Agenda

Minutes

Present: Tim, Josh, Mikhail, Beni, Edy, Eugene, Sashi, Hovanes, Lubomir, Moskov, Marshall, Richard, Pavel

Moskov, Hovanes, and Edy were present at the BTeam meeting on November 12th to discuss the possibilities of beam tests during 2025 running.

The estimated time for setting up the laser for KLF, conducting the tests, removing KLF laser, and replacing GlueX laser was about 3 to 4 calendar days.

Physics division representative (Doug) did not think that the benefits from these beam tests would justify spending that much beam test time considering that there are other beam tests that would need to happen.

There should not be any problem to do the tests requiring beam only in the injector. They could be done right after the spring 2025 is competed but before SAD starts. These tests would give us some idea on the amount of bleedthrough beam between the main bunches and possibly on the impact of KLF beam on Moller (one of the Riad's tests).

Doug stated during that BTeam meeting it is possible that the only way to check compatibility of MOLLER and KLF is after the whole MOLLER instrumentation is installed, that is earliest time is 2027. It was not also certain when MOLLER installation will be complete. This would jeopardize the installation scheduling of KLF experiment this summer or fall, according to Hovanes. Some of the meeting participants think that there needs to be a discussion with the physics division leadership about the tests of compatibility between KLF and MOLLER.

Richard presented the 2D histograms for FDC showing the hit count in 64ns bursts in the FDC wires versus wire number and the plane number. He presented this plot for 10cm W-plug, 14cm W-plug, and 18cm W-plug.

Based on these 2D histograms, Lubomir estimated that max FDC occupancies with 14cm plug would be 50% , assuming thresholds used in GEANT4 program. The maximum occupancy during GlueX runs (with real thresholds) is about 10%. The occupancies with 18cm plug would correspond to about 10% occupancies, again assuming thresholds used in GEANT4 program.

There was a long brainstorming discussion on how to optimize the count rate in FDC by adjusting the beam diameter at the target and the tungsten plug thickness. One of the main reasons for the high counting rate seems to be the fact that at the first FDC package the size of the beam spot from photons directly reaching the FDC from the tungsten plug is more than 6cm.

Richard will think about the optimization of the tungsten plug and the beam collimation in GEANT4. Either narrowing the beam pipe or thickening the tungsten plug reduces kaon flux. We should expect reduction of kaon flux with respect to 10cm plug and 6cm beam pipe configuration of about factor of 2 or more.

It was pointed out that some of the kaon flux losses can be recovered by increasing the CPS radiator thickness. But that part of optimization should be done only after KPT design and the downstream beam pipe configuration is finalized.

(Later note by Hovanes) After the meeting Richard added the plots of FDC and TOF hit rates using GlueX-II conditions in GEANT4. The FDC wire rates with GlueX-II conditions are not lower than FDC wire rates in KLF conditions with 14cm tungsten plug. These plots are in the link in the wiki for this meeting. Since GlueX-II condition plots were not presented at the meeting, the group never had a chance to discuss the comparison at this meeting.