Proposal of the Crystal Experiment

The CRYSTAL experiment intends to assess the possibility of using bent silicon crystals as primary collimators to direct the beam halo onto the secondary absorber thus reducing outscattering, beam losses in critical regions and radiation load. CRYSTAL has received full support from the LHC Technical Committee on the 30th of January. Four agencies have expressed their interest in the project: CERN, the Russian Institutions (PNPI, IHEP, JINR), INFN (Sections of Ferrara, Legnaro, Milano Bicocca, Roma1) and US LARP (BNL, FNAL, SLAC). The first version of the MoU is circulating among the collaboration and will be ready to be sent to the funding agencies before the end of April. This document briefly reviews the CRYSTAL experiment goals, its organization, the cost sharing among the agencies, the needed manpower and the time schedule. Appendix A describes what has already been done with crystals in collimation and why crystals could play a fundamental role while Appendix B analyzes in detail the items summarized in this Executive Summary

SYRMEP: ALLE FRONTIERE DELLA MAMMOGRAFIA DIGITALE

1995/1996L'esperimento SYRMEP (SYnchrotron Radiation for MEdical Physics) si muove nell'ambito della mammografia digitale per superare i limiti intrinseci dei sistemi standard di mammografia (pellicola e tubo a raggi X) e cioè alte dosi alla paziente, perdita di contrasto a causa della radiazione diffusa, bassa efficienza di rivelazione. SYRMEP ha agito su tutti gli elementi sostituendo il tubo a raggi X con un fascio monocromatico e laminare di luce di sincrotrone e utilizzando un rivelatore a strip di silicio capace di contare i singoli fotoni e caratterizzato da alta efficienza e range dinamico. La tesi presenta il sistema SYRMEP concentrandosi sullo sviluppo e la caratterizzazione del rivelatore al silicio e delle sue performance.IX Ciclo1968Versione digitalizzata della tesi di dottorato cartacea

Steering efficiency of a ultrarelativistic proton beam in a thin bent crystal

Crystals with small thickness along the beam exhibit top performance for steering particle beams through planar channeling. For such crystals, the effect of nuclear dechanneling plays an important role because it affects their efficiency. We addressed the problem through experimental work carried out with 400 GeV/c protons at fixed-target facilities of CERN-SPS. The dependence of efficiency vs. curvature radius has been investigated and compared favourably to the results of modeling. A realistic estimate of the performance of a crystal designed for LHC energy including nuclear dechanneling has been achieved.Comment: 16 pages, 6 figure

GRID LEVEL-1.5 TRIGGER SPECIFICATIONS

This document contains the requirements of the Level-1.5 Trigger of the GRID Instrument onboard the AGILE satellite

The upgrade of the ASACUSA scintillating bar detector for antiproton annihilation measurements

Antiproton annihilations on matter nuclei are usually detected by tracking the charged pions emitted in the process. A detector made of plastic scintillating bars have been built and used in the ASACUSA experiment for the last 10 years. Ageing, movements and transports caused stress on the internal mechanical structure and impacted mostly on the optical readout system which was eventually upgraded: the so far used multi-anode photo-multiplier tubes (PMTs) have been replaced by silicon photomultipliers (SiPM) and the front-end electronics had to be adapted to cope with the new signal formation. This work describes the design and operations of the upgrade, as well as the validation tests with cosmic rays

Next-generation ultra-compact calorimeters based on oriented crystals

Calorimeters based on oriented crystals provide unparalleled compactness and resolution in measuring the energy of electromagnetic particles. Recent experiments performed at CERN and DESY beamlines by the AXIAL/ELIOT experiments demonstrated a significant reduction in the radiation length inside tungsten and PbWO4, the latter being the scintillator used for the CMS ECAL, observed when the incident particle trajectory is aligned with a lattice axis within ∼1∘. This remarkable effect, being observed over the wide energy range from a few GeV to 1 TeV or higher, paves the way for the development of innovative calorimeters based on oriented crystals, featuring a design significantly more compact than currently achievable while rivaling the current state of the art in terms of energy resolution in the range of interest for present and future forward detectors (such as the KLEVER Small Angle Calorimeter at CERN SPS) and source-pointing space-borne γ-ray telescopes

Experimental study of the radiation emitted by 180-GeV/c electrons and positrons volume-reflected in a bent crystal

The radiation emitted by 180-GeV/c volume-reflected electrons and positrons impinging on a bent crystal has been measured by the H8RD22 Collaboration on the H8 beamline at the CERN SPS. A dedicated spectrometer has been developed to measure high-energy photon spectra (up to similar to 100 GeV) under volume reflection: photon and charged particle beams have been separated by a bending magnet and leptons were detected and tagged by microstrip silicon detectors and a Pb-scintillator sampling calorimeter. A comparison between the experimental and analytical data for the amorphous and volume-reflection cases is presented and the differences are discussed

Experimental study of the radiation emitted by 180-GeV/c electrons and positrons volume-reflected in a bent crystal

The radiation emitted by 180-GeV/c volume-reflected electrons and positrons impinging on a bent crystal has been measured by the H8RD22 Collaboration on the H8 beamline at the CERN SPS. A dedicated spectrometer has been developed to measure high-energy photon spectra (up to similar to 100 GeV) under volume reflection: photon and charged particle beams have been separated by a bending magnet and leptons were detected and tagged by microstrip silicon detectors and a Pb-scintillator sampling calorimeter. A comparison between the experimental and analytical data for the amorphous and volume-reflection cases is presented and the differences are discussed

GRB 070724B: the first gamma ray burst localized by SuperAGILE and its Swift X-ray afterglow

GRB 070724B is the first gamma ray burst localized by SuperAGILE, the hard X-ray monitor aboard the AGILE satellite. The coordinates of the event were published similar to 19 h after the trigger. The Swift X-Ray Telescope pointed at the SuperAGILE location and detected the X-ray afterglow inside the SuperAGILE error circle. The AGILE gamma-ray Tracker and Minicalorimeter did not detect any significant gamma ray emission associated with GRB 070724B in the MeV and GeV range, neither prompt nor delayed. Searches for the optical afterglow were performed by the Swift UVOT and the Palomar automated 60-inch telescopes, resulting in no significant detection. Similarly, the Very Large Array did not detect any radio afterglow. This is the first GRB event associated with an X-ray afterglow with a firm upper limit in the 100 MeV-30 GeV energy range

Erratum to: "Double volume reflection of a proton beam by a sequence of two bent crystals" [Phys. Lett. B 658 (2008) 109]

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