Workpackage 3

Towards the Hyper-Kamiokande detector

coordinator prof. Francesca Di Lodovico (KCL)
Hyper-Kamiokande is the third generation water Cherenkov detector in Kamioka. Many different aspects are being developed in parallel towards finalizing the design and starting the construction of the Hyper-Kamiokande detector.
Task 3.1: Study of a gadolinium-doped water Cherenkov detector
A detailed monitoring and analysis of the data is required to check the water properties once the gadolinium has been added, as well as checking that the performance of the detector improved for the analyses. We are working on an optical method using hard ultraviolet light (UV) to measure the gadolinium concentration in water.
Furthemore, 50 new PMTs of the same type planned for Hyper-Kamiokande will be installed in Super-Kamiokande to be tested in real conditions.

Task 3.2: Development of a calibration system for a water Cherenkov detector

A calibration system that injects light pulses of known emission time and intensity at several visible wavelengths into the detector using fibre coupled solid state devices such as LEDs or laser diodes as a light source is being developed. This allows  to calibrate and monitor the photodetector response and  can also monitor the optical properties of the water, both attenuation and scattering.

Further analysis power can be obtained via neutron detection. The neutron response of the detector will be measured and monitored using encapsulated neutron sources.

 Task 3.3: Hyper-Kamiokande Outer Detector
Yhe Outer Detector (OD) consists of PMTs lying in the crown of the detector, but facing outwards. Its aim is to reject the external background, i.e. to detect interactions originating from particles outside of the detector.  The OD’s design and PMTs are subject to an optimization that takes into account the required signal identification efficiencies, background rejection power, and cost.  Three main items are afforded: an original geometrical setup, improved PMT performance and the best trigger system to reject external background.
Task 3.4: Design of a low noise front end electronics for large area photodetectors
We are currently considering two options for waveform digitization – one based on a Flash-ADCs coupled with anti-aliasing filters , the other on switched capacitor arrays. The major requirement of the acquisition electronics is limitation of dissipated power, which is necessary in order to ensure proper circulation of water within the tank.
Task 3.5: Hyper-Kamiokande simulation
The simulation of the detector needs to follow the development of the design to provide a tool to describe the impact of the design on the physics and optimize the experimental reach. Full implementation of the trigger algorithms, and improved simulation of Gd neutron captures in the Hyper-Kamiokande simulation package, WCSim, developed by the Hyper-Kamiokande collaboration will be provided. Existing reconstruction algorithms will be investigated and adapted as required and new tagging algorithms will be developed.