Re: [Brahms-l] run progress -particular p/p-bar

Let me just correct a typo pointed out to me. The K+ is greater than k- as obvious from the mass plots
K-/K+ ~ 0.33;

----------------------------------------------------------------
Flemming Videbaek
Physics Department
Brookhaven National Laboratory

e-mail: videbaek@bnl.gov
phone: 631-344-4106
  ----- Original Message ----- 
  From: flemming videbaek 
  To: brahms-l 
  Sent: Saturday, March 27, 2004 2:58 PM
  Subject: [Brahms-l] run progress -particular p/p-bar


  We have had some reasonable progress since Thursday in collecting data at 63 GeV (or 62.4).The data so far consists of
  ~500k trigger 3 MRS for 40 deg, MRS was move to 45 last afternoon.
  at 3 deg we have 2M trigger 6 for B-pol (protons) an ~ 800k for A-Pol. So have well are we doing?

  I analyzed run11344 and 11333 and got a rough statistics for particles with PID in Rich with a first
  non-opt matching, geometry etc... The setting is 1/2A,B accepting momenta in range ~8-20 GeV.
  I attach the mass plots for pos and neg. Recal that most protons (p-bar) are in fact below the rich threshold
  so most particle with mass=-1 are protons (apart from an effeciency corrections).
  The two runs have ~175k tr6 an 125 k.

  Based on this the rough counts are

  p        192 + 1200
  p-bar     5  + 180-60
  pi+      1801
  pi-        2907
  K+       718
  K-        333.

  the statistics for protons is ~10* times this i.e. 14k which I guess is quite good.
  (What did we have in run-2 at 3 deg?? (peter)).
  Since the p-bar are very much reduced compared to p. it will be impossible to get a comparable 
  spectra for p-bars'. Since the 3 deg is essentially at the peak of the net-p istr, as evaluated from Hijing
  it seems to me best after the completion of the 3 deg B pol (same # triggers) to measure around y~2.1
  since 1/2 units change does not tell us so much.

  regards
  Flemming


  Since I gave you the numbers let me also do the particlae ratios since otherwise someone else in the coll.
  will do so:

  Normalise to N(tr)
  pi+/pi- ~ 0.85
  K+/K- ~ 0.33
  p-bar/p ~ 0.03-0.07 

  (which is right on Becatinis curve if you wonder)


  ----------------------------------------------------------------
  Flemming Videbaek
  Physics Department
  Brookhaven National Laboratory

  e-mail: videbaek@bnl.gov
  phone: 631-344-4106


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