arXiv subjects

M. A. Unland Elorrieta

Publications and source records attributed to M. A. Unland Elorrieta.

3 recordsLinked to original sources

arXiv2021

Homogeneity of the Photocathode in the Hamamatsu R15458-02 Photomultiplier Tube

It is common practice to test the optical properties of photomultiplier tubes (PMTs) by illuminating the entire photocathode region from the front at once and measuring the average performance. However, for optimal utilisation of the PMT performance in experiments, especially in the single-photon region, it is essential to also know the systematic variations across the photocathode, which requires measurements with focused light sources that illuminate only small regions of the PMT. We present a detailed uniformity characterisation of the gain, transit time, transit time spread, and pulse shape of the 80$\,$mm Hamamatsu R15458-02 PMT. We find that the parameters exhibit asymmetry along one axis, likely caused by the position and geometry of the dynode system. For all parameters except the transit time, the observed variations are small given the intrinsic variation of the parameters. For positions with shifted transit time we observe on average underamplified pulses which can potentially be exploited to improve the pulse reconstruction.

physics.ins-det↗

arXiv2021

Design and performance of the multi-PMT optical module for IceCube Upgrade

The IceCube Upgrade is the first step towards the next-generation neutrino observatory at the South Pole, IceCube-Gen2, and will be installed in the central region of the existing array. The Upgrade will consist of 693 newly developed, densely spaced optical sensors and 50 standalone calibration devices, which will enhance IceCube's capabilities both at low and high neutrino energies. Of the new sensors, 402 will be multi-PMT Digital Optical Modules (mDOMs). Consisting of 24 small photomultipliers arranged inside a pressure vessel, the mDOM features a large sensitive area distributed nearly homogeneously over the full solid angle. The use of multiple, individually read-out PMTs allows directional information to be obtained for the registered photons and enables the use of multiplicity triggering within a single module, e.g., for background suppression. The challenges driving the mDOM development included tight restrictions on module size, data-transfer rate, and power consumption as well as the harsh environment in the deep ice at the South Pole. In this contribution we present the final mDOM design that meets these challenges.

astro-ph.IM↗

arXiv2019

Characterisation of the Hamamatsu R12199-01 HA MOD photomultiplier tube for low temperature applications

We present a detailed characterisation of the new Hamamatsu R12199-01 HA MOD 3-inch photomultiplier tube (PMT) which is under consideration for the use in segmented optical modules of deep-ice neutrino detectors at the South Pole. Because of the significantly lower operation-temperature range compared to standard applications, a focus of our studies lies on the investigation of the temperature dependence of background characteristics (dark count rate, probability of correlated pulses), timing properties, gain and peak-to-valley ratio of this PMT type. In addition, the performance of the `HA coating' intended for background reduction was tested, as well as the influence of conductive objects near the photocathode like reflectors on the PMT noise rate. A low background rate is of particular importance as the deep ice at the South Pole features negligible optical background. We find that the new PMT type is well suited for the intended applications.

physics.ins-det↗