a rms of 5.7% at E = 130 MeV and 1.7% at E = 1200 MeV. The measurements are compared to Monte Carlo simulations.

Investigation of an electromagnetic calorimeter based on liquid krypton

Results of the experimental measurement of space and energy resolutions of a liquid krypton (LKr) e.m. calorimeter are presented. A prototype has been exposed to a positron test-beam in the energy range 130–1300 MeV at the VEPP-3 storage ring.

Yu.V. Pril

Papers

Investigation of an electromagnetic calorimeter based on liquid krypton

Space and energy resolutions in a liquid krypton e.m. calorimeter