Difference between revisions of "First look at TOF calibration"
From GlueXWiki
Line 27: | Line 27: | ||
*# calculate time difference: <math> \Delta t^{i}_{plane j} = (t_{right} - t_{left})/2. </math> | *# calculate time difference: <math> \Delta t^{i}_{plane j} = (t_{right} - t_{left})/2. </math> | ||
*# plot this time difference vs. paddle number of paddles that got hit in the other plane | *# plot this time difference vs. paddle number of paddles that got hit in the other plane | ||
− | *# [[File:PaddleNumber_vs_deltat_example.gif|200px]] | + | *# [[File:PaddleNumber_vs_deltat_example.gif|200px]] |
*# again look at each projection and fit the <math>\Delta t</math> peak | *# again look at each projection and fit the <math>\Delta t</math> peak | ||
− | *# [[File:deltat_fitposition_example.gif|200px]] example | + | *# [[File:deltat_fitposition_example.gif|200px]] [[File:deltat_fitposition_p18_example.pdf|200px]] example fits |
*# now one can also plot the fit results as a function of paddle number. The inverse slope is the speed module paddle pitch | *# now one can also plot the fit results as a function of paddle number. The inverse slope is the speed module paddle pitch | ||
*# [[File:velocity_example.gif|200px]] | *# [[File:velocity_example.gif|200px]] |
Revision as of 15:59, 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
- 200px example fits
- 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.