KLF beamline meeting - July 12, 2024
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Agenda
- Announcements
- Cryotarget for KLF (Chris)
- CPS simulation updates (Pavel)
- Do we need photon beam in the hall during KLF? (Sean, Mikhail, Ig)
- Any other business
Minutes
Present: Hovanes, Chris, Tim, Josh, Vitaly, Eugene, Beni, Edy, Richard, Marshall, Sean, Pavel
- Hovanes announced that KLF is at the stage where procurements with large amounts are going to be made soon. KLF leadership will need to carefully check the drawings of the beamline components as they become available to make sure that they satisfy the needs of the core physics program of the experiments. It is not necessary to check the mechanical stability, thermal aspects, or the radiation control issues assuming that they have been addressed by the experts. The drawings will be posted by Tim or Hovanes as they become available well before Purchase Requests are submitted.
- Chris discussed the current status of the KLF cryo-target, see his presentation for details.
- The target cell will be 40cm long and 6cm in diameter. It will support LH2 and LD2. It is highly unlikely that the sign will be able to accommodate liquid helium target. If there are plans for liquid helium, Chris would have to be notified about those as soon as possible.
- The liquid in the cell will be boiling which will sightly reduce the density of the target. The bubbles will form on the button and propagate up. It is expected to be stable without bursts.
- Chris expects to have 9 hours of cool-down time, 90 minutes of refill time and 45 minutes emptying time. They can evacuate the hydrogen gas from the cell if the experiment needs a really empty target operations.
- KLF target cell will use more liquid hydrogen volume than for GlueX, therefore either the gas tanks will need to be larger, or the gas pressure will need to be higher (45psi) than for GlueX. Chris is currently leaning towards latter.
- Thicker aluminum walls for the target.
- New carbon fiber scattering chamber will need to be manufactured. Similar one have been used in the other halls.
- Switching between LH2 and LD2 will take about 24 hours. The run plans will need to be properly adjusted.
- There needs to be a meeting with engineers and designers of the target group and Hall D to decided on size of the new scattering chamber and to suggest the length of the target cell that would not extend upstream of the plumbing material of the target.
- Tim W., Chris K. and James Brock will exchange necessary information/drawings/models before the meeting is arranged.
- Eugene commented that current plans for upgrading the Start Counter do not include changing the scintillators.
- Pavel showed some plots from his FLUKA simulations regarding the beam excursion monitoring device in front of CPS to generate the FSD signal, material available on the web site.
- One of the main components is a small carbon ring (4.5mm IR) around the ring.
- He found that although a device similar to Hall B BOM placed upstream of the ring will work, the rates for the charged particles in it coming from the CPS background would be comparable to what comes from the narrow ring. He found out that looking at the charged particles farther away from the beam (~10cm) would reduce the background from CPS back-scattering to level.
- The current model he is considering has four PMT-based counters around the beamline. Cerenkov light propagation is not modeled yet.
- His studies showed that each counter will see about 250KHz of charged particle rates at 1mm beam offset. At the nominal beam position, he expects to see ~$75KHz rates in each counter (a factor of x3 sensitivity to 1mm shift in beam). Hovanes thought that such counting rates would be good.
- Pavel also sees that there is significant left-right and up-and-down asymmetry in the counting rates when beam is shifted. If the counters are balanced at the nominal beam position, this could be used to monitor the beam position.
- Tim commented that it is possible to make a metal ring a few hundred microns thick instead of 1mm carbon. Metal would be a better choice for power dissipation purposes as the ring is expected to be in the vacuum.
- Pavel will continue his studies with different configurations to further optimize the setup.
- Tim said that the engineers and designers are working on Pavel's recent geometry defining the shielding around the absorber.
- During last couple of weeks they were focusing on KPT to make final changes. There was a meeting to discuss the last details of the KPT. PDF file of the drawing has been posted to the beamline page and to the page of this meeting.
- The plan is to buy things that we are sure we need for KPT this year (roughly ~$100K).
- Drawings for the CPS magnet are expected to be complete in a couple of weeks. The plan is to submit the PR for the CPS magnet this fiscal year (another ~$100K).
- The test of the degaussing of the magnet similar to the tagger magnet has been postponed due to LOTO related delays. It may happen in December.
- The new tagger magnet power supply is expected to arrive in February.
- 3000 lead bricks are being painted by the contractor. Painting of 1/3 of them is complete.
- Eugene pointed out that due to the budget cuts, we may not have all of the $400K that he tried to allocate for this fiscal year. This is not clear yet.
- Sean had a brief discussion about the need for a photon beam before K-long running during KLF for calibration purposes.
- The understanding was that no final decision can be on this yet. Mikhail sent data files from neutron beam data to Igal to check the possibility of using neutrons for calibrations.
- Also the kinematic coverage for the photons was not known for all the physics reactions that need to be studied.
- The decision on this item will need to have to wait for another two weeks.
- Our next meeting will be in two weeks.