114 research outputs found
One-Loop Corrections to Radiative Muon Decay
One-loop QED corrections to the differential width of radiative muon decay
are considered. Results can be used to analyze high statistics data of modern
and future experiments.Comment: 16 pp, 3 PostScript figure
Radiative corrections to pion Compton scattering
We calculate the one-photon loop radiative corrections to charged pion
Compton scattering, . Ultraviolet and infrared
divergencies are both treated in dimensional regularization. Analytical
expressions for the corrections to the invariant Compton
scattering amplitudes, and , are presented for 11 classes of
contributing one-loop diagrams. Infrared finiteness of the virtual radiative
corrections is achieved (in the standard way) by including soft photon
radiation below an energy threshold , and its relation to the
experimental detection threshold is discussed. We find that the radiative
corrections are maximal in backward directions, reaching e.g. -2.4% for a
center-of-mass energy of and MeV. Furthermore, we
extend our calculation of the radiative corrections by including the leading
pion structure effect (at low energies) in form of its electric and magnetic
polarizability difference, fm. We find that this structure effect does not change the relative size
and angular dependence of the radiative corrections to pion Compton scattering.
Our results are particularly relevant for analyzing the COMPASS experiment at
CERN which aims at measuring the pion electric and magnetic polarizabilities
with high statistics using the Primakoff effect.Comment: 14 pages, 5 figure
Data acquisition system for the MuLan muon lifetime experiment
We describe the data acquisition system for the MuLan muon lifetime
experiment at Paul Scherrer Institute. The system was designed to record muon
decays at rates up to 1 MHz and acquire data at rates up to 60 MB/sec. The
system employed a parallel network of dual-processor machines and repeating
acquisition cycles of deadtime-free time segments in order to reach the design
goals. The system incorporated a versatile scheme for control and diagnostics
and a custom web interface for monitoring experimental conditions.Comment: 19 pages, 8 figures, submitted to Nuclear Instruments and Methods
The WITCH experiment: Acquiring the first recoil ion spectrum
The standard model of the electroweak interaction describes beta-decay in the
well-known V-A form. Nevertheless, the most general Hamiltonian of a beta-decay
includes also other possible interaction types, e.g. scalar (S) and tensor (T)
contributions, which are not fully ruled out yet experimentally. The WITCH
experiment aims to study a possible admixture of these exotic interaction types
in nuclear beta-decay by a precise measurement of the shape of the recoil ion
energy spectrum. The experimental set-up couples a double Penning trap system
and a retardation spectrometer. The set-up is installed in ISOLDE/CERN and was
recently shown to be fully operational. The current status of the experiment is
presented together with the data acquired during the 2006 campaign, showing the
first recoil ion energy spectrum obtained. The data taking procedure and
corresponding data acquisition system are described in more detail. Several
further technical improvements are briefly reviewed.Comment: 11 pages, 6 figures, conference proceedings EMIS 2007
(http://emis2007.ganil.fr), published also in NIM B:
doi:10.1016/j.nimb.2008.05.15
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