Thu·Oct 23, 2014Thursday·October 23, 2014

1. 01*

   Baseline LHC machine parameters and configuration of the 2015 proton run

   R. Bruce🇨🇭 · G. Arduini🇨🇭 · S. Fartoukh🇨🇭 · M. Giovannozzi🇨🇭 · M. Lamont🇨🇭 · E. Metral🇨🇭 · T. Pieloni🇨🇭 · S. Redaelli🇨🇭 · J. Wenninger🇨🇭

   This paper shows the baseline LHC machine parameters for the 2015 start-up. Many systems have been upgraded during LS1 and in 2015 the LHC will operate at a higher energy than before and with a tighter filling scheme. Therefore, the 2015 commissioning phase risks to be less smooth than in 2012. The proposed starting configuration puts the focus on feasibility rather than peak performance and includes margins for operational uncertainties. Instead, once beam experience and a better machine knowledge has been obtained, a push in ${\beta }^{\ast }$ and performance can be envisaged. In this paper, the focus is on collimation settings and reach in ${\beta }^{\ast }$---other parameters are covered in greater depth by other papers in these proceedings.

   ↳ physics.acc-phnucl-ex9 citations
2. 02*

   Search for Quasi Bound $\eta$ Mesons

   H. Machner🇩🇪

   The search for a quasi bound $\eta$ meson in atomic nuclei is reviewed. This tentative state is studied theoretically as well as experimentally. The theory starts from elastic $\eta$ nucleon scattering which is derived from production data within some models. From this interaction the $\eta$ nucleus interaction is derived. Model calculations predict binding energies and widths of the quasi bound state. Another method is to derive the $\eta$ nucleus interaction from excitation functions of $\eta$ production experiments. The $s$ wave interaction is extracted from such data via final state interaction theorem. We give the derivation of $s$ wave amplitudes in partial wave expansion and in helicity amplitudes and their relation to observables. Different experiments extracting the final state interaction are discussed as are production experiments. So far only three experiments give evidence for the existence of the quasi bound state: a pion double charge exchange experiment, an effective mass measurement, and a transfer reaction at recoil free kinematics with observation of the decay of the state.

   ↳ nucl-thhep-exhep-phnucl-exJ.Phys.G(2015)·42 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.