WLS Covered Foils in DUNE Andrzej Szelc University of Manchester - PowerPoint PPT Presentation

WLS Covered Foils in DUNE Andrzej Szelc University of Manchester

Introduction ● Wavelength-shifter covered reflector foils installed on the CPA can enhance the light collection efficiency in the DUNE far detectors. ● Would improve uniformity (useful for triggering), timing and potentially enable x-position resolution with light. ● Not a new idea: similar solutions used by DM detectors, and LArIAT and SBND. ● Tests and measurements to find optimal solution for DUNE are planned or ongoing. 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 2

Practical Considerations ● VUV light is absorbed by most materials – in the baseline design light impinging on the CPA is lost. ● Covering the CPA with reflective foils covered with a wavelength-shifter compound recovers this light. Direct-VUV ● Baseline choice would be TPB (known and used in light large scale projects). Potential to use PEN, a new idea that would simplify engineering. ● To profit from this, the sensitive detectors need to be sensitive to visible light as well as VUV. WL-shifted ● The foils are di-electric, which means care needs visible light. to be taken they do not affect the CPA performance. 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 3

Foils in SBND/LArIAT ● LArIAT, a test beam • SBND will implement WLS- covered refmector foils on the experiment has cathode to improve light completed three full collection. runs with WLS- • Sandwiched between two covered foils layers of metallic mesh. installed. • Production is halfway First SBND foil plate complete. V. Basque LArTPC 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 4

Effect of foils Assuming 2.5% ARAPUCA efficiency. Applying measured transmittance of TPB coated glass Keeping 50% of detectors not covered in WLS to improve uniformity. (not best case scenario) Assuming 80% cathode coverage (potentially conservative) O. Bazavan, V. Griguta, Manchester 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 5

Supernova calorimetry? (10 MeV point like sources) %] [ r o 1 ARAPUCAS, 1% r r e e v i t Preliminary a l 0 . 8 e R VUV/direct 0 . 6 Visible/reemitted T otal 0 . 4 0 . 2 0 0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0 d i s t a n c e t o p h o t o c a t h o d e p l a n e [ c m ] %] 0 . 3 ARAPUCAS with scintillation @ center [ r o of Y-Z plane with no border efgects r r e 0 . 2 5 e v i t a l e Preliminary R 0 . 2 0 . 1 5 Blue points 0 . 1 agree with theoretical T otal component better than 0 . 0 5 calculations 10% 0 0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0 d i s t a n c e t o p h o t o c a t h o d e p l a n e [ c m ] D. Garcia-Gamez 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 6

X-drift position resolution (SBND geometry) ● If able to differentiate VUV With TPB coated foils from Visible (re-emitted) possible to get position in x “on the fly”. ● Additional handle to disentangle multiple events in the same frame. ● Needs relatively good MC - Preliminary timing resolution (under study for DUNE) With ARAPUCAs can Plots shown for obtain this effect by SBND config. leaving some Tool almost ported detectors uncoated To DUNE geom. with WLS. 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 7

Foils in DUNE ● The main questions are: – Compatibility with the HV system. – Sensitivity of light detectors (ARAPUCA/X- ARAPUCA) to visible light. – Need to understand engineering and installation procedures (work being performed by the HV consortium). 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 8

H o w d o w e k n o w t h e f o i l s a r e d i e l e c t r i c ? +HV • f o i l s o n c a t h o d e w i l l n e e d t o t o l e r a t e s o m e c h a r g e b u i l d - u p o r v o l t a g e v a r i a t i o n - e g 0 . 5 c m p e r f o r a t i o n s l e a d t o 3 0 0 V v a r i a t i o n o n f o i l s u r f a c e ( f r o m s i m u l a t i o n s ) • C h e c k e d H V b r e a k d o w n s t r e n g t h a c r o s s fj l m / f o i l s a m p l e s s u b m e r g e d i n L N - s a m p l e s s a n d w i c h e d b e t w e e n 6 c m d i a m e t e r e l e c t r o d e s - s t e p p e d u p v o l t a g e u n t i l b r e a k d o w n o c c u r r e d Clark Griffith, Sussex 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 9

How to mount foils on the CPA • The goal is to minimize the impact on the CPA construction. The reflector foils could be implemented post CPA production. • The preferred solution is to maintain the current CPA design, and include a set of attachment holes on each CPA resistive panel to allow the installation of reflector foils in smaller tiles on both sides of the CPA surfaces at ITF or in the UG cleanroom. From Bo Yu, and Francesco 10 11/11/18 A. M. Szelc @ DUNE PDS 30% Review Pietropaolo 10

Reflector mounting options: Reduces coverage, but electric field goes back to normal quickly. Preliminary measurements by F. Pietropaolo at CERN Show v. high, but finite resistivity High resistivity acrylic has been – may not need perforation. Identified. Need to measure after evaporation and performance of the whole system. (in progress) Potential distribution on a 1cm square cell with 5mm hole. The maximum voltage at the corners of the cell is 290V. From Bo Yu, and Francesco Pietropaolo 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 11

Ongoing Tests/Alternative Options. ● Test behaviour of glass, filters, resistive acrylic to visible light. Test behaviour of PEN in cold and to VUV. ● Plan to test performance of foils on CPA in CERN test stand – aiming to start in a couple of weeks. ● Next steps – protoDUNE run II tests. ● In parallel, simulations ongoing to repeat performance studies being done or already done without foils. 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 12

PEN as an alternative to TPB Kuzniak & Broerman ● PEN is a wavelength-shifter arXiv:1806.04020 that is delivered in sheets. Recently proposed as an idea for large scale PEN detectors. TPB ● Foils with PEN ● Need to figure out coupling to foils, and behaviour in cold. ● Need to measure performance on foils (in progress) ● Potentially could make foil preparation much easier. 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 13

Measurements of Transmittance/Reflectance to Visible ● Performing a suite of measurements to benchmark the Y R A N transmittance and reflectivity of I M I L various detector elements glass, E R P filters, foils, acrylic (and the effect of TPB and PEN coverage). ● Will try to expand to pTp. ● Currently measuring at visible Y R A Wavelengths. N I M I L ● May expand to VUV later this E R P month with UNICAMP setup. S. Cotton, C. Harrison, 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 14 Manchester

Tests at CERN test stand (Foil – CPA, HV Compatibility) ● Plan to run in CERN 50 l dewar, start in a few weeks. ● Look for discharges and space-charge effects. ● CPA plate in Manchester, will be evaporated in next days. ● Potentially repeat with PEN in the new year. Wysuwalny przepust CPA plate with Scyntylator Dewar cap Glued on Reflective foil. Scyntylator LAr Promień kosmiczny 50 l LAr-TPC 10 PMTs Źródło promieniowania α Courtesy of M. Babicz, CERN 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 15

Conclusions ● Wavelength-Shifter covered reflector foils can improve the DUNE Light Collection System performance, especially close to the cathode. ● The production technology is understood, and has been employed in relatively large scale projects before. ● R&D needed to ensure it works in DUNE is underway. 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 16

Backup 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 17

(slides in indico) (best current ARAPUCA expectations) 18 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 18

Foils in LArIAT Wavelength shifting ● LArIAT has reflector foil completed three full runs with foils installed. LArTPC Two cryogenic PMTS - one 3” high QE (30%) - one 2” standard QE Michel Electrons (20%) Hamamatsu +3 SiPMs R11065 M C P r e d i c t i o n M C P r e d i c t i o n Different foil ● configuration μ e n d p o i n t w i t h i n than proposed 1 5 c m o f T P C c e n t e r for SBND/DUNE, but same W. Foreman simulation methods.  p r e d i c t e d L Y : 2 . 4 p e / M e V 11/11/18 A. M. Szelc @ DUNE PDS 30% Review f o r 2 ” E T L P M T ( R u n I ) 19

Matching WLS between foils and ARAPUCA ARAPUCA coating→ pT TPB PEN Other Foil Coating pTerphenyl TPB Starting Point PEN Other 11/11/18 A. M. Szelc @ DUNE PDS 30% Review 20