1. 1 LMVM RBUB numbers (update) R. Seto Light-Heavy PWG July 9, 2006 2:30PM BNL time (post World cup)

2. 2 Outline HW Lum (not finalized) Most data sets will be DAQ limited (5kHz) –NOT true for low energy (63 GeV) AuAu –Propose to run 63 GeV Iodine on Iodine (A=127) to increase rate; we will then be DAQ limited for 63 GeV Iodine on Iodine –Eg. Run 7: AuAu 200, Run 8: 63 GeV Iodine, Run 9: something else(dAu…) or some permutation Some assumptions –63 GeV 10% of 200 GeV –Iodine is 10x Au –  production scales with Nch

3. 3 Rho assumptions –  rate = 2x  –  bkg integration = 600 MeV NA60

4. 4 HW Use Kozlov post-QM numbers shown at the pwg last week –1030M min bias –1740 , S/B=1/76 Some volunteer should go through last year's BUP and this year's CAD guidance and formulate the prescription for the assumed evts recorded that all people should be using in formulating their contributions to this year's BUP. –Eff~0.36=0.6(RHIC)*0.6(PHENIX) –Min Bias recorded ~ 5kHz –Use CAD delivered Lum/week 0.290 nb -1 /wk for 200 GeV AuAu

5. 5 Luminosity Assumptions: –DAQ 5 KHz recorded –RHIC Z vertex  = 20 cm, 80% in central peak –Eff for phenix =0.6 –Eff for RHIC 0.6 For 200 GeV AuAu –L/week=0.290 nb -1 –L(avg)=8E26 L(max)=3.6E27 –min bias rate avg= 5.0 kHz (4.5-round up) max = 20. kHz so limit to 5kHz 63 GeV AuAU –L=10% of 200 GeV –Min bias 0.5kHz (avg) 2.kHz (max) 63 GeV Iodine on Iodine –L=13x AuAuGeV –Min bias  =5.8b 5kHz (avg) (4.8-round up) 20.kHz (max) so limit to 5kHz

6. 6 Events DAQ limited –5kHz*6Msecs(10 weeks) *0.6(phenix eff)*0.6(RHIC eff)= 1.1E10 events Rate limited, e.g. AuAu at 63 –L/week*bbcz *10 weeks *  *PHENIX eff= –.029 nb -1 /week*0.8*10weeks*7b*0.6=9.7E8 ~1B events

7. 7 Run 4 200 GeV AuAu   Ozawa et al 700M evts Counted events  30 MeV=60 MeV  –Saw 644  330 –S/B=644/100K  –Saw 748  200 –S./B=750/40K Kozlov et al 1030M events (corrected from PWG) Counted events 0.997 to 1.041=44 MeV  –Saw 1740 –S./B=1/76=1740/132K –Kozlov should have seen 1502  Background 196K (see spares for calculation)

8. 8 Scaling signal and background Scale signal with dN/dy Scale background with (dN/dy) 2 AuAu min bias Np=109 –200 GeV dN/dy=332 –63 GeV dN/dy=223 II min bias Np=66 (updated from Klaus, I had guessed 90) –63 GeV II dN/dy=127 HBD –Signal eff 0.4 –S/B in central AuAu improves by factor 100 Signal suppressed by 0.4 background suppressed by.004.06 for background electrons From Milov Analysis note

9. 9 Numbers (the bottom line) HBD A – HBD as in CDR HBD B – HBD 4x poorer in rejecting bkg, i.e. 2x worse per electron HBD A HBD B Iodine 63 GeV Au 63 GeVAu 200 GeV For  : Good measurement at 200 GeV AuAu, 63 GeV Iodine i.e. ~ 5K events can be broken up into bins of pt and centrality and still Give a reasonable signal Iodine at 63 will give connection to NA 60 result. Updated from the PWG. Note that the Npart for II=66 not 90 which I guessed before

10. 10 HW from PWG of July 6, 2006 Check Lum numbers for II –email exchange between Worlfram and me Rich: The average luminosity possible now for AuAu at 200 GeV is 8E26. At 62 GeV (using 10% from the above plots-ZDCrate) I get 8E25. From looking at the scaling of the original RHIC proposal I see that that IodineIodine can give a luminosity of about 13 times AuAu giving me that II at 63 GeV would have a luminosity of 1.04E27, somewhat larger than the luminosity of AuAu at 200 GeV. Note that given somewhat smaller cross section for Iodine (I get 5.8b) the Collision Rate for AuAu 200 GeV and of II at 63 GeV is about the same under these assumptions. Wolfram: I think we know the limits in RHIC fairly well, but Iodine is more difficult to make than other species, and we may be limited by the source. Jim Alessi is looking into what would be available. If we were not limited by the source, I would expect for I-I collisions at 100 GeV beam energy: Lpeak between 0.7 and 3.5e28 cm^-2s^-1, and (min and max) Lavg between 0.2 and 1.2e28 cm^-2s^-1 (min and max) At 31.2 GeV beam energy these numbers are reduced by a factor 10, thus your estimate is correct.

11. 11 HW- cont Plot pp equivalent luminosity and check that the decrease in Ncoll balances out the increase in Lum as we go to lighter species At the moment their looks like a broad peak at II/CuCu which is a factor 5x Pp and AuAu Note that the pp eqivalent (pp equivalent = A 2 L) for AuAu, dAu, amd pp are Very close.

12. 12 Status/plan/results –Recorded L: from rbup in nb-1 –pb-1 pp equiv : pp equiv from rbup –Calc recorded pp equiv= A 2 Lrecorded – same as in RBUP –Delivered lum – from RHIC homepage –Days – days of beam – from RHIC homepage –Calculated Lum – delivered lum/days –Cal pp delivered. A 2( Calculated Lum) –Cu L increase: increase in Cu L between Run 5 and present numbers from CAD –Au days more – ratio of Au more days than Cu –Cu pp greater: Cu vs Au pp equiv ratio- note that this is almost 2 –pp gr/Au more: reason that pp equiv is similar between run 4 and 5 –Cu pp gr* Cu L increase: factor from RHIC due to L increase and run-4/5 difference Try to understand the numbers used in the original idea of Ncoll*Lum being similar for all species. How are my numbers different? In particular for Cu or I The pp, dAu, and AuAu pp equiv already look similar Look at CuCu and AuAu from Run4 and Run 5. Note that from the RBUP, there is a similar number of pp equiv. So there are 2 factors – first, the pp-equiv is already bigger by 2. Then the Luminosity of Cu actually increases in the CAD prediction by 2.7 for a factor of 5

13. 13 A simple chart pp equiv=L*A*B Get L/week from RHIC writeup There is a ~ factor of 5 peak at CuCu (II)

14. 14 Arguments pro and con for II at 63 vs Au at 63 Pro –More rate ~ 5K , a factor of 5 or 6 better Can split into pt and centrality bins More robust against HBD high multiplicity difficulty –Similar species to NA 60 Con –A=127 (Npart=66 vs 106) (less baryon density) –Different species at 200 and 63 Note: we might want to wait till we see the HBD in operation before we decide. If its rejection is extremely good giving us an increase in S/B by 100 and if RHIC can perhaps increase the L by perhaps a factor of 2 then Au at 63 might work. We also need to see what L RHIC can give us for Iodine or whatever we choose

15. 15 Spares and Backup information

16. 16

17. 17

18. 18 Between Ozawa and Kozlov new phi and omega– just use the ratio signal/signal, bkg/bkg Kozlov new has a different “looser” cut for electrons – which means –He keeps more electrons in the case of both signal and background –He also introduces more π’s for bkg Signal –Let a=eff old, b=eff new (a<b) and X is the total number of events with  ’s (or equivalently the number of  ’s total –a 2 X=748 b 2 X=1740 –So in the case of the ,X is different (call it X’), but the old to new ratio of  ’s is just a 2 /b 2 or the ratio of old to new  ’s Bkg –Let M=# ee pairs per event N=  M=# ππ pairs, c,d be prob that π is misidentified as an electron in the “old” and “new” schemes respectively –Bkg (M+  M)2= (1+  ) 2 M 2 if you take everything –Bkg old (aM+cN) 2 ~ (a+ c  ) 2 M 2 ~40K –Bkg new (bM+dN) 2 ~ (b+ d  ) 2 M 2 ~1320K –In the case of the  we have a new M and N, i.e. M’ and N’ N=  M N’=  ’M’ –BIG Assumption?  =  ’ –Then in you work out the algebra you can just use the ratios i.e.

19. 19 phi production (ppg016) I assume phi production proportional to dNch/dy at energies greater than 60 63 200

20. 20 HW Increase in lum going to lower A is balanced by Ncoll to factor of 2 –Find ncoll, npart for lighter species Milov/workarea/tmp –Ask Roser et al for RHIC lums at lower energy, lighter species, specifically 62 GeV AuAu, II, CuCu, SiSi, dAu, pp

21. 21

22. 22

23. 23

24. 24 Luminosity at lower energy Full energy 63 GeV

25. 25 http://www.agsrhichome.bnl.gov/RHIC/Runs/index.html#RHIC_Runs

26. 26