KLF beamline meeting - August 9, 2024

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Agenda

  • Announcements
  • KFM update (Mikhail)
  • Beam for detector calibrations (Sean, Mikhail, Igal)
  • Updates on CPS simulations (Pavel)
  • CPS, KPT, and cryo-target design progress (Tim)
  • Bleedthrough specifications (Vitaly)
  • Any other business

Minutes

Present: Pavel, Igor, Hovanes, Josh, Eugene, Edy, Beni, Marshall, Vitaly, Sean, Moskov, Richard, Ryan, Sean, Tim


  • Mikhail was traveling and was not present at the meeting, but he sent Hovanes a message with a very brief status update. Al detectors that KFM needs are uninstalled and prepared for packing (tracker is packed). The moving company wants to pack everything by their own crew to be sure that all pieces are safe. Nothing is shipped yet, since the paperwork is not complete.
  • Eugene said that in order to bring the KFM detectors here we do not need to have any new documentation. In order to have some kind of insurance, we would need to have at least a loan agreement, or Non-proprietary User Agreement. We do not have to have an MOU to bring in the KFM equipment.



  • Sean discussed the need for photon beam to calibrate the RF-signal, GlueX detector timing, and GlueX calorimeters.
  • Sean presented kinematics of photons that would be detected in the final states of the reactions of interest to KLF. His simulations were based on phase space distributions with some t-slope parameters, when needed. Most of the channels seem to produce photons mostly in BCAL with energies going up to 2.5 GeV. The K*p channel produces a lot of photons in FCAL as well , with energies going up to 3.5 GeV.
  • In Sean's opinion, photon beam would match the kinematics better than neutron or kaon beams.
  • There is still question of characteristics such a photon beam would need to have to satisfy the calibration needs in a reasonable amount of time.



  • Pavel reported on his progress with CPS simulations. He has a new model, KLCPS81, which incorporates magnetic field from the OPERA model corresponding to the official engineering design, the new beam displacement monitor in front of the CPS, and modifications to reduce the photon flux on the cryo-target when running without 10% radiator.
  • In order to reduce the effective number of radiation lengths of the vacuum window and the gas in front of the CPS magnet, Pavel replaced the Aluminum vacuum window with 350 μm Beryllium window, and moved the window, collimator and the radiator downstream by about 10 cm to reduce the amount of nitrogen gas before the magnet. He also had to put some magnetic shielding around the CPS collimator and the radiator to reduce the bending of the electrons in the fringe magnetic field before reaching the radiator.
  • He observed that the "no radiator" configuration with the new modifications provides 2x10-3 radiation lengths, which is about factor ~2 to ~2.5 reduction with respect to the effective thickness without the modifications. He also estimated the effect of using 3mm collimator in front of KPT which should reduce the photon flux by a factor of x10. Hovanes commented that, in terms of the photon flux on the cryo-target, having a 100nA electron beam with the modified configuration of the CPS radiator assembly without an actual radiator and the 3mm collimator aperture for photons would be equivalent to the GlueX photons rates at LH2 with 200nA electron beam on 5x10-4 radiator with 5mm collimator aperture downstream. These numbers for equivalent GlueX running were mentioned by Sean during the previous meetings.
  • Pavel pointed out that photon beam with "no radiator" is significantly narrower at KPT than regular KLF photon beam with 10% radiator. The y-distribution has a long tail from bremsstrahlung in the nitrogen gas. Beni suggested to have another collimator right after CPS to remove those tails from the photon beam so that they do not affect the readings of the Active Collimator or Beam Profiler which are expected to be in front of the 3mm collimator.
  • Pavel needs a feedback on what is really required for detector calibration to decide which option to chose for the design of the collimator assembly in front of CPS.



  • Tim gave an update on the engineering design of CPS and KPT.
  • Tim showed slides discussing the test of the cooling of the prototype for the CPS absorber. The prototype is 1/2 of the absorber in the transverse direction and 1/8 of the length of the absorber. They installed a 500W heater to the prototype and connected to a chiller than can provide total of 7.8 G/m flow. There was no brazing used for the cooling channels of the prototype. THere were temperature sensors installed and continuously monitored during the test.
  • The results for the temperatures sensors in the test setup are mostly consistent with the ANSYS model. Tim using these measurements to tube his phenomenological parameters, such as cooling gap size and the heat exchange coefficient, used in ANSYS model for actual CPS.
  • Tim also plans to try indium for the cooling channels during the test to see if it can be used for the actual CPS absorber.
  • Tim also reported that we had to go back to 16.5g/cm3 density tungsten/copper compound (90/10) for the KPT blocker as the 18g/cm3 we wanted to use had four times lower thermal conductivity than expected. He pointed out that 16.5g/cm3 density is approximately the same as Igor and Vitaly used in the simulations during conceptual design stage.
  • Magnet specification documentation has been submitted to the procurement department. Waiting for vendors to respond with bids.
  • In addition to the magnet, this fiscal year Tim plans to buy about $100K hardware for KPT, which includes Beryllium, tungsten compound, and lead bricks.



  • Vitaly reported on his studies of the effects of the out-of-time beam bleed-through to the K+n final states. In particular, he simulated the background created by the K+Ξ0 final state under the neutron missing mass peak.
  • He estimated that the amounted of the background from K+Ξ0 channel would be 5% or less. This was not taking into account that the cross sections for producing K+Ξ0 final state should be lower than for the K+Ξ0 final state. Vitaly also presented ideas trying to actually measure the bleed-through effect for that channel from the data.
  • Hovanes and Eugene suggested to look also at other physics channels that produce K+ and neutron that can spill under the neutron mass distribution and to cause uncertainties. It was not clear what event generator would be optimal to be used for such studies.
  • The discussion has to be cut short since the meeting went over 1.5 hour mark.



  • The next meeting will be in two weeks.


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