496 research outputs found
A simple high-sensitivity technique for purity analysis of xenon gas
We report on the development and performance of a high-sensitivity
purity-analysis technique for gaseous xenon. The gas is sampled at macroscopic
pressure from the system of interest using a UHV leak valve. The xenon present
in the sample is removed with a liquid-nitrogen cold trap, and the remaining
impurities are observed with a standard vacuum mass-spectroscopy device. Using
calibrated samples of xenon gas spiked with known levels of impurities, we find
that the minimum detectable levels of N2, O2, and methane are 1 ppb, 160 ppt,
and 60 ppt respectively. This represents an improvement of about a factor of
10,000 compared to measurements performed without a coldtrap.Comment: 20 pages, 5 figure
First operation of a liquid Argon TPC embedded in a magnetic field
We have operated for the first time a liquid Argon TPC immersed in a magnetic
field up to 0.55 T. We show that the imaging properties of the detector are not
affected by the presence of the magnetic field. The magnetic bending of the
ionizing particle allows to discriminate their charge and estimate their
momentum. These figures were up to now not accessible in the non-magnetized
liquid Argon TPC.Comment: 9 pages, 3 figure
Tunneling out of a time-dependent well
Solutions to explicit time-dependent problems in quantum mechanics are rare.
In fact, all known solutions are coupled to specific properties of the
Hamiltonian and may be divided into two categories: One class consists of
time-dependent Hamiltonians which are not higher than quadratic in the position
operator, like i.e the driven harmonic oscillator with time-dependent
frequency. The second class is related to the existence of additional
invariants in the Hamiltonian, which can be used to map the solution of the
time-dependent problem to that of a related time-independent one.
In this article we discuss and develop analytic methods for solving
time-dependent tunneling problems, which cannot be addressed by using quadratic
Hamiltonians. Specifically, we give an analytic solution to the problem of
tunneling from an attractive time-dependent potential which is embedded in a
long-range repulsive potential.
Recent progress in atomic physics makes it possible to observe experimentally
time-dependent phenomena and record the probability distribution over a long
range of time. Of special interest is the observation of macroscopical
quantum-tunneling phenomena in Bose-Einstein condensates with time-dependent
trapping potentials. We apply our model to such a case in the last section.Comment: 11 pages, 3 figure
A slow gravity compensated Atom Laser
We report on a slow guided atom laser beam outcoupled from a Bose-Einstein
condensate of 87Rb atoms in a hybrid trap. The acceleration of the atom laser
beam can be controlled by compensating the gravitational acceleration and we
reach residual accelerations as low as 0.0027 g. The outcoupling mechanism
allows for the production of a constant flux of 4.5x10^6 atoms per second and
due to transverse guiding we obtain an upper limit for the mean beam width of
4.6 \mu\m. The transverse velocity spread is only 0.2 mm/s and thus an upper
limit for the beam quality parameter is M^2=2.5. We demonstrate the potential
of the long interrogation times available with this atom laser beam by
measuring the trap frequency in a single measurement. The small beam width
together with the long evolution and interrogation time makes this atom laser
beam a promising tool for continuous interferometric measurements.Comment: 7 pages, 8 figures, to be published in Applied Physics
A Regenerable Filter for Liquid Argon Purification
A filter system for removing electronegative impurities from liquid argon is
described. The active components of the filter are adsorbing molecular sieve
and activated-copper-coated alumina granules. The system is capable of
purifying liquid argon to an oxygen-equivalent impurity concentration of better
than 30 parts per trillion, corresponding to an electron drift lifetime of at
least 10 ms. Reduction reactions that occur at about 250 degrees Celsius allow
the filter material to be regenerated in-situ through a simple procedure. In
the following work we describe the filter design, performance, and regeneration
process.Comment: 12 pages with 9 figure
Feasibility Study of a Neutron Time Of Flight Facility at the CERN-PS
This report summarises the feasibility study of a neutron time-of-flight facility at the CERN-PS as described in Refs. [1] and [2]. The idea is to extract at 24 GeV/cproton bunches (r.m.s. length ~7 ns) on to a target. The neutrons produced by spallation are directed to an experimental area located 230 m downstream throughout a vacuum pipe (diameter ~80 cm) making use of the existing TT2A tunnel about 7 m below the ISR tunne
Addendum to the letter of intent: a CERN-PS experimental campaign to measure neutron cross sections from 1 eV to 250 MeV with high resolution
Letter of intent: a CERN-PS experimental campaign to measure neutron cross sections from 1 eV to 250 MeV with high resolution
Performance Of A Liquid Argon Time Projection Chamber Exposed To The WANF Neutrino Beam
We present the results of the first exposure of a Liquid Argon TPC to a
multi-GeV neutrino beam. The data have been collected with a 50 liters
ICARUS-like chamber located between the CHORUS and NOMAD experiments at the
CERN West Area Neutrino Facility (WANF). We discuss both the instrumental
performance of the detector and its capability to identify and reconstruct low
multiplicity neutrino interactions.Comment: 14 pages, 12 figures. Submitted for publication to Physical Review
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