Jefferson Lab Weekly Briefs February 23, 2011
Jefferson Lab Weekly Briefs
February 23, 2011
Open Letter on the Budget From Mont
It will not have escaped your attention that Congress is engaged in many discussions of budgets. A little more than a week ago, we made our presentations to the Office of Nuclear Physics in preparation for the FY2013 budget. The President made his FY2012 budget proposal, which is generally favorable to the DOE Office of Science and Nuclear Physics. For FY2011 we are still under a continuing resolution. There is an enormous range of possibilities and some would indeed be very difficult for the laboratory, others are relatively good given the perceived economic situation. We track many of the changes but do not try to develop detailed reactions to each possibility reported in the press.
You can be assured that we will provide you with any concrete developments as soon as we can. In particular, we are trying to understand the commitment we can make to running the accelerator during the period from April 1 to May 15, when the six-month installation shutdown begins.
12 GeV Upgrade
The first of the 13 kilowatt klystrons was received last week; onsite testing will begin after completion of the non-electrical checks. Assembly of the first 12 GeV cryomodule continues. The first two of the new curved spreader/recombiner magnets have been received; initial testing indicates that the field quality is well within the specification. The arc dipole rework/refurbishment plans were reviewed by the Accelerator Division and the 12 GeV team. Assembly has started on the quadrupole-beam position monitor-corrector girder assemblies for arc 10.
The first Hall A experiment scheduled to run this spring, E08-008: Electrodisintegration of the deuteron near threshold, was completed on schedule.
Q-weak data taking in Hall C was interrupted by worsening vacuum in the beamline downstream of the target. Hall C technicians patched a suspected leak location on a bellows, a replacement for which is under fabrication. While the downstream vacuum fluctuates with beam on, the vacuum has remained good enough to continue production data taking at 150 microamps.
The accelerator has been running well, with beam to three halls. The injector may need some fine tuning to improve beam quality for Hall C; the width of Hall C’s beam charge asymmetry is larger than the specification. Last week, a few hours were lost due to a bad fast shutdown card, a faulty beamline valve position indicator and a failed viewer camera. Over the holiday weekend, two injector radiofrequency control modules and the arc 2 box supply current regulator board were replaced, which caused several hours of downtime.
The Gun Test Stand gun held 500 kilovolts for more than eight total hours, using krypton at 1E-4 torr with no evidence of field emission. This is a major achievement and the culmination of almost six years of effort to improve the voltage standoff of DC Guns. It will make feasible significantly higher brightness from DC gun injectors. The ultraviolet optical transport to lab 1, including the collimator and alignment system, were all completed and placed under vacuum last week in preparation for operations.
Theoretical and Computational Physics
A new global analysis <arXiv:1102.3686 [hep-ph]> of parton distribution functions (PDFs) by the "CJ" (CTEQ-JLab) Collaboration has critically examined uncertainties in PDFs arising from nuclear effects in deuterium structure function data. The down quark and gluon PDFs are found to vary significantly with the choice of nuclear model, which impacts the determination of the neutron structure function, as well as W-boson production and parton luminosity at the Tevatron and the LHC. The report discusses prospects for new measurements at JLab sensitive to the down quark and gluon distributions but insensitive to nuclear corrections.
Environment, Safety, Health and Quality
As noted in the 12 GeV brief, the first 12 GeV klystron has been delivered to the radiofrequency systems group for final acceptance testing. The tube and solenoid has undergone rigorous testing at the vendor already.
The alignment group inspected eight end plates, which will be used for the new CLAS region 2 as part of the Hall B 12 GeV upgrade. Control survey work continued in support of Hall D construction to connect the main accelerator to the new end station. The Hall D tagger pipe was verified and work continues on verification of the position of the photon beam pipe into the hall D end station.
2011 Benefits Open Enrollment Underway
Lost and Found
JLab Calendar of Events
Feb. 23-25: Excited Hadronic States and the Deconfinement Transition Workshop