Abstract

The SoLid experiment aims to measure neutrino oscillation at a baseline of 6.4 m from the BR2 nuclear reactor in Belgium. Anti-neutrinos interact via inverse beta decay (IBD), resulting in a positron and neutron signal that are correlated in time and space. The detector operates in a surface building, with modest shielding, and relies on extremely efficient online rejection of backgrounds in order to identify these interactions. A novel detector design has been developed using 12800 5 cm cubes for high segmentation. Each cube is formed of a sandwich of two scintillators, PVT and 6LiF:ZnS(Ag), allowing the detection and identification of positrons and neutrons respectively. The active volume of the detector is an array of cubes measuring 80× 80× 250 cm (corresponding to a fiducial mass of 1.6 T), which is read out in layers using two dimensional arrays of wavelength shifting fibres and silicon photomultipliers, for a total of 3200 readout channels. Signals are recorded with 14 bit resolution, and at 40 MHz sampling frequency, for a total raw data rate of over 2 Tbit/s. In this paper, we describe a novel readout and trigger system built for the experiment, that satisfies requirements on: compactness, low power, high performance, and very low cost per channel. The system uses a combination of high price-performance FPGAs with a gigabit Ethernet based readout system, and its total power consumption is under 1 kW. The use of zero suppression techniques, combined with pulse shape discrimination trigger algorithms to detect neutrons, results in an online data reduction factor of around 10000. The neutron trigger is combined with a large per-channel history time buffer, allowing for unbiased positron detection. The system was commissioned in late 2017, with successful physics data taking established in early 2018.

Highlights

  • 1.1 The SoLid experimentSoLid is designed to measure neutrino oscillations at very short baselines, O(10) m, from a nuclear reactor core

  • We describe a novel readout and trigger system built for the experiment, that satisfies requirements on: compactness, low power, high performance, and very low cost per channel

  • This paper describes a readout system for the SoLid experiment that fulfils all these requirements

Read more

Summary

The SoLid experiment

SoLid is designed to measure neutrino oscillations at very short baselines, O(10) m, from a nuclear reactor core. One proposed explanation is the existence of an additional non-interacting ‘sterile’ neutrino state, and a corresponding mass eigenstate; this fourth neutrino could influence the neutrino flavour transitions (oscillations) at very short distances. The existence of such oscillations can be tested using measurements of the νe energy spectrum as a function of distance from a neutrino source. Previous experience of running a 288 kg (20% scale) prototype of the detector in spring 2015 [3], demonstrated the need for a controlled temperature environment to reduce and stabilise the SiPM dark count rate, as well as a need for electromagnetic shielding to prevent pickup of electronic noise. Efficient online signal tagging is required in order to reach the experiment’s physics aims in this time period

Detector design
Readout system design
Detector planes
Analogue electronics
Detector modules
Prototyping
Readout software and communication
ADC alignment
SiPM characterisation
Gain equalisation
Dark count rate
Zero suppression reduction factor
Trigger strategy and implementation
Triggers
High energy
Zero-bias trigger
Event building and zero suppression
Firmware implementation
Trigger settings summary
DAQ performance
Run control
Online monitoring
Detector stability
Findings
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call