TOF for New-TPC experiment

1. Time-of-Flight2. Missing mass of single-K+, proton3. New-DC

Mizuki SumihamaMay, 2nd, 2008

Setup of forward

-1745 -830 -460 +1000 +3100 [mm]

~ 1 m

TPC New-DC DC1 DC2 DC3 TOF

FWD(Plastic)

Dipole

Momentum: No SVTX(SSD) , New-DCTOF : rf-TOF-wall , (Distance between target and fwd is ~1m.)

Tagger-Plastic counters for 2 nsec structure of RF signals

Standard setup : We use Start counter to solve 2 ns ambiguity of RF signals. ButNew-TPC exp. : Distance between TGT and FWD is about 1m (too long!), and TOF between TGT and FWD is not negligible and difficult to solve the 2 ns ambiguity. Use tagger plastic counters

2 nsec structure in Tagger

2 ns ambiguity can be solved by Tagger plastic counters

After time-work correctionBefore time-work correction

Mass spectra

Few events not to solve 2ns-ambiguity.

Missing mass spectra

MM(K+)

MM(p)

Eg < 2 GeV Eg < 2.4 GeV All

n(p+)

p0, h

E g function up to 3GeV temporary determined by Kato

Require a hit in outers No signal of p0, h

w

~5 days

Plots from the data with standard setup –Not any request at side region

MM(K+) MM(p)

n p0 h

q<25 degree

Z-vertex Target position

Vertex resolution for 2 track events is not good because of No SVTX(SSD) and small opening angles. improvement including New-DC ??

q < 14 degree

Polar angle for single track

TOF with Tag-PL and Outers

Front view of TDC, Inner and Outer•One-side readout for Inner counters, time resolution is about 800 ps by Yamamura.• Start timing is determined by RF signals and solve 2 ns ambiguity by Tagger-PL.•Stop timing is determined by Outers. Time resolution is about 200 ps by Yamamura.

b vs. momentum,dE/dxInformation of path length, momentum and dEdx by Nakatsugawa-kun.

New-DC

•Pitch 14 mm•YY’UU’VV’ 6 planes•U/V angle 30 degree the same as DC2 and DC3

•Accept events go through forward.•Help to determine momentum vector and vertex points in mixed magnetic field of Dipole and Solenoid .

TPC

New-DC

Installation of NDC in program for side tracking (TPCana) is by Uchida.

Forward LEPS

Magnetic field

~0.1T

~0.05T

New-DC

97mm

sense wire (Au-W) φ30μm #50×6 Layer

potential wire (Au-BeCu) φ100μm #50×6 Layer

7mm

7mm7mm

Cathode sheet (aluminized mylar) 12.5μm

V

V’

U

U’

Y

Y’

New DC DC0

xt-curveTrace back from DC1 to each planes of NDC and determine initial xt-curve.

iteration to have better xt curve.

Solve left-right ambiguity By positions of fired wiresIn Y/Y’, U/U’ and V/V’.

Require 6 hits in NDC.

Y Y’

U U’

V V’

Expected hit position - Wire position

outlook

Egamma calibration up to 3 GeV Alignment of New-DCRequire hits in all 6 planes relax to 5 or 4 hits.The number of clusters in NDC is sometime huge. need a cut condition by an efficient /safety wayCheck run dependence of t0/xt-curve………………..