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- Bubble Chamber work at Argonne

4- Background and simulation

5- Absolute beam energy

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

6- Safety

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Notes from this meeting:

• Radiator:

- The power deposited in the radiator for 200 uA and 8.5 MeV electron beam:
  for 0.02 mm radiator, average energy loss is about 24 keV, P = 4.8 W
  for 0.10 mm radiator, average energy loss is about 120 keV, P = 24 W
  re-evaluate radiator cooling 
  what is the temperature of the LCW that will be used to cool the radiator?
  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

• 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
- How 17O(γ,n) compares to 13C(γ,n)?

• Infrastructure:

- The chamber weighs about 600 lb and comes with a compressor (3.5 ft by 3.5 ft footprint), a chiller (10 C)
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 and injector floor: 42 inches
- Distance from center of beam pipe and Step: 27 inches
- Need 208 VAC outlet
- 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

Pros: 
  - No other users
  - 9.5 MeV Injector (with field emission)

Cons:
  - completely new beam line