Agenda

Minutes

Present: Eugene, Moskov, Vitaly, Mikhail, Igor, Edy, Pavel, Hovanes, Tim, Sean, Stuart, Beni

Mikhail announced that Take Saito from RIKEN won a ~$1M grant for hyper-nuclear stations in KLF. The grant is for 5 years. It should cover the procurements and labor for both emulsions and germanium segments.

Moskov suggest that the collaboration needs to figure out a strategy on how to approach the upcoming readiness review , and he also suggested that we have a morning meeting that would be at a time that Japanese collaborators could attend.

Edy said that the run is postponed until March 21st. The accelerator division is working hard to start the run at that date. The injector is broken, so the bleed-through tests are very unlikely to be done before the run, as previously planned.

SLAC data at non-zero angles are fitted, then extrapolated to zero degrees and interpolated to 12 GeV beam energy. the extrapolation takes into account that KLF uses 20% radiator rather than putting the electron beam onto the Be target.

The procedure uses parameterisation for the kaon absorption in the materials that is based on measurements from the 1960s.

Using his simple model, Hovanes checked that 40cm is close to the optimal value for Be target length and that improvements will not result in significant kaon rate changes as we are in the pretty flat are of the rate maximum.

Kaon rates Hovanes expects during KLF is 3.1 KHz , based on the SLAC data and his fit and extrapolation procedure.

Pavel commented that there are kaons produced at the forward angles that are not properly taken into account by Hovanes' procedure.

Hovanes also ran his procedure on SLAC pseudo data simulated by Pavel using FLUKA. The projection for KLF rate using these pseudo SLAC data instead of SLAC data is 5.4 KHz versus 8.2KHz from direct FLUKA prediction for KLF.

Adjusting kaon absorption cross section by a 20% decrease at all kaon momenta would make the pseudo data extrapolation match FLUKA KLF prediction, according to Hovanes. The real SLAC data prediction with 20% lower absorption cross sections for kaons would be about 4.6 KHz.

Hovanes suggested that since the kaon rates can potentially be significantly lower than what the proposal expected, it would be wise to avoid making the tungsten abosrber "permanently" long by encasing all of it into the KPT assembly. Instead, we can design KPT with a tungsten plug with a thickness absolutely necessary to get the right order of magnitude of low energy photon rates, and then to use tungsten disks to finely optimize the kaon and photon absorption during the commissioning with actual beam.

Moskov pointed out that the integrated rate is not the only metrics that defines the FOM for the experiments in the proposal.

Vitaly asked for a kaon rate estimate for P_K=0.44 GeV/c momentum for his simulations and analyses of pentaquark state. Hovanes will sent Vitaly an e-mail with an estimate.

Pavel showed results of his FLUKA simulations with different photon absorption configurations in KPT.

Considering that lead is better photon absorber per unit of material and is worse kaon absorber per unit of material, it would be beneficial for us to use lead as photon absorber. It would have to after a pretty thick tungsten absorber.

He found that a 19cm (10cm+9cm) combination of tungsten compound and lead absorber would be better than 16 cm of tungsten plug in terms photon rates, but would be 10% better in terms of kaon flux.

The power deposition in the lead is expected to be about 20W for 19cm absorber. Pavel also thought that it would be a good idea to add separate lead (or tungsten) layer downstream of KPT as it would not add much of a background.

Pavel estimation for kaon absorption in the tungsten compound is 11%±5% percent per 1cm of thickness. Hovanes pointed out that this is what was needed to reconcile some of the disagreements between the KLF projected rates from FLUKA and fitting procedure based on the SLAC pseudo-data from FLUKA.

Moskov asked if Pavel could get the momentum dependent absorption coefficient from FLUKA. Pavel thinks that it is not easy to get that much statistics without spending huge amount of CPU power.

Igor would like some legends on the slides to specify what color indicates which material in the FLUKA model.

Pavel also pointed out that one of his main concerns is the muon background in the main detector and it is hopefully accounted for in the GEANT4 simulations by Richard.