Dark Matter Searches in PPD
PPD has been involved in and played a central role in the dark matter searches in the UK since its inception almost two decades ago. One of the co-founders of the UK dark matter searches was Peter Smith from PPD who pioneered liquid xenon technology and initiated the ZEPLIN programme at Boulby Underground Laboratory. ZEPLIN-I experiment was one of the first dark matter experiments in the world using a xenon singe-phase detector. The follow-on, ZEPLIN-II, led by Nigel Smith from PPD (currently director of SNOLAB), was the first world's dark matter experiment using xenon double-phase technology. ZEPLIN-III led by Imperial College, concluded the programme. It operated at high electric field achieving the best discrimination of any xenon detector. Its second science run, lasting almost a year, was the world's longest continuously run of any dark matter experiment with a double-phase xenon detector, proving the maturity of the technology to be used in the future experiments and achieving competitive limits in WIMP searches.
After many years of working on liquid xenon for dark matter searches and helping two-phase xenon to become a world-leading technology, the group found a new home in the LUX-ZEPLIN (LZ) collaboration.
We actively participated in the ZEPLIN-III experiment exploitation and its decommissioning. Main responsibilities were: project management, including reporting to the OsC, liaison between the Boulby Underground Laboratory and the experiment, frequent visits to Boulby to oversee experiment operations and supervise people working underground, detector calibration, radiation protection supervision, management of the data centrally stored at RAL and relevant equipment repatriation to RAL.
After a successful R&D phase, the group has been awarded an STFC 3-year grant to deliver: an ultra-radio-pure titanium cryostat for LZ and a calibration source deployment system.
Our responsibilities in LZ cover the following:
- STFC LZ project management, including: reporting to the STFC OsC, budget and project progress oversight, participation in internal reviews, cryostat fabricator selection committee chair.
- Fabrication of the LZ cryostat, cleaning and delivery to SURF, which includes: work-package management, raw material procurement, cryostat tender management, cryostat documentation, issue of cryostat technical drawings with a level of details the same as for production drawings (TD),oversee cryostat fabrication (TD), oversee cryostat cleaning and transportation to SURF (TD), assistance in cryostat integration at SURF (TD)
- Mechanical and electrical design, fabrication, tests and commissioning of the sealed sources deployment system for LZ calibration
- Simulations of: the LZ detector response chain and LZ calibration with external gamma and neutron sources
In 2012 we joined a new liquid-argon dark matter experiment, DEAP-3600, at SNOLAB and started LAr R&D activities related to a liquid argon detector calibration system using external sources. Our responsibilities in DEAP-3600 are: initial simulations of detector calibration using external gamma sources, mechanical and electrical designs, and manufacture of the calibration deployment system using a tagged 22Na source. The system is now taking science data.