FVTX Trigger Performance on p Au RIKENRBRC Itaru

FVTX Trigger Performance on p. Au RIKEN/RBRC Itaru Nakagawa 1

FVTX Trig Threshold Dependence (South Au-going) ≥ 12 MB ≥ 12 ≥ 14 ≥ 16 ≥ 18 #track Threshold 12 14 16 18 Rates [k. Hz] 60 32 18 8. 6 Purity >=25 0. 31 0. 46 0. 65 0. 79 The trigger performance of Au-going direction is much better than pp case. We are running at threshold ≥ 18 which provides about 80% purity. 2

FVTX Trig Threshold Dependence (North p-going) 3

Started Data Taking from May 7 th So far coincidence with BBCLL 1 narrow 4

Running Condition Efficiency w. r. t BBC narrow • Trigger threshold>=18/arm • Good GL 1 matching efficiency > 95% 5

High Multiplicity Trigger Allocated Rates Total Expected Trigger BBC Centrarity 500 ~ 2 k. Hz 500~2000 Mevents FVTX South High. Mult 100~200 Hz 100~200 Mevents FVTX North High. Mult 100~200 Hz 100~200 Mevents • The main triggers will be Au-going side trigger. • South FVTX High multiplicity trigger will have 100 Mevents whose purity is about 80%. Thus we will have 80 M real high multiplicity events on data. • Signal is expected to be smaller than d. Au. 80 M x 2~3 will be a good goal to be set. 6

Homeworks from the last week • Online track vs. Offline track correlation for North and South, separately to address why Au-going turn on is so good. (Se. Young) • # of track distribution comparison between 500 Ge. V, 200 Ge. V pp, and p. Au (North and South separately). (Toru) • BBC high multiplicity trigger vs. FVTX high multiplicity trigger (Hiroshi, Itaru) • # of track distribution in VTX for FVTX trigger and BBCLL 1(>0 tubes)_central 35_narrowvtx (Theo) • Correlation between North vs. South high multiplicity (Itaru) • Investigate if the long tail of p-going direction in FVTX track multiplicity distribution disappears by Narrow z-VTX cut (Itaru) • Process more MB events to argue higher multiplicity for North performance (itaru/Volunteer? ) 7

FVTX Track Multiplicities pp vs p. Au Plot by Toru Nagashima Track multiplicity/arm in FVTX l Multiplicity : pp 200 < p-going (p. A) < pp 500 < p. Au as expected. l p-going dist shows extensively long and flat tail towards higher multiplicity which is unique compared to pp. 8

Long flat tail of p-going side North FVTX Track Multpilicity pp BBC no. VTX BBC narrow VTX The long and flat tail seems to stay even the narrow VTX is required. 9

FVTX North vs South Correlation 510 Ge. V pp 200 Ge. V Barely seen correlation in pp Rather visible correlation is seen in between large rapidity gap N and South. May be worthy to consider S&N trigger. Presently, South trigger is prescaled by 4~8. South p. Au 200 Ge. V S & N North 10

Summary • Started physics data taking with FVTX high multi trigger from May 7 th at total rates ~300 Hz. • Long tail in FVTX track multiplicity of p-going remains after BBC narrow cut. Not yet sure if it is background or physics. • Multiplicity correlation for MB, BBC-centrarity, FVTX trigger study of in BBC, FVTX, CNT, VTX for pp/p. A analysis is ongoing with Hiroshi’s and Theo’s help. 11

From May 7 th presentation BACKUP 12

# of Track Distribution in FVTX Hists are not normalized. South (Au-going) North (p-going) # of reconstructed track in FVTX / arm 13

South (Au-going) North (p-going) Threshold>=12 track/arm (same as pp run) 14

Turn On (South) ≥ 18 ≥ 14 ≥ 16 Somehow South trigger is not suffered from low # of track events. Very good purity. 15

Turn On (North) ≥ 18 ≥ 14 ≥ 16 16

Threshold Dependence ≥ 12 ≥ 14 ≥ 16 ≥ 18 South (Au-going) North (p-going) 17

Rates and Purity North (p-going) Threshold 12 14 16 18 Rates [k. Hz] 27 9. 2 4. 5 2. 7 Purity >=20 0. 124 0. 225 0. 215 Purity >=25 0. 06 0. 112 0. 147 Threshold 12 14 16 18 Rates [k. Hz] 60 32 18 8. 6 Purity >=20 0. 60 0. 78 0. 89 0. 92 Purity >=25 0. 31 0. 46 0. 65 0. 79 South (Au-going) • BBC rate of 350 k. Hz. The rates can be increased > 1 MHz as MCR improves the beam • Rates are before BBCnarrow coincidence. The rates will go down by factor of 5 with BBCnarraw. • 100 Hz data taking will provides 100 Mevents total in p. Au. Thanks to good South 18 purity, we can expect 100 Mevents * 0. 7 = 70 M high multiplicity events.