HES HKS collaboration meeting 3/11/2010 T.Gogami

T-zero adjustment WC AC High current run beta distribution

ideally, detectors are plane Detectors have segments timing differences of each segment cable length, module propagation time …. Need to be correct  Time–zero adjustment The ways to correct 1. with t-zero counters (HTOF2Y, EHODO3) 2. without t-zero counter

set parameters to be T 1 =T 2 =T 3 =…. T1T1 T2T2 T3T3 t – zero counter TOF [ns] in the case of EHOOD2 during experiment HES side

assumption d = d’ T0T0 T1T1 T2T2 d d’ set parameters to be 1. T 0 = T 1 2. (T 0 = ) T 1 = T 2 3. (T 0 = T 1 = ) T 2 = T 3 =… T1T1 1 2 during experiment HES side (edge) HKS side after experiment (fine tune) HES side HKS side

correlation is straighter in FP x vs. β - β K Kaon peak is on “0” in β - β K

TOF resolution σ ; 460 [ps]  360 [ps] long tale

Odd number counter’s TOF have long tale EH1 ID – EH2 ID

EHODO2 – 17, 19, 21, 23, (25, 27, 29) are bad  Discriminator ?, ECL cable ?, TDC slot? EH1 ID – EH2 ID

event loss  EH2 bad channel should be excepted K + coincidence time K+K

EHODO1 EHODO2

separate clearly

easier to select K + than before need two cut

hwatnkn1+2 > 1.2 X = 1.2 X = 0 K+K+ K+K+ p p 1 dimensional cut X cut β - β K

new box 4/15/2009 – 7/1/2009 (78 days) Trigger EH1 × EH2 78 days EHODO WC EHODO μ stable

days 63 days NPE high momentum side low momentum side 39 days 63 days NPE 39 days 63 days NPE 24 days

teflon  if so, only high momentum side PMT thermal dependence water (chemicals … ) …. etc reduced ~10 % cause

X AC NPE1+2+3 < X π K+K+ X at X = 10 K + 93 % π + 10 % X = Be, 40 [μA] β - β K π+π+ K+K+

High current run  K + beta distribution is not clear at low momentum side PMT sagging ?, TOF parameters ?, high multiplicity ? CH2 2uA Cr 8uA WC 1-1 & 1-2 K + NPE distribution

T-zero adjustment 1 st fine tuned EHODO2-17, 19, 21, 23, 25, 27, 29 are bad  should except WC normalized NPE survival ratio of different threshold K + NPE reduction AC survival ratio of different threshold High current run beta distribution low momentum side beta is not clear at high current run

selected bad counter

1-dimensional cut

NPE fit resultCosmic & HYCS From kaon NPE reduction parameter  estimate Kaon NPE just after beam time ratio of expected value from cosmic ray study + HYCS ~88%

in the Hall

in counting room

during experiment σ~420[ps] TOF Counter ID TOF