BESIII宇宙线实验

朱科军高能物理研究所

BEPCII Project

Luminosity: 3~10×1032cm-2s-1 @ 3.77GeV

Milestones Barrel EMC and electronics was ready on 11/30/2007 Trigger system for EMC was ready on 11/30/2007 Started MUON test since 12/3/2007 Barrel TOF and electronics was ready on 12/20/2007 MDC and electronics was ready on 1/2/2008 Cosmic ray w/o end-cap seen on 1/6/2008 End-cap of EMC and TOF was ready on 2/12/2008 Cosmic ray with full detector seen on 2/14/2008 Cosmic ray data taking finished on 3/16/2008 Moved to the BEPCII IR by mid-April, 2008 Data taking is expected around mid-June, 2008.

System overview

TOF Electronics

MDC Electronics

TOF Trigger

MDC Trigger

Global Trigger &

Fast Control

MDC Electronics

Fanout

T0

Optical Fiber Cable

L1*

EMC Electronics

MU Electronics

MU Trigger

EMC Trigger

MDC Electronics

Fanout

MDC Electronics

Fanout

MDC Electronics

Fanout

触发条件和定时 00 to 15 :::::: EMC 00 : NCluster >= 1 01 : NCluster >= 2 02 : Barrel Cluster back to back 03 : Endcap Cluster back to back 04 : Cluster Balance in Z direction 05 : Barrel Cluster Balance in Phi direction 06 : Endcap Cluster phi Balance 07 : Barrel total Energy Higher threshold 08 : Endcap total Energy Higher threshold 09 : total Energy Lower threshold 10 : total Energy Middle threshold 11 : Energy Balance in "Z" direction 12 : Barrel Energy difference Balance 13 : Endcap Energy difference Balance 14 : Energy Block Balance 15 : Endcap Energy Balance

16 to 21 :::::: TOF 16 : Endcap TOF back to back 17 : Barrel TOF back to back 18 : NETOF >= 2 19 : NETOF >= 1 20 : NBTOF >= 2 21 : NBTOF >= 1 (0x15) 32 to 37 :::::: MUON 32 : MUON Back to Back 3478 33 : MUON Back to Back 37 38 to 47 :::::: MDC 38 : Short Track back to back 39 : NStrk >= N 40 : NStrk >= 2 41 : NStrk >= 1 42 : Long Track back to back 43 : NLtrk >= N 44 : NLtrk >= 2 45 : NLtrk >= 1 46 : NItrk >= 1 47 : NItrk >= 2

触发道 0x1 => EMC Ncluster >= 1 0x2 => NBTOF >= 1 0x4 => BTOF back to back 0x8 => EMC Cluster back to back 0x10 => Short Track Back to Back 0x20 => Long Track Back to Back && BTOF Back to

Back 0x100 => BTOF back to back && Ncluster >= 1 0x200 => random trigger 0x400 => Long Track Back to Back && NCluster >= 1 0x800 => NLtrk >= 1 0x1000 => MUON Back to Back 3478 0x2000 => MUON Back to Back 37 0x4000 => NBTOF >= 1 && NClus >= 1 0x8000 => NLtrk >= N

Run2414: 2008-03-06 18:17 to 03-07 09:00

Trigger channels: 0x441cEndcap Cluster phi Balance

Long Track Back to Back && NCluster >= 1

ETOF back to back

EMC Cluster back to back

BTOF back to back

Timing: 0x8022a11Barrel TOF back to back

Long Track back to back

Barrel Cluster back to back

时间低阈的选取

在 3# 厅进行的宇宙线测试中，按噪声水平 1% 为标准，设置的时间低阈为内室 110 ； 台阶 70 ； 大端板 50内室 120 ； 台阶 80 ； 大端板 60 ( 数据分析得到的理想低阈 )

当前条件下，如果按 1% 的标准，时间低阈应为内室 100 ； 台阶 70 ； 大端板 40

随机触发，设置时间道高低阈相等，在不同时间阈值下测量漂移室各通道的时间计数，计数值阈触发数之比反映了漂移室在该时间阈下的噪声计数水平

Hitmap and distribution of T and Q (run1963)

T hitmap Q hitmap

T distribution Q distribution

Drift distance (mm)

Dri

ft ti

me

(ns)

Time-to-distance relation(layer 12)

Drift time (ns)

Ent

ries

Distribution of drift time(layer 12)

Results of calibration and reconstruction

Spatial resolution(after calibration and alignment)

• HV: 2150V

• T threshold:

120/150(inner section), 80/110(stepped section), 60/80(outer section)

Spatial resolution vs layer

Efficiency vs layer

TOF Calibration Using Cosmic Ray Data

Time Difference of Each Counter

The distribution of sum time of two end. The fitting function isError Function.

x 2x dxe

2

1xD

22

')( )/()'(

Mean value vs counter number

Sigma value vs counter number

T0 Extract

σ=317ps σ=164ps

σ=283psOriginal T0

T0 after calibration

T0 Difference before and after T0 extract

Delta T distribution before and after T0 extract

Single End Readout Time Resolution (Preliminary!)

East and West end readout time resolution with unit/ps

Using time difference of each counter and T0 extraction, with an approximation of β ＝ 0.99, the single end readout time resolution are shown.

• event Selection

– EMCb2b

– Energy of digi>10MeV, and only two digis

• Check ADC(MeV) distribution for each crystal

– First calibrated by using relative light yield data,

– and comparison with the MCdata

• Finally give the Preliminarycalibration constant for every crystal

How to calibrate by using cosmic rawdata

Hitmap of sample events

宇宙线事例： EMC b2b 触发 选择只击中两块晶体的事例

ADC (MeV) vs nphi

Barrel light yield by PMT

crystal-per

lightyieldlightyield lightyield

meanCalibConst

PMT RLY calibrationNo calibration

No-calib

Sig/mean=

32.57/239.7=13.6%

PMT RLY calib

Sig/mean=

26.95/265.8=10.1%

Cosmic RLY calib

Sig/mean=

29.59/265=11.2%

Fiber RLY calib

Sig/mean=

29.01/262.3=11.1%

Barrel_all

Preliminary results only using relative light yield data

Gaus_landau fitting

adc2-28l-2930

Mean=267MeV

Phi=29&30

Mean/RMS=

187.6/19.55

RawDataMCData

C1=Mean_mc/Mean_raw~188/267=0.7

1Cyieldlight relative

yield)light iveMean(relattCalib.Cons

First calibration by Cosmic rawdata

Cosmic_mc Cosmic_rawdata , barrel_all

The22&phi29

Sig/mean=

11.38/182.1

=6.25%

Barrel_all

Sig/mean=

12.34/184.4

=6.7%

Only relative light yield by PMT testSig/Mean=27/265.9=10.1%

relative light yield by PMT test +mc_calibSig/Mean=16.7/183.4=9.1%

Preliminary results using relative light yield data & MC_calib

Barrel_all Barrel_28cm Barrel_24cmBarrel_ntheta2

1Barrel_nthe21&

nphi29

Cosmic Rawdata

32.57/239.7=13.6%

32.56/239.6

=13.6%

27.57/247.7

=11.1%

22.84/228.7

=10%

Relatvie light yield

calib(PMT)

27/265.9

=10.1%

26.63/266.2

=10%

21.28/216.1

=9.85%

24.97/266.8

=9.36%

26.5/293.9

=9%

Relatvie light yield

calib(PMT) +mc_calib

16.7/183.4

=9.1%

16.52/183.6

=9%

15.23/158.3

=9.6%

16.23/182.4

=8.9%

16.55/183.6

=9%

Mc simulation 12.23/184.2=

6.64%11.93/184.3

=6.47%

10.95/158.4

=6.91%

11.75/183.1

=6.42%6.25%

Sigma/mean by Gaus+landau fit

Preliminary results

By layer By segment

Hit map

Hit maps show pretty well, noise and dead channel have been checked and repaired

Counting rate

Trigger rate: 75~90Hz, Counting rate of MUC at 10-4 Hz/cm2 level

总结 BESIII 宇宙线调试总的来说进展顺利 已获取一定数量的宇宙线事例供离线进

行软件调试和探测器性能的初步研究，帮助查找硬件中存在的问题

下月初进行第二轮宇宙线测试 准备迎接对撞取数

谢谢