Each hodoscope box has either 80 channels (station 1 quadrant) or 50 (station 2 quadrant). Each channel comprises an SiPM and a preamp. Low voltage and bias are supplied to the preamp through a 10-pin ribbon cable.

Power and bias are supplied through distribution boards. Each distribution board supplies up to 24 ribbon cables; with one exception, each ribbon cable supplies a single preamp. For the station 1 boxes, the 80 preamps are divided in four equal groups of 20. For the station 2 boxes, the four outermost (furthest from beam) preamps are paired up: two preamps (with gain-matched SiPMs) are connected to the same ribbon cable. Now there are only 48 ribbon cables, so we have two groups.

Preamp, SiPM and pigtail

The SiPM is Hamamatsu S13360-3050CS.

The preamp is connected to the SiPM by a short pigtail of 24 AWG wire (shielded twisted pair, shield grounded to the preamp ground). The SiPM end of the pigtail terminates in a 2-pin connector, so SiPMs can be replaced if necessary.

Pinout:

1. Bias
2. Ground
3. N.C.
4. N.C.
5. RTD bias
6. N.C. (would be temp/humidity sensor)
7. RTD output
8. RTD ground
9. +6V
10. Ground

Distribution board

This board patches through all the DC voltages for a set of 24 preamps:

• Bias (+50-60 V, <100 uA)
• +6V power, common to all preamps (16 mA per preamp, total of 0.4 A)
• Ground: the preamps have a common ground for bias and power. These grounds are also tied together on the distribution board. The board is meant to be electrically isolated from the frame (no conductive layers extend to the mounting holes).
• RTDs: the control board exposes two ADC inputs and a regulated +VDD. The distribution board connects these to RTD voltage dividers: one on the first preamp, one using an external RTD (Heraeus 32208711), which we will glue somewhere near the SiPMs.

• ExpressSCH schematic file
• ExpressPCB layout file
• DXF file of the layout
• BOM (Digi-Key CSV format)

The ExpressPCB screenshot on the right shows a 100 mil grid.

On the inside (these are drawn in green):

• 24 10-pin ribbon connectors
• One 2-pin connector for external RTD

On the outside (these are drawn in red):

• Four 10-pin ribbon connectors: three for BV (each connector carries 8 voltages), one for RTD connections
• One big 2-pin connector: +6V
• One LED to indicate the board is getting +6V, and test points for the BVs
• Mounting holes to accept 4/40 standoffs: these support a plastic protective cover. The mounting holes have 1.1" vertical separation, 2.7" horizontal.

Hodoscope box

The detectors are divided into "hodoscope boxes." DC voltages (preamp power and SiPM bias) enter through "distribution boards." Detector signals exit through "patch panels."

Both sides of the 80-bar preamp plate: left shows the preamps, right shows the pigtails and SiPMs.

Internal cabling of the 80-bar hodoscope box.

Internal cabling of the 50-bar hodoscope box.

Grounding. Left photo shows the ground wire from the preamp plate to the patch panel, right photo shows the ground wire from the patch panel. This shows a 50-bar box.