Wednesday July 24, 2013

We will meet in TED 2561B on Wednesday July 24 at 3:00 pm EST.

For those calling in we'll use the ReadyTalk audio conference system.

1. Dial Toll-Free Number: 866-740-1260 (U.S. & Canada)
2. Enter 7-digit access code 4402297, followed by “#”

Agenda:

 media:Meeting_24July_2013.pdf
 media:Meeting_24July_2013.pptx  

1- Schedule

2- Design of beamline, radiator and dump

• Experiment beam line today is presently decommissioned, ready for modification:

3- Background and simulation

4- Absolute beam energy

• One slide on beam momentum Media:130724_Bubble_Grames.pdf

5- Safety

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Notes from this meeting:

• Radiator:

- The power deposited in the radiator for 100 uA and 8.5 MeV (K.E.) electron beam:
  for 0.02 mm radiator, average energy loss is about 21 keV, P = 2.1 W
  for 0.10 mm radiator, average energy loss is about 112 keV, P = 11 W
  re-evaluate radiator cooling 
  what is the temperature of the LCW that will be used to cool the radiator? 35C (95F)
  what is the minimum allowed spot size on radiator. Do we need a raster? Typical sizes are about 1-2 mm sigma 
- On the radiator ladder, we should have a viewer and preferable a YAG viewer to check the beam size
- Need a camera to look at the OTR light coming from the radiator
- What is the energy distribution of the electron beam after radiator

• Beamline:

- Need a layout of the beam line. Where is the location of the radiator on the beam line?
- Need a HARP in the new Bubble Chamber line to measure beam profile and energy spread
- Where to put the electron dump (2-ft cube footprint)? Injector floor or on the Step
- Electron dump must be of pure copper, contaminants must have high photo-neutron threshold (>8.5 MeV)
- Photon dump must be of pure 1100 aluminum

• Beam Energy:

- Goal: absolute beam energy uncertainty of 0.1%
- Need new dipole with better field uniformity
- New power supply. What are specs on this supply? Must have an EPICS driver
- Put mu metal on all beam pipes to shield earth magnetic field (done)

• Safety:

- The sweep dipole must be in FSD to protect the exit window
- There will be about 500 ml of mercury used as a buffer liquid in the chamber

• Simulation and Backgrounds:

- Send Claudio the GEANT4 photon spectra
- Calculate the systematic errors due to absolute beam energy uncertainty with full error propagation in
Penfold-liess unfolding 
- Consider the beam energy spread in Penfold-liess unfolding
- Find the background contribution from the reaction 17O(γ,n)16O and subsequent neutron elastic scattering
with 16O and 14N nuclei

• Infrastructure:

- The chamber weighs about 600 lb and comes with a compressor (3.5 ft by 3.5 ft footprint), a chiller (10C)
and an electronics rack
- What is the clearance between the wall and the Laser Room in the Injector? 4.0 ft
- Distance from center of beam pipe to injector floor: 42 inches
- Distance from center of beam pipe to Step: 27 inches
- Need 208 VAC outlet in the 5 MeV region of the Injector
- Need a layout of the compressor and electronics platforms

• There is a possibility of a HIgS run next Spring
• Need Bubble Chamber cost estimate: procurement and labor
• We will meet every two weeks on Wednesdays at 3:00 to 5:00 EST

• Running at FEL pros and cons? Must compile a complete list