Analysis of Tagger high resolution TDC for separating RF

2004. 7. 14

Hideki Kohri

Mass spectrum

Although we started taking high resolution TDC data of tagger PL for improving mass spectrum, the mass spectrum was improved by considering the flight time between target and start counter.

But the TDC data of tagger PL can be also used for TPC trigger counter.

Mass / charge GeV/c2

Momentum (GeV/c)

r29511 - 29514

Tagger high resolution TDC analysis

RMS 330ps

SUMTDC channel

TDC channel TDC channel

Tagger PL#3

ADC ADC After slewing correctionrfrawTDC-TagTDC

What makes tail?

Correlation between two PL’s

RF bunch number PL#2

RF bunch number PL#3

RF bunch PL#3 - PL#2

Tagger multiplicity 2 events

# of +1 / # of 0 = 3.3 %# of -1 / # 0f 0 = 4.5 %

Pion events

Mass/charge GeV/c2

RF number LEPS - TaggerPL

Solid : good pionsDashed: bad pions

RF number LEPS - TaggerPL

Good pions: Pions whose RF is correctly identified by LEPS spectrometer

Momentum (GeV/c)Abilities of start counter and tagger PLfor separating RF are not so different.Advantage of using tagger PL TDC for forward spectrometer analysis seems to be small.But it would be a help for TPC analysis.

RF timing shift ?

Particle ID by new start counter

Mass / charge GeV/c2

Momentum (GeV/c) Sigma = 28 MeV/c2

Mass / charge (GeV/c2)

There are some events whose RF is not correctly identified. Currently, it is difficult to say that new start counter is better than old one.

r29552 - 29556