[Clas12_rich] May 23th Meeting Minutes

[MMarco Contalbrigo]

Dear all,
let me first thanks again the DSG for the essential support they
are giving to the project.

During May 23th meeting we reviewed various aspects of the RICH 
preparation. Given the readiness review, we are forced to 
converge pretty soon on something realistic. The real working
considitions will be tested while assembling and may eventually
require later adjustments.

Below we review the discussed arguments and actions, adding few 
questions we would like to clarify together with DSG.

--------------------------------------
Components
--------------------------------------
Aerogel: forniture will flow on a regular basis. In EEL-121 clean
room we plan to
- keep logbook of arrivals 
- store the aerogel inside the dry cabinets
- perform visual inspection
- weight the tiles to get the density <--> refractive index
        --> INFN: the scale DSG proposes is fine with us
- (maybe) check dimensions with a mold
- (maybe) study optical effects with low-power lasers
        --> INFN: going to supply information on the lasers we
            are using in Ferrara, to check which kind of safety
            regulations they would require at JLab
We will organize few trips in Washington to measure the 
aerogel transmission. We assume italian personnel will do
the trip.
        --> DSG: could be available to help in this task ?

Spherical Mirrors: 4 mirrors have arrived at Jlab.
We are going to open and validate them together with DSG
starting the week of 13th of June, while we will be at JLab.
We will concentrate in accepting tests, as likely we will not 
have available all the tools for characterization that week.
We plan to
- keep logbook
- perform visual insepction
- perform a pointlike-source spot image measure
- (maybe) perform a Shack-Hartmann surface analysis
- perform a dimensional check with a CMM machine
         --> DSG: please check availability of the 60 um CMM
             machine in the dates 14-17 or 21-22 June.

Planar mirror: they are being produced, but will be delivered 
at JLab only after the summer.

Mechanics: an assembling test will be performed in Italy 
the first half of June. The RICH module + assembling 
structure will then be transported at JLab. Except for 
storing, no action is foreseen at JLab before enough space 
in EEL-124 will become available (i.e. October).

Electronics: the JLab FPGA boards should have been produced
already. The production of the adapter+Asics boards will
start in June. A small quantity will be produced in advance 
to allow a final check before moving ahead with the massive
production (planned in July). In July Matteo Turisini 
will be at JLab for defining all the procedures and software 
tools, in collaboration with Ben and DSG, for the electronics 
acceptance and characterization. The ideal scenario would
be DSG will be available to start testing the electronics 
boards in August. In June Paolo Musico will also visit JLab
and work with Ben to the SSP protocol for RICH.

--------------------------------------
Assembling
--------------------------------------
We plan to perform the RICH assembling in EEL-124 starting
not before October 2016.

Mechanics: we will mount the RICH case inside the assembing
structure.
         --> INFN: has to define the bolt size and lift points.

Electronics: it can initially be a stand-alone item. With a 
proper cover of the PMT side, is can run under cosmics and 
allow for daq, slow control and reconstruction tests. With 
the back panel in place it will allow for cooling tests.
Ideally, we would like to develop/test the same systems we 
are going to use in the Hall. This means power supplies, 
cooling system, interlock system, slow control etc...
         --> INFN: has to discuss with Hall-B management and
             engineers how to best proceed.

--------------------------------------
Cooling + Interlock
--------------------------------------
The inlet lines are designed for a typical flux of 100 slm,
and a 1 inch size. This flux was tested in a half-size 
prototype and in a simplified heat load configuration. We
would therefore suggest to plan a typical 250 slm with a 
large safety coefficient (> 50 %).
         --> DSG: it would be nice to have the presssure
             sets of the relief valves and the pressure
             regulators visible in the interlock sketch,
             as done for the N2 line.
         --> DSG: should the line from compressor to tank
             design to sustain the full compressor flux
             (1200 slm) ?
         --> DSG: is the current line from tank to RICH
             suitable for maximum 283 slm (due to the
             proposed rotameter) ? How complicate is to
             upgrade it to reach 400 or 600 slm maximum ?
         --> DSG: The space inside the RICH case is limited:
             we assume to split the 1 inch tube into few
             smaller (9-10 mm diameter) plastic tubes for
             the last part of the line. This may correspond
             to the ~4m from the patch panel till the electronic
             panel. Which is the maximum pressure we should
             aim in this last part of the line ?
         --> DSG: do we need an interlock for maximum
             pressure in the tank or in the inlet line or
             everything is set by the relief valves ?
             The compressor has its on interlocked limit.
         --> DSG: the tank you propose is fine with us.

The interlock logic is relative to the cooling circuit 
functionality. Other anables for the HV and LV power 
supplies should come from temperature sensors in few
relevant places, i.e. inlet, inner volume, exhaust, FTOF.
         --> DSG: may you provide information on your
             board controlling temperature and humidity
             sensors ? We usually use SHT75 sensors form
             sensiron
         --> INFN: should provide detailed information
             in the compressor and power supply
             hardware controls.

--------------------------------------
Nitrogen line
--------------------------------------
We plan to refresh the full RICH volume, close to 5000 
liters, in about one day. The current inlet lines are 
able to provide a maximum of 7200 l/day, with almost a 
50 % safety factor. We consider it a realistic starting
point. We would anyway need to minimize the RICH vessel 
leaks.

The LN2 dewar provides a nitrogen with enough purity,
with a water content smaller than 0.002%. The filters
are just for safety.

We will need to monitor temperature + humidity with 
sensors inside the RICH volume.

          --> DSG: do we need an interlock logic for the
              N2 line, i.e. a shutter to isolate the RICH
              volume in case of problems ?
          --> DSG: for example we would be in favor to use
              humidity sensors to monitor the inlet line
              quality (the N2 should be fine but we may
              have leaks or breaks in the line).
              May we implement those in an cRio interlock
              logic ?
          --> DSG: do we need a interlock shutting the N2
              line in case of over-pressure of the RICH
              module or relief valves would be enough ?
          --> DSG: The RICH N2 inner volume is supposed to stay
              at ~0.5-1 mbar higher pressure than atmospheric,
              to prevent water flowing in. Is the bubble
              control system sensible enough to prevent
              over- or under-pressure ?
          --> DSG: the N2 line starts with a LN2 dewar:
              do we need dedicated equipement to prevent
              moinsture along the line and/or injecting
              low temperature gas inside the RICH ?


Thank you, Marco.