Summary notes 4 February 2020

CPS CONCEPT (Bogdan)

• Magnet

• Yoke
• Radiation hard coil

• Inside the magnet: Copper absorber and W-Cu inserts

• Segmented radiation shield

• Tungsten powder, perhaps lead

• Photon beam physics - requires 2mm diameter photon beam to allow for accurate reconstruction of the exclusive process

• Compact beam dump:

• shielding - 20 interaction lengths
• absorb beam power - raster the beam
• distribute load over target aread - two concepts: rotate target, vertical oscillation magnet

RADIATION SIMULATION (Gabriel)

• Software tools:

• OPERA - magnet
• GEANT4 - photon beam profile
• FLUKA - activation (Note: Fortran based software)
• ROOT, PYTHON

• Full CPS+target field model has been implemented and background radiation simulations were carried out

• W powder is most effective for all shielding - for activation in backward direction lead may be preferable
• Overall radiation level seems comparable to PREX-II (~60 rem/hr at 2m from beamline near exit)
• Note: < 1 rem/hr is the requirement for people to work

• CPS studies suggest that this is fulfilled in the backward and target region
• Forward region is not dominated by CPS, but by the intensity of target/beamline

BEAM BACKGROUND SIMULATIONS (Lorenzo)

• Simulations getting more reliable and validating results against data (nuclear target data, Hall B)

• Geant4 had bugs in D2 (fixed), still present for He3 and tritium

• Discussion about possible "freezing" a JLab Geant4 version
• Discussion about publishing the results from RadCon group

CPS4KLF and KL EXPERIMENT (Sean)

• Presentation of the general requirements for a CPS in Hall D

• 60 kW (12 GeV electrons at 5 uA_, 64ns bunch spacing, beam size ~500um (c.f. Hall A/C: ~100uA)
• Target: Be - distance CPS to Be target is 55 meters
• Keep similar inner design with main items to optimize:

• Weight - should be < 100 tons (size and composition)
• Collimation/exit for beam properties (electron beam raster)

• radiation level requirements in Hall D can be higher than Hall A/C (there protect the polarized target), so can make the forward piece shorter
• Note that there is permanent magnet in the beam line that requires moving the CPS from where it was shown
• Double raster to focus on target - need this raster since travel over long distance and cannot afford up/down movement (must compensate) as in Hall A/C

• where should the raster be located? - In Hall A/C it is ~2-5 meters from the target

• Presentation of the To-Do list towards a fully approved proposal

TIMELIKE COMPTON SCATTERING (Marie, Vardan)

• Presentation of the theory and work to address PAC report

• Presentation of simulations to demonstrate the feasibility of the experiment