CPS meeting - March 25, 2022

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Agenda

  • Other items
  • Cooling for 60KW electron beam (can we reuse tagger dump cooling?)


Minutes

Present: Eugene, Hovanes, Igor, Tim, Justin, Sean, Vitaly, Moskov

Hovanes announced that there is a new Hall D logbook called HDCPS in the standard JLAB online logbook for keeping track of the work related on CPS design and construction.

  • Simulation updates (Vitaly)
  • Vitaly sees 2.5cm y-offset at the beryllium target when the radiator is at the position that Gabriel used.
  • Moving radiator to -41cm in z completely gets rid of the offset. This is due to the fact that the magnetic field map does not extend beyond -40cm.
Vitaly added a new magnet to steer the beam in the vertical position to compensate for the deflection of the beam before bremsstrahlung. The magnet he used is 50cm long at 0.032T field.
  • With FWHM=1.2mm beam size he sees a hot spot where he estimates 15KW/cm^3 power deposition.
  • Eugene commented that such a magnet could be installed and should not be very expensive considering that it is small and weak. But we need to have some understanding of the fringe field magnitude to have the right magnet.
  • Hovanes pointed out that this magnet is very likely to be needed anyway to be able to tune the electron beam to the radiator and the photon beam to the beryllium target.
  • Moskov reminded us that some small angle (resulting in an offset at the Be target) may be beneficial to the experiment.
  • Vitaly is going to simulate energy deposition with a wider beam (FMWH=2.5mm) and wider beam hole size (5x5mm).
  • Eugene commented that the increase in the beam hole size will increase the radiation in the hall and it needs to be evaluated as well.
  • Magnetic field (Hovanes, Vitaly)
  • Hovanes plotted the magnetic fields x-component vs Z that is used in FLUKA. This confirms that the "fringe" field is not that small.
  • The radiator position in the Gabriel's FLUKA file is in the area that has significant magnetic field in the x-direction. It is where there is a large gradient in Z. Vitaly already verified that shifting the radiator by a small amount will reduce the y-offset at the Beryllium target substantially.
  • Hovanes has access to a JLAB computer with OPERA license that is shared with some other people, and he will try to calculate the field in a wider range in Z.
  • Other items
  • Eugene asked about the deformation of the copper core due to the heat. Hovanes said that the copper core in Hall C design is split in many segments in z to avoid stress due to the heat.
  • Sean pointed out that we will need to think about some instrumentation (similar to the beam profiler or active collimator) to be able to setup the photon beam to the beryllium target. Currently, there is are no such plans and the design does not reserve any space in the collimator hall for such a device.
  • Tim thinks that the water cooling system used for the tagger dump can be repurposed to be used for CPS during KL running. He will check on that.

Action items

  • Check for a new model from Gabriel. (Hovanes)
  • New magnetic field map for CPS. (Hovanes)
  • FLUKA simulations with beam FWHM=2.5mm and 5x5mm beam hole and the new deflecting magnet to determine energy deposition profile in the CPS. (Vitaly)
  • Check the value of the photon beam angle with respect to z-axis needed to improve the Kaon flux at the LH2 target. (Moskov)
  • Determine a good lattice for energy power deposition map for CPS simulations in FLUKA.
  • Check if the tagger dump cooling water skit can be used to cool the CPS core. (Tim)


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