209 research outputs found
Design and commissioning of a timestamp-based data acquisition system for the DRAGON recoil mass separator
The DRAGON recoil mass separator at TRIUMF exists to study radiative proton
and alpha capture reactions, which are important in a variety of astrophysical
scenarios. DRAGON experiments require a data acquisition system that can be
triggered on either reaction product ( ray or heavy ion), with the
additional requirement of being able to promptly recognize coincidence events
in an online environment. To this end, we have designed and implemented a new
data acquisition system for DRAGON which consists of two independently
triggered readouts. Events from both systems are recorded with timestamps from
a MHz clock that are used to tag coincidences in the earliest possible
stage of the data analysis. Here we report on the design, implementation, and
commissioning of the new DRAGON data acquisition system, including the
hardware, trigger logic, coincidence reconstruction algorithm, and live time
considerations. We also discuss the results of an experiment commissioning the
new system, which measured the strength of the
keV resonance in the NeNa radiative proton
capture reaction.Comment: 11 pages, 7 figures, accepted for publication in EPJ A "tools for
experiment and theory
Longitudinal muon spin relaxation in high purity aluminum and silver
The time dependence of muon spin relaxation has been measured in high purity
aluminum and silver samples in a longitudinal 2 T magnetic field at room
temperature, using time-differential \musr. For times greater than 10 ns, the
shape fits well to a single exponential with relaxation rates of
\lambda_{\textrm{Al}} = 1.3 \pm 0.2\,(\textrm{stat.}) \pm
0.3\,(\textrm{syst.})\,\pms and \lambda_{\textrm{Ag}} = 1.0 \pm
0.2\,(\textrm{stat.}) \pm 0.2\,(\textrm{syst.})\,\pms
Production of antihydrogen at reduced magnetic field for anti-atom trapping
We have demonstrated production of antihydrogen in a 1T solenoidal
magnetic field. This field strength is significantly smaller than that used in
the first generation experiments ATHENA (3T) and ATRAP (5T). The
motivation for using a smaller magnetic field is to facilitate trapping of
antihydrogen atoms in a neutral atom trap surrounding the production region. We
report the results of measurements with the ALPHA (Antihydrogen Laser PHysics
Apparatus) device, which can capture and cool antiprotons at 3T, and then
mix the antiprotons with positrons at 1T. We infer antihydrogen production
from the time structure of antiproton annihilations during mixing, using mixing
with heated positrons as the null experiment, as demonstrated in ATHENA.
Implications for antihydrogen trapping are discussed
Nuclear Stopping in Au+Au Collisions at sqrt(sNN) = 200 GeV
Transverse momentum spectra and rapidity densities, dN/dy, of protons,
anti-protons, and net--protons (p-pbar) from central (0-5%) Au+Au collisions at
sqrt(sNN) = 200 GeV were measured with the BRAHMS experiment within the
rapidity range 0 < y < 3. The proton and anti-proton dN/dy decrease from
mid-rapidity to y=3. The net-proton yield is roughly constant for y<1 at
dN/dy~7, and increases to dN/dy~12 at y~3. The data show that collisions at
this energy exhibit a high degree of transparency and that the linear scaling
of rapidity loss with rapidity observed at lower energies is broken. The energy
loss per participant nucleon is estimated to be 73 +- 6 GeV.Comment: 5 pages, 4 figure
A search for two body muon decay signals
Lepton family number violation is tested by searching for
decays among the 5.8 positive muon decay events analyzed by the
TWIST collaboration. Limits are set on the production of both massless and
massive bosons. The large angular acceptance of this experiment allows
limits to be placed on anisotropic decays, which can arise
from interactions violating both lepton flavor and parity conservation.
Branching ratio limits of order are obtained for bosons with masses
of 13 - 80 MeV/c and with different decay asymmetries. For bosons with
masses less than 13 MeV/c the asymmetry dependence is much stronger and
the 90% limit on the branching ratio varies up to . This is
the first study that explicitly evaluates the limits for anisotropic two body
muon decays.Comment: 7 pages, 5 figures, 2 tables, accepted by PR
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