EXP1803

data from the files 159.93.80.161:/LynxOS/mbsusr/mbsdaq/mbsrun/exp201804/data/calib/si_after/si-1_si-20_35cm_45deg_new1_00*.lmd
(discription of the measurement geometry see in task №197) were processed. On next pictures for time-saving not all events were taken into account.

• TOP LEFT: calibrated spectrum obtained in middle Y strip  (horizontal, on the front side) of 1mm left detector
• BOTTOM LEFT:  calibrated spectrum obtained in last Y strips 

from these pics we can suggest that left edges of all Y strips were irradiated with alphas with initial energies. Such particles did not pass through 20mkm detector cuz of geometry scheme. 

• TOP MIDDLE:  calibrated spectrum obtained in middle(blue) and first/left(green) X strip (horizontal, on the front side) of 1mm left detector
• BOTTOM MIDDLE: calibrated spectrum obtained in last/right X strip

Here there is a proovement that left side of the 1-mm detector was irradiated with alphas with initial energies. Also data from strips irradiated with large big angle is not nice to get energy losses (we cant analyse green distribution on middle top pic). Thats why we will make measurements from the opposite side with the same conditions.
X strips of 1mm det were counted from right to left. 

• TOP RIGHT: non-calibrated spectrum obtained in first(left) strip (horizontal, on the front side) of 20 mkm detector
• BOTTOM RIGHT: non-calibrated spectrum obtained in last(right) strip (horizontal, on the front side) of 20 mkm detector

One may suggest that strip 0 was on the left side of the 20 mkm detector cuz we see that 3 of 4 particles were stopped in the 20 mkm det. In 15 strip the data is not clear, anyway 3 alphas were not stopped in this strip due to lower irradiating angle and effective 20mkm det thickness. 
Stipps in 20 mkm det were couned from left to right

• TOP LEFT: non calibrated spec from last/right(15) strip of 20 mkm det with selection: strips 0-7 of SQY_L were fired. Fired means that signal amp was higher than pedestal right edge.
• TOP RIGHT: non calibrated spec from last/right(15) strip of 20 mkm det with selection: strips 8-15 of SQY_L were fired. 

with this election we kinda split strip for 2 parts, top and bottom. As far as Edeposits in 20 mkm det do not depend on the azimuth angle one may assume that this difference caused by inhomogeneity of 20 mkm detector.

• BOTTOM LEFT: non calibrated spec from last/right(15) strip of 20 mkm det with selection: any strips (0-15) of SQY_L were fired. this means that we see signals from alphas passed throught 20 mkm det and deposited some energy in 1-mm det.
• BOTTOM RIGHT: non calibrated spec from last/right(15) strip of 20 mkm det with selection: NO strips (0-15) of SQY_L were fired. this means that we see signals from alphas stopped throught 20 mkm det.

raw Data without any selections (except pedestal cut) from all strips of 20 mcm det looks like:

files 159.93.80.161:/LynxOS/mbsusr/mbsdaq/mbsrun/exp201804/data/calib/si_after/si-1_si-20_35cm_0deg_new1_*.lmd were processed with macro drawRaw.C

Thickness of SQ20 det were calculated by energy losses in the SQ_L detector.  Data in SQY_L strips were processed because SQ20 had vertical orientation and SQY_L horizontal one. So the each strip of SQ20 were divided by 15 areas corresponding to 15 fired strips in SQY_L.
In SQY_L one could observe energy deposits of at least 2 of 4alphas with hightest energies.
The method of determiming the Edep is shown on pictures:  for the distribution in order to find peaks method TSpectrum were used  and then it was fitted by gaus functions from 50% to 50% of maximum heights of each peak. Position (mean) of the peak was taken as a Edep in channels.

Taking calibration parameters from issue 187 for SQY_L  energy deposits were obtained.
From them energy deposits in all material volumes before sensitive part of SQY_L (these volumes consist of: source dead layer, SQ20 thickness and SQ_L dead layer) were calculated. source dead layer was taken as 0.2 mcm (see http://www.khlopin.ru/docs/products/source/E_OSAI.pdf)
Correlation of effective thicknesses with the angle between alpha-trajectory and material planes were taken into account (effective DL of SQ_L is different for different strips etc.)
Thickness distribution was written into the file: thick.root and showed at the pictures:

One may find that the maximum difference of thickness in SQ20 is more than 8.5 mcm.

the same macros was used for determination of thickness of 20um det, but this time each SQY_L strips was separated into 32 areas corresponding to SQX_L strips. As the distance between 20um and 1mm detectors was 10.5 mm the expected thickness distribution should have the same structure as in previous comment #4.

Signals from different SQY_L strips corresponding to SQX_L strip number 22. one may see that last (15) strip of SQY_L are in shadow of 20um detector. As not in all spectra peaks from 2 alphas are observed the 20um thickness are calculating by last alpha with the hightest energy.
As we wanted to determine the position of 20um corresponding to 1mm detector the thickness of areas in SQ20 plane which correspond to not fired areas of SQY_L strips (etc. SQY_L[15]) are set as 40 um. This trick is determining borders SQ20.

thick40.png:Thickess distrubution with 40um bins: SQ20 sensitive area borders.



thick.png:Thickess distrubution of SQ20

One may suggest that the difference between maximum and minimum thickness is more than 8.5um. Minimum thickness is 17.6 and maximum 26.1 um. Thickness distribution is written into thick32.root file