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PHENIX Status. John Haggerty Brookhaven National Laboratory. This week’s stores. We had two reasonable stores this week We were able to use a few shorter stores longer than an hour for HBD commissioning. Two reasonable stores this week. Background.
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PHENIX Status John Haggerty Brookhaven National Laboratory
This week’s stores • We had two reasonable stores this week • We were able to use a few shorter stores longer than an hour for HBD commissioning Two reasonable stores this week
Background • Backgrounds have been high, and we have been working to learn how to tune them away • Collimation this morning worked really well
Local polarimetry • We have a new scheme for local polarimetry that Manabu Togowa has been analyzing using the asymmetry of neutrons detected in the “Show Max” detector segment of the ZDC • With scaler readout developed with John Lajoie and Cheng-Yi Chi, this gives us powerful and rapid polarimetry
HBD • Of the 20 HBD modules, 19 are fully functional • Gain balancing has been done by a voltage scan with beam collisions+background • Now taking data with central arm triggers
Physics running? • We should be able to have our EMCAL trigger rejection working to our satisfaction soon, so I hope to start accumulating luminosity in the next few stores • That is a necessary, but not sufficient, prelude to the physics measurement we want to make, but is interesting in itself • To make a physics measurement, we need: • Polarization (more than 30%, plan to increase it) • Repeatable stores (low background, good rates) • Spin rotators
Coming up • We’ll need to change the magnetic field from +- to ++ after the HBD has gotten an adequate sample of data • It was true at our first meetings and it’s still true that the game depends on • Luminosity • Polarization • Backgrounds • We’re studying beam position effects