Minutes of meeting:

Mauri
HPS Test Vacuum Box, side walls 1/2 " thick SS Flange 1" thick, 63.93" long
HPS Test Magnets
Field Maps from Stephan CLAS note 2011-2  Frascati Magnets current for 0.25 tesla
Chicane Alignment 2.2 GeV electrons how to scale pair spectrometer magnet and Frascati magnet (range adequate). Can set pair spectrometer magnet of set Frascati magnet (20 by 10 cm opening H-magnet), both work. Whatever work for tracking can work for beam line. Decision is to pick 0.5 for the analyzing magnet.

Stepan
Do we need to change distances between magnets?  No
TPE chicane setup for HPS test (85.87 ") Can bring Frascati closer (~10") Magnet-1 0.25 Tm  Magnet 11 at 0.5 Tm, f0r 17 mr, The way they are will work. Extra space behind calorimeter may be desired and helps. 

Electron beam line and photon dump
How do dump photon beam?
We need to dump photon beam. Dump before entering GLAS wall (need window and shielding for protecting our experiment. 

Dumps 
Use existing equipment, photon beam into lead. (1.5 % RL) bremsstrahlung, neutron radiation is problem need heavy shielding. Mauri simulated this. Between beam dump and Ical is 324" (7.5 to 8 meters)

Dieter comments that location of photons dump it will be best to use copper dump and surrounded with borax will minimize neutrons.

Displacement of electron beam is only 3 cm at front face of ecal. Use flange and bellows after standard beam pipe to go up to a vacuum beam tube (5" diameter ~ 10 to 15 cm). Need room for silicon, etc. In vertical direction all ok with and without field on. Primary, photon beam: design should allow all to stay in vacuum. All want to stay with present distance between magnets. MC will be done to check all this and backgrounds.

Dieter comments that Ecal vacuum chamber must be thicker than 5mm (1mm will collapse). Width of 200mm used. Need ribs or strong members on the sides.

Takashi
Beam distribution at 136 cm from target (at Ecal) shown with photons, brems electron and beam. He shows vacuum walls on plot in red. Minimum is +- 5mm. Present design in proposal is +-1 cm. Put rib between photon and electrons to support vacuum chamber. Takashi's plots show numbers (slide 2) shows at least 1 cm needed. (get 221 at >7cm from photons from 10 million electrons on target. We have 15000 beam particles in 25nsec so background from 221/1000 should be ok for occupancy point of view. Roha cell 31 (RL 5,450mm) may be ok bridging 5cm for support of a thin walled vac chamber. Atlas found degrading of Roha after 9.2 mega rads.