Tue·Mar 24, 2015Tuesday·March 24, 2015

1. 01*

   Three-body correlations in the ground-state decay of 26O

   Z. Kohley🇺🇸 · T. Baumann🇺🇸 · G. Christian🇺🇸 · P. A. DeYoung🇺🇸 · J. E. Finck🇺🇸 · N. Frank🇺🇸 · B. Luther🇺🇸 · E. Lunderberg🇺🇸 · M. Jones🇺🇸 · S. Mosby🇺🇸 · J. K. Smith🇺🇸 · A. Spyrou🇺🇸 · M. Thoennessen🇺🇸

   Background: Theoretical calculations have shown that the energy and angular correlations in the three-body decay of the two-neutron unbound O26 can provide information on the ground-state wave function, which has been predicted to have a dineutron configuration and 2n halo structure. Purpose: To use the experimentally measured three-body correlations to gain insight into the properties of O26, including the decay mechanism and ground-state resonance energy. Method: O26 was produced in a one-proton knockout reaction from F27 and the O24+n+n decay products were measured using the MoNA-Sweeper setup. The three-body correlations from the O26 ground-state resonance decay were extracted. The experimental results were compared to Monte Carlo simulations in which the resonance energy and decay mechanism were varied. Results: The measured three-body correlations were well reproduced by the Monte Carlo simulations but were not sensitive to the decay mechanism due to the experimental resolutions. However, the three-body correlations were found to be sensitive to the resonance energy of O26. A 1{\sigma} upper limit of 53 keV was extracted for the ground-state resonance energy of O26. Conclusions: Future attempts to measure the three-body correlations from the ground-state decay of O26 will be very challenging due to the need for a precise measurement of the O24 momentum at the reaction point in the target.

   nucl-exPRC(2015)·28 citations
2. 02*

   Centrality dependence of charged jets in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV measured with the ALICE detector

   Rüdiger Haake (for the ALICE Collaboration)🇩🇪

   Highly energetic jets are sensitive probes for the kinematics and the topology of nuclear collisions. Jets are collimated sprays of charged and neutral particles, which are produced in the fragmentation of hard scattered partons in an early stage of the collision. The measurement of jet spectra in p-Pb collisions provides an important way of quantifying the effects of cold nuclear matter in the initial state on jet production, fragmentation, and hadronization. Unlike in Pb-Pb collisions, strong hot nuclear matter effects - e.g. from quark-gluon plasma formation - are not expected to occur in p-Pb collisions. Hence, cold nuclear matter effects can be investigated in isolation. The impact of cold nuclear matter effects on charged jet spectra is expected to depend on the event centrality. Higher event centralities are principally connected to a higher probability for an interaction of proton and lead-nucleus and therefore also for a possible nuclear modification. This article is the conference proceeding of a talk, in which centrality-dependent properties of charged jets in p-Pb measured by ALICE were shown for the first time. The focus is here on the fully corrected jet production cross sections and the nuclear modification factors. Additionally, the jet radial structure is explored by comparing jet spectra reconstructed with different resolution parameters.

   nucl-exPoS(2015)·1 citation
3. 03*

   Bremsstrahlung from relativistic heavy ions in a fixed target experiment at the LHC

   Rune E. Mikkelsen🇩🇰 · Allan H. Sørensen · Ulrik I. Uggerhøj🇩🇰

   We calculate the emission of bremsstrahlung from lead and argon ions in A Fixed Target ExpeRiment (AFTER) that uses the LHC beams. With nuclear charges of $Ze$ equal $208$ and $18$ respectively, these ions are accelerated to energies of $7$ TeV$\times Z$. The bremsstrahlung peaks around $\approx 100$ GeV and the spectrum exposes the nuclear structure of the incoming ion. The peak structure is significantly different from the flat power spectrum pertaining to a point charge. Photons are predominantly emitted within an angle of $1/\gamma$ to the direction of ion propagation. Our calculations are based on the Weizsäcker-Williams method of virtual quanta with application of existing experimental data on photonuclear interactions.

   nucl-exhep-exhep-phAdv.High Energy Phys.(2015)·3 citations
4. 04*

   Coulomb and even-odd effects in cold and super-asymmetric fragmentation for thermal neutron induced fission of 235U

   Modesto Montoya🇵🇪

   The Coulomb effects hypothesis is used to interpret even-odd effects of maximum total kinetic energy as a function of mass and charge of fragments from thermal neutron induced fission of 235U. Assuming spherical fragments at scission, the Coulomb interaction energy between fragments (C_sph) is higher than the Q-value, the available energy. Therefore at scission the fragments must be deformed, so that the Coulomb interaction energy does not exceed the Q-value. The fact that the even-odd effects in the maximum total kinetic energy as a function of the charge and mass, respectively, are lower than the even-odd effects of Q is consistent with the assumption that odd mass fragments are softer than the even-even fragments. Even-odd effects of charge distribution in super asymmetric fragmentation also are interpreted with the Coulomb effect hypothesis. Because the difference between C_sph and Q increases with asymmetry, fragmentations require higher total deformation energy to occur. Higher deformation energy of the fragments implies lower free energy to break pairs of nucleons. This explains why in the asymmetric fragmentation region, the even-odd effects of the distribution of proton number and neutron number increases with asymmetry. Based on a similar reasoning, a prediction of a relatively high even-odd effect in symmetric fragmentations is proposed.

   nucl-exnucl-thAIP Conf.Proc.(2016)·0 citations
5. 05*

   Investigation of radioactivity-induced backgrounds in EXO-200

   J.B. Albert🇺🇸 · D.J. Auty🇺🇸 · P.S. Barbeau🇺🇸 · D. Beck🇺🇸 · V. Belov🇷🇺 · C. Benitez-Medina🇺🇸 · M. Breidenbach🇺🇸 · T. Brunner🇺🇸 · A. Burenkov🇷🇺 · G.F. Cao🇨🇳 · C. Chambers🇺🇸 · B. Cleveland🇨🇦 and 74 other authors

   The search for neutrinoless double-beta decay (0{\nu}{\beta}{\beta}) requires extremely low background and a good understanding of their sources and their influence on the rate in the region of parameter space relevant to the 0{\nu}{\beta}{\beta} signal. We report on studies of various {\beta}- and {\gamma}-backgrounds in the liquid- xenon-based EXO-200 0{\nu}{\beta}{\beta} experiment. With this work we try to better understand the location and strength of specific background sources and compare the conclusions to radioassay results taken before and during detector construction. Finally, we discuss the implications of these studies for EXO-200 as well as for the next-generation, tonne-scale nEXO detector.

   ↳ physics.ins-dethep-exnucl-exPRC(2015)·59 citations
6. 06*

   The Intermediate Neutrino Program

   C. Adams🇺🇸 · J.R. Alonso🇺🇸 · A.M. Ankowski🇺🇸 · J.A. Asaadi🇺🇸 · J. Ashenfelter🇺🇸 · S.N. Axani🇺🇸 · K. Babu🇺🇸 · C. Backhouse🇺🇸 · H.R. Band🇺🇸 · P.S. Barbeau🇺🇸 · N. Barros🇩🇪 · A. Bernstein🇺🇸 and 177 other authors

   The US neutrino community gathered at the Workshop on the Intermediate Neutrino Program (WINP) at Brookhaven National Laboratory February 4-6, 2015 to explore opportunities in neutrino physics over the next five to ten years. Scientists from particle, astroparticle and nuclear physics participated in the workshop. The workshop examined promising opportunities for neutrino physics in the intermediate term, including possible new small to mid-scale experiments, US contributions to large experiments, upgrades to existing experiments, R&D plans and theory. The workshop was organized into two sets of parallel working group sessions, divided by physics topics and technology. Physics working groups covered topics on Sterile Neutrinos, Neutrino Mixing, Neutrino Interactions, Neutrino Properties and Astrophysical Neutrinos. Technology sessions were organized into Theory, Short-Baseline Accelerator Neutrinos, Reactor Neutrinos, Detector R&D and Source, Cyclotron and Meson Decay at Rest sessions.This report summarizes discussion and conclusions from the workshop.

   ↳ hep-exnucl-exphysics.ins-det12 citations
7. 07*

   On the Extraction of Cross Sections for pi0 and eta Photoproduction off Neutrons from Deuteron Data

   V. E. Tarasov (ITEP)🇷🇺 · W. J. Briscoe (GW)🇺🇸 · M. Dieterle (Basel U.)🇨🇭 · B. Krusche (Basel U.)🇨🇭 · A. E. Kudryavtsev (ITEP/GW)🇷🇺 · M. Ostrick (JGU)🇩🇪 · I. I. Strakovsky (GW)🇺🇸

   We discuss the procedure of extracting the photoproduction cross section for neutral pseudoscalar mesons off neutrons from deuteron data. The main statement is that the final-state interaction (FSI) corrections for the proton and neutron target are in general not equal, but for pi0 production there are special cases were they have to be identical and there are large regions in the parameter space of incident photon energy and pion polar angle, \theta^*, where they happen to be quite similar. The corrections for both target nucleons are practically identical for ${\pi }_0$ production in the energy range of the Delta(1232)3/2+ resonance due to the specific isospin structure of this excitation. Also above the $\Delta$-isobar range large differences between proton and neutron correction factors are only predicted for extreme forward angles (${\theta }^{\ast }$ < 20 deg), but the results are similar for larger angles. Numerical results for the gp-->pi0p and gn-->pi0n correction factors are discussed. Also the model description for the available data on the differential gd-->pi0pn cross sections are given.

   ↳ hep-phhep-exnucl-exnucl-thPhys.Atom.Nucl.(2016)·25 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.