Wed·Dec 12, 2018Wednesday·December 12, 2018

1. 01*

   Measurement of isolated photon-hadron and jet correlations in 5 TeV pp and p-Pb collisions with the ALICE detector at the LHC

   Miguel Arratia (for the ALICE Collaboration)🇺🇸

   Photon-jet correlations are a promising channel for the study of parton energy loss in nuclear collisions. While existing measurements in pp and nuclear collisions have used high energy photons and jets, we focus on an unexplored kinematic range given by $12<p_{\mathrm{T}}<30$ GeV/$c$ photons and the corresponding low jet $p_{\mathrm{T}}$. We present results obtained using 5.02 TeV pp and p-Pb collisions. A combination of isolation and electromagnetic shower-shape variables is used to reduce the large background from meson decays and fragmentation photons. We show how the access to this kinematic range of hard probes was achieved with a novel combination of high rate and low-momentum tracking using the electromagnetic calorimeters and the inner tracking system of the ALICE experiment.

   nucl-exhep-exPoS(2018)·2 citations
2. 02*

   Invariant-mass spectroscopy of ${}^{18}$Ne, ${}^{16}$O, and ${}^{10}$C excited states formed in neutron transfer reactions

   R.J. Charity🇺🇸 · K. W. Brown🇺🇸 · J. M. Elson🇺🇸 · W. Reviol🇺🇸 · L. G. Sobotka🇺🇸 · W. W. Buhro🇺🇸 · Z. Chajecki🇺🇸 · W. G. Lynch🇺🇸 · J. Manfredi🇺🇸 · R. Shane🇺🇸 · R. H. Showalter🇺🇸 · M. B. Tsang🇺🇸 and 5 other authors

   Neutron transfer reactions with fast secondary beams of ${}^{17}$Ne, ${}^{15}$O, and ${}^9$C have been studied with the HiRA and CAESAR arrays. Excited states of ${}^{18}$Ne, ${}^{16}$O, and ${}^{10}$C in the continuum have been identified using invariant-mass spectroscopy. The best experimental resolution of these states is achieved by selecting events where the decay fragments are emitted transverse to the beam direction. We have confirmed a number of spin assignments made in previous works for the negative-parity states of ${}^{18}$Ne. In addition we have found new higher-lying excited states in ${}^{16}$O and ${}^{18}$Ne, some of which fission into two ground-state ${}^8$Be fragments. Finally for ${}^{10}$C, a new excited state was observed. These transfer reactions were found to leave the remnant of the ${}^9$Be target nuclei at very high excitation energies and maybe associated with the pickup of a deeply-bound ${}^9$Be neutron.

   nucl-exPRC(2019)·34 citations
3. 03*

   Impact of ${}^{16}$O($\gamma$,$\alpha$)${}^{12}$C measurements on the ${}^{12}$C($\alpha ,\gamma$)${}^{16}$O astrophysical reaction rate

   R. J. Holt🇺🇸 · B. W. Filippone🇺🇸 · Steven C. Pieper🇺🇸

   The ${}^{12}$C($\alpha ,\gamma$)${}^{16}$O reaction, an important component of stellar helium burning, plays a key role in nuclear astrophysics. It has direct impact on the evolution and final state of massive stars, while also influencing the elemental abundances resulting from nucleosynthesis in such stars. Providing a reliable estimate for the energy dependence of this reaction at stellar helium burning temperatures has been a major goal for the field. In this work, we study the role of potential new measurements of the inverse reaction, ${}^{16}$O($\gamma ,\alpha$)${}^{12}$C, in reducing the overall uncertainty. A multilevel R-matrix analysis is used to make extrapolations of the astrophysical S factor for this reaction to the stellar energy of 300 keV. The statistical precision of the S-factor extrapolation is determined by performing multiple fits to existing E1 and E2 ground state capture data, including the impact of possible future measurements of the ${}^{16}$O($\gamma ,\alpha$)${}^{12}$C reaction. In particular, we consider a proposed JLab experiment that will make use of a high-intensity low-energy bremsstrahlung beam that impinges on an oxygen-rich single-fluid bubble chamber in order to measure the total cross section for the inverse reaction. The importance of low energy data as well as high precision data is investigated.

   nucl-exnucl-thPRC(2019)·11 citations
4. 04*

   ${}_{\mathrm{\Lambda }}^3\mathrm{H}$ and ${}_{\overline{\mathrm{\Lambda }}}^3\overline{\mathrm{H}}$ production and characterization in Cu+Cu collisions at $\sqrt{s_{\mathrm{NN}}}=200$GeV

   Feng Xian Liu🇨🇳 · Gang Chen🇨🇳 · Zhi Lei She🇨🇳 · Liang Zheng🇨🇳 · Yi Long Xie🇨🇳 · Zi Jian Dong🇨🇳 · Dai Mei Zhou🇨🇳 · Ben Hao Sa🇨🇳

   Production of the (anti)hypertriton nuclei ${}_{\mathrm{\Lambda }}^3\mathrm{H}$ and ${}_{\overline{\mathrm{\Lambda }}}^3\overline{\mathrm{H}}$ in Cu+Cu interactions at $\sqrt{s_{\mathrm{NN}}}=200$GeV is studied at three centrality bins of 0-10\%, 10-30\% and 30-60\% using the dynamically constrained phase-space coalescence model together with [PACIAE] model simulations. The ${}^3\mathrm{H}{(}^3\overline{\mathrm{H}})$ and ${}^3\mathrm{He}{(}^3\overline{\mathrm{He}})$ nuclei has been compared. It is indicated by the study that the yields of light nuclei and hypernuclei increase rapidly from peripheral to central collisions while their anti-particle to particle ratios keep unchanged for different centrality bins. The strangeness population factor $S_3={}_{\mathrm{\Lambda }}^3\mathrm{H}/({}^3\mathrm{He}\times \Lambda /p)$ was found to be close to unity, and was compatible with the STAR data and theoretical model calculation, suggesting that the phase-space population of strange quarks is similar with the ones of light quarks and the creation of deconfined high temperature quark matter in Cu+Cu collisions.

   nucl-exPRC(2019)·7 citations
5. 05*

   $\gamma W$-box Inside-Out: Nuclear Polarizabilities Distort the Beta Decay Spectrum

   Mikhail Gorchtein🇩🇪

   I consider the $\gamma W$-box correction to superallowed nuclear $\beta$-decays in the framework of dispersion relations. I address a novel effect of a distortion of the emitted electron energy spectrum by nuclear polarizabilities and show that this effect, while neglected in the literature, is sizable. I estimate its size in the approximation of a linear energy dependence, and using two models that are expected to give the lower and the upper bound. The respective correction to the ${\beta }^{+}$ spectrum is estimated to be ${\Delta }_R(E)=(1.6\pm 1.6)\times 10^{-4}E/\mathrm{MeV}$ assuming a conservative 100\% uncertainty. The effect is positive-definite and can be observed if a high-precision measurement of the positron spectrum is viable. If only the full rate is observed, it should be included in the calculated $\mathcal{F}t$-values of nuclear decays. I argue that this novel effect should be evaluated in state-of-the-art nuclear models and included in the analyses of nuclear beta decay experiments to ensure the correct extraction of $V_{ud}$ from decay rates, and of the Fierz interference term from precision measurements of decay spectra.

   ↳ nucl-thhep-phnucl-exPRL(2019)·109 citations
6. 06*

   Search for the QCD Critical Point by Transverse Velocity Dependence of Anti-deuteron to Deuteron Ratio

   Ning Yu🇨🇳 · Dingwei Zhang🇨🇳 · Xiaofeng Luo🇨🇳

   We propose the transverse velocity (${\beta }_T$) dependence of the anti-deuteron to deuteron ratio as a new observable to search for the QCD critical point in heavy-ion collisions. The QCD critical point can attract the system evolution trajectory in the QCD phase diagram, which is known as focusing effect. To quantify this effect, we employ thermal model and hadronic transport model to simulate the dynamical particle emission along a hypothetical focusing trajectory near critical point. We found the focusing effect can lead to anomalous ${\beta }_T$ dependence of $\bar{p}/p$, $\bar{d}/d$ and ${}^3\overline{\text{He}}{/}^3\text{He}$ ratios. We examined the ${\beta }_T$ dependence of $\bar{p}/p$ and $\bar{d}/d$ ratios of central Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7 to 200 GeV measured by the STAR experiment at RHIC. Surprisingly, we only observe a negative slope in ${\beta }_T$ dependence of $\bar{d}/d$ ratio at $\sqrt{s_{NN}}$ = 19.6 GeV, which indicates the trajectory evolution has passed through the critical region. In the future, we could constrain the location of the critical point and/or width of the critical region by making precise measurements on the ${\beta }_T$ dependence of $\bar{d}/d$ ratio at different energies and rapidity.

   ↳ nucl-thhep-phnucl-exCPC(2020)·26 citations
7. 07*

   Nuclear Astrophysics in the Multimessenger Era: A Partnership Made in Heaven

   J. Piekarewicz🇺🇸

   On August 17, 2017 the LIGO-Virgo collaboration detected for the first time gravitational waves from the binary merger of two neutron stars (GW170817). Unlike the merger of two black holes, the associated electromagnetic radiation was also detected by a host of telescopes operating over a wide range of frequencies---opening a brand new era of multimessenger astronomy. This historical detection is providing fundamental new insights into the astrophysical site for the r-process and on the nature of dense matter. In this contribution we examine the impact of GW170817 on the equation of state of neutron rich matter, particularly on the density dependence of the symmetry energy. Limits on the tidal polarizability extracted from GW170817 seem to suggest that the symmetry energy is soft, thereby excluding models that predict overly large stellar radii.

   ↳ nucl-thastro-ph.HEnucl-exActa Phys.Polon.B(2019)·4 citations
8. 08*

   Study of MicroPattern Gaseous detectors with novel nanodiamond based photocathodes for single photon detection in EIC RICH

   J. Agarwala🇮🇹 · C. Chatterjee🇮🇹 · G. Cicala🇮🇹 · A. Cicuttin🇮🇹 · P. Ciliberti🇮🇹 · M.L. Crespo🇮🇹 · S. Dalla Torre🇮🇹 · S. Dasgupta🇮🇹 · M. Gregori🇮🇹 · S. Levorato🇮🇹 · G. Menon🇮🇹 · F. Tessarotto🇮🇹 and 3 other authors

   Identification of high momentum hadrons at the future EIC is crucial, gaseous RICH detectors are therefore viable option. Compact collider setups impose to construct RICHes with small radiator length, hence significantly limiting the number of detected photons. More photons can be detected in the far UV region, using a windowless RICH approach. QE of CsI degrades under strong irradiation and air contamination. Nanodiamond based photocathodes (PCs) are being developed as an alternative to CsI. Recent development of layers of hydrogenated nanodiamond powders as an alternative photosensitive material and their performance, when coupled to the THick Gaseous Electron Multipliers (THGEM)-based detectors, are the objects of an ongoing R\&D. We report about the initial phase of our studies.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2020)·7 citations
9. 09*

   Single-Transverse-Spin Asymmetries in Exclusive Photo-production of J/psi in Ultra-Peripheral Collisions in the Fixed-Target Mode at the LHC and in the Collider Mode at RHIC

   J.P. Lansberg🇫🇷 · L. Massacrier🇫🇷 · L. Szymanowski🇵🇱 · J. Wagner🇵🇱

   We investigate the potentialities offered by the study of J/psi exclusive photo-production in ultra-peripheral collisions at a fixed-target experiment using the proton and lead LHC beams (generically denoted as AFTER@LHC) on hydrogen targets and at RHIC in the collider mode. We compare the expected counting rates in both set-ups. Studying Single-Transverse-Spin Asymmetries (A_N) in such a process provides a direct path to the proton Generalised Parton Distribution (GPD) E_g(x,xi,t). We evaluate the expected precision on A_N for realistic conditions with the LHCb detector in pH(pol) and PbH(pol) collisions. We also discuss prospects with polarised deuterium and helium targets in the case of AFTER@LHC.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2019)·15 citations
10. 10*

    Towards a precise determination of the excitation energy of the Thorium nuclear isomer using a magnetic bottle spectrometer

    Benedict Seiferle · Lars von der Wense · Ines Amersdorffer · Nicolas Arlt · Benjamin Kotulski · Peter G. Thirolf🇩🇪

    ${}^{229}$Th is the only known nucleus with an excited state that offers the possibility for a direct laser excitation using existing laser technology. Its excitation energy has been measured indirectly to be 7.8(5) eV ($\approx$160 nm). The energy and lifetime of the isomeric state make it the presently only suitable candidate for a nuclear optical clock, the uncertainty of the excitation energy is, however, still too large to allow for a direct laser excitation in a Paul trap. Therefore, a major goal during the past years has been an improved energy determination. One possible approach is to measure the kinetic energy of electrons which are emitted in the internal conversion decay of the first isomeric state in ${}^{229}$Th. For this reason an electron spectrometer based on a magnetic bottle combined with electrical retarding fields has been built. Its design, as well as first test measurements are presented, which reveal a relative energy resolution of 3 % and thus enable to measure the electrons' expected kinetic energy to better than 0.1 eV. This is sufficiently precise to specify a laser system able to drive the nuclear clock transition in ${}^{229}$Th.

    ↳ physics.ins-detnucl-exNucl.Instrum.Meth.B(2020)·6 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.