This article reviews the progress made over the last 20 years in the development and applications of liquid xenon detectors in particle physics, astrophysics, and medical imaging experiments. A summary of the fundamental properties of liquid xenon as radiation detection medium, in light of the most current theoretical and experimental information is first provided. After an introduction of the different type of liquid xenon detectors, a review of past, current, and future experiments using liquid xenon to search for rare processes and to image radiation in space and in medicine is given. Each application is introduced with a survey of the underlying scientific motivation and experimental requirements before reviewing the basic characteristics and expected performance of each experiment. Within this decade it appears likely that large volume liquid xenon detectors operated in different modes will contribute to answering some of the most fundamental questions in particle physics, astrophysics, and cosmology, fulfilling the most demanding detection challenges. From detectors based solely on liquid xenon (LXe) scintillation, such as in the MEG experiment for the search of the rare ''{mu}{yields}e{gamma}'' decay, currently the largest liquid xenon detector in operation, and in the XMASS experiment for dark matter detection, to the class ofmore » time projection chambers which exploit both scintillation and ionization of LXe, such as in the XENON dark matter search experiment and in the Enriched Xenon Observatory for neutrinoless double beta decay, unrivaled performance and important contributions to physics in the next few years are anticipated.« less

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Liquid Xenon Detectors for Particle Physics and Astrophysics

We review the current status of liquid noble gas radiation detectors with energy threshold in the keV range, which are of interest for direct dark matter searches, measurement of coherent neutrino scattering and other low energy particle physics experiments. Emphasis is given to the operation principles and the most important instrumentation aspects of these detectors, principally of those operated in the double-phase mode. Recent technological advances and relevant developments in photon detection and charge readout are discussed in the context of their applicability to those experiments.

Liquid noble gas detectors for low energy particle physics

A comprehensive model for explaining scintillation yield in liquid xenon is introduced. We unify various definitions of work function which abound in the literature and incorporate all available data on electron recoil scintillation yield. This results in a better understanding of electron recoil, and facilitates an improved description of nuclear recoil. An incident gamma energy range of O(1 keV) to O(1 MeV) and electric fields between 0 and O(10 kV/cm) are incorporated into this heuristic model. We show results from a Geant4 implementation, but because the model has a few free parameters, implementation in any simulation package should be simple. We use a quasi-empirical approach with an objective of improving detector calibrations and performance verification. The model will aid in the design and optimization of future detectors. This model is also easy to extend to other noble elements. In this paper we lay the foundation for an exhaustive simulation code which we call NEST (Noble Element Simulation Technique).

https://iopscience.iop.org/article/10.1088/1748-0221/6/10/P10002/pdf

NEST: A Comprehensive Model for Scintillation Yield in Liquid Xenon

The density and temperature dependences of the mean energy to form an ion pair, W-value, and the intrinsic energy resolution, ΔE0, of high-pressure Xe were investigated with a parallel plate ionization chamber. A temperature and pressure independent technique to monitor the density of Xe was used. Changes in both the W-value and ΔE0 were observed, as a function of temperature between 14°C and 70°C and density between 0.12 and 1.7 g/cm3, and these were found to correlate with the formation of energy bands in Xe, for the former, and changes in the recombination rate, for the latter. Qualitative analysis of the experimental results is presented.

The spectroscopic properties of high-pressure xenon

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 charge and energy resolution response of a liquid xenon ionization chamber has been measured with 207Bi electrons and gamma-rays. The applied electric field was varied in the range 0.06–12 kV/cm. After an initial steep rise, charge collection increases slowly above a few kV/cm and does not reach saturation within our range. This field dependence has been analyzed in view of different recombination models. The best agreement is obtained by including the contribution of delta electrons. The best energy resolution, measured at 12 kV/cm, is 5.9% FWHM for gamma-rays of 570 keV. This value is consistent with the expected recombination fluctuations in the number of electron-ion pairs associated with low energy delta electron tracks.

Performance of a liquid xenon ionization chamber irradiated with electrons and gamma-rays

The time dependence and the intensity of the primary scintillation light in liquid xenon excited by /sup 241/Am alpha particles and /sup 207/Bi internal conversion electrons were measured at different electric field strengths. High-purity liquid xenon was used to fill a parallel-plate ionization chamber equipped with a CaF/sub 2/ window coupled to a UV (ultraviolet) sensitive photomultiplier tube. The effect of the specific ionization density on the scintillation light as well as the time correlation between the light signal and the charge signal is reported. It is demonstrated that the fast scintillation signal produced in liquid xenon by an ionizing particle provides an ideal trigger in a detector aiming at a complete three-dimensional event reconstruction with an excellent background rejection capability. >

A study of the scintillation light induced in liquid xenon by electrons and alpha particles

A gridded ionization chamber with a gap of 5.9 cm was used to study the drift of conduction electrons in liquid xenon. Electrons were generated by cosmic rays traversing the active volume of 0.6 liter. To be sensitive to the effect of electron attachment by electronegative impurities, long drift distances, or equivalently, long drift times, were achieved by reducing the electric field strength. Data were recorded for the range 7 V/cm ≤ E

Measurements of the lifetime of conduction electrons in liquid xenon

The ionization yield of 241 Am 5.49 MeV and 210 Po 5.31 MeV alpha particles in liquid xenon has been measured as a function of electric field strength in the range 0.05 kV/cm to 20 kV/cm. Consistent results are obtained with the two sources. The maximum charge collected at 10 kV/cm is less than 10% of the total and the noise subtracted energy resolution is 2.5% FWHM at 5.49 MeV, dominated by statistical fluctuations in the number of electron—ion pairs escaping recombination. A comparison with our alpha particle data in liquid argon shows a much worse energy resolution and a different slope of the ionization curve at a given field. The different response of the two liquids is explained in terms of track ionization density and recombination dependence on track emission angle.

Ionization of liquid xenon by 241Am and 210Po alpha particles

The spatial resolution of a liquid xenon ionization chamber operated in the time projection mode was measured with a multiwire anode structure, using cosmic rays traversing a maximum drift gap of 5.9 cm. From the digitized pulse shape of the ionization signal induced on the anode wires, the timing information was measured for different track orientations in space. In order to estimate the resolution capability of the chamber, tracks entering the chamber at about 50° with respect to the horizontal were selected, as they would most likely induce a signal on all the wires. The accuracy on the measured drift time, limited mostly by electronic noise and electric field shaping, translates into a spatial resolution of 180 μm rms for the z -coordinate along the drift direction.

M. Suzuki

Papers

Performance of a liquid xenon ionization chamber irradiated with electrons and gamma-rays

A study of the scintillation light induced in liquid xenon by electrons and alpha particles

Measurements of the lifetime of conduction electrons in liquid xenon

Ionization of liquid xenon by 241Am and 210Po alpha particles

Test of a two-dimensional liquid xenon TPC