24,497 research outputs found
A Pulsed Synchrotron for Muon Acceleration at a Neutrino Factory
A 4600 Hz pulsed synchrotron is considered as a means of accelerating cool
muons with superconducting RF cavities from 4 to 20 GeV/c for a neutrino
factory. Eddy current losses are held to less than a megawatt by the low
machine duty cycle plus 100 micron thick grain oriented silicon steel
laminations and 250 micron diameter copper wires. Combined function magnets
with 20 T/m gradients alternating within single magnets form the lattice. Muon
survival is 83%.Comment: 4 pages, 1 figures, LaTeX, 5th International Workshop on Neutrino
Factories and Superbeams (NuFact 03), 5-11 Jun 2003, New Yor
6D Muon Ionization Cooling with an Inverse Cyclotron
A large admittance sector cyclotron filled with LiH wedges surrounded by
helium or hydrogen gas is explored. Muons are cooled as they spiral
adiabatically into a central swarm. As momentum approaches zero, the momentum
spread also approaches zero. Long bunch trains coalesce. Energy loss is used to
inject the muons into the outer rim of the cyclotron. The density of material
in the cyclotron decreases adiabatically with radius. The sector cyclotron
magnetic fields are transformed into an azimuthally symmetric magnetic bottle
in the center. Helium gas is used to inhibit muonium formation by positive
muons. Deuterium gas is used to allow captured negative muons to escape via the
muon catalyzed fusion process. The presence of ionized gas in the center may
automatically neutralize space charge. When a bunch train has coalesced into a
central swarm, it is ejected axially with an electric kicker pulse.Comment: Five pages. LaTeX, three postscript figure files. To appear in the
AIP Conference Proceedings for COOL05: International Workshop on Beam
Cooling, Galena, IL, 18-23 Sept. 200
MONTE CARLO SIMULATIONS OF MUON PRODUCTION
Muon production requirements for a muon collider are presented. Production of
muons from pion decay is studied. Lithium lenses and solenoids are considered
for focussing pions from a target, and for matching the pions into a decay
channel. Pion decay channels of alternating quadrupoles and long solenoids are
compared. Monte Carlo simulations are presented for production of by protons over a wide energy range, and criteria for
choosing the best proton energy are discussed.Comment: Latex uses mu95.sty, 19 pages, 5 postscript figures. A postscript
file can be seen at URL http://www.cap.bnl.gov/~cap/mumu/important.html
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TGRS Observations of Positron Annihilation in Classical Novae
The TGRS experiment on board the Wind spacecraft has many advantages as a sky
monitor --- broad field of view (~2 pi) centered on the south ecliptic pole),
long life (1994-present), and stable low background and continuous coverage due
to Wind's high altitude high eccentricity orbit. The Ge detector has sufficient
energy resolution (3-4 keV at 511 keV) to resolve a cosmic positron
annihilation line from the strong background annihilation line from beta-decays
induced by cosmic ray impacts on the instrument, if the cosmic line is
Doppler-shifted by this amount. Such lines (blueshifted) are predicted from
nucleosynthesis in classical novae. We have searched the entire TGRS database
for 1995-1997 for this line, with negative results. In principle such a search
could yield an unbiased upper limit on the highly-uncertain Galactic nova rate.
We carefully examined the times around the known nova events during this
period, also with negative results. The upper limit on the nova line flux in a
6-hr interval is typically <3.8 E-3 photon/(cm2 s) at 4.6 sigma. We performed
the same analysis for times around the outburst of Nova Vel 1999, obtaining a
worse limit due to recent degradation of the detector response caused by cosmic
ray induced damage.Comment: 5 pp. inc. 3 figs. Proc. 5th Compton Symposium (AIP Conf. Series),
ed. M. McConnell, in pres
Ab Initio Liquid Hydrogen Muon Cooling Simulations with ELMS in ICOOL
This paper presents new theoretical results on the passage of muons through
liquid hydrogen which have been confirmed in a recent experiment. These are
used to demonstrate that muon bunches may be compressed by ionisation cooling
more effectively than suggested by previous calculations.
Muon cooling depends on the differential cross section for energy loss and
scattering of muons. We have calculated this cross section for liquid H2 from
first principles and atomic data, avoiding traditional assumptions. Thence, 2-D
probability maps of energy loss and scattering in mm-scale thicknesses are
derived by folding, and stored in a database. Large first-order correlations
between energy loss and scattering are found for H2, which are absent in other
simulations. This code is named ELMS, Energy Loss & Multiple Scattering. Single
particle trajectories may then be tracked by Monte Carlo sampling from this
database on a scale of 1 mm or less. This processor has been inserted into the
cooling code ICOOL. Significant improvements in 6-D muon cooling are predicted
compared with previous predictions based on GEANT. This is examined in various
geometries. The large correlation effect is found to have only a small effect
on cooling. The experimental scattering observed for liquid H2 in the MUSCAT
experiment has recently been reported to be in good agreement with the ELMS
prediction, but in poor agreement with GEANT simulation.Comment: 6 pages, 3 figure
Precision metering of microliter volumes of biological fluids in micro-gravity
Concepts were demonstrated and investigated for transferring accurately known and reproducible microliter volumes of biological fluids from sample container onto dry chemistry slides in microgravity environment. Specific liquid transfer tip designs were compared. Information was obtained for design of a liquid sample handling system to enable clinical chemical analysis in microgravity. Disposable pipet tips and pipet devices that were designed to transfer microliter volumes of biological fluid from a (test tube) sample container in 1-G environment were used during microgravity periods of parabolic trajectories of the KC-135 aircraft. The transfer process was recorded using charge coupled device camera and video cassette equipment. Metering behavior of water, a synthetic aqueous protein solution, and anticoagulated human blood was compared. Transfer of these liquids to 2 substrate materials representative of rapidly wettable and slowly wettable dry chemistry slide surface was compared
Decoupling a Cooper-pair box to enhance the lifetime to 0.2 ms
We present a circuit QED experiment in which a separate transmission line is
used to address a quasi-lumped element superconducting microwave resonator
which is in turn coupled to an Al/AlO/Al Cooper-pair box (CPB) charge
qubit. In our measurements we find a strong correlation between the measured
lifetime of the CPB and the coupling between the qubit and the transmission
line. By monitoring perturbations of the resonator's 5.44 GHz resonant
frequency, we have measured the spectrum, lifetime (), Rabi, and Ramsey
oscillations of the CPB at the charge degeneracy point while the CPB was
detuned by up to 2.5 GHz . We find a maximum lifetime of the CPB was s for to 4.5 GHz. Our measured 's are consistent with
loss due to coupling to the transmission line, spurious microwave circuit
resonances, and a background decay rate on the order of
s of unknown origin, implying that the loss tangent in the AlO
junction barrier must be less than about at 4.5 GHz, about 4
orders of magnitude less than reported in larger area Al/AlO/Al tunnel
junctions
Ample consumption period available until use-by dates: a potential, marketing position for store brands
Traditionally store brands in Australia are viewed with suspicion in regard to their quality and are usually purchased because of the "value for money" that they offer. Australian supermarket majors are considering introducing a new suite of store brands in the higher price brackets. The danger of moving upscale however is that these store brands are relinquishing their value for money appeal and will come head to head with the manufactured brands. Store brands will now require some quality dimension to compete. This paper after studying the attitudes and behavioural response of grocery shoppers to use by dates, is proposing that that the promise of "generous" use-by dates as a surrogate for quality, could be considered as a positioning plank to promote store brands as alternatives to manufactured brands. Logit analysis is employed to explain shoppers' perception and response to use-by dates, of products that they regularly buy, and of alternative products which they have never bought before if the use-by dates of their regular items are perceived to be too shor
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