Massive Calorimeter Research Articles

Heat capacity of liquid Cs80Bi20 alloy with a partly ionic character of interatomic interaction

Enthalpy increment of CS80Bi20 liquid alloy in the temperature range of 857–1076 K was measured by mixing method on a massive calorimeter with an isothermal shell. The heat capacity of the melt was determined and it was found that for the studied temperature range it remains constant, and its absolute value exceeds significantly the calculation by the additivity rule. The estimated errors for enthalpy and heat capacity of the melt were 0.4 and 1%, respectively. An approximation equation was obtained for the dependence of the mass heat capacity of the solid alloys of the cesium-bismuth system at 298.15 K by the atomic concentration of bismuth.

The ν-cleus experiment: Gram-scale cryogenic calorimeters for a discovery of coherent neutrino scattering

We investigate new gram-scale cryogenic detectors, 1-2 orders of magnitude smaller in size than previous devices. These are expected to reach unprecedentedly low energy thresholds, in the 10 eV-regime and below. This technology allows new approaches in rare-event searches, including the search for MeV-scale dark matter, detection of solar neutrinos and a rapid discovery of coherent neutrino-nucleus scattering (CNNS) at a nuclear reactor. We show a simple scaling law for the performance of cryogenic calorimeters, allowing the extrapolation of existing device performances to smaller sizes. Measurement results with a 0.5 g sapphire detector are presented. This prototype reached a threshold of 20 eV, which is one order of magnitude lower than previous results with massive calorimeters. We discuss an experiment, called ν-cleus, which enables a 5-σ discovery of CNNS within about 2 weeks of measuring time at 40 m distance from a power reactor. In a second stage, this experiment enables precision measurements of the CNNS cross-section and spectral shape for new physics within and beyond the Standard Model.

Operation Features of the Electronic Circuit of the Warm Liquid Tetramethylsilane (TMS) Detector

It is urgent to use a “warm liquid” TMS in large massive calorimeters (with a volume of several hundred liters). This direction in modern nuclear physics is referred to as “non-accelerator” experiments with low-background detectors. Such experiments are associated with the solution of most important problems to understand the Universe structure and search for new particles. These are the well-known problems for searching “dark matter” in the form of new weakly interacting particles, i.e., wimps, observations of coherent scattering of reactor neutrinos. Using this experiment, the standard model of electroweak interactions can be tested. The fully developed fabrication technology of large amounts of “warm liquid” ТМS (in collaboration with the State Research Institute of Chemistry and Technology of Organoelement Compounds) makes it possible to perform such experiments.

Pilot installation for the purificationof the «warm liquid» of tetramethylsilane and conducting «non-accelerating experiments»

The use of «warm liquid» tetramethylsilane (TMS) is relevant in large massive calorimeters (with a volume of several hundred liters) to search for processes with very low energy releases. This direction is called «non-accelerator» experiments with low-background detectors.

The Distinctive Features of Anticoincidence Detector System of the GAMMA-400 Gamma-ray Telescope

Some features of scintillation anticoincidence system (includes ACtop detector section located upper the converter-tracker and four AClat ones placed from its lateral sides) of the GАММА-400 gamma-ray telescope, related to joint operations with another fast scintillation systems: SDC (scintillation detector system of calorimeter) and TOF (time-of-flight system) are considered. The main problem for high-energy (over 50GeV) gamma-rays registration by gamma-telescopes is the presence of so-called «backsplash current» (BS) of particles from massive calorimeter when detecting of particles is provided. BS is a set of low energy particles, moving up from the calorimeter and producing triggering of the anticoincidence detectors, imitating detection of a charged particle. As an additional indicator of BS particles presence of in the ACtop detector, we offer the value of energy release in the S3 scintillation detector placing between two parts of the calorimeter (CC1 and CC2). Fast trigger signal in the main aperture for gamma-quanta is composed of analysis of TOF system signal, showing that charged particle or particles move in the direction from up to down, and ACtop energy deposition taking in to account specially designed for GAMMA-400 algorithms of backsplash rejection.

Cross-section measurements in the NOMAD experiment

The NOMAD experiment collected valuable neutrino data samples, matching both the large statistics of massive calorimeters and the reconstruction quality of bubble chambers. This paper describes the recent measurements of neutrino cross-sections on carbon target. The approach followed for cross-section modeling is also explained.

Observation and simulations of the backsplash effects in high-energy γ-ray telescopes containing a massive calorimeter

Beam test and simulation results are presented for a study of the backsplash effects produced in a high-energy γ-ray detector containing a massive calorimeter. An empirical formula is developed to estimate the probability (per unit area) of backsplash for different calorimeter materials and thicknesses, different incident particle energies, and at different distances from the calorimeter. The results obtained are applied to the design of the Anti-Coincidence Detector (ACD) for the Large Area Telescope (LAT) on the Gamma-ray Large Area Space Telescope (GLAST).

Science with low temperature detectors

The novel technique of particle detection with low temperature detectors opens a number of new scientific opportunities. We review some of these, focusing on three generic applications: far infrared bolometry taking as an example the cosmic microwave background, X-ray spectroscopy for astrophysics and biological applications, and massive calorimeters for dark matter searches and neutrino physics.

Scintillation yields by relativistic heavy ions and the relation between ionization and scintillation in liquid argon

Scintillation yields per unit energy deposited by relativistic heavy ions in liquid argon have been measured. They are (1.41 ± 0.07) for 613 MeV/n Ne ions and (1.39 ± 0.07) for 705 MeV/n Fe ions, if the value is normalized to unity for 5.3 MeV alpha particles. These results show that the scintillation intensity for relativistic heavy ions in liquid argon is proportional to the deposited energy, that is, to Z 1 2, where Z 1 is the nuclear charge of heavy ions. Furthermore, the variation of ionization and scintillation in liquid argon has been investigated as a function of electric field using relativistic Ne and Fe ions. It is shown that a linear combination of ionization signal I and scintillation signal S, I + aS, is proportional to the deposited energy, independently of electric field strength and types of incident particles. This suggests that if we use both signals, we may construct a massive calorimeter that can be used for nuclear reactions induced by relativistic heavy ions.

High-temperature enthalpy of silicon nitride base materials

1. In the work described, using the method of mixing in a massive calorimeter, the enthalpy of Si3N4+5% MgO, Si3N4+10% MgO, Si3N4+5% MgO+20% BN, and Si3N4+10% MgO+20% BN materials was measured for the first time. 2. Equations describing the temperature dependence of the enthalpy and heat capacity of these silicon nitride base materials were obtained by the least-squares method. On the basis of the data yielded by this work, a temperature range is recommended for the practical employment of the composites investigated.

Enthalpy and specific heat of tantalum carbide in its homogeneity region

1. Using the method of mixing in a massive calorimeter, measurements were made of the enthalpy of the carbides TaC0.70, TaC0.78, TaC0.85, and TaC0.99 over the temperature range 1200–2200°K. 2. The specific heat of the cubic tantalum carbide TaCx in its homogeneity region over the temperature range 1200–2200°K can be described, as a function of temperature, by the equation:Cp=7.3−1.5· 10−3T+(0.773+1. 467·10−3T·ex. 3. The results obtained together with literature data were used in compiling a table of values of enthalpy, specific heat, entropy, and reduced thermodynamic potential for the carbide TaC0.99 over the temperature range 298–2500°K.

Experimental determinaton of the enthalpy and heat capacity of molybdenum up to 2337°C

Results of the experimental determination of the enthalpy and heat capacity of molybdenum between 700°C and 2337°C are presented in the form of a table, diagram and equations. Experimental data were obtained by the method of mixtures using a massive calorimeter with an isothermal shell. A sample was heated to a high temperature in a furnace with a tungsten heater, in a vacuum or in an argon medium. The paper deals with some methods of an experimental determination of the enthalpy at very high temperatures. The experimental results are compared with those in the literature. For the determination of enthalpy the limiting accidental error was ±0.4 per cent using a thermocouple to measure temperature up to 1300°C, and ±0.9 and ± 1.2 per cent using a disappearing-filament optical pyrometer for temperatures up to 2000°C and 2400°C, respectively.