Difference between revisions of "Technical Board Meeting Oct 23, 2023"

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=Minutes=
 
=Minutes=
 +
 +
Drift pipe end:
 +
* Drift pipe end cap was "dish" shaped, about 1" thick, to avoid an excessively thick wall. This added cost and schedule concerns, which can be relieved with a flat, 3" thick flange. 
 +
* There is a 5" thick wall just upstream of this, at the end of the downstream torus vacuum enclosure.
 +
* Simulations confirm this understanding: the additional thickness at the upstream end of the drift pipe do not add significantly to backgrounds.
 +
* There might even be a very small benefit, but at this level the statistical significance of the simulation is not fully sufficient.
 +
 +
 +
Scattering Chamber Exit Window:
 +
 +
Cip: Physics simulation
 +
* added Al window at the scattering chamber exit
 +
* found that 400micron roughly doubles the total Al contributions from the target windows.  The additional contribution is consistent with linear scaling with thickness of the scattering chamber windown
 +
* "deconvolution" results don't degrade, but this is based on assumptions of Al fractions and asymmetries being perfectly known
 +
* In fact, Al corrections will be uncertain at the 10% level due to uncertainty in the Al asymmetry
 +
* Qweak measured APV to 10%  (Note in chat: SM coupling known better than this, so this would be a worst-case limit for knowledge of asymmetry.)
 +
* DA: what about uncertainty in rate?
 +
** rates with gas-filled target are hard to get, since knowing the gas density was difficulty
 +
** KK: simulation is required, other studies will be possible
 +
**  KK : Be window would be very valuable to have, even if installed later.  So we should keep this development alive, even if we got with the Al window to start Run1.
 +
 +
Meekins:
 +
* delivery is not going to be available from previous vendor.
 +
* Materian (now purchased and absorbed into another company) will no longer provide flanges.
 +
** Al is easy, but Be is difficult
 +
** Be brazing is possible, (in conversation with WessDel) but this is also challenging to move forward due to inconsistent vendor response.
 +
***This would require the experiment is accept brazing alloy of zinc/Al
 +
**  Be: better thermal conduction, better cyclic loading, low Z for backgrounds
 +
* Aim to prepare to handle 20psi load if H2 cell failure. 15pse for atmosphere
 +
* Dishing is required, allows for relief of mechanical stress under thermal load
 +
* This design has 10 mils in vacuum window, 25 mils in 3" diameter for accepted scattered particles
 +
* Old window, was about 1 calendar year replacement cycle at 10trips/hr
 +
** new design is probably much better, but not so clear yet. Now looking at 70k cycles compared to 45k in flat design.
 +
* status: "Its done", this can be built in machine shop.
 +
* May need to make several to meet thickness goals, with reasonably small variation. There are measurement tools to know what we have well.
 +
* KK: Summary from the experiment side: we would prefer Be window to improve physics, but we are ok with this Al design even for full experiment.
  
 
=Attendance=
 
=Attendance=

Revision as of 17:11, 23 October 2023

Back to Main Page >> Technical Board

Technical Board Meeting September 18, 2023 << >> Technical Board Meeting October 30, 2023

Online: see email

Agenda

  • Scattering chamber exit window design and lead time [Dave Meekins] Slides
  • Effect of Aluminum Scagttering chamber exit window on MOLLER backgrounds Ciprian docdb:1172
  • Physics evaluation of Drift pipe end cap design change [Kent] docdb:1171

Minutes

Drift pipe end:

  • Drift pipe end cap was "dish" shaped, about 1" thick, to avoid an excessively thick wall. This added cost and schedule concerns, which can be relieved with a flat, 3" thick flange.
  • There is a 5" thick wall just upstream of this, at the end of the downstream torus vacuum enclosure.
  • Simulations confirm this understanding: the additional thickness at the upstream end of the drift pipe do not add significantly to backgrounds.
  • There might even be a very small benefit, but at this level the statistical significance of the simulation is not fully sufficient.


Scattering Chamber Exit Window:

Cip: Physics simulation

  • added Al window at the scattering chamber exit
  • found that 400micron roughly doubles the total Al contributions from the target windows. The additional contribution is consistent with linear scaling with thickness of the scattering chamber windown
  • "deconvolution" results don't degrade, but this is based on assumptions of Al fractions and asymmetries being perfectly known
  • In fact, Al corrections will be uncertain at the 10% level due to uncertainty in the Al asymmetry
  • Qweak measured APV to 10% (Note in chat: SM coupling known better than this, so this would be a worst-case limit for knowledge of asymmetry.)
  • DA: what about uncertainty in rate?
    • rates with gas-filled target are hard to get, since knowing the gas density was difficulty
    • KK: simulation is required, other studies will be possible
    • KK : Be window would be very valuable to have, even if installed later. So we should keep this development alive, even if we got with the Al window to start Run1.

Meekins:

  • delivery is not going to be available from previous vendor.
  • Materian (now purchased and absorbed into another company) will no longer provide flanges.
    • Al is easy, but Be is difficult
    • Be brazing is possible, (in conversation with WessDel) but this is also challenging to move forward due to inconsistent vendor response.
      • This would require the experiment is accept brazing alloy of zinc/Al
    • Be: better thermal conduction, better cyclic loading, low Z for backgrounds
  • Aim to prepare to handle 20psi load if H2 cell failure. 15pse for atmosphere
  • Dishing is required, allows for relief of mechanical stress under thermal load
  • This design has 10 mils in vacuum window, 25 mils in 3" diameter for accepted scattered particles
  • Old window, was about 1 calendar year replacement cycle at 10trips/hr
    • new design is probably much better, but not so clear yet. Now looking at 70k cycles compared to 45k in flat design.
  • status: "Its done", this can be built in machine shop.
  • May need to make several to meet thickness goals, with reasonably small variation. There are measurement tools to know what we have well.
  • KK: Summary from the experiment side: we would prefer Be window to improve physics, but we are ok with this Al design even for full experiment.

Attendance

Technical Board Members

  • Kent Paschke, Chair (MOLLER Scientific Coordinator)
  • Krishna Kumar (MOLLER Spokesperson)
  • Mark Pitt (Deputy Spokesperson, MOLLER-NSF Project Coordinator)
  • Ruben Fair (DOE Project Manager)
  • Klaus Dehmelt (Deputy DOE Project Manager)
  • Michael Gericke (MOLLER-CFI Project Coordinator)
  • Juliette Mammei (Executive Board International Representative)
  • Mark Jones (Hall A Leader)
  • Paul A Souder (Elected Executive Board Member)
  • David Armstrong (Elected Executive Board Member)
  • Robin Wines (Project Engineer)
  • Dave Meekins (L2 CAM: Target)
  • Mike Dion (L2 CAM: Spectrometer)
  • Carl Zorn (L2 CAM: Detectors)
  • Ciprian Gal (L2 CAM: Infrastructure)
  • Robert Michaels (L2 CAM: DAQ)
  • Vladimir Berdnikov (L2 CAM: Installation)
  • Silviu Covrig (Working Group Convener: Target)
  • Caryn Palatchi (Working Group Convener: Polarized Beam)
  • Dustin McNulty (Working Group Convener: Integrating Detectors)
  • Paul King (Working Group Convener: DAQ)
  • Nilanga Liyanage (Working Group Convener: Tracking Detectors)
  • Jim Napolitano (Working Group Convener: Polarimetry)
  • Rakitha Beminiwattha (Working Group Convener: Simulations)
  • Yury Kolomensky (Working Group Convener: Physics Extraction)
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