A
bstract
In this paper we discuss the possibility of measuring the anomalous magnetic and electric dipole moments of the
τ
lepton. The method consists in studying the spin precession induced by the ...strong effective magnetic field inside channels of a bent crystal with a dedicated setup at the CERN Large Hadron Collider.
In this paper, we discuss the theoretical framework and the experimental measurements of the magnetic moment of the charmed baryons. We first review the theoretical predictions of the
Λ
c
+
magnetic ...moment and show that the measurements of the magnetic moments of other charmed baryons, such as
Ξ
c
, allow to perform detailed spectroscopy studies. The magnetic moment of the charm quark can be determined using radiative charmonium decay, which can be compared to the
Λ
c
+
magnetic moment within theoretical models. The present results show a tension with majority of theoretical predictions. The magnetic moment of the charmed baryons could potentially be measured directly, using bent-crystal experiments at LHC. The possibility to measure precisely the magnetic moments of charmed baryons needs precise measurement of their polarisation and weak decay parameters. In this paper, we revisit the formalism of the angular analysis needed for these measurements and make a detailed evaluation of initial polarisation of deflected
Λ
c
baryons as a function of crystal orientation. We found a special orientation of the crystal that gives the opportunity to measure the
Λ
c
dimensionless electric dipole moment almost with the same precision as its
g
-factor, which is more than an order of magnitude more efficient than suggested before.
Classical and quantum properties of scattering of ultrarelativistic electrons in ultrathin crystals are considered. A comparison is made of these two ways of study of scattering process. In classical ...consideration we remark the appearance of sharp peaks in angular distribution of scattered particles, that is treated as a manifestation of the rainbow scattering phenomenon, and in quantum case we show sharp peaks in the angular distribution that arise from the interference of single electrons on numerous crystal planes and can be expressed in terms of reciprocal lattice vectors. We show that for some parameters the quantum predictions substantially differ from the classical ones. The influence of beam divergence on the possibility of experimental observation of the studied effects is estimated.
Results of simulation and measurements on the LEETECH facility with quartz Cherenkov detector prototype which is one of the candidates for the time-of-flight technique implementation at the upgraded ...BES-III and HIEPA (China) experiments are presented. The dependence of the electrons time variation from opening of the collimators is determined. The results of the dependence of time registration of Cherenkov exposure from spatial displacement of the quartz bar with the size 20 ⨯ 40 ⨯ 200 mm are presented. Time resolution of 50 ps was measured during the experiment. The obtained results are in agreement with the expected and demonstrate the possibility of the application of quartz detectors of this type for determining the kinds of the particles.
A new versatile facility LEETECH for detector R&D, tests and calibration is designed and constructed. It uses electrons produced by the photoinjector PHIL at LAL, Orsay and provides a powerful tool ...for wide range R&D studies of different detector concepts delivering “mono-chromatic” samples of low energy electrons with adjustable energy and intensity. Among other innovative instrumentation techniques, LEETECH will be used for testing various gaseous tracking detectors and studying new Micromegas/InGrid concept which has very promising characteristics of spatial resolution and can be a good candidate for particle tracking and identification. In this paper the importance and expected characteristics of such facility based on detailed simulation studies are addressed.
The LEETECH (Low Energy Electron TECHnique) electron test beam facility has been designed and manufactured at Laboratoire de l’Accelerateur Lineaire (Orsay, France). Energy of electron beam can vary ...from 100 keV to 5 MeV. Two measurement sessions with application of the diamond sensor and the Micromegas/InGrid tracking module characterization were performed. Complete facility design with the Geant4 simulation, mechanical design, implementation of remote control and readout system is presented. An option to generate the electron bunches including a few particles only is confirmed, the obtained results are in rather good agreement with the corresponding simulation within uncertainty. Main results with the preliminary analysis from the Micromegas/InGrid measurement session are also presented.
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