MDC4 BNL May 2001

1
Update on Kaon (Kink) Spectra

• K/K- Ratio
• Assumption Everything is symmetric
• Only Background subtraction might go wrong
• Extensive systematic tests of ratio stability vs
  cuts
• Still a couple of checks to go
• Ratio comes always in range 1.16 1.18
• The lowest best value if we clean background at
  low pt using dE/dx info

2
Kink Ratio (2)

• VERY soon we will be ready to publish the ratio
• With proper errors
• We migh want to wait a couple of weeks to
  re-check this with the new production.

3
Ratio all
dedx
Ratio all pt

4
dedx
dedx

5
Ratio Hijing
6
Ratio dE/dx
7
Yields

• Data shown at QM were 00m production using 00i
  embedding corrections
• Since a couple of weeks ago a new PSF embedding
  is available on 00m
• Also Wen did some on his own here at RCF
• Overall efficiency went down 30-40
• It does not affect spectra slopes (still 280
  MeV)
• It results in remarkable agreement with dE/dx
  (F.Wang)
• Things we checked so far are all compatible
  except the ratio Associated-kaon-decays-in-fiducia
  l/All-kaon-decays-in-fiducial

8
pt

9
mt
mt

10
dN/dy
11
Yields

• Checks will continue but
• If not bug is found in 00i then we are in
  trouble believeving our efficiency correction
  method
• K0s would help settling this issue in an
  independent way
• More really soon