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

Data is taken from [36] [39] [40] [41] [42] [43]. 
Chemical structure, name 
Abbreviation 
λ
abs
 
[nm] 
λ
em
 
[nm] 
Φ
f 
τ
[ns] 
R 
[g/dm
3
] 
p-terphenyl 
PTP 
288mb 
276c 
335mb 
339c 
0.85mb 
1.2mb 
1.05e 
1.16me 
0.99c 
8.6mb 
6k 
2,5-diphenyloxazole 
PPO 
308mb 
303e 
365mb 
361e 
375d 
0.8mb 
1.6mb 
1.3b 
1.35c 
1.4e 
414mb 
335k 
2,5-diphenyl-1,3,4-
oxadiazole 
PPD 
283mb 
355mb 
0.9mb 
1.5mb 
1.2e 
70mb 
O
N
O
N
N

---

19 
2,5-bis(4-biphenyl)-
1,3,4-oxadiazol 
BBD 
314d 
315mb 
373d 
380mb 
0.85mb 
1.4mb 
2.5mb 
1k 
2-phenyl-5(4-biphenyl)-
1,3,4-oxadiazole 
PBD 
305mb 
302e 
360-
356mb 
362e 
0.8mb 
1.2mb 
21mb 
18k 
2-(4-tert-buthylphenyl)-
5-(4-biphenylo)-1,3,4-
oxadiazole 
BPBD 
308mb 365mb 
368c 
0.85mb 
1.2mb 
119mb 
77k 
 
Decay times of light pulses in all substances from Tab. 4 are similar. However they 
have different maxima of emission wavelength, so one can adjust the substance to 
particular application. Solubility in a given solvent is very important parameter because 
only complete dissolution enables proper scintillator acting. 
There are also large number of substances that can be used as wavelength shifters in 
plastic scintillators. Some of them are presented in Tab. 5. 
 
 
O
N
N
O
N
N
O
N N

---

20 
Table 5 Substances used as wavelength shifters in plastic scintillators. The source of data and used notations are 
the same as in Table 4. 
Chemical structure, name 
Abbreviation 
λ
abs
 
[nm] 
λ
em
 
[nm] 
Φ
f 
τ [ns] 
R 
[g/dm
3
] 
1,4-bis(5-phenyl-2-
oxazolyl)benzen 
POPOP 
365mb 
358c 
358e 
415-
417mb 
410c 
425e 
0.85mb 
0.97c 
1.13c 
1.5mb 
1.35e 
2.2mb 
1.4k 
1,4-bis(4-methyl-5-phenyl-
2-oxazolyl)benzene 
DM-POPOP 370mb 430mb 0.93mb 1.5mb 
1.45e 
3.9mb 
2.6k 
1,4-bis(2-
methylostyryl)benzene 
Bis-MSB 
347mb 
350c 
418e 
420mb 
420c 
423d 
0.96c 
1.6c 
No 
data 
2,5-di(4-biphenylo)oxazole 
BBO 
340mb 
342b 
410-
412mb 
409b 
0.75mb 1.4mb 
3.1mb 
1.3k 
trans-4,4’-diphenylstilbene 
DPS 
337mb 
340d 
341b 
410mb 
408b 
0.8mb 
1.0mb 
1.1mb 
1.5mb 
0.9k 
9,10-diphenylanthracene 
DPA 
366-
375c 
430c 
0.95-
1.0c 
8.7me 
7.3c 
9.35c 
35mb 
One can notice that solubility of wavelength shifters in given solvents is rather 
weak. However, the amount of WLS in plastic scintillator is about 1 ‰, thus dissolution of 
such portion is possible. 

---

21 
3.3. Commercial plastic scintillators
There are many worldwide companies producing plastic scintillators e.g. Saint 
Gobain [12], Eljen Technology [13] or Rexon [44]. Headquarters and production lines of 
these companies are placed in United States. In Europe, there are two companies 
developing plastic scintillators: Nuvia in Czech Republic [45] and Amcrys in Ukraine [46]. 
Moreover, there is an Epic Crystal company in China [47] which also produces plastic 
scintillators. 
Plastic scintillators offered by the European and Chinese companies are based on 
polystyrene. This polymer does not work as efficiently as polyvinyltoluene as a scintillator 
matrix, decreasing the scintillators performance by 15 - 20 % [48]. Because of that, the 
best scintillators should be purchased in USA, however this is connected with additional 
delivery charges and duty. 
Development in the field of photoelectric converters, e.g. replacing of vacuum 
photomultipliers by silicon ones, forces improvements of plastic scintillator to match them 
to the new photomultipliers, in order to construct efficient detectors. This includes the 
increase of wavelength of scintillation light, which is justified by better propagation of 
light in the scintillating material and matching to the SiPM quantum efficiency wavelength 
dependence. Development of fast signals processing electronics opens possibility of using 
scintillators with short rise time of signals.
Worldwide manufacturers offer plastic scintillators with different values of light 
output, light attenuation length, rise and decay times of signals, and different emission 
spectra. Planning an experiment, one can chose the best scintillator for a particular 
application.
However, vast majority of plastic scintillators offered by companies is well adjusted 
to traditional vacuum photomultipliers, popular by many years. The demand of SiPMs is to 
shift the emission spectrum of scintillators towards longer wavelengths.
Market of plastic scintillators is widely opened for the new solution. For example, 
slogan of Rexon is: "IF WE DON'T HAVE IT, WE'LL MAKE IT". The company offers 
designing and manufacturing of plastic scintillators to the particular need, concerning 
scintillator's composition and shape. However, it is much better to have developed and 
tested scintillator because the elaboration of the novel scintillator is a time-consuming

---

22 
and labour - intensive process. New scintillators are utilized usually in the laboratory 
experiments, having financial support given for the particular time of the project 
realization. That is why, it is important to have the new scintillator available and fully 
characterized, to enable its immediate use for building detectors. 
Because of specific needs of plastic scintillators market, in this thesis a novel 
solution was proposed. Novel plastic scintillator was elaborated and tested. Its novelty lies 
in the use of 2-(4-styrylphenyl)benzoxazole as a wavelength shifter. The scintillator can be 
used in many experiments of physics.