DataAnalysisTech11-ch09, Study notes of Advanced Data Analysis

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第第第 第第  (^) 第第第第第第第第  (^) 第第第第第第第第第第第第第第第  (^) 第第第第第第第第第第第第第第第第第第第第  (^) 第第第第第第第第第第第第第第第  (^) 第第第第第第第第第第第第 第第第 第第第第第第第第第第第第第第  (^) 第第第第第第第第第第第第  (^) 第第第第第第第第第第第第第第第第 第第第 第第第第第第第第  (^) 第第第第第第第第第第第第第第第第第第第第第  (^) 第第第第第第第第第第第第  (^) 第第第第第第第第第第第第第第第第 第第第 第第第第  (^) 第第第第第第第第第第第第第第第第第第第第  (^) 第第第第第第第第第第第第第  (^) 第第第第第第第第第第第第第第第第第第第 第第第 第第第第第第第第第第第第第第第第第  (^) 第第第第第第第第第第第  (^) 第第第第第第第第第第第第第第第第第 第第第 第第第第第第第第第  (^) 第第第第第第第第第第第第

第第第第第第第第第第第第第第第第第第第第 PIDPID 第第  (^) 第第第第第第第第  (^)  K+K-^ 第第第第第第

第第第第第第第第第第第第  (^) 第第第第第第第第第第第第第第  (^)  E - E 第第  (^) ToF-E 第第  (^) ToF-  E 第第  (^) 第第 B  第第第第第第第  (^) Bragg 第第第第  (^) 第第第第第第  (^) 第第第第第第第第第第第第第第第第第第第  (^) d E/ d x - B  第第  (^) ToF-B  第第  (^) 第第第第第第第  (^) 第第第第第

sub system global combination control samples Physics Analysis cuts BESIII BESIII 第第第第 PIDPID 第第第第

第第第第第第第第第第 TOFTOF 第第第第第第第第第第第第

TOFTOF 第第第第第第第第第第第第第第

A scintillation counter measures ionizing radiation PMT: PhotoMultiplier Tube PMT output signal  (^) Scintillator & PMT  (^) For PMT output signal, we measure:  (^) Time (TDC)  (^) Amplitude (ADC) (proportion to number of photons produced ) 第第第第第第第第第 第第第第第第第第第

TOF PIDTOF PID measure raw 0 cor t  t  t  t z= Qraw traw Qraw traw charged track z PMT2 PMT Empirical ： 第第 ： form:^ test Time walk correction

t

Q

P

0

- P

6

(determination: see next slides) 1 2 3 0 2 3 4 5 6 cor P P z^ P t P Q Q P z P z P z           

 Calibration constants

 (^) P 0 : delay time  (^) P 1 - P 2 : time walk effect  (^) P 3 : saturation of PMTs  (^) P 4 - P 6 : correction to the effective velocity

 Another way to obtain the TOF:

predicted time from tracking

(independent to tmeasure )

 χ^2 minimization method

 P

0 -^ P 6 : obtained from

2 2 / , : flight path, / predicted

t  L  c L   p p  m

2 events 2

(counter, readout unit) ( )

measure predicted   (^)  t  t 2 0, 0,1 6 i i P

   K TOF TOF 第第第第

 (^) 2-layer TOF system → One charged particle can hit 1 or 2 scintillators (2 or 4 PMTs readout)  (^) combine 2 PMTs readout for the scintillator in each layer  (^) combine 2 layers results  (^) Correlations have to be considered!  (^) General averaging method (correlations → wi see next slide): , 1 , : each PMT readout i i i i i t  w t w  i   第第第第第第 第第第第第第

 (^) Covariant matrix:  (^) 2 PMTs case:  (^) For convenient:  (^) Eventually, we got: eve 1 1 nts 2 1 cov , ( )( ) , : PMT readout , ( ) ( ) ij measure measure measure measure i i j j i j k t i^ j^ i ij i jk ik j jk V t t t t t t n i j w w w V V V                   1 2 1 2 2 2 1 2 2 2

measure measure c c t t t V t

1 2 1 2 2 2 , 2 2 c t t t t t t               2 2 2 2 2 1 (^1 2 2 2 22 2 ) 2 2 4 (^2 1 ) 1 2 2 1 2 1 2 2 2 , 2 2 2 c t c c c c c w w                               第第第第第第 第第第第第第

 (^) One-step combining (?):  (^) Combined resolution (one-step vs two-step combination) 2 2 2 2 1 2 2 2 2 2 2 2 2 2 3 2 2 2 2 4 c c c c c c c c c c c c V                                two-step combination one-step combination consistent results! 第第第第第第 第第第第第第

 (^) TOF measurements: 1 TDC & 1 ADC values for each PMT  (^) TDC value → t measure (a function of ADC, Hit position z, entrance angle → a set constants)  (^) Track fitting → t predict  (^) Minimize to get constants for each PMT  (^) For each track, combining (correlation) several tmeasure results to get best resolution 2 events ( ) measure predicted t  t  TOF TOF 第第第第第第第第