Physics analysis

PANDA Management Quarterly Report 19Q3

In high energy particle experiments one is interested in observables that require a transverse target polarization. The particle physics experiment PANDA consists of a detector at the particle accelerator FAIR currently under construction at GSI Helmholtz Centre for Heavy Ion Research, Darmstadt (GSI). The detector requires a high magnetic field in longitudinal direction with respect to the antiproton beam to provide high momentum resolution of the electrically charged particles. For the feasibility of a transverse polarized target in PANDA, it is essential to shield the longitudinal magnetic field.
The ability to shield an intense magnetic flux with a high temperature superconductor BSCCO in form of a shielding tube was investigated experimentally.
A shielding factor was extracted. A measurement of the stability of the shielding in time and a measurement of the residual magnetic
flux density along the axis of the tube was performed. A numerical simulation of the induced current in the shielding tube and the residual magnetic flux density along its axis was developed. The experimental results were compared to the predictions based on the numerical simulation. For the measurements a dedicated apparatus consisting of a cryostat, filled with liquid helium, at a temperature of 4.2 K was developed and constructed at the Helmholtz-Institut Mainz (HIM). The shielding tube was equipped with a movable Hall probe, with a Zero-eld Magnet on top. The external magnetic eld was generated by a purpose-built superconducting solenoid, which can be mounted on top of the shielding tube. An external magnetic flux density of 1 T was applied and shielded with
a shielding factor of at least 3:2
105 with a 95 % confidence level. In a measurement over four days a penetration of it into the shielding tube could
not be observed. The measurement of the residual magnetic flux density along the axis of the tube showed a shielding of the the central region of 80 mm (from total 150 mm shielding tube) up to 1 T. BSCCO is a good shielding material and can be used to shield the high magnetic field within the PANDA spectrometer.

PANDA Collaboration Meeting 19/2 Minutes

PANDA Management Quarterly Report 19Q2

See uploaded material

Report of the FAIR Progress and Cost Review Board:
Detailed Review of Progress and Financial Status of the FAIR Project
29 April 2019

\panda\ at FAIR will address the physics of strangeness in nuclei by several novel and unique measurements. These studies are only made possible by the
one-of-a-kind combination of the stored antiproton beam at FAIR and the modular \panda\ detector which will be complemented by a germanium detector array. The latter was made available by a cooperation with the NUSTAR collaboration.
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\panda\ also offers the unique possibility to search for X-rays from very heavy hyperatoms such as e.g. $\Xi^-$-$^{208}$Pb. This will complement experiments at J-PARC which attempt to measure X-rays in light and (possibly) medium-heavy nuclei by the J-PARC E03 and E07 experiments. The measurement at \panda\ will allow to constrain the real and imaginary potential of $\Xi^-$ hyperons in the neutron skin
of the lead nucleus.
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\panda\ will extend the studies on double hypernuclei by performing for the first time high resolution $\gamma$-spectroscopy of these nuclei. Thus, \Panda\ complements measurements of ground state masses of double hypernuclei in emulsions at J-PARC conducted by the E07 Collaboration \cite{E07-proposal,doi:10.1142/9789814618229_0025} or the production of excited resonant states in heavy ion reactions which may, for example, be explored in future by the CBM Collaboration. Together, these measurements will provide a as yet unrivaled information on the structure of double $\Lambda\Lambda$ hypernuclei.

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Furthermore, the exclusive production of hyperon-antihyperon pairs close to their production threshold in $\Pap$ - nucleus collisions offers a unique and hitherto unexplored opportunity to elucidate the behaviour of antihyperons in cold nuclei which is intimately related to the short-range part of the baryonic interaction.
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In all these studies, the production of low momentum {\PagL} within nuclei or slow $\Xi^-$ hyperons which can eventually be stopped in a secondary target material play an essential role.