GlueX Electronics Review
JLab, July 23-24, 2003

This background information is meant to supply information on electronics issues and progress since November 2002 when the latest version (4) of the GlueX/Hall D Design Report was issued.

This review of the GlueX electronics is being conducted as the collaboration prepares for a 'Lehman-type' Review as part of Critical Decision 1 (CD1) approval. The GlueX physics and detector are described in version-4 of the GlueX/Hall D Design Report. The entire Design Report can be downloaded and in particular the electronics are described in Chapter 7 (Readout Electronics) and Chapter 8 (Trigger and Data Acquisition).

GlueX/Hall D and the Jefferson Lab 12 GeV Upgrade, of which it is a subset, are not yet approved - although based on recommendations from the Nuclear Science Advisory Committee the prospects of timely approval are very good. Based on this the GlueX Collaboration has been working on R&D at a level appropriate for our pre-CD0 status - that is - generic detector R&D. The major areas of concentration involving electronics include studies of a FADC and TDC appropriate to rates and resolution requirements for a spectrometer for meson spectroscopy. Other electronics issues include the operation of photomultipliers or other similar devices (hybrid photodiodes) in the primary or fringe field of a large solenoid. A low-power PMT base design has also been developed. In addition, since cost optimization and quality control (and testing) are issues for the construction phase, we have have started to explore the use of robotics for electronics assembly. Monte Carlo studies are also underway to optimize the higher-level trigger.

Although the GlueX detector will be state-of-the-art it does not push the envolope compared to experiments already taking data or planned for the near future. The channel count is modest (approximately 20k channels for fast control and 10k for slow). The events are relatively simple (about 5kB/event) with an average of about five charged particles and two to four photons per event. The data rates are also modest (about 400kHz for the total hadronic rate). At the highest beam flux of 10^8 photons/s the archived data rate will be 100 mB/s. Pipelining will be built into the entire trigger, digitizer and data acquisition systems at the outset. This will allow seamless upgrades from initial photon fluxes of 10^7 photons/s up to the design goal of 10^8/s. Recent development of a high speed network will be used to develop a fully pipelined Level 1 trigger. Event reconstruction will also be straightforward and we expect to exploit Grid architectural tools that will be in place by that time. The challenge unique to GlueX will be developing the phenomenological and software tools needed to do the amplitude analysis required for identifying meson quantum numbers.

Radiation effects are also not an issue. They will be lower than those experienced by the CLAS detector in Hall B at Jefferson Lab which has been in operation now for several years. Background sudies for GlueX have been made.

It is expected that the detector will be ready for data-taking in 2009 which means that production of electronics must start in 2006. That implies that final designs of critical components must be finialized in the next 30 months. During this period we also need to:

• Put in place a design team with an appropriate management structure.
• Develop a plan for manufacturing, testing, quality control that takes into account component availability and maintenance.
• Decide on packaging and bussing.
• Decide on a data acquisition system that exploits the expected advances in computational power and data storage.

The agenda shown below has links to current versions of the presentations being prepared for the review. They will be updated by Wednesday July 16, or as they become available

Review Committee

Letter from Larry Cardman

• Andrew Lankford (University of California - Irvine)
• Glenn Young (Oak Ridge National Lab)
• John Domingo (Jefferson Lab)

• Continental breakfast on Wed and Thu
• Coffee during the day
• Lunch for Committee on Wed and Thu