Search results for "electromagnetic"
showing 10 items of 1595 documents
NTD-GE-based microcalorimeter performance
2000
Our group has been developing x-ray microcalorimeters consisting of neutron transmutation doped (NTD) germanium thermistors attached to superconducting tin absorbers. We discuss the performance of single pixel x-ray detectors, and describe an array technology. In this paper we describe the read-out circuit that allows us to measure fast signals in our detectors as this will be important in understanding the primary cause of resolution broadening. We describe briefly a multiplexing scheme that allows a number of different calorimeters to be read out using a single JFET. We list the possible causes of broadening and give a description of the experiment which best demonstrates the cause of the…
Tau spin correlations and the anomalous magnetic moment
2009
We show that the precise determination of the Tau magnetic properties is possible in the next generation accelerators, specially at B/Flavour factories. We define spin correlation observables suitable to extract the real part of the magnetic form factor that, for the first time, will allow to test the standard model-QED predictions. In particular, the predicted QED-dependence with both the momentum transfer and the lepton mass can be precisely measured. Until now, the most stringent bounds on the $\tau$ magnetic moment $a_\tau$ come from LEP data with strong assumptions on the physics involved on the observed process. In this paper, we find three different combinations of spin correlations …
The (K-, p) reaction on nuclei with in-flight kaons
2010
10th International Conference on Hypernuclear and Strange Particle Physics. Tokai, JAPAN, SEP 14-18, 2009
Performance of the photon spectrometer TAPS for deep subthreshold pion detection
2005
Abstract We present in this paper the characteristics of the BaF 2 spectrometer, TAPS, which allow to detect rare electromagnetic events in a high hadronic background. The case of deep subthreshold pions produced in 36 Ar+ 197 Au collisions at 25A and 35A MeV, in which the pion signal is much weaker than the hadronic background and comparable to the cosmic ray background, is studied.
Calculation of the two-loop heavy-flavor contribution to Bhabha scattering
2008
We describe in detail the calculation of the two-loop corrections to the QED Bhabha scattering cross section due to the vacuum polarization by heavy fermions. Our approach eliminates one mass scale from the most challenging part of the calculation and allows us to obtain the corrections in a closed analytical form. The result is valid for arbitrary values of the heavy fermion mass and the Mandelstam invariants, as long as s,t,u >> m_e^2.
Pion vs. photon absorption on the deuteron
1995
Abstract Using an NN → ΔN transition potential fixed by the reaction pp ↔ dπ+ a good agreement can be obtained also for the reaction γd → pn in the Δ region. Further it is seen that the πNΔ and ϱNΔ parameters of the widely used Bonn potential, fitting the NN sector, yield a transition potential too weak to reproduce the pion production or absorption cross section.
Performance of the ALICE photon spectrometer PHOS
2003
Abstract We present in this paper the measured characteristics of a 64 lead–tungstate crystal array designed to detect high-energy photons and neutral mesons with the ALICE photon spectrometer PHOS. The array has been tested with electron and charged pion secondary beams delivered by the CERN PS and SPS synchrotrons. Photon energy and π 0 invariant mass resolutions are presented. The PHOS particle identification performance for data simulated with the AliRoot package is studied.
Scintillators for photon detection at medium energies—a comparative study of BaF2, CeF3 and PbWO4
2002
Abstract In a comparative study, the performance of sub-arrays consisting of large CeF 3 and PbWO 4 crystals has been investigated with high-energy photons below 1 GeV. Energy and time resolutions are determined and compared with the corresponding values for BaF 2 based on the experience of operating the electromagnetic calorimeter Taps .
The isospin structure of photoproduction of πη pairs from the nucleon in the threshold region
2015
Abstract Photoproduction of πη-pairs from nucleons has been investigated from threshold up to incident photon energies of ≈ 1.4 GeV. The quasi-free reactions γ p → p π 0 η , γ n → n π 0 η , γ p → n π + η , and γ n → p π − η were for the first time measured from nucleons bound in the deuteron. The corresponding reactions from a free-proton target were also studied to investigate final-state interaction effects (for neutral pions the free-proton results could be compared to previous measurements; the γ p → n π + η reaction was measured for the first time). For the π 0 η final state coherent production via the γ d → d π 0 η reaction was also investigated. The experiments were performed at the …
The magnetic shielding for the neutron decay spectrometer aSPECT
2014
Abstract Many experiments in nuclear and neutron physics are confronted with the problem that they use a superconducting magnetic spectrometer which potentially affects other experiments by their stray magnetic field. The retardation spectrometer a SPECT consists, inter alia, of a superconducting magnet system that produces a strong longitudinal magnetic field of up to 6.2 T. In order not to disturb other experiments in the vicinity of a SPECT, we had to develop a magnetic field return yoke for the magnet system. While the return yoke must reduce the stray magnetic field, the internal magnetic field and its homogeneity should not be affected. As in many cases, the magnetic shielding for a S…