Event Start Time Determination Ma Xiang 2005.12.14

Event Start Time Determination

Ma Xiang2005.12.14

内容1. 修改MdcFastTrkAlg,修改过程及修改后结果，包括效率，分辨率等2. TOF端盖部分算法设计，用MC数据检验的结果3. MDC部分算法，用MC数据检验的结果4. 总结

1.MdcFastTrkAlg(1) When track angle cosθwithin 0.84-0.94,the trackin

g efficiency less than 20%. Fast Tracking must be modified to suite the END cap case.

* Due to superlayer 0,5,7 slant is wrong in the code, hits on those layers can’t be used in the tracking.

(slant 0,5,7 is -,1,6,8 is + in Geometry, but all are + in code)

* If track can not reach axial segment 9 &10, cut the requirements for Seg.9 &10.

* Min. requirements only one stereo segment. (Normal case: 6 stereo Seg. 5 axial seg.) After modification the tracking efficiency achieve ove

r 90% for single particle with1.5Gev.

Quality checking between the old and new e- , 1.5Gev,2000,cosθ∈(0.85,0.94)

Old Code efficiency: 5.3%

Modified efficiency:89%

Quality checking between the old and new

P Resolution old cosθ(-0.8,0.8)p:1.497Gev/c σ:0.022

P Resolution new cosθ(0.85,0.94)

p:1.491Gev/c σ:0.124

Quality checking between the old and new

XY 空间分辨cosθ(-0.8,0.8)136μm

XY 空间分辨cosθ(0.85, 0.

94)180μm

Quality checking between the old and new

• Z 空间分辨

z 空间分辨cosθ(-0.8,0.8)5mm

z 空间分辨cosθ(0.85,0.

94)9.3mm

2.End-cap TOF • Check 2* helix_ radius > R_tof in xy plane?Yes, an intersection in xy plane =>calculate

Z_tof , if Z_tof >120cm(<-120cm), assume hit on EndTOF, calculate TOF ID, if ID matches MC, calculate evtime

A

Barrel TOF

End-cap TOF

.Ax

y

Barrel TOF

z

y

End-cap TOF

No, no intersection in x-y plane ,=>if tanl>0, assume hit on endTof: w

hether TOF ID matches? If matching, calculate evtime

=>if tanl<0, assume hit on End-cap TOF: whether TOF ID matches? If matching, calculate evtime

Barrel TOF x

y

.AHelix

Result

• e- ,1.5Gev,2000 MC data,

cosθ∈(0.85,0.94)

• t0: -0.0048ns• σ: 0.29ns

End-cap TOF

Single match multi matches

End-cap TOF(e-,0.3Gev,2000, cosθ∈(0.85,0.94))

Entries:741

t0: 0.044ns

σ: 0.397ns

Entries:1365

t0: 0.092ns

σ: 0.649ns

Sense wire

Field wireDrift cell

A (test)

BC

D

elcwpdriftfev ttttt

3. ESTime Calculation by MDC

根据 MDC 快速重建结果计算 常数

Test = TDCM － tev

1.tdrift : Axial segments Stereo segments2.tf : Axial segments Stereo segmentse-,1.5Gev,3000,MCt0: 0.08nsσ:3.49ns

elcwpdriftfev ttttt

Test = TDCMC － tev

~~~~~~~~~~~~~~

总结1.修改MdcFastTrkAlg，提高了 TOF端盖部分径迹重建效率，但空间分辨和动量分辨变差2.TOF端盖部分算法基本完成，时间分辨达到要求3.MDC部分算法，还需要完善