Mu2e Tracker Review
First video meeting on
15/6/2015
Minutes
Present:
Mu2e
members:
Aseet Mukherjee (FNAL)
Robert L. Wagner
Marjorie D Corcoran
Vadim L Rusu
Review
members:
Hans Danielsson (CERN)
Hogan Nguyen (FNAL)
Brendan Casey (FNAL)
Rick Van Berg (U of Penn)
Short
Summary:
A
TDR has been submitted and a full-size prototype is under construction. It is
scheduled for CD-3c approval in June 2016, at which point it can begin tracker
production related purchases. Several design concepts have been tested. The
electronics in inserted in the active gas while the detector is operated in
vacuum. The straw is standard PET (Mylar) 15mm thick, with a
deposit of 500A Aluminum and 200A Gold (inside only) using the
"standard" method of two films glued back to back. The main challenge
for the detector construction is the leak tightness both of the straws and the
mechanical parts.
Initial
questions arising from the first meeting:
1. Detector requirement:
Spatial
Resolution:
- What is the required
resolution in the spectrometer?
- What is the
simulated and measured resolution (with prototype) ?
Occupancy:
- What is the
maximum total and local (Hz/cm2) hit rate in the straw during
data taking and beam splash?
- What is the
expected total charge/cm?
- Is aging an
issue?
Cross talk
and noise behavior
- Has the
cross-talk been measured? If yes what is the level cross-talk? Has the
final front-end boards been used?
2.
Operation conditions
Counting
gas:
What are the main arguments behind the
choice of Ar/CO2 (80/20) ? What is the nominal high-voltage and what
is the gas gain?
3.
Material and coating of the cathode foil
Cathode
material: As cathode
material a 36mm thick PET (2x15 +6mm
glue) has been chosen
- How and where
is the base material produced (coating)?
- What are the
QC steps on the base material?
- Are the two
sides electrically connected and if yes how?
- Has any
studies concerning effects on discharges on the straws been carried out
and is there any risk of increased leak/permeation?
- Has any large
surface irradiation tests been carried out on the straws in order to look
for Malter effects?
Straw
gluing:
- Given the
axial tension applied during the detector assembly, has (glue) adhesion to
the straw wall been made?
- Which glue is
proposed?
Permeation: The coating of the straws
- Are there any
studies made on the base material concerning permeation? How big is the
contribution from the glue joint between the films?
4.
Straw production and QC
Straw
winding:
- Is the winding
process defined?
- How is the
cleanliness guaranteed and is the production lubricant free? (In case
aging is issue)?
- Where are the
straws produced?
- How is the
production quality ensured?
Quality
insurance:
- How is the
leak tightness measured and what is the specification?
- What is the
expected failure rate (major leak or straw failure)?
- What is the
experience from prototypes in terms of failure/major leak?
5.
Detector construction and QC
- How is the pretension
applied and the straightness guaranteed?
- What is the
sag for the horizontal 1200 mm long straws ?
- How is the
straightness of the straws checked during assembly and what is the
specification?
- How is the
leak tightness verified before installation
6.
Electronics and HV
- What is the
modularity of the high voltage?
- If there is a
problem with FE electronics how is it repaired?
- Has the
components inside the gas manifolds been tested for aging (if aging is an
issue)
- How is the
cooling of the electronics done?
- What is the
estimated radiation levels for the FE-electronics? Is it an issue?
6.
Operation of the detector
- How is the
sudden leak in the straw handled?
- How many
straws have to be turned off in case of sudden failure during operation?
- Can a straw
be replaced?
- How is the T0
found?