Jefferson Lab Weekly Briefs December 8, 2010
Jefferson Lab Weekly Briefs
December 8, 2010
12 GeV Upgrade
Seventy of the total order of 86 niobium cavities for the 12 GeV cryomodules have been received. Welding has been completed of the helium vessels onto the cavities for the first 12 GeV cryomodule. Thirty-one of the total order of thirty-six 4-meter dipole magnets for the beam transport lines have been received; testing of those magnets continues. All beam transport quadrupole magnets have been received and accepted. Forty-five RF circulators/isolators have been received. The results from the klystron-circulator/isolator testing found that the second harmonic amplitude is less than -40 decibels of the fundamental mode’s power; that result simplifies the design of the second harmonic filters that will go into the waveguides between the isolator/circulators and the cavities. The request for proposals was released for the purchase of two hundred and sixty 20 Amp/70 Volt power supplies for the beam transport quadrupole magnets and corrector dipole magnets.
The Q-weak experiment has been taking high-current hydrogen target production data in Hall C, mixed with commissioning activities. The electron detector in the Compton polarimeter achieved an important milestone with the observation of the Compton edge, which arises from the most head-on collisions of the laser photons with the beam. The high-current power supply for the Qtor magnet is down for repairs and is awaiting delivery of replacement parts this week. The experiment has been able to use the beam to perform tests to understand and reduce backgrounds, identify noise sources and commission the beamline polarimeters.
APS April Meeting Abstracts Due
AIP Seeking Applicants for Congressional Fellowship Program
The week started with instabilities in the solid state amplifier for the first pass radiofrequency beam separator. A replacement spare unit also suffered from instabilities. With the RF separator down, the beam was separated magnetically, allowing only one hall to receive beam at a time (Halls A and C split the time the beam was available). An offline inductive output tube amplifier was temporarily rigged in place of the solid state amplifier and has been working well since. On Tuesday, the late-day startup of Hall B was hampered by interlocks left in place for vacuum valves that were no longer installed; the interlocks were reconfigured for the new lineup. Thursday was a beam studies day, with a cathode spot move and some Q-weak parity beam development time. Some time was lost Sunday due to a loose connector on a safety system beam current monitor. Beam optics troubleshooting determined that a 1 millimeter change in what already appeared to be a clean vertical orbit in the 9S region eliminated trips due to beam loss and eliminated current instabilities seen all weekend in Hall B.
After some final FEL characterization studies, the team spent the week preparing to make measurements of the vacuum-ultraviolet harmonic radiation. A new mirror and photon characterization instrumentation were installed on the beamline for tests this week. The FEL team also worked to repair the UV wiggler drive mechanism and beamline vacuum hardware and performed a gun bake.
Center for Theoretical and Computational Physics
In one of the first calculations of its kind, researchers in the Theory Center and at Trinity College Dublin have demonstrated in <arXiv:1011.6352 [hep-ph]> that an energy-dependent scattering phase shift can be mapped out using lattice QCD methods. The techniques developed will soon be applied to hadron-scattering channels with resonant behavior to study excited-hadron decays of the type that will be measured in GlueX and CLAS12.
Facilities Management and Logistics
Appropriate Use of Golf Carts Onsite
Holiday Shutdown Power Outage Planned
JLab Calendar of Events
Dec. 10: Toys for Tots Toy Drive concludes
Environment, Health, Safety and Quality
With the Northeast already hit with its first snowstorm, it's time to review cold weather protection basics. According to OSHA, prolonged exposure to freezing or cold temperatures may cause serious health problems such as trench foot, frostbite and hypothermia. In extreme cases, including cold water immersion, exposure can lead to death. Danger signs include uncontrolled shivering, slurred speech, clumsy movements, fatigue and confused behavior. If these signs are observed, call for emergency help.
OSHA's Cold Stress Card provides a reference guide and recommendations to combat and prevent many illnesses and injuries. Tips include:
JLab's 2011 Holiday Calendar Posted Online
Radiation Worker I Training Credit Change
2011 General Access RWP Available for Signature
Holiday Hideaway at the SURA Residence Facility
JLab Children Invited to Winter Wonderland Party
Quark Cafe Hosts Holiday Bake Sale on Tuesday, Dec. 21
Personal Dosimeter Change Out Will Be Dec. 22