Photon Detection Simulation utilizing Geant4 and GATE Kyle Spurgeon Syracuse University October 9, 2018 1/25
Up to Now We have been simulating the various photon detector designs for DUNE. All tested geometries begin with the frame model from Dave Warner, pictured below. We began by verifying out Geant4 simulation with data for thin layers of TPB and measurements of the dougle shift light guide. We applied these to the Double-shift light guide, ARAPUCA, and X-ARAPUCA models. 2/25
End scheme detector geometry. 12 Sensl C-series SiPMs on each end, for a total of 24. Side scheme detector geometry. 48 Sensl C-series SiPMs on each side, for a total of 96. 3/25
Effective Area of SiPM The SensL C-series SiPMs are simulated throughout, and for use in calculations of optical gain for comparison, we find the effective area of a TPB coated SiPM. This effective area is affected by its detection efficiency, the efficiency of the TPB wavelength shifter, and associated geometrical factors. This system was simulated to have a detection efficiency of . 127, leading to a SiPM effective area of A SiPM , eff = . 046 cm 2 4/25
Results for Double Shift Light Guide Geometry 0.01 4 A eff , end ( FullModuke ) = 0.009 4 2 0.008 14 . 7 cm 2 0 − 2 2 0.007 − 4 0.006 − − − − − 50 40 30 20 10 0 10 20 30 40 50 0 0.005 0.004 4 − A eff , side ( FullModule ) = 2 2 0.003 0 14 cm 2 0.002 − − 4 2 0.001 − 4 − − − − − 0 − 40 − 20 0 20 40 50 40 30 20 10 0 10 20 30 40 50 End Scheme ◮ Average area per SiPM = . 306 m 2 ◮ Optical Gain ( g ), defined as A eff / A SiPM , eff ,= 6 . 66 Side Scheme ◮ Average area per SiPM = . 073 cm 2 ◮ g = 1 . 59 5/25
0.003 A eff = . 294 cm 2 0.0025 0.002 4 A eff = 2 . 293 cm 2 0 0.0015 − 2 − 4 − − − − − 50 40 30 20 10 0 10 20 30 40 50 0.001 4 0.0005 2 A eff = 0 . 290 cm 2 − 2 − 0 4 − − − − − 50 40 30 20 10 0 10 20 30 40 50 The efficiency maps for three of the detectors from the end scheme simulation. We can see that the detectors in the end scheme see photons from the entirety of the bar, with a cone of maximal absorption. 6/25
0.003 A eff = . 054 cm 2 0.0025 4 2 A eff = 0.002 0 . 067 cm 2 − 2 − 4 − − − − − 50 40 30 20 10 0 10 20 30 40 50 0.0015 4 A eff = 2 0 . 048 cm 2 0.001 − 2 − 4 − 50 − 40 − 30 − 20 − 10 0 10 20 30 40 50 0.0005 4 A eff = 2 0 . 059 cm 2 − 2 0 − 4 − − − − − 50 40 30 20 10 0 10 20 30 40 50 The efficiency maps for four of the detectors from the side scheme simulation. We can see that the detectors this scheme see substantially less of the light guide, but the cone of maximal absorption is still present. 7/25
Double Shift Light Guide Conclusions It can be seen that, for the double-shift light guide (DSLG) geometeries, the End scheme results in an overall higher effective area than the side scheme, while only using 1/4 of the SiPMs, due to each SiPM having a larger effective area. A eff ( cm 2 ) A eff / SiPM ( cm 2 ) Design # SiPMs g End DSLG 14.7 48 .31 6.66 Side DSLG 14 192 .07 1.59 8/25
ARAPUCA Designs Two ARAPUCA designs were tested, with one being the proposed pTP based design while the other is a logical step from that design to the proposed XARAPUCA design. The first has pTP as the outer WLS, and TPB as the inner. All parts of the prior simulations are well validated, so there is a lot of confidence in those results. For the ARAPUCA simulations, there are some components that lack such confidence ◮ pTP is not well known: we have modeled the VUV response identically to TPB ◮ The properties of the green WLS layer we use have been adopted from EJ-280, where some of the physical properties have been adjusted to reflect those of a thin crystal layer. ◮ Acrylic was used instead of fused silica ◮ We use the same SiPM model throughout, that of the SensL C-series. ◮ The original dichroic filter data was obtained from Carlos Escobar, and was edited for implementation with the green WLS. 9/25
TallBo 2017 validation Detection Efficiency full_bar full_bar Entries Entries 360 360 Mean y Mean x Mean x Mean y 0.004789 − 0.07315 0.004789 − 0.07315 Std Dev x Std Dev x 12.29 12.29 4 Std Dev y Std Dev y 2.252 2.252 0.014 3 0.012 2 0.01 1 0.008 0 − 0.006 1 − 0.004 2 − 3 0.002 − 0 4 − − − − 20 15 10 5 0 5 10 15 20 A cartoon for the geometry of this design can be seen to the right. The resulting effective area is A eff ( FullModule ) = 3 . 44 cm 2 A eff / SiPM = . 215 cm 2 g = 4 . 67 10/25
TallBo 2017 Validation Dante Totani presented results from the TallBo 2017 run. It was found that the ARAPUCAs tested (of the design on the previous page) had an average efficiency of ¯ η = . 0077. The total area of the design is 9 . 8 × 7 . 8 × 4 = 305 . 76 cm 2 . Multiplying this by the average efficiency gives and effective area of A eff ( FullModule ) = 2 . 35 cm 2 . The simulated geometry has an effective area of 3 . 44 cm 2 . Data shows that the actual effective area of this geometry is 70% of this, so we have implement a TallBo Factor of . 7 and applied it to the pTP layer, to account for this discrepancy between experiment and the simulation. 11/25
pTP - TPB Design for Outer ARAPUCA 0.03 4 0.025 2 0.02 0 0.015 − 0.01 2 − 0.005 4 0 − 40 − 20 0 20 40 pTP Acrylic Dichroic filter TPB LAr A cartoon for the geometry of this design Reflective Surface can be seen to the right. SiPM The resulting effective area is A eff ( FullModule ) = 33 . 25 cm 2 A eff / SiPM = . 35 cm 2 g = 7 . 53 12/25
TPB - Green WLS Design for Outer ARAPUCA 0.03 4 0.025 2 0.02 0 0.015 − 0.01 2 − 0.005 4 0 − 40 − 20 0 20 40 A cartoon for the geometry of this design TPB Acrylic Dichroic filter can be seen to the right. The emission Green WLS LAr Reflective Surface spectrum for this WLS is that of EJ-280, for simplicity. The modeled absorption SiPM lengths are those of EJ-280 scaled so that the absorption characteristics of a 2 µ m thin layer of pure WLS is analogous to that of TPB. The resulting effective area is: A eff ( FullModule ) = 45 . 7 cm 2 A eff / SiPM = . 17 cm 2 g = 3 . 70 13/25
pTP - TPB Design for Inner ARAPUCA 0.03 4 0.025 2 0.02 0 0.015 − 0.01 2 − 0.005 4 0 − 40 − 20 0 20 40 pTP Acrylic Dichroic filter TPB LAr A cartoon for the geometry of this design can be seen to the right. SiPM The resulting effective area is A eff ( FullModule ) = 27 . 9 cm 2 A eff / SiPM = . 21 cm 2 g = 4 . 50 14/25
TPB - Green WLS Design for Inner ARAPUCA 0.03 4 0.025 2 0.02 0 0.015 − 0.01 2 − 0.005 4 0 − 40 − 20 0 20 40 TPB Acrylic Dichroic filter Green WLS LAr A cartoon for the geometry of this design can be seen to the right. SiPM The resulting effective area is A eff ( FullModule ) = 21 cm 2 A eff / SiPM = . 11 cm 2 g = 2 . 38 15/25
ARAPUCA Conclusions A eff ( cm 2 ) A eff / SiPM ( cm 2 ) Design # SiPMs g End DSLG 14.7 48 .31 6.66 Side DSLG 14 192 .07 1.59 pTP Inner 27.9 192 .15 3.16 Green Inner 21 192 .11 2.38 pTP Outer 33.25 192 .17 3.7 Green Outer 32.6 192 .17 3.70 The summary table for the geometries discussed to this point, comparing the optical gain, effective areas, and number of SiPMs present. Note: the green WLS geometries could be significantly improved with a more selective choice of wavelength shifter. 16/25
Dichroic Filter Implementation- XARAPUCA The geometries implemented for this design is the same as the Double Shift Light Guide, but with a dichroic filter placed on the inside of the acrylic plates along the exterior. A cartoon is given. The SiPMs are located either along the sides (long edge) of the frame, or on the ends (short edge) as with the DSLG. TPB Acrylic Dichroic filter LAr EJ-280 WLS 17/25
Efficiency Maps Detectors on Ends Dichroic Filter 0.04 A eff = 4 4 0.035 2 48 . 5 cm 2 0 0.03 − 2 2 − 4 0.025 − − 40 20 0 20 40 0 0.02 4 0.015 − 2 2 0.01 0 − − 4 2 0.005 − 4 − − 0 − 50 − 40 − 30 − 20 − 10 0 10 20 30 40 50 40 20 0 20 40 Without filter- see slide 1 A eff / SiPM = 1 . 01, g = 21 . 97 Detectors on Sides Dichroic Filter 0.04 4 A eff = 4 0.035 2 49 . 62 cm 2 0 0.03 − 2 2 − 4 0.025 − 40 − 20 0 20 40 0 0.02 4 0.015 − 2 2 0.01 0 − 4 − 2 0.005 − 4 0 − − − − 40 20 0 20 40 40 20 0 20 40 Without filter- see slide 1 A eff / SiPM = . 39, g = 6 . 30 18/25
0.01 A eff = 1 . 005 cm 2 0.009 0.008 0.007 4 0.006 A eff = 2 1 . 002 cm 2 0 0.005 − 2 − 4 0.004 − − − − − 50 40 30 20 10 0 10 20 30 40 50 0.003 4 0.002 2 A eff = 0.001 0 . 971 cm 2 − 2 − 0 4 − − − − − 50 40 30 20 10 0 10 20 30 40 50 The efficiency maps for three of the detectors from the end scheme simulation. We can see that the detectors in the end scheme see photons from the entirety of the bar, with a cone of maximal absorption. 19/25
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