WA105 experiment (LBNO-DEMO)
Following the recommendations of the 2013 European Strategy for Particle Physics, CERN has created the Neutrino Platform Facility in a test-beam hall on CERN’s Prévessin site to allow the global community of neutrino experts to develop and prototype the next generation of neutrino detectors. In this context, two large-scale LAr TPC prototypes are being built aiming to test both single-phase and dual-phase LAr TPC technologies. Compared to the single-phase, the dual-phase design will provide a fully active volume without dead material with a smaller number of readout channels, a finer readout pitch, a more robust signal-to-noise ratio with tunable gain, a lower detection energy threshold, and a better pattern reconstruction of the events. These will allow to best exploit the “bubble chamber”-like features of the liquid argon TPC at the 10-kt scale.
WA105/protoDUNE-Dual Phase is a CERN experiment (NP02) approved by the SPS Committee to build and operate a 6x6x6 m3 dual-phase LAr detector at the CERN Neutrino Platform to demonstrate the technology to leverage large risks associated to the extrapolation from existing experience to the huge mass required for future neutrino detectors. The reconstruction of electrons, protons, neutral and charged pions and muons will be demonstrated in dedicated test beam campaigns. A Memorandum of Understanding between CERN as host laboratory and the contributing institutes has been signed, including CIEMAT.
(Left) Internal view of the protoDUNE-DP cryostat installed at the EHN1 area at CERN. (Right) Drawing of the WA105 detector with 36 PMTs placed at the bottom.
ProtoDUNE-DP is now under construction and it will be operated at the CERN Neutrino Platform starting in 2018. The figure displayed above shows a picture of the internal membrane of the protoDUNE-DP cryostat already finished. In ProtoDUNE-DP, the charge read-out occurs in the gas phase, where the charge is amplified and collected on a 2D anode. The TPC has a 6x6x6 m3 active volume. The TPC has a unique drift volume, while the charge read-out is built from four independent 3x3 m2 units called Charge Read-out Planes (CRP). Each CRP has X and Y charge collection strips, at 3.125 mm pitch.
CIEMAT contributions to WA105
CIEMAT, together with IFAE, is responsible for the light detection system of the protoDUNE-DP experiment, including the acquisition and characterization of 40 8” cryogenic photomultipliers, coating with wavelength-shifters, design and production of the voltage circuit and HV splitters, production of the associated mechanics, PMT calibration system, and final installation and commissioning of the light detection system in the detector. CIEMAT also contributes to the development of the simulation and reconstruction software for both charge and light readout and the study of the detector performance for low energy interactions. The group will participate in the analysis of data from cosmic muons and charged- particle test beam in 2018-2019.
A cryogenic test facility has been developed at CIEMAT where 40 PMTs have been characterized at room and LN2 temperature inside a 300 litre vessel, including final mechanical structures, HV dividers and cables. The dark current and gain as a function of the applied voltage are measured for each PMT. The response of the PMTs with respect to the amount and frequency of the light received is also studied. A publication is under preparation.
A PMT calibration system integrated in ProtoDUNE-DP detector has been designed to calibrate the response of the PMTs installed inside the LAr volume. The goal is to determine the PMT gain and study the PMT stability. An optical fiber will be installed at each PMT in order to provide a configurable amount of light from a LED source.
The CIEMAT group has important responsibilities inside the WA105 experiment as leaders of the Photon Detection subgroup and members of the Technical Coordination Group and Dissemination Board.
Cryogenic test facility at CIEMAT to test 10 PMT at the same time inside a vessel filled with LN2.