UK Activities on (LAr) Photon Detection Andrzej Szelc (University of Manchester)
Introduction ● Brief recap about scintillation light and how to detect it in liquid argon. ● Developing physics applications and methods of simulation for scintillation light. ● Hardware activities. ● Opportunities for collaboration. 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 2
Scintillation Light in Argon Emission: Transport: Ar Ar Detection: Liquid argon is mostly Ar g transparent to its Ar Excited dimer Liquid argon is almost the scintillation. state only thing transparent to its scintillation. At longer distances Photons are all ~128 nm – VUV Rayleigh scattering ~55cm Detection is challenging – f( l ) and absorption, e.g. most often need to use on nitrogen ~30 m Wavelength shifting @2ppm N 2 begins to play compounds, like TPB. a role. Note high refractive index ~1.5 for VUV. Two-component light, 7ns + 1.3 us E. Segreto 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 3
How to collect LAr light PMTs SiPMs Proven detector ● SiPMs: excellent ● technology in liquid performance in liquid argon. argon. Small voltage needed to operate. Small ● Small active size – channel/active area ● need to be clever to ratio. avoid large channel Non-negligible size, ● number. relatively high voltage. SiPM+ Light Collector The ARAPUCA light ● WLS coated trap bars coupled ● Use dichroic filters + to SiPMs 2 WLS to trap the (current light inside of the box DUNE ● Detection with SiPMs baseline design). 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 4
Passive elements of light collection ● Coating the detector walls with a wavelength shifting compound allows the recovery of VUV light. ● Adding highly reflective foils underneath enhances light collection. ● Used extensively in DM experiments, not tried in neutrino experiments. Applying TPB to the reflective foil used inside of the LArIAT TPC WArP DM detector VETO (8 tons of LAr) 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 5
Physics and Simulations SBND (and DUNE) 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 6
Light Detection in SBND ● UK focus on developing the simulation framework for scintillation light This was useful in developing foils as a solution to enhance light collection. ● SBND has a high LY setup which leads to potential intereting physics applications. ● Porting the experience to DUNE simulations. 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 7
Simulating light in argon (LArSoft) voxels • Argon is a prolific scintillator, so at beam neutrino energies simulating each optical photon is not feasible. • We use an optical lookup library (developed by uBooNE) to mitigate this problem. 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 8
Light Collection Effjciency in SBND “Cathode only confjguration” Field cage Note: from now on, visible refers To light wavelength-shifted and reflected off of the foils, while TPB-coated foils cathode VUV refers to light directly hitting the PMTs. s PMT s PMT VUV Visible Total No foils Cathode only D. Garcia-Gamez, Manchester 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 9
Direct light (VUV) timing parametrization: MC - Preliminary A combination of Landau and exponential functions fits practically every distribution of photon arrival times. The fit parameters turn out to be monotonic functions of distance. MC - Preliminary (works for reflected light too) MC - Preliminary MC - Preliminary MC - Preliminary D. Garcia-Gamez, Manchester 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 10
Effects on timing constants Fast component life MC - Preliminary time changes as a function of distance. Will affect triggers focusing on the fast component D. Garcia-Gamez, Manchester 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 11
Y-Z Positional Resolution MC - Preliminary D. Garcia-Gamez 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 12
X-drift position resolution ● If able to differentiate With TPB coated foils VUV from Visible (re- emitted) possible to get position in x on the fly. ● Additional information, crucial for disentangling MC - Preliminary multiple events in the same frame. MC - Preliminary ● Could decide to readout just parts of detector. New idea for LArTPCs! 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 13
Simulations for DUNE Hot off the press from Diego Garcia-Gamez (more in talk at DUNE CM) 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 14
Long Term Goals ● Use scintillation light to R Acciarri et al. 2012 JINST 7 P01016 enhance the physics of SBND and DUNE (and not only for triggering). 59.5 keV 241 Am peak LY @7phel/keV ● Calorimetry and timing are clear potential improvements. P. Benetti et al. (WARP), NIM A 574 (2007) 83 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 15
Hardware Activities (LArIAT/SBND and DUNE) 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 16
LArIAT Mesh Cathode Runs Prototype of SBND mesh cathode manufactured in Manchester was installed in LArIAT beginning of March 2017. Ran with and without foils (change-over happened in early June). No problems in TPC operation observed. Final BEFORE results in preparation. Important R&D for SBND Help from Liverpool grp. AFTER 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 17
Foil Installation in SBND ● The infrastructure needed to manufacture the reflective foils for SBND is ready. ● Installation in CPA and tensioning procedure developed (help from Liverpool group). ● Manchester has infrastructure needed to manufacture large evaporated surfaces (up to 60x60 cm 2 ). 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 18
Evaporated Foil Plates ● Preparations for SBND installation going well. ● Finalizing installation procedure. ● Evaporations will be done in Manchester and UNICAMP over the summer. 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 19
Towards DUNE ● Foils on cathode are now considered as an enhancement option by the PDS consortium (photon collection boosters). ● UK groups involved: SP: Edinburgh, Manchester, Sussex, Warwick. ● DUNE cathode is resistive - need R&D to develop mounting method, see next slide. ● UCL performing SiPM test-stand for DUNE-DP. 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 20
H V R & D • N e e d t o a v o i d e x c e s s i v e c h a r g e b u i l d - u p o n f o i l s u r f a c e l e a d i n g t o d i s c h a r g e s • E x a m p l e o p t i o n : 5 m m d i a m . h o l e s o n a 1 c m g r i d - a l l o w s d i r e c t p a t h f o r i o n s t o r e s i s t i v e c a t h o d e • C a n t h e f o i l s w i t h s t a n d 3 0 0 V w i t h o u t b r e a k i n g d o w n ? - V i K u i t y f o i l w i t h T P B c o a t i n g s a n d w i c h e d b e t w e e n m e t a l e l e c t r o d e s - y ✓ e s : 1 8 k V a t r o o m t e m p . i n a i r , > 4 0 k V i n L N N e x t : s m a l l T P C - l i k e s e t u p w i t h D U N E - l i k e c a t h o d e w i t h T P B c o a t e d p e r f o r a t e d f o i l a p p l i e d , a n d a n o d e e l e c t r o d e ( n o w i r e g r i d ) , L A r l o o k f o r s i g n s o f d i s c h a r g e s b y m o n i t o r i n g c u r r e n t fm o w t o c a t h o d e FEM sim. from Bo Yu: 2 1 M a y 1 4 , 2 0 1 8 S u s s e x H V t e s t s
Manchester SiPM Test-Stand ● Funds secured to set up a Test-Stand to characterize SiPMs. ● Start with Dark-Box to test at visible light, ● Chamber with cryo-cooler + gas argon to test in cold and at VUV planned. ● In talks with DUNE consortium leadership on optimizing components. 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 22
Opportunities for Collaboration ● A link is already established (SPRINT-FAPESP funds linking Manchester and UNICAMP). ● Brazilian groups getting involved in simulation for SBND and DUNE (UFABC, UFSCAR, UNICAMP). More definitely welcome. ● Hardware collaboration on foil production and development. ● UK Manchester LArSoft workshop in the fall – gather all new UK students/PDRAs to learn about LArSoft. Possibility to deepen the light simulation part this year and hopefully include LA participants. ● Alternatively, UNICAMP organizing a school in December – potential for workshop in light sim before or after. 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 23
Summary ● UK groups have built up the expertise in simulation of scintillation light in LArSoft for SBND, and are beginning to port it to DUNE. ● Lots of places to get involved - dedicated simulations (made in Brazil) already being implemented. ● We have developed the idea of WLS-covered foils as a “photon-collection booster”. Will be installed in SBND, developing the idea for DUNE. ● Developing hardware capabilities to test SiPMs. ● We have a strong basis on which to build collaboration between UK and Latin America. 14/05/18 A. M. Szelc @ LA-UK meeting Fermilab 24
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