Investigating luminescence characteristics of ultra-purified water and ice Sarah Pieper sarah.pieper@uni-wuppertal.de Bergische Universität Wuppertal 9 th October, 2018 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 1 / 16
Production of luminescence Luminescence characteristics: • light yield • emission spectrum • decay kinetics 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 2 / 16
Motivation • Luminescence is produced in water and ice cherenkov detectors − Can be used as a new detection channel for particles that do not produce Cherenkov light, e.g. low-relativistic magnetic monopoles − Needs to be considered for the detector calibration → Therefore the luminescence characteristics of water and ice need to be known 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 3 / 16
Goals of our investigation Lab measurements: • Determining luminescence characteristics for water and ice in dependance of • temperature • pressure • charge • purity In-situ measurements: • Determining the luminescence characteristics of Antarctica ice on site → luminescence logger 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 4 / 16
Setup for light yield measurement • Production of luminescence light with α -particles from 241 Am-source temperature cup with photomultiplier gauge water / ice black cover cup source (+holder) temperature photomultiplier gauge source frozen black cover cup into ice surface 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 5 / 16
Light yield results 10 2 PRELIMINARY IceCube BAIKAL SNO Super-K KM3NeT Steen Radiation 1972 Light yield / / MeV 10 1 Quickenden 1982/91 Tarasov 2007 Duquesne 10 0 1960 This Measurement Trofimenko 1 10 1992 200 170 40 30 20 10 0 10 20 30 Temperature / °C doi: 10.22323/1.301.1060 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 6 / 16
Luminescence spectrum • Motivation: identifying electronic transitions in molecules contributing to luminescence • Only a few investigations have been performed so far measured @ 88K Quickenden, 1982 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 7 / 16
Choice of setup for spectral measurements • Challenge: Very low detection rates due to low light yield • Three different options were investigated concerning detection efficiency: − Transmissive grating → 0.37 % − Monochromator → 0.077 % − Linear variable filter → 0.46 % 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 8 / 16
Experimental setup 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9 / 16
Calibration of the setup • Measurement of transmission curves at different positions • Using a tunable light source with 10nm steps and a calibrated photodiode 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 10 / 16
Calibration of the setup - results 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 11 / 16
Deconvolution of the signal • Convolution of the unknown spectrum s and the response function of the filter A � y ( x ) = A ( x , λ ) s ( λ ) d λ • In this case discretized form is used − → y = A · − → s • First try: solve by inverting the response matrix A • This is an ill-posed problem, uncertainties of − → y and A lead to very high uncertainties in − → s → Regularisation is needed 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 12 / 16
Gold iteration • Iteration of − → i / � n s using the recursion formula s m + 1 = s m ij s m i y ′ j = 1 A ′ i j 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 13 / 16
Measurement of the emission spectrum • First measurements show that the measured rate is still to low → New radioactive source with higher activity is needed 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 14 / 16
Outlook: Luminescence Logger • Goal: Measure light yield and decay times of antarctica ice in different depths in the SPICE hole • Production of luminescence with 36 Cl-source that emits β -radiation • Measurements will be performed in november 2018 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 15 / 16
Summary • Investigation of luminescence characteristics is ongoing • Light yield and its temperature dependence has been determined in the temperature range − 40 ◦ C to 20 ◦ C • Setup for measurements of luminescene spectra has been developed and calibrated • A new source is needed for measurements of luminescence spectra • In november 2018, a device will be send to the south pole to measure luminescence characteristics of antarctica ice on site 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 16 / 16
Jablonski diagramm 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 16 / 16
Measuring principle threshold noise cut X ray and radiation 10 2 X ray Water in front of PMT PMT dark rate Rate / Hz 10 1 overflow bin noise cut 10 0 1 10 0 10 20 30 40 50 60 70 80 90 Amplitude / mV 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 16 / 16
Temperature dependency of light yield 11000 900 1200 50 10000 800 1150 40 9000 Background Rate / Hz Glass Scintillation Background Rate / Hz Signal Signal Rate / Hz Signal Rate / Hz 8000 700 S 1100 30 i g n 7000 PMT Dark Rate a l 600 6000 1050 20 Glass Scintillation 5000 500 4000 1000 10 3000 400 2000 950 0 40 30 20 10 0 0 5 10 15 20 Temperature / ◦ C Temperature / ◦ C 9 th October, 2018 sarah.pieper@uni-wuppertal.de Luminescence of water and ice 16 / 16
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