For a short interim period we actually have a scheduling phys. who cares about communicating progress to the community. Enjoy. Flemming ---------------------------------------------------------------- Flemming Videbaek Physics Department Brookhaven National Laboratory e-mail: videbaek@bnl.gov phone: 631-344-4106 ----- Original Message ----- From: Kin Yip To: kinyip@fnal.gov Sent: Thursday, April 21, 2005 10:33 AM Subject: A-SPY news: ... a collection of news ... ====== Acting Scheduling Physicist -YIP (ie. A-SPY) news channel ======== Here are just a collection of news that I've learnt in the last few days --- I didn't know most of them before this week. *********************************************************************************************** (1) RHIC polarization and experiments ... The problem/"mystery" of the polarization of the Yellow ring at ~100 GeV at RHIC being lower than injection seems to be understood/solved since Monday night. It was apparently due to inappropriate upper energy threshold set in the FPGA (Field Programmable Gate Arrays) firmware leading to incorrect online analysis. Correct threshold (1.4 MeV instead of 3.2 MeV) is now set and the polarization values seem to be consistent. The bigger experiments PHENIX and STAR seem to be much happier since then --- an subjective observation. BRAHMS in principle only concerns about the Blue ring polarization for doing their single spin transfer asymmetry measurement at the very forward region (mainly pion production). PHOBOS is not running at the moment but they're waiting for their requested 24 hour run when RHIC will increase the beam energy to above 200 GeV (ie. > 400 GeV in the center-of-mass). This is likely their last physics run at RHIC as they have revealed recently. *********************************************************************************************** (2) BLIP and NSRL (NASA Space Radiation Lab.) BLIP (Brookhaven LINAC Isotope Producer) is happily making their isotopes. With a lot of improvements in the beam line etc., the rate of increase of beam-time has exceeded that of last year. In 2-3 weeks, they will stop producing isotopes for this run and switch to bombarding beams at a 2 dimensional Carbon-carbon target which has low thermal expansion coefficient and is a candiate material for collimators at the Large Hadron Collider at CERN. The NSRL-5 run should end on May 5, 2005. The NSRL-6 run may start ~June 7, 2005. In this run, we have essentially replaced the cumbersome X-ray film and film developing/scanning with a new camera system. I showed this in the Time Meeting 2 days ago. Now, we take pictures like every 5 seconds (=the beam pulse rate at the moment) and we can see it from a computer screen without going in and out of the NSRL target room. Since we use heavy ion beams or protons instead of light, this is probably not called "photography" but nuclear-graphy or ion-graphy ??? You name it. *********************************************************************************************** (3) AGS cold snake After the maintenance work (including some safety check-off list --- installing scaffoldings around it etc. etc.) this Tuesday, the power supply experts are now working with the Cryogenic group to try to start powering the AGS cold (cold == helium temperature, 4K, for the superconduction) snake. They may start with as low as 1-2 amps. The ultimate goal for using this cold snake is to increase the RHIC injection beam polarization (or not losing too much polarization in AGS). *********************************************************************************************** (4) Wonderful memory ... One remaining issue for the RHIC operation that I've learnt this week is the myterious orbit variation --- the beam orbit seems to drift away. People are suspecting magnet temperature etc... Somebody jokingly suggested ground motion due to the moon due to its daily pattern... This has immediately reminded me of the old days at LEP (Large Electron Position) Collider at CERN, Switzerland for the LEP energy calibration. LEP has a circumference of ~27 km and the gravitational force from the moon on the LEP ring actually has an impact on the precise electron-positron beam energy calibration. Since ~1991, a code (written by meteorologists/geologists in a Belgian Observatory, as I remember) has been used to correct for the LEP energy. It could be 10 MeV (compared to center-of-mass energy ~92 GeV). I remember using this code to calculate energy and there were a lot of French comments among the FORTRAN lines. In 1995, there have been a long period of mystery of periodic LEP energy changes ... People have thought about all sorts of crazy ideas, eg. people leaving works in the evening and taking shower (using electric heater) at about the same time etc. This was ultimately proven to be due to leakage current from the French train TGV down to the LEP ring (~100 m below ground) which creates an additional magnetic field changing the beam energy. Just another wonderful memory ... ======= ====== ======= ======= ====== ======= ======= ====== ======= This A-SPY news channel solicits YOUR input of any sorts. You'll be paid back with loads of gratefulness :-) ================================================================= Disclaimer: Whatever is being said here is not always 100% accurate though I try my best to avoid being 100% inaccurate :-) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++ A-SPY contacts for the remaining days before Apr. 25, 2005 (monday) Pager: x4300 Office Phone: x4116 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ _______________________________________________ Brahms-l mailing list Brahms-l@lists.bnl.gov http://lists.bnl.gov/mailman/listinfo/brahms-lReceived on Thu Apr 21 20:34:18 2005
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