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Link to the Upgrade Tracker TDR


  1. Detector Layout in Sec. 3.3 of TDR: 3 stations, with four detection layers (XUVX) per station.
  2. Each layer consists of 12 SciFi modules (Sec. 3.6 of TDR).
  3. Each module has a surface of about 540 × 4900 mm2. It consists of several layers (six) of scintillating fibers densely packed supported on either side by cored carbon-fibers panels, for a total thickness of approximately 45 mm, depending on the details of the panel design.
  4. The fibers at both ends of a SciFi module are directly connected to 16 photon-detector arrays (SiPM, Sec. 3.5 of TDR), each with 128 channels, making a total width of 32.6 mm.
  5. The SiPM signals are connected to the Front-End electronics (Sec. 3.7 of TDR) by flexible kapton cables.
  6. By ”Readout Box” (Sec. 3.6 of TDR) we intend the region at the end of each module that include the SiPMs, the FE electronics, cables, pipes and all other services to and from the module. Readout Boxes will henceforth be referred to as ROBs.


  1. Historical: the space occupied by the present FE Boxes and gas pipes is 250 mm high (YLHCb) and 40 mm thick (beam direction, ZLHCb). The envelope actually reserved in ZLHCb was 45 mm (total envelope for one C-Frame was 100 mm: 2x45 mm for the two layers at each side of the C-Frame and 10 mm for the aluminum panel of the C-Frame itself). The envelope in YLHCb was somewhat arbitrary, since it was a choice of how much of the total space of about 450 mm between the module and the frame edge we reserved to route cables, pipes, etc.
  2. In case we use the IT rails for the first two layers (X-U), we can enlarge the Z-envelop. Assuming the present rail position and the present configuration of the C-Frames, we estimated a ZLHCb envelope of 160 mm for each C-Frame. We assume that 10 mm of this envelope are reserved for a horizontal plate supporting the ROBs on both sides of the C-Frame. This leaves a ZLHCb envelope of 75 mm for each ROB. For a detailed description see this presentation: Antonio_SciFiEnvelope_15Jul2014.pptx.
  3. The YLHCb envelope of the ROB box is once more to some extent arbitrary depending on the space requirements of cables and pipes routing. Let us assume a figure between 250 and 300 mm.
  4. The ROB is 524.4 mm wide (see Fig. 3.30 in Sect.3.6 of TDR) . This allows a space between the ROBs of 1 mm. The space between the modules is 3 mm, since the module is 522.40 mm (see Fig. 3.42 in Sect. 3.6.5 of TDR). The small space between ROBs puts severe requirements on the cooling, insulation and prevention of condensation.

Access Requirements:

  1. The possible scenarios for access to the LHCb cavern are: emergency access (1/2 day), short technical stop (1 week, about once every two months), winter stop (December and January), and long shutdowns.
  2. We want to be able to replace each FE electronics board or the whole set very quickly, say about 1 hour.
  3. We plan to exchange modules only during winter stops or long shutdowns.
  4. Replacement of SiPMs during technical stops (about one week) should be possible.


  1. The ROB will consist of several materials:
    1. Insulating materials for the SiPM cooling
    2. Stainless steel for the SiPM cooling pipes
    3. Copper for the FE electronics water cooling pipes
    4. PCBs for the FE electronics boards
    5. Internal cabling and optical fibers
    6. Etc.
  2. One has to cope with materials at different temperatures and with different expansion coefficients.
  3. During thermal cycling (ΔT > 60 degrees), a good contact between the SiPM and the cooling block, and between the SiPM and the fibres needs to be maintained.


  1. FE Electronics boards can have a temperature between +35 and +50 degrees, that can be ensured by the present demineralized water cooling system (+19 degrees).
  2. SiPMs have to be cooled at -40 degrees, with a max non-uniformity of 1 degree (within one SiPM) and a stability of ±0.5 degrees.
  3. Heat attacks are expected from the flex cables, the edges of the ROB, and from the fibres and polycarbonate.
  4. We want to be able to warm up SiPMs up in the range 20-80 degrees.
  5. We need some specs for the SciFi module temperature gradient.

Vacuum or pressure:

  1. No vacuum foreseen
  2. Demineralized cooling water pressure about 7 bars.
  3. SiPM cooling system pressure about 3 bars (but keep in mind a large safety factor here).

Fluids and/or gasses:

  1. SiPM coolant Novec 649. The use of C6F14 is deprecated due to the GWP (Global Warming Potential).
  2. FE coolant demineralised water.
  3. Possibly flushing with dry gas needed to avoid condensation (frost).


  1. Described in Sec. 3.7 of TDR, FE electronics is part of the ROB
  2. In addition to what already described, a chassis and thermal dissipation elements are needed to interface to the demi water system
  3. Other info needed?


  1. In the hottest region where SiPM are located in station T3, we expect a total integrated dose of about 8 krad (no safety factor) and about 6 x 1011 neutrons per cm2, assuming 50 fb-1 of data are collected (see Sec. 3.2.3 of TDR).
  2. ROB and C-Frame design might require the additional complication of shielding to cope with the high neutron fluency. This is not yet a spec, but might become one.


  1. Not much field, but I forgot the reference figure for the ROB location of the T1 station. To be checked.
  2. Avoid use of ferromagnetic materials.

Other technical requirements:

  1. ...
Topic attachments
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Unknown file formatpptx Antonio_SciFiEnvelope_15Jul2014.pptx r1 manage 291.7 K 2014-07-17 - 09:22 JeroenVanTilburg Estimation of Z envelop
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