Avalanche fluctuations set a limit to the energy and position resolutions that can be reached by gaseous detectors. This paper presents a method based on a laser test-bench to measure the absolute ...gain and the relative gain variance of a Micro-Pattern Gaseous Detector from its single-electron response. A Micromegas detector was operated with three binary gas mixtures, composed of 5% isobutane as a quencher, with argon, neon or helium, at atmospheric pressure. The anode signals were read out by low-noise, high-gain Cremat CR-110 charge preamplifiers to enable single-electron detection down to gain of 5 10 super(3) for the first time. The argon mixture shows the lowest gain at a given amplification field together with the lowest breakdown limit, which is at a gain of 210 super(4) an order of magnitude lower than that of neon or helium. For each gas, the relative gain variance f is almost unchanged in the range of amplification field studied. It was found that f is twice higher (f~0.6) in argon than in the two other mixtures. This hierarchy of gain and relative gain variance agrees with predictions of analytic models, based on gas ionisation yields, and a Monte-Carlo model included in the simulation software Magboltz version 10.1.
We conducted a series of beam tests of prototype TPCs for the International Linear Collider (ILC) experiment, equipped with an MWPC, a MicroMEGAS, or GEMs as a readout device. The prototype operated ...successfully in a test beam at KEK under an axial magnetic field of up to 1
T. The analysis of data is now in progress and some of the preliminary results obtained with GEMs and MicroMEGAS are presented along with our interpretation. Also given is the extrapolation of the obtained spatial resolution to that of a large TPC expected as the central tracker of the ILC experiment.
The possibility of measuring the proton electromagnetic form factors in the time-like region at FAIR with the \PANDA detector is discussed. Detailed simulations on signal efficiency for the ...annihilation of $\bar p +p $ into a lepton pair as well as for the most important background channels have been performed. It is shown that precision measurements of the differential cross section of the reaction $\bar p +p \to e^++ e^-$ can be obtained in a wide angular and kinematical range. The individual determination of the moduli of the electric and magnetic proton form factors will be possible up to a value of momentum transfer squared of $q^2\simeq 14$ (GeV/c)$^2$. The total $\bar p +p\to e^++e^-$ cross section will be measured up to $q^2\simeq 28$ (GeV/c)$^2$. The results obtained from simulated events are compared to the existing data. Sensitivity to the two photons exchange mechanism is also investigated.
In the present paper, we describe recent results on two-proton mission studies. In the first part, new results on two proton emission from excited states in
17Ne are presented. In these complete ...kinematics measurements performed at the SPEG facility of GANIL, the angle between the two proton has been measured evidencing a
2He emission pattern. In a second part, recent results on the two-proton radioactivity of
45Fe from GANIL and GSI are presented, which show the first evidence of this new radioactivity.
Inelastic scattering of 40Ca on 40Ca at 50 MeV/A has been measured at the GANIL facility in coincidence with light charged particles. For the first time, the SPEG spectrometer was associated with 240 ...CsI(Tl) scintillators of the INDRA 4π array. The missing energy method, successfully used in previous experiments to study the nucleon decay of collective states is applied to the study of alpha-particle decay of the GQR. A significant direct decay branch by alpha-particles of the GQR in 40Ca is measured for the first time.
Elastic and inelastic proton scattering on 11Be were measured in inverse kinematics up to a 11Be excitation energy of 7 MeV. Continuum discretised coupled-channels (CDCC) calculations using a ...Be10(0+)+n cluster model of 11Be are able to explain the elastic scattering data. However, for the inelastic scattering angular distributions for 11Be excitation energy bins of 0.5–3 and 3–5.5 MeV the CDCC calculations under-predict the data, indicating the presence of contributions due to the deformed and active 10Be core to the 11Be breakup process.
We studied the performances of the LaBr3:Ce scintillator when optically coupled to NaI:Tl and CsI:Na in a Phoswich detector for the R&D phase of the gamma ray calorimeter PARIS (Photon Array for the ...studies with Radioactive Ion and Stable beams). This detector has the purpose to measure γ-energies in a wide range (100keV–40MeV), and it will be used principally as a part of the SPIRAL2 instrumentation at GANIL.
In this communication we report on the study of the light yield and energy resolution for gamma detection realized by coupling the phoswiches with various photomultiplier tubes, providing different characteristics. We were interested in investigating the possible degradation of the scintillation light produced by the LaBr3:Ce due to the presence of NaI:Tl/CsI:Na crystals, before being detected on the photocathode. For this purpose we realized all the measurements employing a standard ADC and QDC read-out system leading the possibility to perform a gate-based event selection.
In this study we measured an energy resolution of 4.6% with an uncollimated 137Cs source for a 50.8×50.8×50.8mm3 LaBr3:Ce coupled to a 50.8×50.8×152.4mm3 NaI:Tl. This value is 30% bigger than the energy resolution measured for a 50.8×50.8×101.6mm3 stand-alone LaBr3:Ce but still in the specifications for the PARIS collaboration physics list.
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