13,952 research outputs found
Organic Liquid TPCs for Neutrino Physics
We present a new concept for anti-neutrino detection, an organic liquid TPC
with a volume of the order of m and an energy resolution of the order of 1%
at 3 MeV and a sub-cm spatial resolution.Comment: 11 pages, 3 figure
Commissioning the Double Chooz detector
The Double Chooz experiment is the first of the next wave of reactor experiments searching for a non-vanishing value of the mixing angle θ13. The experimental concept and detector design are presented, and the most pertinent
backgrounds are discussed. Operation of the far detector began in early 2011. Installation of the near detector will occur in 2012. Double Chooz has the capacity to measure sin2(2θ13) to 3σ if sin2(2θ13) > 0.05 or exclude sin2(2θ13) down to 0.03 at 90% for Δm2 31 = 2.5 × 10−3 eV2 with three years of data with both near and far detectors
Retention of Low Income Children in Three Dental Studies Investigating Early Childhood Caries
Background: To our knowledge no dental studies have looked closely at subject retention, which is crucial to better understand oral health disparities. In this paper, we report retention rates and review and attempt to assess which retention strategies utilized in 3 dental research studies investigating ECC were effective for retaining WIC-enrolled children. The purpose of this paper is to discuss challenges that were encountered when working with these populations, describe characteristics of those not retained, and summarize some recommendations for future dental studies working at WIC sites. Methods: Three dental studies were conducted at WIC clinics in Iowa. Retention strategies focused on maintenance of contact over time, persistence in rescheduling appointments, utilization of incentives, high recruitment, and frequent communication with parents and program staff. Results: Retention rates in the studies ranged from 60 to 75 percent at the final research interventions. Studies were challenged by frequent moves of subjects, missed appointments, disconnected phones, busy schedules of parents, transportation problems, loss of child custody, family illness, and lack of interest. Those not retained in the studies were more likely to be younger, single, and less educated, with a lower household income and a non-Caucasian child. Lower retention was also associated with the presence of carious lesions. Conclusions: Despite many challenges, studies had good retention rates and benefited from the retention strategies. Future dental studies at WIC clinics may also benefit from arranging transportation, obtaining a free, 800 callback number, and offering after-hours appointments for working parents
Proton decay matrix elements with domain-wall fermions
Hadronic matrix elements of operators relevant to nucleon decay in grand
unified theories are calculated numerically using lattice QCD. In this context,
the domain-wall fermion formulation, combined with non-perturbative
renormalization, is used for the first time. These techniques bring reduction
of a large fraction of the systematic error from the finite lattice spacing.
Our main effort is devoted to a calculation performed in the quenched
approximation, where the direct calculation of the nucleon to pseudoscalar
matrix elements, as well as the indirect estimate of them from the nucleon to
vacuum matrix elements, are performed. First results, using two flavors of
dynamical domain-wall quarks for the nucleon to vacuum matrix elements are also
presented to address the systematic error of quenching, which appears to be
small compared to the other errors. Our results suggest that the representative
value for the low energy constants from the nucleon to vacuum matrix elements
are given as |alpha| simeq |beta| simeq 0.01 GeV^3. For a more reliable
estimate of the physical low energy matrix elements, it is better to use the
relevant form factors calculated in the direct method. The direct method tends
to give smaller value of the form factors, compared to the indirect one, thus
enhancing the proton life-time; indeed for the pi^0 final state the difference
between the two methods is quite appreciable.Comment: 56 pages, 17 figures, a comment and two references added in the
introduction, typo corrected in Eq.1
The Carina Flare: What can fragments in the wall tell us?
CO(J=2--1) and CO(J=2--1) observations of the molecular cloud
G285.90+4.53 (Cloud~16) in the Carina Flare supershell (GSH287+04-17) with the
APEX telescope are presented. With an algorithm DENDROFIND we identify 51
fragments and compute their sizes and masses. We discuss their mass spectrum
and interpret it as being the result of the shell fragmentation process
described by the pressure assisted gravitational instability - PAGI. We
conclude that the explanation of the clump mass function needs a combination of
gravity with pressure external to the shell.Comment: 19 pages, 14 figures, accepted by A&
Renormalized broken-symmetry Schwinger-Dyson equations and the 2PI-1/N expansion for the O(N) model
We derive the renormalized Schwinger-Dyson equations for the one- and
two-point functions in the auxiliary field formulation of
field theory to order 1/N in the 2PI-1/N expansion. We show that the
renormalization of the broken-symmetry theory depends only on the counter terms
of the symmetric theory with . We find that the 2PI-1/N expansion
violates the Goldstone theorem at order 1/N. In using the O(4) model as a low
energy effective field theory of pions to study the time evolution of
disoriented chiral condensates one has to {\em{explicitly}} break the O(4)
symmetry to give the physical pions a nonzero mass. In this effective theory
the {\em additional} small contribution to the pion mass due to the violation
of the Goldstone theorem in the 2-PI-1/N equations should be numerically
unimportant
Simulation Study of TenTen: A new Multi-TeV IACT array
TenTen is a proposed array of Imaging Atmospheric Cherenkov Telescopes (IACT)
optimized for the gamma ray energy regime of 10 TeV to 100 TeV, but with a
threshold of ~1 to a few TeV. It will offer a collecting area of 10 km2 above
energies of 10 TeV. In the initial phase, a cell of 3 to 5 modest-sized
telescopes, each with 10-30 m2 mirror area, is suggested for an Australian
site. A possible expansion of the array could comprise many such cells. Here we
present work on configuration and technical issues from our simulation studies
of the array. Working topics include array layout, telescope size and optics,
camera field of view, telescope trigger system, electronics, and site surveys.Comment: 4 pages, 7 figures, submitted to Proceedings of the ICRC 2007, pdf
forma
TenTen: A New Array of Multi-TeV Imaging Cherenkov Telescopes
The exciting results from H.E.S.S. point to a new population of gamma-ray
sources at energies E > 10 TeV, paving the way for future studies and new
discoveries in the multi-TeV energy range. Connected with these energies is the
search for sources of PeV cosmic-rays (CRs) and the study of multi-TeV
gamma-ray production in a growing number of astrophysical environments. TenTen
is a proposed stereoscopic array (with a suggested site in Australia) of
modest-sized (10 to 30m^2) Cherenkov imaging telescopes with a wide field of
view (8 to 10deg diameter) optimised for the E~10 to 100 TeV range. TenTen will
achieve an effective area of ~10 km^2 at energies above 10 TeV. We outline here
the motivation for TenTen and summarise key performance parameters.Comment: 4 pages, 2 figures, proceedings of the 30th ICRC, Merida, Mexico,
200
- …