Mu2e Tracker Review

 

Second video meeting on 12/8/2015                                                    

 

Minutes

 

Present:

Mu2e members:

Aseet Mukherjee (FNAL)

Robert L. Wagner (FNAL)

Marjorie D Corcoran

Vadim L Rusu   (FNAL)

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 500Ĺ Aluminum and 200Ĺ 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.

         

The initial conclusions and recommendations by the reviewers after the first two video meetings are listed at the end of the document.

Video Meeting held on 12/8/2015

Additional questions and answers with reference to the initial list of questions in « Answers_to_questions1.doc »  (from 17/7/201)

 

Backup documents are: 3879, 2310, 2535, 5777, 5331, 1808, 5256, 5246, 2633, 1343.

 

1.     Looking at the layout the straws do not overlap around the straw center. Can you provide plots from MC of the straw resolution versus distance including electronics?  (even if it is not exactly within the scope to review the performance requirements).

a.     How do you verify these with the prototypes?

b.     Does the MC include the discriminator threshold level achieved with the prototype electronics?

c.     What is the gas gain and how has it been measured?

d.     Has the noise level been measured?

e.     Can you meet the required resolution and efficiency specs with present S/N?

2.     Can you describe in more detail the cooling system? Have you done any simulations or tests with realistic geometry of heat loads (boards) and cooling interfaces? What is the temperature of the coolant and electronics (overall temperature gradient)?

3.     Can you provide details (drawings) of the vacuum sealing of the panels and how the assembly and leak testing is carried out?

4.     What are the characteristics of the fuses and have they been tested?

5.     How have you reached the conclusion that the inside and outside of the straw do not have to be connected?

6.     Can you explain in some more detail with a drawing or diagram the connections of the services (HV, LV and gas) i.e., patch panels, position of connections and modularity?

7.     Can you describe the plan in case of failure/problem with HV, LV, leaking straw and readout problem?

8.     It would be good to produce a detailed circuit diagram with characteristics and values of the components.

9.     In the aging test you have seen no change in gain up to 1C/cm. Have you seen any effects on the straws?

10.  Can you outline the development plan towards the final electronics?

a.     What additional prototypes are planned?

b.     What questions remain unanswered and when do they think they will know enough to go into production?

c.     What risks do they see in the near future?

d.     How much schedule and cash contingency do they have in the baseline plan?

Comments:

1.     It is important to do the radiation test of the electronics.

2.     It is recommended to repeat the discharge tests with the smaller blocking cap.

 

Comments:

 

This section summarizes the comments and conclusions by the review committee after the first two video meetings:

 

1.    It is the review opinion that the project is in good shape in view of the present schedule.

2.    The review committee thinks it would be useful to establish a clear grounding and shielding plan that is based on their present design status.

  1. A simple drawing of how signal and HV currents flow might be instructive (and also help define the grounding and shielding plan).
  2. Interaction at an early stage with the FNAL safety team in order to get the green light for the planned electrical scheme and choice of components may avoid surprises and problems in the future.
  3. The reviewers felt that the layout and choice of components should not be left entirely to the DAQ group - the reliability problems with commercial electro-optical converters (let alone radiation hardness issues) are not to be ignored. The possibility to move the sensitive parts/components outside the detector to a more accessible area with little cost, should be considered
  4. The idea of using the CERN rad hard I/O equipment, as a fall back is plausible, but expensive. However, this option also contains a reliability worry and it needs to be examined in more detail, if considered as a real option.
  5. Concerning the fuses, a document describing design and validation is required.

8.    It would be to useful to establish a plan including the different tests and validations foreseen before CD3b e.g., electronics tests, radiations tests and a full system test.

9.    A link to the plots from the simulations (by Dave B) including momentum resolution should be provided. The space resolution close to the wire is usually not so good and there is a gap between the straws in the double layer of ~1.3mm.

10.  A lot of work has been done on testing and validation. A link to beam test set-up, noise measurements, gain measurements and results would be useful.