Comparison of gradients obtained using PSplot and Perl Scripts

							    Comparison of gradients obtained
      using PSplot and Perl Scripts
                   Chow, Yeuk Chun UCLA

Abstract
The gradients of leakage currents against luminosities for SVX and
Layer 00 were obtained using web-based PSplot and Perl scripts
written by Saverio D’Auria. The data used were between store
number 1663 and 2155. The integrated luminosity in this period is
100.3 pb −1 . The two different methods will be described and the
results obtained will be compared.

Introduction
The SVX and Layer 00 are constantly exposed to high dose of
radiation. The radiation damage sustained leads to an increase of
leakage current in every components of the detector. As it
increases, a higher biased voltage will need to be applied to deplete
the detector of free charge carriers. Eventually the biased voltage
required will exceed the limit that can be supplied and the detector
will longer be operational. The gradients of the leakage current are
thus important quantities in estimating the longevity of the
detector. Two ways of obtaining the gradients are using PSplot or
processing the raw data from the online machines with perl scripts.
Both methods are described and the numerical results they
produced will be compared.


PSplot ( http://nucsb03.fnal.gov/cgi-bin/PSPlot )
The parameters used to plot the graphs are as follows (SB0W0L0
was used in this example):

Type of plot : ScatterPlot variable for scatter plot-Days
Axes for plots: #x bins 10 min x 550 Max x 950 #y bins 10 min y 0
Max y30
Plot options OptSta 0 graphoption P showtitle t titile SB0W0L0
1st variable: Wedge SB0W0 Var Ibias0L0 color cyan fillcolor
white Marker 8 Linewidth 3 Scale factor X 1 Y 1
Apply selection cuts: 591 <= Days <=740 AND 80 <= Vbias0L0
<=999
Draw vertical line: 15.2835
Fit function: pol1

For different components the parameters will have to be modified
accordingly. A perl script (grabFile) was written to speed up
plotting and downloading the graphs. All the .jpg files produced,
the perl script and the documented results can be found in
fcdflnx2:/cdf/home/yckchow/graphs/

Note that the gradient on the graphs produced are in the unit of
µA/ Day so the number have to be multiplied by 150/(1000*100.3)
to covert it into unit of µA / nb −1 .

Using Perl Scripts
The perl script files used are (1) nice_readstores.pl (2)
file_scrambler_hdi.pl (3) generate_gnuplot.pl (4) runfits_oop.pl (5)
readfits.pl. The raw data from the online machines have to be
processed using (1) first. Then 2, 3 , 4 and 5 were run in turn and
the final output is a file named “datafile”, it contains for each
component, the corresponding gradient and error.

All the perl files used and data obtained can be found in
(i)fcdflnx2:/cdf/home/yckchow/automation
(ii)b0pcucla7:/cdf/home/yckchow/data

Comparison
The gradients obtained using the two methods are plotted against
each other (by Gino Bolla) and is shown below




It can be seen that the two methods gave very consistent results
they are within 4% of each other.

Conclusion
It was shown that the two methods agreed very well for most of the
component. However, large discrepancies were found in some of
the them. For example SB0W0L0, SB0W1L0, SB0W2L4,
SB0W3L4, SB0W9L0, SB0W9L2, SB0W3L2. By comparing the
jpg file produced by PSplot and the gnuplot graph using the perl
script. The conclusion is that for the components in L2 and L4, the
discrepancy was caused by the difference in the cutoff voltage
used. In SB4W9L2 for example, the range of current plotted was
0-30 using PSplot but it can be seen in the gnuplot graph that the
currents was actually in the range 80 – 120 . For L0 the reason for
the discrepancies is still unexplained.

Although the graph showed that the gradients obtained using the
two different methods are very close to each other. But in terms of
efficiency and reliability, the perl scripts are recommended since
they are quicker and easier to run overall and there will be no need
to adjust the scales of cutoff voltage/current used.