Expected Count Rates Research Articles

Sensitivity of the CUORE detector to 14.4 keV solar axions emitted by the M1 nuclear transition of 57Fe

In this paper we present a calculation of the sensitivity of the CUORE detector to the monoenergetic 14.4 keV solar axions emitted by the M1 nuclear transition of 57Fe in the Sun and detected by inverse coherent Bragg-Primakoff conversion in single-crystal TeO2 bolometers. The expected counting rate is calculated using density functional theory for the electron charge density of TeO2 and realistic background and energy resolution of CUORE. Monte Carlo simulations for 5y × 741 kg=3705 kg y of exposure are analyzed using time correlation of individual events with the theoretical time-dependent counting rate. We find an expected model-independent limit on the product of the axion-photon coupling and the axion-nucleon coupling gaγγgaNeff < 1.105 × 10−16 /GeV for axion masses less than 500 eV with 95% confidence level.

Simulations on the measurement of the Ds meson semileptonic form factor with the PANDA detector

We report on software development to evaluate the expected performance of the PANDA detector to measure the semileptonic form factor Ds → e + v + π, η,η'. The related decay models in this chain are checked via a Dalitz plot analysis; the present version of EvtGen in PandaRoot has been enhanced by a new model describing the Ds → KKπ decay. With the help of theoretical predictions of the cross section, the expected count rate is estimated.

Neutron production during thunderstorms

We have analyzed the neutron fluxes correlated with thunderstorm activity recently measured at mountain altitudes by Tien-Shan, Tibet and Aragats groups. We perform simulations of the photonuclear reactions of gamma rays born in the electron-gamma ray avalanches in the thunderstorm atmosphere and calculate expected count rates of the neutron counters used by 3 groups. Our analysis supported the Tibet group conclusion on the photonuclear nature of thunderstorm-correlated neutrons. The photonuclear reactions of the gamma rays born in the electron-photon avalanches in the thunderstorm atmospheres interacting in the lead producer of a Neutron monitor can provide neutron yield compatible with additional count of NM at least for the largest Thunderstorm Ground Enhancements (TGEs).

Remarks on recent results on neutron production during thunderstorms

We analyze the neutron fluxes correlated with thunderstorm activity recently measured at mountain altitudes by the Tien-Shan, Tibet, and Aragats groups. We perform simulations of the photonuclear reactions of gamma rays born in the electron-gamma ray avalanches and calculate the expected count rates of the neutron detectors used by the three groups. We also present results of an independent experiment performed at the Nor Amberd high altitude research station in Armenia. Our analysis supports the Tibet and Aragats groups' conclusions on the photonuclear nature of thunderstorm-correlated neutrons (directly in the neutron monitor and in the atmosphere). The photonuclear reactions of the gamma rays born in the electron-photon avalanches in the thunderstorm atmospheres interacting with the air atoms and with lead producer of a neutron monitor can provide neutron yield compatible with additional count of neutron monitors registered during thunderstorm ground enhancements.

Neutrino oscillometry

Neutrino oscillations are studied employing sources of low energy monoenergetic neutrinos following electron capture by the nucleus and measuring electron recoils. Since the neutrino energy is very low the oscillation length L23 appearing in this electronic neutrino disappearance experiment can be so small that the full oscillation can take place inside the detector so that one may determine very accurately the neutrino oscillation parameters. In particular, since the oscillation probability is proportional to sin22θ13, one can measure or set a better limit on the unknown parameter θ13. One, however, has to pay the price that the expected counting rates are very small. Thus one needs a very intensive neutrino source and a large detector with as low as possible energy threshold and high energy and position resolution. Both spherical gaseous and cylindrical liquid detectors are studied. Different source candidates are considered.

Bound–free pair production in ultra–relativistic ion collisions at the LHC collider: analytic approach to the total and differential cross sections

A theoretical investigation of the bound-free electron-positron pair production in relativistic heavy ion collisions is presented. Special attention is paid to the positrons emitted under large angles with respect to the beam direction. The measurement of these positrons in coincidence with the down--charged ions is in principle feasible by LHC experiments. In order to provide reliable estimates for such measurements, we employ the equivalent photon approximation together with the Sauter approach and derive simple analytic expressions for the differential pair--production cross section, which compare favorably to the results of available numerical calculations. Based on the analytic expressions, detailed calculations are performed for collisions of bare Pb$^{82+}$ ions, taking typical experimental conditions of the LHC experiments into account. We find that the expected count rate strongly depends on the experimental parameters and may be significantly enhanced by increasing the positron-detector acceptance cone.

Neutrino oscillometry

Neutrino oscillations are studied employing sources of low energy monoenergetic neutrinos following electron capture by the nucleus and measuring electron recoils. Since the neutrino energy is very low the oscillation length L23 appearing in this electronic neutrino disappearance experiment can be so small that the full oscillation can take place inside the detector so that one may determine very accurately the neutrino oscillation parameters. In particular, since the oscillation probability is proportional to sin2 2θ13, one can measure or set a better limit on the unknown parameter θ13. One, however, has to pay the price that the expected counting rates are very small. Thus one needs a very intensive neutrino source and a large detector with as low as possible energy threshold and high energy and position resolution. Both spherical gaseous and cylindrical liquid detectors are studied. Different source candidates are considered

Exploring new features of neutrino oscillations with very low energy monoenergetic neutrinos

In the present work we propose to study neutrino oscillations employing sources of monoenergetic neutrinos following electron capture by the nucleus. Since the neutrino energy is very low the smaller of the two oscillation lengths, L 23 , appearing in this electronic neutrino disappearance experiment can be so small that the full oscillation can take place inside the detector and one may determine very accurately the neutrino oscillation parameters. Since in this case the oscillation probability is proportional to sin 2 2 θ 13 , one can measure or set a better limit on the unknown parameter θ 13 . This is quite important, since, if this mixing angle vanishes, there is not going to be CP violation in the leptonic sector. The best way to detect it is by measuring electron recoils in neutrino–electron scattering. One, however, has to pay the price that the expected counting rates are very small. Thus one needs a very intensive neutrino source and a large detector with as low as possible energy threshold and high energy and position resolution. Both spherical gaseous and cylindrical liquid detectors are studied. Different source candidates are considered.

Development of gamma spectrometric method for the determination of thorium in phosphoric acid solution

Abstract Gamma spectrometric determination of thorium in sintered thoria dissolved in strong phosphoric acid was studied using a high purity germanium (HPGe) detector. 232Th was determined using the highly abundant (27%) gamma ray (911.4 keV) emitted by its daughter 228Ac. The count rates in peak regions were plotted against the amount of thorium present in thorium nitrate working standard solution to obtain a calibration curve and the extent of thoria dissolved in 88% phosphoric acid was determined. Further studies on determination of thorium were carried out using thorium phosphate solutions, instead of using thorium nitrate working standard solutions. The solution of thorium phosphate obtained after quantitative dissolution of thoria in 88% phosphoric acid was also found to give a linear calibration curve at 911.4 keV. Using the calibration curves, expected count rates for thorium in sintered thoria dissolved in 88% phosphoric acid were calculated and were in good agreement (±3%) with the observed count rates.

A Beam Profile Monitor for Rare Isotopes in Accelerator Mass Spectrometry: Preliminary Measurements

In accelerator systems, beam lines are generally equipped with diagnostic elements, such as Faraday cups and beam profile monitors (BPM), to optimize beam transport. These diagnostic elements, or at least commercial ones, are designed to only work with continuous beams, and their typical maximum sensitivity is about few tens of pA. Thus, in the case of diagnosis of rare isotope beams in accelerator mass spectrometry (AMS), Faraday cups and BPMs are not suitable on the high-energy side of the tandem accelerator, after energy-mass-charge analysis. For example, in 14C AMS, even for a modern sample, the expected counting rate is a few tens of Hz; in these conditions, a commercial BPM cannot be used. On the other hand, checking the shape and the position of the rare isotope beam hitting the detector can be important in order to better identify signals in the detector itself, thus also helping in reducing the measurement background.This paper presents a prototype BPM especially designed for low-intensity beams. The BPM is based on a multiwire proportional chamber characterized by 2 grids of anode wires, oriented perpendicular to each other in order to measure both the x and the y coordinates of the particle impact point. Details about the design and the electronics of the device are given, and the first test measurements are discussed.

Characterisation, modelling and optimisation of the model of a HPGe detector with the aid of point sources

A virtual model of a Canberra HPGe detector was produced with the aid of MCNPX and of different point sources. The measured and expected count rates were compared. The initial results showed significant discrepancies, therefore additional parametric simulations have been used to improve the model. As a result, the agreement between theoretical and measured performances in the middle-upper part of the spectrum improved, while low energy photons still score the worst, due to incomplete knowledge of the inner structure of the housing that would require additional extensive measurements.

The IBEX Background Monitor

The IBEX Background Monitor (IBaM) provides a small and lightweight method for independently measuring IBEX’s high-energy proton background by integrating the flux of >∼14 keV protons over a ∼7° conical FOV. The IBaM is part of the IBEX-Hi sensor and has a co-aligned look direction. This paper describes the principle of the IBaM and details its design and responses. In particular, we show the response of major components to both ions and ultraviolet (UV) light background. We also provide the geometric factor and calculate expected count rates.

Prospects for precision measurements on ammonia molecules in a fountain

The recent demonstration of cooling and manipulation techniques for molecules offer newpossibilities for precision measurements in molecules. Here, we present the design of a molecularfountain based on a Stark decelerated molecular beam. In this fountain, ammonia molecules aredecelerated to a few meter per second, cooled to sub microKelvin temperatures and subsequentlylaunched. The molecules fly upwards some 30 cm before falling back under gravity, thereby passing amicrowave cavity twice – as they fly up and as they fall back down. The effective interrogationtime in such a Ramsey type measurement scheme includes the entire flight time between the twotraversals through the driving field, which is on the order of a 1/2 second. We present numericalsimulations of the trajectories through the decelerator and estimate the expected count rate. Wepresent an evaluation of the expected stability and accuracy for the inversion transition in15NH3 around 22.6 GHz. The estimated frequency instability is \(7\times10^{-12}~\tau^{-1/2}\), with τ being the measurement time in seconds. With a careful design ofthe interogation zone, systematic frequency shifts are kept below 10-14. Besides serving as aproof-of-principle, these measurements may be used as a test of the time-variation of fundamentalconstants using the sensitivity of the tunneling motion to a change of the proton-electron massratio.

Artificial neural networks technology for neutron spectrometry and dosimetry

Artificial Neural Network Technology has been applied to unfold neutron spectra and to calculate 13 dosimetric quantities using seven count rates from a Bonner Sphere Spectrometer with a (6)LiI(Eu). Two different networks, one for spectrometry and another for dosimetry, were designed. To train and test both networks, 177 neutron spectra from the IAEA compilation were utilised. Spectra were re-binned into 31 energy groups, and the dosimetric quantities were calculated using the MCNP code and the fluence-to-dose conversion coefficients from ICRP 74. Neutron spectra and UTA4 response matrix were used to calculate the expected count rates in the Bonner spectrometer. Spectra and H(10) of (239)PuBe and (241)AmBe were experimentally obtained and compared with those determined with the artificial neural networks.

Aging studies on atlas muon spectrometer drift tubes

The Atlas muon spectrometer relies on Monitored Drift Tubes (MDTs) for track reconstruction in most regions. Expected count rates due to photons reach up to 1500 Hz/cm for the innermost MDTs. For a gas gain of 2middot104 this corresponds to an overall accumulated charge of up to 0.6 C/cm which the MDTs must be able to withstand in 10 years of LHC operation without a degradation in their performance. With the main MDT parameters and the design frozen and chamber production well under way the focus of present aging studies is on testing final Atlas chambers instead of using small, dedicated setups under very well controlled conditions as in the past. This paper summarizes the results of such a study performed at the CERN Gamma Irradiation Facility GIF, that aims to emulate LHC background conditions. One of the main goals was to evaluate the principle of gas recirculation and a prototype of the Atlas circulation system

Neutron spectrometry using artificial neural networks

An artificial neural network has been designed to obtain neutron spectra from Bonner spheres spectrometer count rates. The neural network was trained using 129 neutron spectra. These include spectra from isotopic neutron sources; reference and operational spectra from accelerators and nuclear reactors, spectra based on mathematical functions as well as few energy groups and monoenergetic spectra. The spectra were transformed from lethargy to energy distribution and were re-binned to 31 energy groups using the MCNP 4C code. The re-binned spectra and the UTA4 response matrix were used to calculate the expected count rates in Bonner spheres spectrometer. These count rates were used as input and their respective spectra were used as output during the neural network training. After training, the network was tested with the Bonner spheres count rates produced by folding a set of neutron spectra with the response matrix. This set contains data used during network training as well as data not used. Training and testing was carried out using the Matlab ® program. To verify the network unfolding performance, the original and unfolded spectra were compared using the root mean square error. The use of artificial neural networks to unfold neutron spectra in neutron spectrometry is an alternative procedure that overcomes the drawbacks associated with this ill-conditioned problem.

Ageing studies for the Atlas muon spectrometer drift tubes

The Atlas muon spectrometer relies on Monitored Drift Tubes (MDTs) for track reconstruction in most regions. Expected count rates due to background photons reach up to 1500 Hz/cm for the innermost MDTs. For a gas gain of 2 ⋅ 10 4 this rate corresponds to an overall accumulated charge of up to 0.6 C/cm in 10 years of LHC operation. The focus of the present ageing studies is on testing complete modules from the ongoing chamber production chain in realistic Atlas conditions. This paper summarizes the results of such a study performed at the CERN Gamma Irradiation Facility GIF. One of the main goals was to evaluate for the first time the principle of gas recirculation with a prototype of the Atlas circulation system.

Searching for continuum $\gamma$-ray emission from OB associations with INTEGRAL, some preliminary results

Recent studies suggested that there might be a correlation between unidentified -ray sources from the third EGRET catalogue and OB associations. Moreover, when extrapolating the fluxes measured by EGRET at energies above 100 MeV with a power-law down to the energy range of ISGRI, the expected count rates should be large enough to be detectable with INTEGRAL. Most of those OB associations being located in the Galactic plane, they are monitored by INTEGRAL as part of the Core Program during both the Galactic Plane Scans and the Galactic Center Deep Exposure. Combining public and CP data, we have performed a search for gamma-ray emission from OB associations and the first results are presented.

Recent and ongoing ageing studies for the Atlas muon spectrometer drift tubes

The Atlas muon spectrometer relies on Monitored Drift Tubes (MDTs) for track reconstruction in most regions. Expected count rates due to photons reach up to 1500 Hz/cm for the innermost MDTs. For a gas gain of 2 × 10 4 , this corresponds to an overall accumulated charge of up to 0.6 C/cm, which the MDTs must be able to withstand in 10 years of LHC operation without a degradation in their performance. With the main MDT parameters and the design frozen and chamber production well under way, the focus of present ageing studies is on testing final Atlas chambers instead of using small, dedicated setups under very well-controlled conditions as in the past. This paper summarizes the results of such a study performed at the CERN Gamma Irradiation Facility GIF under realistic Atlas conditions. One of the main goals was to evaluate for the first time the principle of gas recirculation and a prototype of the Atlas circulation system. The paper also reviews ongoing measurements at CERN and in Freiburg.

Recent and ongoing ageing studies for the Atlas muon spectrometer drift tubes

The Atlas muon spectrometer relies on Monitored Drift Tubes (MDTs) for track reconstruction in most regions. Expected count rates due to photons reach up to 1500 Hz/cm for the innermost MDTs. For a gas gain of 2 × 10 4 , this corresponds to an overall accumulated charge of up to 0.6 C/cm, which the MDTs must be able to withstand in 10 years of LHC operation without a degradation in their performance. With the main MDT parameters and the design frozen and chamber production well under way, the focus of present ageing studies is on testing final Atlas chambers instead of using small, dedicated setups under very well-controlled conditions as in the past. This paper summarizes the results of such a study performed at the CERN Gamma Irradiation Facility GIF under realistic Atlas conditions. One of the main goals was to evaluate for the first time the principle of gas recirculation and a prototype of the Atlas circulation system. The paper also reviews ongoing measurements at CERN and in Freiburg.