Mechanical and fluidic integration of scintillating microfluidic channels into detector system 1 Davy Brouzet 10 th September 2014

Presentation guideline I. Context and primary information II. Pumping system for experiments and application to microchannels III. Pumping for future applications IV. Radiation damage characterization V. Temperature dependence of the scintillation efficiency VI. Conclusion 2

I. Context of the project Large Hadron Collider used for high energy particle experiments at CERN Engineering Office in the Detector Technologies section takes part in the development of new detectors Solid scintillators are the main material of several detectors. They produces photons when exposed to particle radiations 3

I. Scintillation process in liquids and photobleaching effect Another cause of light output decrease: Radiation damage in the scintillator due to radiations  Need to replace periodically the detectors in the LHC 4 Photobleaching effect: Decreases the light output

I. Scintillating microfluidic detector’s technology 5 Principle of the particle detector Typical microfluidic microchannels used for experiments Liquid scintillators could be pumped in order to replace the damaged fluid  Combine liquid scintillators with the microfluidic technology to create reliable detectors

I. Future applications 1. Single particle tracking in HEP experiments  Position detection of particles with double layer microchannels 2. Beam monitoring in hadrotherapy  High particle flux  Quicker radiation damage 6 Project’s aim: Design the pumping system and go further in the development of the detectors x Energy distribution Particle beam x

II. Pumping system for experiments 7 For MicroScint experiments: Syringe pump Large flow rate range and pressure up to 2.2 bars Glass syringe and materials chosen for chemical compatibility

II. Pumping applied to microchannels 1. Replacement with fresh scintillator  Validity of the technique proved! 8

II. Pumping applied to microchannels 1. o 2. Light output/Flow rate dependence  The higher the flow rate, the lower the damage and the higher the light output 9

II. Pumping applied to microchannels 1. D 2. D 3. Difference in light intensity between the channels  May have a difference of scintillation efficiency in the detector with continuous pumping 10

II. Pumping applied to microchannels Main difference of the photobleaching experiments with respect to radiation damage: Probable threshold value for the radiation damage  To avoid any flow rate dependence or any light output difference between the microchannels, possibility to have a flow rate high enough to avoid measurable radiation damage  Behaviour will depend on the type of pumping: continuous or periodic pumping Next step: What are the requirements for a pumping system in hadrotherapy or HEP experiments? 11

III. Pumping system flow rate estimation 12

III. Pumping system for application For HEP experiments or higher dose rate applications, such as hadrotherapy : Positive displacement pump 13

III. Radiation damage state of the art Lack of information concerning the radiation damage! Literature Efficiency decrease of solid scintillator detectors in ATLAS for dose greater than 3 kGy Very complex phenomenon, strongly depends on particle type, solvent, wave-shifters used and the parameters of the experiment  Not possible to extract from the literature a value of the maximum absorbed dose First measurable damages should appear between 1 and 1’000 kGy Plan some experiment to irradiate the scintillator in the irradiation facilities at CERN 14

IV. Radiation damage experiment Tunnel closed at least until November  Make research and develop a possible design 15 De-activation of the exposed elements Scintillation measurement Proton exposition   Avoid external contamination Container + Scintillator  Damage the scintillator but not the container  Excite the scintillator with electrons to quantify the scintillation process

IV. Container Design Very tight regulation constraint to expose a liquid to radiations  Best to keep the scintillator in a closed reservoir Multiple discussions with the CERN Irradiation Facilities department to find a design that fulfill all the requirements Material choice to assure chemical and radiation compatibility 16

V. Temperature dependence of the scintillation efficiency Temperature dependence of the scintillation efficiency: Up to 100% difference between 80°C and 20°C Source of heating: electronic devices and radiation thermal dissipation could decrease the light output  See if any dependence with the EJ-305 liquid scintillator 17

V. Temperature dependence results Temperature dependence in the experiment Importance of the PMT temperature sensitivity of -0.4% per °C ?  Still those primary results tend to indicate a temperature dependence of the liquid scintillator 18

VI. Conclusion Pumping system designed for MicroScint experiments and validity of the replacement with fresh scintillator proved Set of solutions for future application Need to characterize the radiation damage: Contact with the irradiation facilities department and first design made to expose a liquid scintillator Experiments tend to confirm the temperature dependence of the EJ-305 Oral self evaluation Acknowledgments 19

Thank you for your attention, Any question is welcomed! 20

III. Energy loss through matter Two main radioactivity quantities:  Absorbed dose: Quantity of radiation energy absorbed by a material. Units in J/kg = Gray (Gy)  Dose rate: Absorbed dose per unit time. Energy losses strongly depend on particle and initial energy 21  Coding of a software that integrates the energy loss over the material’s depth