Mon·Nov 2, 2020Monday·November 2, 2020

1. 01*

   Spectroscopic study of ${}^{47}$Ca from the ${\beta }^{-}$ decay of ${}^{47}$K

   J.K. Smith🇨🇦 · A.B. Garnsworthy🇨🇦 · J.L. Pore🇨🇦 · C. Andreoiu🇨🇦 · A.D. MacLean🇨🇦 · A. Chester🇨🇦 · Z. Beadle🇺🇸 · G.C. Ball🇨🇦 · P.C. Bender🇨🇦 · V. Bildstein🇨🇦 · R. Braid🇺🇸 · A. Diaz Varela🇨🇦 and 21 other authors

   The ${\beta }^{-}$ decay of ${}^{47}$K to ${}^{47}$Ca is an appropriate mechanism for benchmarking interactions spanning the $sd$ and $pf$ shells, but current knowledge of the ${\beta }^{-}$-decay scheme is limited. We have performed a high-resolution, high-efficiency study of the ${\beta }^{-}$-decay of ${}^{47}$K with the GRIFFIN spectrometer at TRIUMF-ISAC. The study revealed 48 new transitions, a more precise value for the ${}^{47}$K half-life (17.38(3)~s), and new spin and parity assignments for eight excited states. Levels placed for the first time here raise the highest state observed in ${\beta }^{-}$ decay to within 568(3) keV of the $Q$-value and confirm the previously measured large ${\beta }^{-}$-decay branching ratios to the low-lying states. Previously unobserved ${\beta }^{-}$-feeding to 3/2${}^{+}$ states between 4.5 and 6.1~MeV excitation energy was identified with a total ${\beta }^{-}$-feeding intensity of 1.29(2)\%. The sum of the $B(GT)$ values for these states indicates that the $1s_{1/2}$ proton hole strength near this excitation energy is comparable to the previously known $1s_{1/2}$ proton and neutron hole strengths near 2.6 MeV.

   nucl-exPRC(2020)·5 citations
2. 02*

   Photoproduction of the $f_2(1270)$ meson using the CLAS detector

   M.~Carver · A.~Celentano · K.~Hicks · L.~Marsicano · V.~Mathieu · A.~Pilloni · K.P.~Adhikari · S. Adhikari · M.J.~Amaryan · Giovanni Angelini · H.~Atac · N.A.~Baltzell and 128 other authors

   The quark structure of the $f_2(1270)$ meson has, for many years, been assumed to be a pure quark-antiquark ($q\bar{q}$) resonance with quantum numbers $J^{PC}=2^{++}$. Recently, it was proposed that the $f_2(1270)$ is a molecular state made from the attractive interaction of two $\rho$-mesons. Such a state would be expected to decay strongly to final states with charged pions, due to the dominant decay $\rho \to {\pi }^{+}{\pi }^{-}$, whereas decay to two neutral pions would likely be suppressed. Here, we measure for the first time the reaction $\gamma p\to {\pi }^0{\pi }^{0}p$, using the CLAS detector at Jefferson Lab for incident beam energies between 3.6-5.4~GeV. Differential cross sections, $d\sigma /dt$, for $f_2(1270)$ photoproduction are extracted with good precision, due to low backgrounds, and are compared with theoretical calculations.

   nucl-exhep-exPRL(2021)·11 citations
3. 03*

   Ambiguities in the definition of local spatial densities in light hadrons

   Robert L. Jaffe🇺🇸

   The relationship between the matrix element of a local operator and the Fourier transform of the associated form factor fails for systems such as the nucleon where its intrinsic size is of order its Compton wavelength. Although one can conceive of an intrinsic charge density distribution in the proton, there does not seem to be an unambiguous way to define, compute, or measure it precisely.

   ↳ hep-phhep-latnucl-exnucl-thPRD(2021)·87 citations
4. 04*

   Neutron-pair structure in the continuum spectrum of ${}^{26}$O

   S. Affranchino · R.M. Id Betan🇦🇷

   The structure of ${}^{26}$O is currently being investigated on both theoretical and experimental fronts. It is well established that it is unbound and the resonance parameters are fairly well-known. The theoretical analysis may involved two- and three-body interactions, as well as correlations with the continuum spectrum of energy. In order to properly assess the structure of the ground and excited states, it is imperative to include a large single particle representation with the right asymptotic behavior. The purpose of this work is to provide details of the single particle continuum configurations of the ground and excited $0^{+}$ states. We use a large complex energy single particle basis, formed by resonances and complex energy scattering states, the so called Berggren basis, and a separable interaction, which is convenient to solve in a large model space. Three $0^{+}$ states were found in the complex energy plane. Changes of the resonant parameters, i.e. energy and width, were analyzed as a function of strength of the residual interaction. It is shown how a subtle difference in the interaction could change the unbound character of ${}^{26}$O into a Borromean nucleus. Only one of the two excited states can be considered as a candidate for a physical meaningful resonance. The calculated occupation probabilities are in agreement with other theoretical approaches although the calculated half live is three-order of magnitude smaller than the experimental one.

   ↳ nucl-thnucl-exPRC(2020)·1 citation
5. 05*

   MSS: a new way for high energy-resolution on any accelerator when using magnetic spectrometers

   A. Gafarov

   An innovative approach: MSS - the Method of Spectra Superposition for high energy-resolution (Delta-E) studies on any accelerator of nuclear reactions at fixed targets by magnetic spectrometers, has been invented. For thin targets MSS provides a Delta-E which depends only on the detector's energy-resolution. The MSS can bring huge benefits to experiments with fixed targets at all types of accelerators and also on colliders. The MSS was used to get precise data with a Delta-E = 10 keV in (p,12C) elastic scattering for the energy region Ep 16 - 19.5 MeV at cyclotron U-150 of INP Ulugbek (Tashkent, AS of Uzbekistan) with a beam energy spread of about 200 keV. The proton energy control was performed with a 20-step Energy Moderator which provides Ep interval of 3.5 MeV without any energy-readjustment of cyclotron and all the ion optics of a 41-meter-long beam pipe. A multichannel Magnetic Spectrograph (Apelsin) was used as the nuclear reaction products detector. The particle-products were detected on focal planes of Apelsin by specially designed Coordinate-sensitive gas MWPCs with two particle counters in coincidence. The acquisition system was based on IBM PC online with a fast CAMAC branch custom-designed at PNPI (St-Petersburg INP, USSR) together with fast TDC modules and other fast electronics providing immediate selection and accumulation of events from the MWPCs. The Apelsin magnetic field was stabilized to 3 ppm by NMR-monitor system The obtained, with statistical error about 6%, excitation function (EF) of (p, 12C), with a resonance reach structure, is in precise agreement with thresholds and levels data [15-18].

   ↳ physics.ins-detnucl-exphysics.acc-ph1 citation
6. 06*

   Topological studies of light-flavor hadron production in high multiplicity pp collisions with ALICE at the LHC

   Sushanta Tripathy (for the ALICE Collaboration)🇲🇽

   Recent measurements in high-multiplicity pp and p-A collisions have revealed that these small collision systems exhibit collective-like behaviour, formerly thought to be achievable only in heavy-ion collisions. To understand the origins of these unexpected phenomena, event shape observables can be exploited, as they serve as a powerful tool to disentangle soft and hard contributions to particle production. Here, results on the production of light flavor hadrons for different classes of unweighted transverse spherocity ($S_0^{p_{\mathrm{T}}=1}$) and relative transverse activity ($R_{\mathrm{T}}$) in high multiplicity pp collisions at $\sqrt{s}$ = 13 $\text{TeV}$ measured with the ALICE detector are presented. Hadron-to-pion ratios in different $S_0^{p_{\mathrm{T}}=1}$ and $R_{\mathrm{T}}$ classes are also presented and compared with state-of-the-art QCD-inspired Monte Carlo event generators. The evolution of charged particle average transverse momentum ($⟨p_{\mathrm{T}}⟩$) with multiplicity and $S_0^{p_{\mathrm{T}}=1}$ is also discussed. In addition, the system size dependence of charged particle production in pp, p-Pb, and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$= 5.02 TeV is presented. Finally, within the same approach, we present a search for jet quenching behavior in small collision systems.

   ↳ hep-exnucl-exPoS(2021)·2 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.