Response of a Li-glass/multi-anode photomultiplier detector to α -particles from 241 Am
E. Rofors, H. Perrey, R. Al Jebali, J.R.M. Annand, L. Boyd, U. Clemens, S. Desert, R. Engels, K.G. Fissum, H. Frielinghaus, C. Gheorghe, R. Hall-Wilton, S. Jaksch, A. Jalgén, K. Kanaki, G. Kemmerling, V. Maulerova, N. Mauritzson, R. Montgomery, J. Scherzinger, B. Seitz
RResponse of a Li-glass/multi-anode photomultiplierdetector to α -particles from Am E. Rofors a , H. Perrey a,b , R. Al Jebali b,c , J.R.M. Annand c , L. Boyd c ,U. Clemens g , S. Desert e , R. Engels f , K.G. Fissum a,b, ∗ , H. Frielinghaus f ,C. Gheorghe h , R. Hall-Wilton b,d , S. Jaksch f , A. Jalg´en a , K. Kanaki b ,G. Kemmerling f , V. Maulerova a , N. Mauritzson a , R. Montgomery c ,J. Scherzinger a,b,1 , B. Seitz c a Division of Nuclear Physics, Lund University, SE-221 00 Lund, Sweden b Detector Group, European Spallation Source ERIC, SE-221 00 Lund, Sweden c SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ,Scotland, UK d Mid-Sweden University, SE-851 70 Sundsvall, Sweden e LLB, CEA, CNRS, Universit´e Paris-Saclay, 91191 Gif-sur-Yvette, France f J¨ulich Centre for Neutron Science JCNS, Forschungszentrum J¨ulich, D-52425 J¨ulich,Germany g Zentrum f¨ur Anwendungsentwicklung und Elektronik ZEA-2, Forschungszentrum J¨ulich,D-52425 J¨ulich, Germany h Integrated Detector Electonics AS, Gjerdrums Vei 19, N-0484 Oslo, Norway
Abstract
The response of a position-sensitive Li-glass scintillator detector to α -particlesfrom a collimated Am source scanned across the face of the detector hasbeen measured. Scintillation light was read out by an 8 × Keywords:
SoNDe thermal neutron detector, GS20 scintillating glass,multi-anode photomultiplier, position-dependent α -particle response, H12700 ∗ Corresponding author. Telephone: +46 46 222 9677; Fax: +46 46 222 4709
Email address: [email protected] (K.G. Fissum) present address: Dipartimento di Fisica, Universit di Pisa, I-56127 Pisa, Italy and INFNSezione di Pisa, I-56127 Pisa, Italy Preprint submitted to Nuclear Instruments and Methods A December 24, 2018 a r X i v : . [ phy s i c s . i n s - d e t ] D ec . Introduction The European Spallation Source (ESS) [1] will soon commence operationsas the most powerful neutron source in the world. Highly efficient, positionsensing neutron detectors are crucial to the scientific mission of ESS. The world-wide shortage of He [2–4] has resulted in considerable effort being undertakento develop new neutron-detector technologies. One such effort is the develop-ment of Solid-state Neutron Detectors SoNDe [5–7] for high-flux applications,motivated by the desire for two-dimensional position-sensitive systems for small-angle neutron-scattering experiments [8–17]. The SoNDe concept features indi-vidual neutron-detector modules which may be easily configured to instrumentessentially any experimental phase space. The specification for the neutroninteraction position reconstruction accuracy for the SoNDe technology is 6 mm.The core components of a SoNDe module are the neutron-sensitive Li-glassscintillator and the pixelated multi-anode photomultiplier tube (MAPMT) usedto collect the scintillation light. The response of MAPMTs to scintillation-emulating laser light has been extensively studied [18–26]. Similar Li-glass/MAPMTdetectors have been tested with thermal neutrons [27] and a SoNDe detectorprototype has been evaluated in a reactor-based thermal-neutron beam [7]. Inthis paper, we present results obtained for the response of a SoNDe detector pro-totype to α -particles from a collimated Am source, scanned across the face ofthe scintillator. Our goal was to examine methods to optimize the localizationof the scintillation signal with a view to optimizing the position resolution ofthe detector, under constraints imposed by envisioned readout schemes for thedetector. We were particularly interested in the behavior of the SoNDe detectorprototype at the vertical and horizontal boundaries between the pixels and thecorners where four pixels meet. 2 . Apparatus α -particle source Fig. 1 shows a sketch of the assembly used to produce a beam of α -particles.It consisted of a Am α -particle source mounted in a 3D-printed holder/collimatorassembly. Figure 1: Am α -particle source mounted in the holder/collimator assembly used to definea beam of α -particles. The radioactive source is a snug fit in the blue holder/collimator. Theassembly shown has a 1 mm thick face plate and a 1 mm diameter hole, resulting in thediverging red beam of α -particles. (For interpretation of the references to color in this figurecaption, the reader is referred to the web version of this article.) The α -particle emission energies of Am are 5.5 MeV ( ∼ ∼ Np has an energy of ∼
60 keV and has a neglible effect on the α -particle response of the SoNDe detector prototype. The α -particle spectrumfrom the present source was measured (Fig. 2) using a high-resolution passive-implanted planar silicon (PIPS) detector system in vacuum, where the PIPSdetector was calibrated using a three-actinide calibration source. The aver-age energy of the α -particles emitted by the presently employed source was ∼ ∼ mployedfor the scan Figure 2: Uncollimated α -particle spectrum emitted by the Am source employed in the suiteof measurements reported on here (broad blue distribution) together with a red fitted Gaussianfunction (indicating peaking at 4.54 MeV) and a triple α -particle spectrum emitted by a verythin-windowed three-actinide calibration source (sharp black primary peaks at 5.155 MeV,5.486 MeV, and 5.805 MeV). (For interpretation of the references to color in this figure caption,the reader is referred to the web version of this article.) Holder/collimator assemblies for the
Am source were 3D-printed frompolyactic acid using the fused deposition modeling technique. For our measure-ments, we used 1 mm thick collimators with either 3 mm (for gain mapping) or1 mm (for border scanning) diameter apertures, resulting in uniform 3 mm or1 mm irradiation spots at the upstream face of the scintillator. The distancefrom the
Am source to this upstream face was ∼ α -particle energy at the surface of the GS20 wafer was ∼ The SoNDe detector prototype investigated in this paper is being devel-oped for large-area arrays to detect thermal to cold neutrons with energies of ≤
25 meV. It consists of a 1 mm thick lithium-silicate scintillating glass wafer4oupled to an MAPMT.
Cerium-activated lithium-silicate glass scintillator GS20 [29–32] purchasedfrom Scintacor [33] was chosen for this application. GS20 has been demon-strated to be an excellent scintillator for the detection of thermal and coldneutrons and arrays of scintillator tiles can be arranged into large area detec-tor systems [8–12]. The lithium content is 6.6% by weight, with a 95% Liisotopic enhancement, giving a Li concentration of 1.58 × atoms/cm . Li has a thermal-neutron capture cross section of ∼
940 b at 25 meV, so thata 1 mm thick wafer of GS20 detects ∼
75% of incident thermal neutrons. Theprocess produces a 2.05 MeV α -particle and a 2.73 MeV triton which have meanranges of 5.3 µ m and 34.7 µ m respectively [34] in GS20. Using the present α -particle source, scintillation light was generated overwhelmingly within ∼ µ mof the upstream face of the scintillating wafer. We note that the scintillationlight-yield outputs for 1 MeV protons is ∼ α -particles [35]. Thus, after thermal-neutron capture, the triton will produce afactor of ∼ α -particle. Tests by van Eijk [36]indicate ∼ ∼
25% of the anthracene benchmark.The sensitivity of GS20 to gamma-rays is energy dependent. A threshold cutwill eliminate the low-energy gamma-rays, but higher-energy gamma-rays canproduce large pulses if the subsequent electrons (from Compton scattering orpair production) traverse sufficient thickness of GS20.Our glass wafer was 1 mm thick and 50 mm ×
50 mm in area. The glass faces,apart from the edges, were polished and the wafer was fitted to the MAPMTwindow without any optical coupling medium. The index of refraction of GS20is 1.55 at 395 nm. We have assumed that the Li distribution in our scintillatingwafer was uniform. 5 .2.2. Multi-anode photomultiplier tube
The Hamamatsu type H12700 MAPMT employed in the SoNDe detectorprototype is an 8 × ×
52 mm andan active cathode area of 48.5 mm × ∼ ∼
380 nm wavelength, which is well matched to the GS20 scintillation. Com-pared to its predecessor type H8500 MAPMT, the H12700 MAPMT achievessimilar overall gain, but with 10 as opposed to 12 dynode stages. The H12700MAPMT employed for the present tests had a gain of 2.09 × and a darkcurrent of 2.67 nA at an anode-cathode potential of − ∼ × pixels in the Hamamatsu 12700 MAPMT has a slightly differentgain, which is measured and documented by the supplier. A typical H12700MAPMT has a factor 2 variation in pixel gain (factor 3 worst case) [38]. Thedatasheet provided by Hamamatsu for the H12700 MAPMT used in this studyhad a worst case anode-to-anode gain difference of a factor 1.7. Figure 3 showsa photograph of the device together with a pixel map.6 a) MAPMT with sctintillator × = . . × (mm) (b) MAPMT pixel map Figure 3: The Hamamatsu 12700 MAPMT. 3(a): Photograph of the MAPMT together withthe GS20 scintillator wafer. 3(b): Numbering of the 64 MAPMT pixels (front view). Pixel 1(P1) is located in the top left-hand corner of the MAPMT looking into it from the front.Sketch from Ref. [38]. The red boxes indicate the region of irradiation reported on in detailin this paper. (For interpretation of the references to color in this figure caption, the readeris referred to the web version of this article.) . Measurement The SoNDe detector prototype was irradiated using the collimated beams of α -particles (Sec. 2.1) where the center of the beam was directed perpendicular tothe face of the GS20 wafer. The downstream face of the source holder/collimatorassembly was translated parallel to the surface of the scintillator wafer on anXY-coordinate scanner, powered by a pair of Thorlabs NRT150 stepping mo-tors [39]. This was programmed to scan a lattice of irradiation points uniformlydistributed across the face of the device. The entire assembly was located withina light-tight box and the temperature ( ∼ ° ), pressure ( ∼ ∼ ∼ ∼
20 ns, and amplitude some tens of mV, which was fed to an ORTECCF8000 constant-fraction discriminator set to a threshold of − ∼
120 s at each point on ascan, so that in total a scan could take several hours.
4. Results
The gain-calibration datasheet provided by Hamamatsu may be used to cor-rect for non-uniform response. However, previous work [18–23, 25] has clearlysuggested that mapping of pixel gains is highly dependent upon the irradiationconditions. Since our α -particle beam results in very short ( ∼
10s of ns) pulses8f highly localized scintillation light, which are in sharp contrast to the steady-state irradiation measurement employed by Hamamatsu, we re-measured thegain-map of our MAPMT in situ using the equipment described previously. Foreach pixel, the 3 mm diameter α -particle collimator was centered on the XYposition of the pixel center of the MAPMT photocathode and 2200 α -particleevents were recorded. The resulting anode-charge distributions were well fittedwith Gaussian functions (average χ per degree of freedom 1.50 with a varianceof 0.14) and the means, µ , and standard deviations, σ , were recorded. Thelargest measured µ -value (corresponding to the pixel with the highest gain) wasnormalized to 100. The relative difference between the Hamamatsu gain-mapvalues, H , and the α -scanned gain-map values, α , was calculated as H − αH on apixel-by-pixel basis. Figure 4 shows the results of our gain-map measurement,where the present results show significant differences to the Hamamatsu mea-surement. General trends in regions of high and low gain agree. Measurementsof a sample of 30 H12700 MAPMTs revealed that the window face is not flatand was systematically ∼ µ m lower at the center compared to the edges. Thenon-uniformity of the air gap between the GS20 and MAPMT window may bea partial cause of the gain discrepancy displayed in Fig. 4, as may reflections atthe edges of the GS20 wafer. In the following, we use the present α -scintillationgenerated gain-map, which in principle will embody non-uniform light-collectioneffects. Nonetheless, scintillation-light propagation through the SoNDe detectorprotoype is being studied in a G EANT HH / % (a) Gain differences, areal HH / % AB (b) Gain differences, projected Figure 4: Differences between the α -scan gain-map and the Hamamatsu gain-map normalizedto the Hamamatsu gain-map in percent. 4(a): 2D representation in which the top-left cornercorresponds to P1. 4(b): 1D representation of the same as a function of pixel. Error barsare derived from fit widths. The values have been joined with a line to guide the eye. Ahistogram of the gain differences is projected in grey on the right vertical axis. Cluster A ofthat histogram corresponds to red pixels in 4(a) while cluster B corresponds to blue pixels.(For interpretation of the references to color in this figure caption, the reader is referred tothe web version of this article.) α -particle source em-ployed for the horizontal, vertical, and diagonal XY scans. The positions are la-beled A–V and color coded (5(d)). The α -particle pulse-height spectra recordedat each of the scan positions are displayed in 5(a)–5(c) for pixels P36, P37,P44, and P45 which encompass the scan coordinates. The QDC pulse-heightdistributions have been pedestal subtracted and corrected for non-uniform pixelgain (Fig. 4). It is obvious that the efficiency of scintillation light collection in asingle pixel is strongly dependent on the position of the α -particle interaction.The signal amplitude is maximized when light is produced at the center of thepixel. This variation in amplitude with position may be seen more clearly in5(e), which shows the mean of the pulse-height distributions as a function ofinteraction position for the horizontal scan (5(a)). The full curves are splines toguide the eye, while the dashed curves display the predictions of a ray-tracingsimulation of light propagation [43]. The simulation is in good agreement withthe measured data. After gain correction, these distributions should be sym-metric about the pixel boundary locations. The system was aligned such thatposition D should have corresponded to the boundary between P36 and P37.However, the fits to the data suggest that the scan positions were offset by0.2 mm to the left (Fig. 5(e)). Corresponding fits to the vertical-scan datashow a 0.4 mm vertical offset. The sum of the means of the two adjacent pixelsscanned is also displayed. This shows that the amount of light collected by thetwo pixels over which the scan is performed is independent of position.11
100 200 300 400 500 600 700 800ADC Channel050100150200250300350 C o un t s P37
E D C B AF C o un t s P37
UT S R AV C o un t s P37
NM L K AO C o un t s P36
EDCBA F (a) Horizontal scan F ← A C o un t s P45
UTSRA V (b) Vertical scan A ↓ V C o un t s P44
NMLKA O (c) Diagonal scan O (cid:46)
A(d) Key S i m u l a t e d % o f s h a r e d li g h t Pixel 36Pixel 37SumSimulationA B C D E F
Am position0100200300400500600 M e a n o f a l p h a p e a k / Q D C C h a nn e l s (e) Light sharing horizontal scan F ← A Figure 5: 5(a)–5(c): Measured charge distributions for four adjacent pixels as the α -particlebeam was translated in 1 mm horizontal and vertical steps across the pixel boundaries. (a):horizontal scan from P37 to P36. (b): vertical scan from P37 to P45. (c): diagonal scan fromP37 to P44. 5(d): Key. The solid (dashed) black lines indicate the pixel boundaries (centers).5(e): Gain-corrected means of the collected charge distributions corresponding to 5(a). Thecurves are splines drawn to guide the eye. Error bars correspond to σ/
10. (For interpretationof the references to color in this figure caption, the reader is referred to the web version ofthis article.)
In general, several pixels adjacent to the target pixel will collect some scin-tillation light and in principle, this could be used to better localize the position12f the scintillation as in an Anger camera [44, 45]. While possible, this will notbe the standard mode of operation for SoNDe modules running at ESS due todata-volume limitations. For production running at ESS, MAPMT pixels willbe read and time-stamped on an event-by-event basis as lying either above orbelow per-pixel discriminator thresholds.The multiplicity of pixels with a signal above discriminator threshold (thehit multiplicity denoted M = 1, M = 2, etc.) has been investigated as a functionof the scintillation position and also the discrimination level. Figure 6 displaysregions in the vicinity of P37 where M = 1, 2, and 3 predominate. Hits havebeen determined according to the pulse heights (Fig. 5) exceeding discriminationlevels of 100 (6(b)), 235 (6(c)), and 500 (6(d)) QDC channels. At the 100-channel threshold, M = 1 events are confined to the center of a pixel. At theedges, events are predominantly M = 2, while in the corners, M = 3. To see anyconsiderable M = 4 contributions around the pixel corners, lower thresholds arerequired as seen in Fig. 7. Raising the threshold to 235 channels extinguishes M = 2 and M = 3 almost completely. Raising even further to 500 channelsserves merely to reduce the number of M = 1 events. The threshold levelobviously affects the relative efficiency with which the SoNDe detector prototyperegisters M = 1, M = 2, etc. events, and Fig. 6 clearly shows that there is anoptimum threshold value to maximize the number of M = 1 events detected andalso to maximze the area of the detector where the M = 1 efficiency is high.13 M = c o un t s M = c o un t s M = c o un t s (a) Key V e r t i c a l s o u r c e p o s i t i o n / mm P37 (b) Threshold 100 QDC channels V e r t i c a l s o u r c e p o s i t i o n / mm P37 (c) Threshold 235 QDC channels V e r t i c a l s o u r c e p o s i t i o n / mm P37 (d) Threshold 500 QDC channels
Figure 6: Contour plots of the multiplicity distributions for pixels lying near P37 for differentthresholds as a function of α -particle beam irradiation location. The black lines denote thepixel boundaries. In all three contour plots, blues indicate M = 1 events, reds indicate M = 2events, and greens indicate M = 3 events. The lighter the shade of the color, the fewerthe counts. (For interpretation of the references to color in this figure caption, the reader isreferred to the web version of this article.) Figure 7 illustrates the trend in M as a function of QDC threshold cut whena series of 36 α -particle beam measurements were performed in a 6 × M = 0 curve and the M > M = 0 curvecorresponds to events which do not exceed the applied threshold in any pixel. M = 0 events start to register at a threshold of ∼
30 channels and rise steeplyafter channel ∼
200 to ∼
95% at channel 600. The
M > ∼ ∼
90% of events are
M >
4, falling essentially to zeroat channel ∼
50. Four other curves are shown in 7(b): M = 1, M = 2, M = 3,and M = 4, corresponding to events which exceed the applied threshold inone, two, three, and four pixels, respectively. Each of these curves demonstrateclear maxima so that the analysis procedure may be “tuned” to select an eventmultiplicity by applying the appropriate threshold. The detection efficiency for M = 1 events peaks at ∼
75% at a threshold of 235 channels, where M = 2,3, and 4 have negligible efficiency as they peak at channels 65, 25, and 18,respectively. 15 F r a c t i o n o f c o un t s M = 0 M > 4 (a) Extreme multiplicities
10 100 235 500Threshold / QDC channel0.00.20.40.60.81.0 F r a c t i o n o f c o un t s M = 1 M = 2 M = 3 M = 4 (b) Practical multiplicities Figure 7: Tuning the analysis using a single QDC threshold. Relationships between therelative number of events and threshold. Top Panel: M = 0 (black dot-dot-dashed line) and M > M = 1 (dark blue solid line), M = 2(orange dashed line), M = 3 (green dot-dashed line), and M = 4 (red dotted line). The greyvertical lines at QDC channel 100, 235, and 500 represent three of the QDC threshold cutsemployed in Fig. 6. Arrows indicate the optimal values for QDC threshold cuts for tuning theresulting data set for a specific value of M . (For interpretation of the references to color inthis figure caption, the reader is referred to the web version of this article.) . Summary and Discussion The position-dependent response of a SoNDe detector prototype, which con-sists of a 1 mm thick wafer of GS20 scintillating glass read out by an 8 × Am source. Thespreading of the scintillation light and the resulting distributions of charge onthe MAPMT anodes were studied as a function of α -particle interaction posi-tion by scanning the collimated α -particle beam across the face of the MAPMTusing a high precision XY coordinate translator.Initially, pixel gain non-uniformity across the 64 MAPMT anodes was mea-sured using the 3 mm collimated source positioned at each pixel center, whichproduced uniform illumination of the pixel centers. The results, which differfrom relative gain data provided by the MAPMT manufacturer on the 10%level (Fig. 4), were used to correct all subsequent 1 mm scan data.Anode charge distributions collected from each MAPMT pixel at each scannedcoordinate show a strong position dependence of the signal amplitude. The sin-gle pixel signal is strongest when the source is located at the pixel center, andfalls away as the pixel boundaries are approached (Fig. 5). At the pixel center,the signal tends to be concentrated in that pixel, while at pixel boundaries, thesignal is shared between the adjacent pixels.Rate and data-volume considerations for operation of SoNDe modules atESS will require a relatively simple mode of operation for the SoNDe data-acquisition system. It will not be possible to read out multiple pixels to constructa weighted-mean interaction position as in an Anger Camera. Instead, it willbe necessary to identify the pixel where the maximum charge occurs and recordonly the identity (P1 – P64) of that pixel. To this end, we studied the effect ofsignal amplitude thresholds on the multiplicity of pixel hits (that is, the numberof signals above threshold) as a function of the α -particle interaction position(Fig. 6). This study showed that there is an optimum discrimination level whichmaximizes the number of single-pixel or M = 1 hits. Below this level, multi-pixel hits start to dominate, while above this level, the single-pixel efficiency17rops (Fig. 7). At the optimum discrimination level, which under the presentoperating conditions was channel 235, ∼
75% of the α -particle interactions wereregistered as single pixel.Further work pertaining to the characterization of the SoNDe detector pro-totype is progressing in parallel to the project reported here. This includes thedevelopment of a simulation within the G EANT
EANT
Acknowledgements
We thank Prof. David Sanderson from the Scottish Universities Environmen-tal Research Centre for providing α -spectroscopy facilities for the calibration ofour Am source. We acknowledge the support of the European Union via theHorizon 2020 Solid-State Neutron Detector Project, Proposal ID 654124, andthe BrightnESS Project, Proposal ID 676548. We also acknowledge the supportof the UK Science and Technology Facilities Council (Grant nos. STFC 57071/1and STFC 50727/1) and UK Engineering and Physical Sciences Research Coun-18il Centre for Doctoral Training in Intelligent Sensing and Measurement (GrantNo. EP/L016753/1). 19 eferences [1] The European Spallation Source, https://europeanspallationsource.se/ [2] K. Zeitelhack, Neutron News, vol. 23, no. 4, pp. 1013, (2012).[3] D.A. Shea, D. Morgan, Technical Report R41419, Congressional ResearchService, (2010).[4] R.T. Kouzes, PNNL-18388 Pacific Northwest National Laboratory, Rich-land, WA, (2009).[5] Solid-State Neutron Detector, https://cordis.europa.eu/project/rcn/194934_en.html [6] Jaksch, S. et al., arXiv:1701.08679.[7] S. Jaksch et al., Proc. Int. Conf. Neutron Optics (NOP2017), JPS Conf.Proc. 22 (2018) 011019. doi:10.7566/JPSCP.22.011019.[8] M. Heiderich et al., Nucl. Instr. and Meth. in Phys. Res. A 305 (1991) 423.doi:10.1016/0168-9002(91)90562-5.[9] G. Kemmerling et al., IEEE Trans. Nucl. Sci. 48 (2001) 1114.doi:10.1109/23.958733.[10] G. Kemmerling et al., IEEE Trans. Nucl. Sci. 51 (2004) 1098.doi:10.1109/TNS.2004.829576.[11] G. Kemmerling et al., IEEE Nucl. Sci. Symp. Conf. Rec 03CH37515 (2003)722. doi:10.1109/NSSMIC.2003.1351801.[12] A.V. Feoktystov et al., J. Appl. Crystallogr. 48 (2015) 61.doi:10.1107/S1600576714025977.[13] S. Jaksch et al., Nucl. Instr. and Meth. in Phys. Res. A 762 (2014) 22.doi:10.1016/j.nima.2014.04.024. 2014] R. Engels et al., IEEE Transactions on Nuclear Science, vol. 44, no. 3, June(1997) doi: 10.1109/23.603701[15] R. Engels et al., IEEE Transactions on Nuclear Science, vol. 45, no. 3, June(1998) doi: 10.1109/NSSMIC.1997.672706[16] R. Engels et al., IEEE Transactions on Nuclear Science, vol. 46, no. 4, Aug(1999) doi: 10.1109/23.790694[17] R. Engels et al., IEEE Transactions on Nuclear Science, vol. 49, no. 3, June(2002) doi: 10.1109/23.790694[18] S. Korpar et al., Nucl. Instr. and Meth. in Phys. Res. A 442 (2000) 316.doi:10.1016/S0168-9002(99)01242-5.[19] K. Rielage et al., Nucl. Instr. and Meth. in Phys. Res. A 463 (2001) 149.doi:10.1016/S0168-9002(01)00448-X.[20] T. Matsumoto et al., Nucl. Instr. and Meth. in Phys. Res. A 521 (2004)367. doi:10.1016/j.nima.2003.11.384.[21] K. Lang et al., Nucl. Instr. and Meth. in Phys. Res. A 545 (2005) 852.doi:10.1016/j.nima.2005.02.041.[22] P. Abbon et al., Nucl. Instr. and Meth. in Phys. Res. A 595 (2008) 177.doi:10.1016/j.nima.2008.07.074.[23] R.A. Montgomery et al., Nucl. Instr. and Meth. in Phys. Res. A 695 (2012)326, doi:10.1016/j.nima.2011.11.026.[24] Rachel Ann Montgomery, Nucl. Instr. and Meth. in Phys. Res. A 732 (2013)732, doi:10.1016/j.nima.2013.08.012”.[25] R.A. Montgomery et al., Nucl. Instr. and Meth. in Phys. Res. A 790 (2015)28. doi:10.1016/j.nima.2015.03.068.[26] X. Wang et al., Chinese Phys. C 40 (2016) 086003. doi:10.1088/1674-1137/40/8/086003. 2127] F. Zai-Wei et al., Chinese Phys. C 36 (2012) 1095. doi:10.1088/1674-1137/36/11/010.[28] K.N Yu et al., Applied Radiation and Isotopes 59, (2003), doi:10.1016/S0969-8043(03)00201-X.[29] F.W.K. Firk et al., Nucl. Instr. and Meth. 13 (1961) 313, doi:10.1016/0029-554X(61)90221-X.[30] A.R. Spowart Nucl. Instr. and Meth. 135 (1976) 441, doi:10.1016/0029-554X(76)90057-4.[31] A.R. Spowart Nucl. Instr. and Meth. 140 (1977) 19, doi:10.1016/0029-554X(77)90059-3.[32] E.J. Fairley et al., Nucl. Instr. and Meth. 150 (1978) 159, doi:10.1016/0029-554X(78)90360-9.[33] Scintacor, https://scintacor.com/products/6-lithium-glass/ [34] B. Jamieson et al., Nucl. Instr. and Meth. in Phys. Res. A 790 (2015) 6,doi:10.1016/j.nima.2015.04.022.[35] A.W. Dalton, Nucl. Instr. and Meth. in Phys. Res. A 254 (1987) 361.doi:10.1016/0168-9002(87)90685-1.[36] C.W.E. van Eijk et al., Nucl. Instr. and Meth. in Phys. Res. A 529 (2004)260. doi:10.1016/j.nima.2004.04.163.[37] G. Kemmerling, S. Jaksch, Forschungszentrum J¨ulich, Solid-State NeutronDetector INFRADEV-1-2014/H2020, Grant Agreement Number: 654124.[38] Hamamatsu Photonics, [39] Thorlabs, Inc., .[40] R. Brun et al., Nucl. Instr. and Meth. in Phys. Res. A 389 (1997) 81. Seealso http://root.cern.ch/ . 2241] S. Agostinelli et al., Nucl. Instr. and Meth. in Phys. Res. A. 506, (2003)250, doi: 10.1016/S0168-9002(03)01368-8.[42] J. Allison et al., IEEE Trans. Nucl. Sci. 53, (2006) 270, doi:10.1109/TNS.2006.869826.[43] Ray Optics Simulation, an open-source web application to simu-late reflection and refraction of light. https://ricktu288.github.io/ray-optics/https://ricktu288.github.io/ray-optics/