The variety of isotopes in cosmic rays allows us to study different aspects of the processes that cosmic rays undergo between the time they are produced and the time of their arrival in the ...heliosphere. In this paper, we present measurements of the isotopic ratios 2H/4He, 3He/4He, 6Li/7Li, 7Be/(9Be+10Be), and 10B/11B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The measurements are based on the data collected by the Alpha Magnetic Spectrometer, AMS-01, during the STS-91 flight in 1998 June.
A measurement of the cosmic ray positron fraction e+/(e++e−) in the energy range of 1–30 GeV is presented. The measurement is based on data taken by the AMS-01 experiment during its 10 day Space ...Shuttle flight in June 1998. A proton background suppression on the order of 106 is reached by identifying converted bremsstrahlung photons emitted from positrons.
The architecture of the data acquisition system foreseen for the LHCb upgrade, to be installed by 2018, is devised to readout events trigger-less, synchronously with the LHC bunch crossing rate at 40 ...MHz. Within this approach the readout boards act as a bridge between the front-end electronics and the High Level Trigger (HLT) computing farm. The baseline design for the LHCb readout is an ATCA board requiring dedicated crates. A local area standard network protocol is implemented in the on-board FPGAs to read out the data. The alternative solution proposed here consists in building the readout boards as PCIe peripherals of the event-builder servers. The main architectural advantage is that protocol and link-technology of the event-builder can be left open until very late, to profit from the most cost-effective industry technology available at the time of the LHC LS2.
The main goal of the FAMU experiment is the measurement of the hyperfine splitting (hfs) in the 1S state of muonic hydrogen ΔEhfs (μ - p)1S. The physical process behind this experiment is the ...following: μp are formed in a mixture of hydrogen and a higher-Z gas. When absorbing a photon at resonance-energy ΔEhfs ≈ 0.182 eV, in subsequent collisions with the surrounding H 2 molecules, the μp is quickly de-excited and accelerated by ∼ 2/3 of the excitation energy. The observable is the time distribution of the K-lines X-rays emitted from the μZ formed by muon transfer (μp) + Z → (μZ)* + p, a reaction whose rate depends on the μp kinetic energy. The maximal response, to the tuned laser wavelength, of the time distribution of X-ray from K-lines of the (μZ)* cascade indicate the resonance. During the preparatory phase of the FAMU experiment, several measurements have been performed both to validate the methodology and to prepare the best configuration of target and detectors for the spectroscopic measurement. We present here the crucial study of the energy dependence of the transfer rate from muonic hydrogen to oxygen (Λ μp → μ0 ), precisely measured for the first time.
Silicon Photomultipliers (SiPM) are considered very promising in many application where high timing performances, low cost, hardness to radiation damage and single photon counting are requested. Such ...applications go from astrophysics, high energy accelerator physics to medical physics. A group of SiPM from Hamamatsu has been tested with a low noise fast amplifier based on a hetero-junction FET, mounted on a proper front end board. A first telescope prototype has been used to test the electronics and results are shown. The SiPM time resolution has been measured to be σ∼30ps, in agreement with other studies reported in literature. The SiPM gain depends critically on temperature and a thermoelectric module to control the circuit was also studied in order to use the system for space detectors.
Protons in near earth orbit Alcaraz, J.; Ambrosi, G.; Ao, L. ...
Physics letters. B,
2000, Letnik:
472, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The proton spectrum in the kinetic energy range 0.1 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at an altitude of 380
km. Above the geomagnetic ...cutoff the observed spectrum is parameterized by a power law. Below the geomagnetic cutoff a substantial second spectrum was observed concentrated at equatorial latitudes with a flux ∼70
m
−2
s
−1
sr
−1. Most of these second spectrum protons follow a complicated trajectory and originate from a restricted geographic region.
Helium in near Earth orbit Ambrosi, G.; Ao, L.; Azzarello, P. ...
Physics letters. B,
2000, Letnik:
494, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The helium spectrum from 0.1 to 100 GeV/nucleon was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at altitudes near 380 km. Above the geomagnetic cutoff the ...spectrum is parameterized by a power law. Below the geomagnetic cutoff a second helium spectrum was observed. In the second helium spectra over the energy range 0.1 to 1.2 GeV/nucleon the flux was measured to be
(6.3±0.9)×10
−3
(
m
2
sec
sr)
−1
and more than ninety percent of the helium was determined to be
3He (at the 90% CL). Tracing helium from the second spectrum shows that about half of the
3He travel for an extended period of time in the geomagnetic field and that they originate from restricted geographic regions similar to protons and positrons.
For the identification of particles in the momentum range 0.5–2.5GeV/c, the ALICE experiment uses a Time Of Flight array consisting of Multigap Resistive Plate Chambers (MRPC) in the form of long ...strips. The design of the detector elements is as follows : double stack MRPCs with glass resistive plates and 5 gas gaps of 250μm per stack. The latest results on the performance of these MRPCs are presented. Typical values of time resolution σ are better than 50ps, with an efficiency of 99.9% and a long, more than 1.5kV, streamer-free plateau.
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