Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The calibration system for the photomultiplier array of the SNO+
  experiment   A light injection system using LEDs and optical fibres was designed for the
calibration and monitoring of the photomultiplier array of the SNO+ experiment
at SNOLAB. Large volume, non-segmented, low-background detectors for rare event
physics, such as the multi-purpose SNO+ experiment, need a calibration system
that allow an accurate and regular measurement of the performance parameters of
their photomultiplier arrays, while minimising the risk of radioactivity
ingress. The design implemented for SNO+ uses a set of optical fibres to inject
light pulses from external LEDs into the detector. The design, fabrication and
installation of this light injection system, as well as the first commissioning
tests, are described in this paper. Monte Carlo simulations were compared with
the commissioning test results, confirming that the system meets the
performance requirements.

20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ