Jonn3 さん 2012年 10月 26日 16時 07分 02秒. Rowla > ぽよ様も言ってましたが、新しい釣り役の育成も大事ですね。 ジョブは限定されませんし（今回も黒が釣ったりナが.
Members of the Muon g-2 collaboration at Fermilab are developing this lead fluoride crystal, 14 centimeters long, and the large-area SiPMs for the experiment’s detector. Slavkin sneg noti de la. They will help scientists measure more precisely the energies of particles from decaying muons, as well as the decay time of the particles. The experiment at Fermilab is under construction in the new MC-1 building. It aims to measure with unprecedented precision — 140 parts per billion — a property of the muon called the anomalous magnetic dipole moment. The effort will improve upon the famous experiment at Brookhaven National Laboratory, which finished data taking in 2001. The new Fermilab experiment aims to improve the precision with 20 times more data and by reducing key systematic uncertainties.
These factors significantly affect the design of the detector, which measures the muon decay data used to deduce the magnetic dipole moment. Now, after six years and four beam tests, members of the original team from Brookhaven along with several new collaborators have finished testing a production prototype of a new calorimeter — the detector that measures particle energies and decay time — for the Fermilab experiment. The new calorimeter design improves on its Brookhaven counterpart by reducing something called detector pile-up, which occurs when two particles strike a detector in rapid succession, and with custom electronics that can withstand higher signal rates.
To address these issues, the collaboration will segment the electromagnetic calorimeter into 54 independent elements, and the signal in each of these will have an ultrashort duration in time. The Fermilab accelerator complex will deliver a beam of polarized muons into a storage ring, which guides the muons around a circular path. Fermilab will deliver the muons at a much higher rate than the Brookhaven experiment. The detectors, positioned along the inside of the ring, are designed to operate near, but not disturb, the highly uniform and strong magnetic field of the storage ring. A combination of lead fluoride crystals, which convert deposited energy into Cherenkov photons (light), and devices called silicon photomultipliers (SiPMs), which collect photons, serves these purposes well. This group participated in the Muon g-2 calorimeter test beam run at SLAC.
After a positive muon stored in the magnetic ring decays into a positron and a pair of neutrinos, the positron curls inward and hits a calorimeter station. Its energy is converted into many thousands of Cherenkov photons in the 14-centimeter-long crystals. The conversion process takes less than a few nanoseconds. Some thousands of these photons successfully propagate through the crystal and strike a SiPM adhered to the crystal’s rear face. This photodetector preserves the very fast nature of the incoming photon pulse and faithfully encodes it into an equally narrow charge pulse, which is finally digitized by electronics. The collaboration performed a at SLAC of a prototype array of 28 crystals read out by 16-channel large-area SiPMs.