# Presentation: 700079

## 62 GeV Luminosity Estimates used in RBUP

**Numbers from Wolfram on Sep. 9th **
- Average Luminosity Scale: 62 GeV / 200 GeV = 0.18
- Average Luminosity Scale: 3 IR / 2 IR = 4/9
- Assuming * = 3.5m
**L****week**** at 62 GeV = 9 pb****-1***** 0.18 * 4/9 = 0.72 pb****-1****/week**
**16 Days = 1.65 pb****-1**

##      BNL PAC Recommendations (PAC Meeting Nov. 3-5, 2005)
     The PAC heard Beam Use Proposals from BRAHMS, PHENIX and STAR, and interim reports from the RHIC II Science Working Groups. There was a status report about eRHIC, as well.

     RHIC Run 6
Because the length of RHIC operations in Run 6 is expected to be 20 weeks, the PAC reluctantly recommends that the run be limited to the study of a single species, in particular polarized protons.  This should be run for a long enough time to provide a significant publishable result at 200 GeV.  BRAHMS should take data during the run at 62 GeV.
The individual experiments, using their spin rotators, can determine whether they study transversely or longitudinally polarized protons.  The PAC believes that the PHENIX and STAR collaborations are best able to decide on the optimal mix of transverse and longitudinal polarizations.  It is important to complete the 2-3 week 62 GeV p-p running, both for heavy ion comparison and equally important the single spin asymmetries AN at lower energy.  BRAHMS should definitely run during this time
The PAC strongly recommends that at least one experiment focus on ALL (longitudinal polarization studies), and is pleased that this is the stated preference for the STAR collaboration.
The PAC also notes that the short runs of different proton energies are most efficiently done at the time when that species is already established in RHIC.  As a result, we urge that, even in the 20 week run, a short 500 GeV run for accelerator development be incorporated and, if possible, a short run at 22 GeV.

-      The PAC heard Beam Use Proposals from BRAHMS, PHENIX and STAR, and interim reports from the RHIC II Science Working Groups. There was a status report about eRHIC, as well.
**     ****RHIC Run 6**
- Because the length of RHIC operations in Run 6 is expected to be 20 weeks, the PAC reluctantly recommends that the run be limited to the study of a single species, in particular polarized protons.  This should be run for a long enough time to provide a significant publishable result at 200 GeV.  **BRAHMS should take data**** during the run at 62 GeV.**
- The individual experiments, using their spin rotators, can determine whether they study transversely or longitudinally polarized protons.  The PAC believes that the PHENIX and STAR collaborations are best able to decide on the optimal mix of transverse and longitudinal polarizations.  **It is important to complete the 2-3 week 62 GeV p-p running, both for heavy ion comparison and equally important the single spin asymmetries AN at lower energy.  ****BRAHMS should definitely run**** during this time**
- The PAC strongly recommends that at least one experiment focus on ALL (longitudinal polarization studies), and is pleased that this is the stated preference for the STAR collaboration.
- The PAC also notes that the short runs of different proton energies are most efficiently done at the time when that species is already established in RHIC.  As a result, we urge that, even in the 20 week run, a short 500 GeV run for accelerator development be incorporated and, if possible, a short run at 22 GeV.

## BRAHMS at 62 GeV

- Reference Spectra (at forward) and SSA measurements at 62 GeV are important measurements not to be missed
- The new and reduced luminosity projection is not ideal for 2 week of running, but BRAHMS STILL can make significant measurements: reduction in pT and xF coverage
- If the 62 GeV  luminosity is significantly lower than the current estimates, BRAHMS will measure only negatively charged identified hadrons
- If the 62 GeV luminosity is significantly higher than the current estimates, BRAHMS will extend pT and xF reach

## Acceptance and Expected rates at 62.4 GeV

-  Charged pions at xF~0.2-0.6 in FS
-  Expect asymmetry in order of  5-30% for +

- Spin Meeting

- November 3,  2005

**Notes:**
The 2 weeks is for the higher luminosities.

## Reference Spectra Measurements at 62 GeV

- Typical reach in pT is ~2 GeV/*c*
- This matches measurements at 62.4 GeV in Au-Au and Cu-Cu at forward rapidities