Conference Call with Hamamatsu Representatives, January 5, 2012

Present:

• JLab: Fernando Barbosa, Mark Ito, Elton Smith, Tim Whitlatch, Beni Zihlmann, Carl Zorn
• Hamamatsu: Earl Hergert, Samir Patel

Mark introduced the general problem of start counter read-out, reviewed the motivation for using SiPM's as the photo-detector and the geometric constraints for mounting them. Reference was made to drawings posted on the Start Counter Cheat Sheet.

We quickly eliminated the possibility of using raw dies from Hamamatsu and packaging them ourselves at JLab or at a sub-contractor. We do not have the facilities to do wire bonding. Hamamatsu has confidence in their in-house process.

Werner Boeglin had drawn up a concept where a 5×1 array of 3×3 mm sensors are arranged at the end of the scintillator. No such packaging is listed in the catalog and in real life the package edges and inter-die spacing would have to be accounted for.

Other options were also discussed including having Hamamatsu do the wire bonding on a JLab supplied package, and using other die sizes, in particular 4×4 mm.

We coalesced around Earl's recommendation of using 4 SMD-type 3×3 mm devices in a row. The radius of the counters would have to moved slightly outward from Werner's nominal 73 mm to allow enough width for package placement, but we thought that could be accommodated. This has the advantage of using a standard package and would cover about 75% of the scintillator face. This design would use 30×4 = 120 devices.

Carl suggested that we consider using the 100 micron pixel device to compensate for the loss in area coverage. It would have higher PDE and gain than the other sizes, but higher noise as well.

We requested quotes from Hamamatsu for a small quantity to do prototyping:

• 10 pieces, 3 × 3 mm, SMD package, 100 micron pixels
• 10 pieces, 3 × 3 mm, SMD package, 50 micron pixels

Also we requested a quote for a complete order for the new reference configuration for budgetary purposes.

• 150 pieces, 3 × 3 mm, SMD package, 100 micron pixels
• 150 pieces, 3 × 3 mm, SMD package, 50 micron pixels

Fernando had questions about special conditions for the reflow process for these devices. Hamamatsu agreed to send that information to us.

Hamamatsu will look into the availability of 4×4 mm dies.

Tim told us he would get us 3-D drawing of the region with the updated dimensions.