Wednesday September 4, 2013

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We will meet in TED 2561B on Wednesday September 4 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_4September_2013.pdf
 media:Meeting_4September_2013.pptx  

1- Bubble Chamber progress at Argonne

2- Superheated Liquids to be used in the experiment

3- Beamline Layout

4- Bubble Chamber cost estimate: procurement and labor

5- Error Analysis media:Bubble_ErrorAnalysis.pdf media:Bubble_ErrorAnalysis.pptx



Notes from this meeting:

  • Bubble Chamber:
- In the process of changing the buffer liquid from water to mercury. Mercury will be in a sealed system that
will allow for changing the active liquid without the need to remove or add mercury.
- Mercury does not tolerate all other metals except for iron. However, CF iron gaskets will destroy the knife edges. 
Still looking for a solution.
- The new design of the chamber will fit in the space between beamline and floor in the Injector (27 inches).
- Adding acoustic signal readout to the chamber.
- For 17O superheated target (needed to measure background), the ratio of 17O nuclei to 18O nuclei should be greater than 100.
Note that the thresholds and cross sections for the reactions: 17O(γ,α)13C and 18O(γ,α)14C are very similar. 
- For 18O superheated target (needed to measure background), the ratio of 18O nuclei to 17O nuclei should be greater than 100.
  • Cost:
- Will pass the Bubble Chamber cost estimate by Jefferson Lab Finance to get more realistic labor, procurement and shop costs
  • Beamline Layout:
- We will not install a new BPM on the Spectrometer line since we have no way to know the absolute positions. The Bubble
Chamber beamline will be equipped with two BPMs and two Super Harps that will be used to measure the beam energy.
- We need to think very carefully if we need a vacuum pipe that connects the vacuum window to the Bubble Chamber. Would it
add more protection to the vacuum window? Now, there is a risk of contaminating the beamline with oil. How to fit in the photon
collimator? Any issues with alignment? Pumping on the vacuum pipe may introduce vibrations that may trigger the acoustic sensors. 
  • Error Analysis:
- Need to do more checks to make sure all is correct. Puzzled by the finding that the errors at higher energies are larger than
those at lower energies. We may want to try a PL unfolding for 7.9-8.5 MeV with 0.2 MeV steps and 8.3-8.5 MeV with 0.1 MeV steps.
- Redo the energy error analysis taking into account the relative vs absolute errors on energy.
- Redo the error analysis using monte carlo techniques.
- Calculate the errors for δe=0.05%.
- Since we do not start the energy scan from Threshold, how to handle the expected yield from threshold to the first energy?