Mon·Jul 20, 2020Monday·July 20, 2020

1. 01*

   Strangeness Photoproduction at the BGO-OD experiment

   T. C. Jude🇩🇪 · S. Alef🇩🇪 · P. Bauer🇩🇪 · R. Beck🇩🇪 · A. Braghieri🇮🇹 · P. L. Cole🇺🇸 · R. Di Salvo🇮🇹 · D. Elsner🇩🇪 · A. Fantini🇮🇹 · O. Freyermuth🇩🇪 · F. Ghio🇮🇹 · A. Gridnev🇷🇺 and 21 other authors

   The BGO-OD experiment at the ELSA accelerator facility uses an energy tagged bremsstrahlung photon beam to investigate the excitation structure of the nucleon. The setup consists of a highly segmented BGO calorimeter surrounding the target, with a particle tracking magnetic spectrometer at forward angles. BGO-OD is ideal for investigating low momentum transfer processes due to the acceptance and high momentum resolution at forward angles. In particular, this enables the investigation of strangeness photoproduction where t-channel exchange mechanisms play an important role. This also allows access to low momentum exchange kinematics where extended, molecular structure may manifest in reaction mechanisms. First key results at low $t$ indicate a cusp-like structure in $K^{+}{\Sigma }^0$ photoproduction at $W=1900$\,MeV, line shapes and differential cross sections for $K^{+}\Lambda$(1405)$\to K^{+}{\Sigma }^0{\pi }^0$, and a peak structure in $K_S^0{\Sigma }^0$ photoproduction. The peak in the $K_S^0{\Sigma }^0$ channel appears consistent with meson-baryon generated states, where equivalent models have been used to describe the $P_C$ pentaquark candidates in the heavy charmed quark sector.

   nucl-exEPJ Web Conf.(2020)·3 citations
2. 02*

   $K^{+}\Lambda$(1405) photoproduction at the BGO-OD experiment

   Georg Scheluchin🇩🇪 · Stefan Alef🇩🇪 · Patrick Bauer🇩🇪 · Reinhard Beck🇩🇪 · Alessandro Braghieri🇮🇹 · Philip Cole🇺🇸 · Rachele Di Salvo🇮🇹 · Daniel Elsner🇩🇪 · Alessia Fantini🇮🇹 · Oliver Freyermuth🇩🇪 · Francesco Ghio🇮🇹 · Anatoly Gridnev🇷🇺 and 21 other authors

   Since the discovery of the $\Lambda (1405)$, it remains poorly described by conventional constituent quark models, and it is a candidate for having an "exotic" meson-baryon or "penta-quark" structure, similar to states recently reported in the hidden charm sector. The $\Lambda (1405)$ can be produced in the reaction $\gamma p\to K^{+}\Lambda (1405)$. The pure I=0 decay mode into ${\Sigma }^0{\pi }^0$ is prohibited for the mass-overlapping $\Sigma (1385)$. Combining a large aperture forward magnetic spectrometer and a central BGO crystal calorimeter, the BGO-OD experiment is ideally suited to measure this decay with the $K^{+}$ in the forward direction. Preliminary results are presented. *Supported by DFG (PN 388979758, 405882627).

   nucl-exEPJ Web Conf.(2020)·3 citations
3. 03*

   Fine structure of the isoscalar giant monopole resonance in ${}^{48}$Ca

   S. D. Olorunfunmi🇿🇦 · I. T. Usman🇿🇦 · J. Carter🇿🇦 · P. T. Molema🇿🇦 · E. Sideras-Haddad🇿🇦 · R. Neveling · F. D. Smit🇿🇦 · P. Adsley · L. M. Donaldson🇿🇦 · L. Pellegri🇿🇦 · G. F. Steyn🇿🇦 · P. von Neumann-Cosel🇩🇪 and 10 other authors

   Experiments investigating the fine structure of the IsoScalar Giant Monopole Resonance (ISGMR) of 48Ca were carried out with a 200 MeV alpha inelastic-scattering reaction, using the high energy-resolution capability and the zero-degree setup at the K600 magnetic spectrometer of iThemba LABS, Cape Town, South Africa. Considerable fine structure is observed in the energy region of the ISGMR. Characteristic energy scales are extracted from the experimental data by means of a wavelet analysis and compared with the state-of-the-art theoretical calculations within a Skyrme-RPA (random phase approximation) approach using the finite-rank separable approximation with the inclusion of phonon-phonon coupling (PPC). Good agreement was observed between the experimental data and the theoretical predictions.

   nucl-exJ.Phys.Conf.Ser.(2020)·2 citations
4. 04*

   Breakup mechanisms in the 6He+64Zn reaction at near-barrier energies

   J. P. Fernández-García🇪🇸 · A. Di Pietro🇮🇹 · P. Figuera🇮🇹 · J. Gómez-Camacho🇪🇸 · M. Lattuada🇮🇹 · J. Lei🇺🇸 · A. M. Moro🇪🇸 · M. Rodríguez-Gallardo🇪🇸 · V. Scuderi🇮🇹

   New experimental results for the elastic scattering of 6He on 64Zn at incident energies of 15.0 and 18.0 MeV and 4He at 17.5 MeV along with results already published at 10.0 and 13.6 MeV, are presented. Elastic and alpha experimental cross sections are compared with coupled-reaction-channel, continuum-discretized coupledchannel, and DWBA inclusive-breakup models. The large yield of alpha particles observed at all measured energies can be explained by considering a nonelastic breakup mechanism.

   nucl-exnucl-thPRC(2019)·16 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.