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D. Karlen

Publications and source records attributed to D. Karlen.

5 recordsLinked to original sources
arXiv2025

Assembly, testing, and installation of mPMT photosensor for the Water Cherenkov Test Experiment

The multi-Photomultiplier Tube (mPMT) photosensors will be used in the Water Cherenkov Test Experiment (WCTE) to efficiently detect the photons produced in the whole detector. One of the aims behind the development of WCTE is to test the technology and implement it in future water Cherenkov experiments such as the Hyper-Kamiokande experiment and its Intermediate Water Cherenkov Detector. Each mPMT is built using nineteen 3-inch PMTs arranged on a semi-spherical support matrix. In this paper, we describe the design and manufacture of the mechanical components, the procedures for casting an optical gel between PMTs and acrylic cover, and the overall assembly procedure of the mPMTs. Details of the electronics used in the mPMT modules are not included in this paper and will be presented in a separate publication. We also report on the R&D performed on the selection of the optical gel ratio along with transmittance measurements and the reflectance measurements performed on the aluminium reflector. We also present the optical tests performed on the mPMT module using a 405 nm LED and the resulting increase in the effective photosensitive area by surrounding the PMTs with a reflector. A summary of the production and installation of the mPMTs for the WCTE is also presented in this paper.

physics.ins-det↗
arXiv2011

Progress on the neutrino mixing angle, theta_13

Until recently, measurements of theta_13, which describes the nu_e component in the nu_3 mass eigenstate, gave only upper limits, leaving open the possibility that it is zero and eliminating a source of CP violation in the neutrino sector. This year has seen significant advances in measuring theta_13 as precision reactor experiments move from construction phase to physics operation and accelerator experiments give first indications that theta_13 differs from zero. In the years to come, the results from these and other experiments will stringently test the PMNS framework for neutrino oscillation and will start to give information about neutrino CP violation and the neutrino mass hierarchy. This paper summarizes the situation for measuring theta_13 at this pivotal time in neutrino research.

hep-ex↗
arXiv2005

TPC Performance in Magnetic Fields with GEM and Pad Readout

A novel charged particle tracking device, a high precision time projection chamber with gas electron multiplier and pad readout, is a leading candidate as the central tracker for an experiment at the International Linear Collider. To characterize the performance of such a system, a small TPC has been operated within a magnetic field, measuring cosmic-ray and laser tracks. Good tracking resolution and two particle separation, sufficient for a large scale ILC central tracker, are achieved.

physics.ins-det↗
arXiv2005

Resolution studies of cosmic-ray tracks in a TPC with GEM readout

A large volume TPC is a leading candidate for the central tracking detector at a future high energy linear collider. To improve the resolution a new readout based on micro-pattern gas detectors is being developed. Measurements of the spatial resolution of cosmic-ray tracks in a GEM TPC are presented. We find that the resolution suffers if the readout pads are too wide with respect to the charge distribution at the readout plane due to insufficient charge sharing. For narrow pads of 2 x 6 mm**2 we measure a resolution of 100 micometer at short drift distances in the absence of an axial magnetic field. The dependence of the spatial resolution as a function of drift distance allows the determination of the underlying electron statistics. Our results show that the present technique uses about half the statistical power available from the number of primary electrons. The track angle effect is observed as expected.

physics.ins-det↗