October 15, 2008
12 GeV Upgrade
The suitability of the FSSR2 ASIC was studied for a potential application for the CLAS12 Silicon Vertex Tracker (SVT) detector. This is the second release of the Fermilab Silicon Strip Readout Chip (FSSR2) application-specific integrated circuit (ASIC). This R&D task encompassed designing and fabricating a dual FSSR2 ASIC test board, an interface board with the regular CLAS12 data acquisition system, and the development of firmware and FSSR2 software. This then constituted a hardware platform to test the FSSR2 ASIC’s suitability to the CLAS12 SVT application. The prototype boards have been successfully designed, fabricated and installed with firmware. Initial tests with pulsers indicate that the hardware and the installed firmware are working properly, which means that the FSSR2 chip is a likely second candidate for CLAS12 SVT readout.
The polarimetry groups of Halls A and Hall C joined efforts to conduct test beam measurements at the High Intensity Gamma-Ray Source photon beam facility at Duke University in North Carolina. At HIGS, photons created in a free-electron laser are scattered off the electron beam to create a high-intesity beam of energetic gamma rays. These gamma rays were used to characterize the polarimetry detectors for the PREx and Q-weak experiments and for the 12 GeV Upgrade. A total of 10 scientists from JLab and Carnegie Mellon University were involved in five days of tests.
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A replacement periodically poled lithium niobate (PPLN) crystal was installed in the injector on the Hall C laser for the upcoming run. The PPLN crystal doubles the frequency of the photons delivered to Hall C. A great deal of time was spent on running Q tests on most of the cavities in the accelerator, as the Operations group is staffing the Machine Control Center 24 hours a day now. Superconducting radiofrequency (SRF) commisioning continued on the cryomodules at NL11 and SL09. Hot checkout began on all systems in preparation for beam operations.
Free-Electron Laser (FEL)
FEL staffers have made better progress on conditioning the FEL gun after switching to helium processing to eliminate field emitters. The voltage was set above 300 kV last Friday, and progress continued over the weekend. Other tasks included hot checkout of individual systems for the rest of the machine. The team is getting close to having everything in running order.
Transverse Momentum Dependent (TMDs) parton distributions play an important role in the description of Semi-Inclusive Deep-Inelastic Scattering (SIDIS), which can be studied in detail at JLab. A complementary process for determining TMDs is the dilepton production in hadron-hadron collisions (Drell-Yan process). A recent paper (arXiv:0809.2262 [hep-ph]) presents a complete decomposition of the Drell-Yan spin observables in terms of structure functions and angular dependencies, supplemented by a parton model calculation of the leading twist structure functions.
Environment, Safety, Health & Quality
Task Hazard Analysis doesn't end when the task list is completed. Underlying hazards, as well as special conditions of the work environment, require awareness at all times and by all personnel.
This concept was demonstrated recently by Bob Adams of the PSS (Personnel Safety System) Group. During the preparation work for reinstallation of the LN-1 transformer, Adams identified a scenario in which faulty switches or breakers could introduce uncontrolled hazardous energy into this locked-out system. The potentially unsafe condition was immediately accounted for and similar work checked. Adams' diligence was recognized at the Oct. 10 MCC meeting, where he was presented with the Safety Incentive Award by the site electrical safety representative, Todd Kujawa.
Adams' awareness of the equipment configuration and hazards prevented the possibility of back-fed energy causing an event during this work. Please remember his example in your own work planning, and be safe.
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JLab's Safety Numbers
35 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
Oct. 13-15: Electromagnetic N-N* Transition Form Factors Workshop