Development of novel plastic scintillators based on polyvinyltoluene for the hybrid j-pet/mr tomograph

Figure 18
 
Charge spectra registered for BC-420 and J-PET scintillators. PM1, PM2, PM3 and PM4 denote 
particular photomultipliers, according to Fig. 17. Spectra are registered for J-PET scintillators containing 
different amounts of novel wavelength shifter, from 0 to 0.5 ‰. Names of scintillators refer to the amount of 
wavelength shifter. In the left panel spectra registered by PM1 and PM2 for BC-420 and J-PET are presented, 
while in the right panel spectra registered by PM3 and PM4 are given.
 

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45 
Table 8 Relative and absolute values of light output for J-PET scintillators determined for several concentrations 
of wavelength shifter. Relative light output was determined with respect to the BC-420 scintillator. 
WLS concentration 
[‰] 
Method 1 
Method 2 
Relative light 
output 
Light output 
[photons/MeV] 
0 
0.636 ± 0.020 0.625 ± 0.002 0.625 ± 0.002 
6397 ± 25 
0.025 
0.939 ± 0.008 0.938 ± 0.016 0.939 ± 0.007 
9613 ± 72 
0.05 
1.009 ± 0.018 1.006 ± 0.021 1.008 ± 0.014 
10318 ± 139 
0.1 
0.968 ± 0.150 0.967 ± 0.019 0.967 ± 0.019 
9902 ± 197 
0.2 
0.965 ± 0.345 0.962 ± 0.031 0.962 ± 0.031 
9853 ± 319 
0.3 
0.913 ± 0.017 0.912 ± 0.023 0.913 ± 0.014 
9346 ± 142 
0.4 
0.910 ± 0.016 0.910 ± 0.035 0.910 ± 0.015 
9317 ± 149 
0.5 
0.895 ± 0.023 0.897 ± 0.031 0.896 ± 0.018 
9172 ± 188 
Results obtained by method 1 and method 2 are consistent within error bars. 
Statistical uncertainties coming from fitting in both methods are of order of one-hundredth 
of the light output value. Therefore, they are negligible in comparison to the systematic 
uncertainties resulting from measurement technique with different photomultipliers.
Uncertainties of light output value given in the second and third columns of Tab. 8 
were estimated conservatively as a half of a difference between the maximal and minimal 
values obtained from measurements with different photomultipliers.
In the fourth column of Tab. 8. results of the relative light output are presented. 
They were calculated as a weighted average light output values determined with method 1 
and method 2. 
In the fifth column of Tab. 8 results of the absolute light output determined for
J-PET scintillators are given. The values were obtained by multiplying of the relative light 
yield by the known light output of BC-420 which is equal to 10240 photons/MeV [12]. The 
relative and absolute light output dependence on the wavelength shifter concentration in 
the J-PET plastic scintillator is presented in Fig. 19. 

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46 
0.6
0.7
0.8
0.9
1.0
1.1
Rela
tiv
e l
ig
ht o
utp
ut
Concentration of 2-(4-styrylphenyl)benzoxazole [
‰
]
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55
6000
7000
8000
9000
10000
11000
Li
ght
ou
tpu
t [ph
oto
ns
/MeV]