Active background reduction in high resolution calorimeters is a promising approach to achieve ultimate sensitivity in neutrinoless double beta decay experiments. We propose Cerenkov emission from ...beta rays in bolometric crystals as a viable alternative to scintillation. This novel approach could broaden the range of materials of interest for calorimetric searches of the double beta decay. We discuss the optical properties of TeO
2
crystals, as a show case.
BACKGROUND A number of factors influence the success of oocyte cryopreservation and subsequent ICSI. The aim of the present study is to establish the ideal time, after oocyte retrieval, for human ...oocyte cryopreservation via slow freezing/rapid thawing protocol with 0.3 M sucrose concentration in cryoprotectant solution (SF/RT 0.3 M). METHODS Retrospective study with 75 patients on the clinical outcome of 93 oocyte thawing cycles divided into three groups. Group A: freezing within 2 h from oocyte retrieval. Group B: freezing between 2 and 3 h from retrieval. Group C: freezing after 3 h. RESULTS The rate of best quality embryos was significantly higher (35.2%; P = 0.050) in Group A than in Group C (14.1%). Pregnancy and implantation rates were 39.1% (9/23) and 18.5% (10/54) in Group A. Nine clinical pregnancies per 124 thawed (7.3%) and 73 injected (12.3%) oocytes were observed in Group A versus 3 pregnancies per 174 thawed, 103 injected (1.7%, 2.9%, P = 0.046 and 0.0049) in Group B and 4 per 139 thawed, 88 injected (2.9%, 4.5%, NS) in Group C. The overall yield from oocytes cryopreserved within 2 h of retrieval was 8.1 implantations per 100 oocytes thawed. CONCLUSIONS Embryo quality and clinical outcome of thawing cycles were significantly improved when oocyte cryopreservation by SF/RT 0.3 M was carried out within 2 h from oocyte retrieval.
The high luminosity upgraded LHC or Phase-II is expected to increase the instantaneous luminosity by a factor of 10 beyond the LHC's design value, expecting to deliver 250fb−1 per year for a further ...10 years of operation. Under these conditions the performance degradation due to integrated radiation dose will need to be addressed.
The CMS collaboration is planning to upgrade the forward calorimeters. The replacement is called the High Granularity Calorimeter (HGC) and it will be realized as a sampling calorimeter with layers of silicon detectors interleaved. The sensors will be realized as pad detectors with sizes of less that ∼1.0cm2 and an active thickness between 100 and 300μm depending on the position, respectively, the expected radiation levels.
For an integrated luminosity of 3000fb−1, the electromagnetic calorimetry will sustain integrated doses of 1.5MGy (150Mrads) and neutron fluences up to 1016neq/cm2. A radiation tolerance study after neutron irradiation of 300, 200, and 100μm n-on-p and p-on-n silicon pads irradiated to fluences up to 1.6×1016neq/cm2 is presented. The properties of these diodes studied before and after irradiation were leakage current, capacitance, charge collection efficiency, annealing effects and timing capability. The results of these measurements validate these sensors as candidates for the HGC system.
Hundreds of concurrent collisions per bunch crossing are expected at future hadron colliders. Precision timing calorimetry has been advocated as a way to mitigate the pileup effects and, thanks to ...their excellent time resolution, microchannel plates (MCPs) are good candidate detectors for this goal. We report on the response of MCPs, used as secondary emission detectors, to single relativistic particles and to electromagnetic showers. Several prototypes, with different geometries and characteristics, were exposed to particle beams at the INFN-LNF Beam Test Facility and at CERN. Their time resolution and efficiency are measured for single particles and as a function of the multiplicity of particles. Efficiencies between 50% and 90% to single relativistic particles are reached, and up to 100% in presence of a large number of particles. Time resolutions between 20 ps and 30 ps are obtained.
We report on the response of microchannel plates (MCPs) to single relativistic particles and to electromagnetic showers. Particle detection by means of secondary emission of electrons at the MCP ...surface has long been proposed and is used extensively in ion time-of-flight mass spectrometers. What has not been investigated in depth is their use to detect the ionizing component of showers. The time resolution of MCPs exceeds anything that has been previously used in calorimeters and, if exploited effectively, could aid in the event reconstruction at high luminosity colliders. Several prototypes of photodetectors with the amplification stage based on MCPs were exposed to cosmic rays and to 491MeV electrons at the INFN-LNF Beam-Test Facility. The time resolution and the efficiency of the MCPs are measured as a function of the particle multiplicity, and the results used to model the response to high-energy showers.
Analytical formulae for the calculation of secondary particle yields in p-A interactions are given. These formulae can be of great practical importance for fast calculations of neutrino fluxes and ...for designing new neutrino beam-lines. The formulae are based on a parameterization of the inclusive invariant cross sections for secondary particle production measured in p-Be interactions. Data collected in different energy ranges and kinematic regions are used. The accuracy of the fit to the data with the empirical formulae adopted is within the experimental uncertainties. Prescriptions to extrapolate this parameterization to finite targets and to targets of different materials are given. The results obtained are then used as an input for the simulation of neutrino beams. We show that our approach describes well the main characteristics of measured neutrino spectra at CERN. Thus it may be used in fast simulations aiming at the optimisation of the long-baseline neutrino beams at CERN and FNAL. In particular we will show our predictions for the CNGS beam from CERN to Gran Sasso.
The distinctive signature of the two-photon decay mode of a low-mass Higgs boson (H → γγ) would be a narrow resonance, smeared by the photon energy and direction resolution, over a non-resonant ...background of diphotons or spurious events. The sensitivity to this decay mode greatly benefits from the energy and position resolution and photon identification capabilities of the electromagnetic calorimeters at the LHC. In this context, the performance of the electromagnetic calorimeter (ECAL) of the CMS experiment - a hermetic, fine grained and homogeneous calorimeter made of lead-tungstate (PbWO4) crystals, completed by a silicon/lead preshower installed in front of the endcaps - is presented.
On the timing performance of thin planar silicon sensors Akchurin, N.; Ciriolo, V.; Currás, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2017, Letnik:
859, Številka:
C
Journal Article
Recenzirano
Odprti dostop
We report on the signal timing capabilities of thin silicon sensors when traversed by multiple simultaneous minimum ionizing particles (MIP). Three different planar sensors, with depletion ...thicknesses 133, 211, and 285µm, have been exposed to high energy muons and electrons at CERN. We describe signal shape and timing resolution measurements as well as the response of these devices as a function of the multiplicity of MIPs. We compare these measurements to simulations where possible. We achieve better than 20ps timing resolution for signals larger than a few tens of MIPs.
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