Difference between revisions of "First look at TOF calibration"
From GlueXWiki
Line 38: | Line 38: | ||
*# offset for the left pmt: <math> c_{left} = (MT-TD)/2. </math> | *# offset for the left pmt: <math> c_{left} = (MT-TD)/2. </math> | ||
*# offset for the right pmt: <math> c_{right} = (MT+TD)/2. </math> | *# offset for the right pmt: <math> c_{right} = (MT+TD)/2. </math> | ||
+ | *# as a bonus we get the effective speed of light for each paddle. |
Revision as of 15:55, 15 April 2015
First Look
- first select data sample with the following conditions:
- only consider hits within 50ns of the timing peak both for ADC data and TDC data
- only consider paddles that have hits on both ends
- take care of the 6fold trigger timing shift in the TDC (24ns window)
- Do a rough determination of the walk correction by using the time in the ADC as reference.
- Do mean time comparison between different planes
- calculate MeanTime of Paddle i in plane j:
- calculate MeanTime for all Paddles n in plane k:
- for each event plot for each paddle in plane k:
- fit the meant time peak of each projection:
- example 1
- example 2
- Do this for each paddle in the first plane as reference paddle.
- Choose one paddle in the first plane as THE REFERENCE PADDLE
- Calculate the difference between the fit results of each paddle in the first plane w.r.t. THE REFERENCE PADDLE and fit the distribution
- average difference of mean time to REFERENCE PADDLE
- Now we have offsets for the Mean-Time for all Paddles w.r.t. THE REFERENCE PADDLE
- Do time difference comparison of one paddle with the paddle number in the other plane
- calculate time difference:
- plot this time difference vs. paddle number of paddles that got hit in the other plane
- again look at each projection and fit the peak
- example fit
- now one can also plot the fit results as a function of paddle number. The inverse slope is the speed module paddle pitch
- one can also plot the difference between symmetric paddles around the beam hole
- choose the intersection at zero for the time difference offset
- Now we have offsets for time difference (TD) and mean time (MT)
- offset for the left pmt:
- offset for the right pmt:
- as a bonus we get the effective speed of light for each paddle.