Investigating luminescence characteristics of ultra-purified water - - PowerPoint PPT Presentation

Investigating luminescence characteristics

• f ultra-purified water and ice

Sarah Pieper

sarah.pieper@uni-wuppertal.de

Bergische Universität Wuppertal

9th October, 2018

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 1 / 16

Production of luminescence

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 2 / 16

Luminescence characteristics:

• light yield
• emission spectrum
• decay kinetics

Motivation

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 3 / 16

• 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

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

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 4 / 16

Setup for light yield measurement

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 5 / 16

• Production of luminescence light with α-particles from 241Am-source

photomultiplier source (+holder) cup with water / ice temperature gauge black cover cup

photomultiplier source frozen into ice surface temperature gauge black cover cup

Light yield results

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 6 / 16

200 170 10

1

100 101 102

Light yield / / MeV

Quickenden 1982/91 Steen 1972

40 30 20 10 10 20 30

Trofimenko 1992 Duquesne 1960 Tarasov 2007

PRELIMINARY

This Measurement

IceCube BAIKAL

Super-K

KM3NeT SNO

Temperature / °C

Radiation

doi: 10.22323/1.301.1060

Luminescence spectrum

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 7 / 16

• Motivation: identifying electronic transitions in molecules contributing

to luminescence

• Only a few investigations have been performed so far

Quickenden, 1982 measured @ 88K

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%

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 8 / 16

Experimental setup

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 9 / 16

Calibration of the setup

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 10 / 16

• Measurement of

transmission curves at different positions

• Using a tunable light

source with 10nm steps and a calibrated photodiode

Calibration of the setup - results

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 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)dλ
• 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

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 12 / 16

Gold iteration

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 13 / 16

• Iteration of −

→ s using the recursion formula sm+1

i

= sm

i y′ i / n j=1A′ ijsm j

Measurement of the emission spectrum

• First measurements show that the measured rate is still to low

→ New radioactive source with higher activity is needed

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 14 / 16

Outlook: Luminescence Logger

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 15 / 16

• Goal: Measure light yield and decay times of antarctica

ice in different depths in the SPICE hole

• Production of luminescence with 36Cl-source that emits

β-radiation

• Measurements will be performed in november 2018

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

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 16 / 16

Jablonski diagramm

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 16 / 16

Measuring principle

10 20 30 40 50 60 70 80 90

Amplitude / mV

10

1

100 101 102

Rate / Hz

• verflow bin

noise cut threshold noise cut X ray and radiation X ray Water in front of PMT PMT dark rate

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 16 / 16

Temperature dependency of light yield

sarah.pieper@uni-wuppertal.de Luminescence of water and ice 9th October, 2018 16 / 16 400 500 600 700 800 900

Background Rate / Hz

40 30 20 10

Temperature / ◦ C

2000 3000 4000 5000 6000 7000 8000 9000 10000 11000

Signal Rate / Hz

Signal Glass Scintillation 10 20 30 40 50

Background Rate / Hz

5 10 15 20

Temperature / ◦ C

950 1000 1050 1100 1150 1200

Signal Rate / Hz

S i g n a l Glass Scintillation PMT Dark Rate