2,750 research outputs found
Measurement of neutron detection efficiency between 22 and 174 MeV using two different kinds of Pb-scintillating fiber sampling calorimeters
We exposed a prototype of the lead-scintillating fiber KLOE calorimeter to
neutron beam of 21, 46 and 174 MeV at The Svedberg Laboratory, Uppsala, to
study its neutron detection efficiency. This has been found larger than what
expected considering the scintillator thickness of the prototype. %To check our
method, we measured also the neutron %detection efficiency of a 5 cm thick
NE110 scintillator. We show preliminary measurement carried out with a
different prototype with a larger lead/fiber ratio, which proves the relevance
of passive material to neutron detection efficiency in this kind of
calorimeters
More Elevated Fastballs Associated with Placement on the Injured List Due to Shoulder Injury
Purpose
To evaluate whether impending shoulder injury was associated with changes in pitch location or velocity immediately preceding injury.
Methods
Pitchers placed on the injured list (IL) due to a shoulder injury between 2015 and 2020 were identified in the Major League Baseball transactions database. Four-seam fastball velocity and frequency of pitch location for each pitch type was collected for each player in the season before placement on the IL and within 1 month of placement on the IL with a minimum of 55 pitches thrown of 1 type. Pitch locations were collected as identified by Baseball Savant’s Game-Day Zones. Game-Day Zones were consolidated into high (above the strike zone midpoint) versus low, arm side (closer to the pitcher’s arm side of the plate) versus opposite side, and within the strike zone versus out of zone. Repeated measures analysis of variance determined differences in four-seam velocity and the location distribution of 4-seam fastballs, change-ups, and breaking balls among each group.
Results In total, 267 pitchers were placed on the IL for a shoulder injury with the majority diagnosed with inflammation (89/267) followed by strain or sprain (69/267). Four-seam fastball locations significantly increased above the mid-point of the zone (45.9% vs 42.4%, P = .008) and out of the strike zone (48.5% vs 46.5%, P = .011) within a month before IL placement. There was no significant change in 4-seam fastball velocity immediately before IL placement.
Conclusions Pitchers threw more elevated 4-seam fastballs and out-of-zone 4-seam fastballs in the month before IL placement for shoulder injury. These findings suggest that a loss of 4-seam fastball command decreases with impending shoulder injury.
Level of Evidence IV, prognostic case series
Measurement of the neutron detection efficiency of a 80% absorber - 20% scintillating fibers calorimeter
The neutron detection efficiency of a sampling calorimeter made of 1 mm
diameter scintillating fibers embedded in a lead/bismuth structure has been
measured at the neutron beam of the The Svedberg Laboratory at Uppsala. A
significant enhancement of the detection efficiency with respect to a bulk
organic scintillator detector with the same thickness is observed.Comment: 10 pages, 7 figure
Superallowed 0+ to 0+ nuclear beta decays: A new survey with precision tests of the conserved vector current hypothesis and the standard model
A new critical survey is presented of all half-life, decay-energy and
branching-ratio measurements related to 20 0+ to 0+ beta decays. Compared with
our last review, there are numerous improvements: First, we have added 27
recently published measurements and eliminated 9 references; of particular
importance, the new data include a number of high-precision Penning-trap
measurements of decay energies. Second, we have used the recently improved
isospin symmetry-breaking corrections. Third, our calculation of the
statistical rate function now accounts for possible excitation in the daughter
atom. Finally, we have re-examined the systematic uncertainty associated with
the isospin symmetry-breaking corrections by evaluating the radial-overlap
correction using Hartree-Fock radial wave functions and comparing the results
with our earlier calculations, which used Saxon-Woods wave functions; the
provision for systematic uncertainty has been changed as a consequence. The new
corrected Ft values are impressively constant and their average, when combined
with the muon liftime, yields the up-down quark-mixing element of the
Cabibbo-Kobayashi-Maskawa (CKM) matrix, V_{ud} = 0.97425(22). The unitarity
test on the top row of the matrix becomes |V_{ud}|^2 + |V_{us}|^2 + |V_{ub}|^2
= 0.99995(61). Both V_{ud} and the unitarity sum have significantly reduced
uncertainties compared with our previous survey, although the new value of
V_{ud} is statistically consistent with the old one. From these data we also
set limits on the possible existence of scalar interactions, right-hand
currents and extra Z bosons. Finally, we discuss the priorities for future
theoretical and experimental work with the goal of making the CKM unitarity
test even more definitive.Comment: 36 pages, 11 tables, 9 figure
Performance of the Muon Identification at LHCb
The performance of the muon identification in LHCb is extracted from data
using muons and hadrons produced in J/\psi->\mu\mu, \Lambda->p\pi and
D^{\star}->\pi D0(K\pi) decays. The muon identification procedure is based on
the pattern of hits in the muon chambers. A momentum dependent binary
requirement is used to reduce the probability of hadrons to be misidentified as
muons to the level of 1%, keeping the muon efficiency in the range of 95-98%.
As further refinement, a likelihood is built for the muon and non-muon
hypotheses. Adding a requirement on this likelihood that provides a total muon
efficiency at the level of 93%, the hadron misidentification rates are below
0.6%.Comment: 17 pages, 10 figure
A global fit to determine the pseudoscalar mixing angle and the gluonium content of the eta' meson
We update the values of the eta-eta' mixing angle and of the eta' gluonium
content by fitting our measurement R_phi = BR(phi to eta' gamma)/ BR(phi to eta
gamma) together with several vector meson radiative decays to pseudoscalars (V
to P gamma), pseudoscalar mesons radiative decays to vectors (P to V gamma) and
the eta' to gamma gamma, pi^0 to gamma gamma widths. From the fit we extract a
gluonium fraction of Z^2_G = 0.12 +- 0.04, the pseudoscalar mixing angle psi_P
= (40.4 +- 0.6) degree and the phi-omega mixing angle psi_V = (3.32 +- 0.09)
degree. Z^2_G and psi_P are fairly consistent with those previously published.
We also evaluate the impact on the eta' gluonium content determination of
future experimental improvements of the eta' branching ratios and decay width.Comment: 13 pages, 7 figures to submit to JHE
Measurement of the front-end dead-time of the LHCb muon detector and evaluation of its contribution to the muon detection inefficiency
A method is described which allows to deduce the dead-time of the front-end
electronics of the LHCb muon detector from a series of measurements performed
at different luminosities at a bunch-crossing rate of 20 MHz. The measured
values of the dead-time range from 70 ns to 100 ns. These results allow to
estimate the performance of the muon detector at the future bunch-crossing rate
of 40 MHz and at higher luminosity
Charged kaon lifetime at KLOE
Preliminary result on the charged kaon lifetime, obtained by the KLOE
experiment operating at DANE, the Frascati -factory, is presentedComment: 3 pages, 3 figures, to appear in the proceedings of 42nd Rencontres
de Moriond on Electroweak Interactions and Unified Theories, La Thuile, Aosta
Valley, Italy, 10-17 Mar 200
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