339 research outputs found
Effect of the momentum dependence of nuclear symmetry potential on the transverse and elliptic flows
In the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck
transport model, effect of the momentum dependence of nuclear symmetry
potential on nuclear transverse and elliptic flows in the neutron-rich reaction
Sn+Sn at a beam energy of 400 MeV/nucleon is studied. We find
that the momentum dependence of nuclear symmetry potential affects the rapidity
distribution of the free neutron to proton ratio, the neutron and the proton
transverse flows as a function of rapidity. The momentum dependence of nuclear
symmetry potential affects the neutron-proton differential transverse flow more
evidently than the difference of neutron and proton transverse flows as well as
the difference of proton and neutron elliptic flows. It is thus better to probe
the symmetry energy by using the difference of neutron and proton flows since
the momentum dependence of nuclear symmetry potential is still an open
question. And it is better to probe the momentum dependence of nuclear symmetry
potential by using the neutron-proton differential transverse flow and the
rapidity distribution of the free neutron to proton ratio.Comment: 6 pages, 6 figures, to be published by EPJ
COSMOGRAIL: XVII. Time delays for the quadruply imaged quasar PG 1115+080
Indexación: Scopus.Acknowledgements. The authors would like to thank R. Gredel for his help in setting up the program at the ESO MPIA 2.2 m telescope, and the anonymous referee for his or her comments on this work. This work is supported by the Swiss National Fundation. This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013, 2018) and the 2D graphics environment Matplotlib (Hunter 2007). K.R. acknowledge support from PhD fellowship FIB-UV 2015/2016 and Becas de Doctorado Nacional CONICYT 2017 and thanks the LSSTC Data Science Fellowship Program, her time as a Fellow has benefited this work. M.T. acknowledges support by the DFG grant Hi 1495/2-1. G. C.-F. C. acknowledges support from the Ministry of Education in Taiwan via Government Scholarship to Study Abroad (GSSA). D. C.-Y. Chao and S. H. Suyu gratefully acknowledge the support from the Max Planck Society through the Max Planck Research Group for S. H. Suyu. T. A. acknowledges support by the Ministry for the Economy, Development, and Tourism’s Programa Inicativa Científica Milenio through grant IC 12009, awarded to The Millennium Institute of Astrophysics (MAS).We present time-delay estimates for the quadruply imaged quasar PG 1115+080. Our results are based on almost daily observations for seven months at the ESO MPIA 2.2 m telescope at La Silla Observatory, reaching a signal-to-noise ratio of about 1000 per quasar image. In addition, we re-analyze existing light curves from the literature that we complete with an additional three seasons of monitoring with the Mercator telescope at La Palma Observatory. When exploring the possible source of bias we considered the so-called microlensing time delay, a potential source of systematic error so far never directly accounted for in previous time-delay publications. In 15 yr of data on PG 1115+080, we find no strong evidence of microlensing time delay. Therefore not accounting for this effect, our time-delay estimates on the individual data sets are in good agreement with each other and with the literature. Combining the data sets, we obtain the most precise time-delay estimates to date on PG 1115+080, with Δt(AB) = 8.3+1.5 -1.6 days (18.7% precision), Δt(AC) = 9.9+1.1 -1.1 days (11.1%) and Δt(BC) = 18.8+1.6 -1.6 days (8.5%). Turning these time delays into cosmological constraints is done in a companion paper that makes use of ground-based Adaptive Optics (AO) with the Keck telescope. © ESO 2018.https://www.aanda.org/articles/aa/abs/2018/08/aa33287-18/aa33287-18.htm
Astroparticle Physics with a Customized Low-Background Broad Energy Germanium Detector
The MAJORANA Collaboration is building the MAJORANA DEMONSTRATOR, a 60 kg
array of high purity germanium detectors housed in an ultra-low background
shield at the Sanford Underground Laboratory in Lead, SD. The MAJORANA
DEMONSTRATOR will search for neutrinoless double-beta decay of 76Ge while
demonstrating the feasibility of a tonne-scale experiment. It may also carry
out a dark matter search in the 1-10 GeV/c^2 mass range. We have found that
customized Broad Energy Germanium (BEGe) detectors produced by Canberra have
several desirable features for a neutrinoless double-beta decay experiment,
including low electronic noise, excellent pulse shape analysis capabilities,
and simple fabrication. We have deployed a customized BEGe, the MAJORANA
Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and
shield at the Kimballton Underground Research Facility in Virginia. This paper
will focus on the detector characteristics and measurements that can be
performed with such a radiation detector in a low-background environment.Comment: Submitted to NIMA Proceedings, SORMA XII. 9 pages, 4 figure
Production and Decay of D_1(2420)^0 and D_2^*(2460)^0
We have investigated and final states and
observed the two established charmed mesons, the with mass
MeV/c and width MeV/c and
the with mass MeV/c and width
MeV/c. Properties of these final states, including
their decay angular distributions and spin-parity assignments, have been
studied. We identify these two mesons as the doublet predicted
by HQET. We also obtain constraints on {\footnotesize } as a function of the cosine of the relative phase of the two
amplitudes in the decay.Comment: 15 pages in REVTEX format. hardcopies with figures can be obtained by
sending mail to: [email protected]
Study of the B^0 Semileptonic Decay Spectrum at the Upsilon(4S) Resonance
We have made a first measurement of the lepton momentum spectrum in a sample
of events enriched in neutral B's through a partial reconstruction of B0 -->
D*- l+ nu. This spectrum, measured with 2.38 fb**-1 of data collected at the
Upsilon(4S) resonance by the CLEO II detector, is compared directly to the
inclusive lepton spectrum from all Upsilon(4S) events in the same data set.
These two spectra are consistent with having the same shape above 1.5 GeV/c.
From the two spectra and two other CLEO measurements, we obtain the B0 and B+
semileptonic branching fractions, b0 and b+, their ratio, and the production
ratio f+-/f00 of B+ and B0 pairs at the Upsilon(4S). We report b+/b0=0.950
(+0.117-0.080) +- 0.091, b0 = (10.78 +- 0.60 +- 0.69)%, and b+ = (10.25 +- 0.57
+- 0.65)%. b+/b0 is equivalent to the ratio of charged to neutral B lifetimes,
tau+/tau0.Comment: 14 page, postscript file also available at
http://w4.lns.cornell.edu/public/CLN
Measurement of the Mass Splittings between the States
We present new measurements of photon energies and branching fractions for
the radiative transitions: Upsilon(2S)->gamma+chi_b(J=0,1,2). The masses of the
chi_b states are determined from the measured radiative photon energies. The
ratio of mass splittings between the chi_b substates,
r==(M[J=2]-M[J=1])/(M[J=1]-M[J=0]) with M the chi_b mass, provides information
on the nature of the bbbar confining potential. We find
r(1P)=0.54+/-0.02+/-0.02. This value is in conflict with the previous world
average, but more consistent with the theoretical expectation that r(1P)<r(2P);
i.e., that this mass splittings ratio is smaller for the chi_b(1P) triplet than
for the chi_b(2P) triplet.Comment: 11 page postscript file, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
Radiative Decay Modes of the Meson
Using data recorded by the CLEO-II detector at CESR we have searched for four
radiative decay modes of the meson: ,
, , and . We
obtain 90% CL upper limits on the branching ratios of these modes of , , and
respectively.Comment: 15 page postscript file, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
Measurement of the branching fraction for
We have studied the leptonic decay of the resonance into tau
pairs using the CLEO II detector. A clean sample of tau pair events is
identified via events containing two charged particles where exactly one of the
particles is an identified electron. We find . The result is consistent with
expectations from lepton universality.Comment: 9 pages, RevTeX, two Postscript figures available upon request, CLNS
94/1297, CLEO 94-20 (submitted to Physics Letters B
Measurement of the Decay Asymmetry Parameters in and
We have measured the weak decay asymmetry parameters (\aLC ) for two \LC\
decay modes. Our measurements are \aLC = -0.94^{+0.21+0.12}_{-0.06-0.06} for
the decay mode and \aLC = -0.45\pm 0.31 \pm
0.06 for the decay mode . By combining these
measurements with the previously measured decay rates, we have extracted the
parity-violating and parity-conserving amplitudes. These amplitudes are used to
test models of nonleptonic charmed baryon decay.Comment: 11 pages including the figures. Uses REVTEX and psfig macros. Figures
as uuencoded postscript. Also available as
http://w4.lns.cornell.edu/public/CLNS/1995/CLNS95-1319.p
Measurements of the Ratios and
Using the CLEO~II detector we measure , and .
We find the vector to pseudoscalar ratio, , which is similar to the
ratio found in non strange decays.Comment: 11 page uuencoded postscript file, postscript file also available
through http://w4.lns.cornell.edu/public/CLN
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