Design, construction and performance of magnetisedmini-ICAL detector module

Pethuraj S, Vivek M Datar and G.Majumder

Tata Institute of Fundamental Research

s.pethuraj@tifr.res.in

30/07/2019

Pethuraj S, Vivek M Datar and G.Majumder (TIFR-INO) Mini-ICAL 30/07/2019 1 / 17

INO-ICAL experiment

INO will be an undergroundexperiment to measure sign ofthe ∆m2

32 mass-squareddifference, through mattereffects, the value of the leptonicCP phase and, last but not theleast, the search for anynon-standard effect beyondneutrino oscillations.

About 28000 glass ResistivePlate Chamber (RPC) of size2 m× 2 m will be used assensitive detectors to measureenergy and direction ofneutrinos.

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mini-Iron CALorimeter (Mini-ICAL)

Before building the 3× 17 kton Iron Calorimenter detector modules, itwas necessary to build a scaled down version, called mini-ICAL.

The size of the mini-ICAL detector, 4 m× 4 m× 11 layers weighingabout 85 tons. The protoype can be built to study the engineeringissues along with the following things,

magnetic field measurement using pickup coil and Hall probes andcompare with simulation by MAGNET software.

Performance of RPCs made in indian industry including the DC-DCHV power supply.

Muon spin rotation to measure the B-field.

Measurement of the charge dependent muon flux upto ∼ 1.5 GeV andcan be used as input to the neutrino event generator.

Proof of principle test of the cosmic muon veto detector for thefeasibility of a shallow depth ICAL detector.

Pethuraj S, Vivek M Datar and G.Majumder (TIFR-INO) Mini-ICAL 30/07/2019 3 / 17

Mini-ICAL magnet

The details of magnet are given below,

Parameters Value (Mini-ICAL magnet)

Magnet size 4 m× 4 m× 1.06 mMagnet weight 84 ton

Magnetic field uniformity F>1 T for 90 % areaNo. of layers 11

Gap between two plates 45 mmNo. of copper coil/No. of turns ineach coil 02/18

Induction (AT rating) 24,000 (nominal)Conductor cross section (mm) 30×30×φ 17 bore

Conductor material Oxygen free copperCoil cooling Low conductivity DM water

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Magnet Assembly

Pethuraj S, Vivek M Datar and G.Majumder (TIFR-INO) Mini-ICAL 30/07/2019 5 / 17

Magnetic field measurement

Pethuraj S, Vivek M Datar and G.Majumder (TIFR-INO) Mini-ICAL 30/07/2019 6 / 17

Magnetic field Simulation

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Gap Measurement before and after magnetisation

There is a small change in the gap between iron layers after magnetisation.

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RPC gap Assembly with Electronics

The RPCs are tested for leak test, HV holding test and efficiency test isused for the mini-ICAL stack.

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Fully Assembly mini-ICAL

Pethuraj S, Vivek M Datar and G.Majumder (TIFR-INO) Mini-ICAL 30/07/2019 10 / 17

Electronics and DAQ scheme

The RPC signals are amplified and discriminated by charge sensitiveAnalog front boards (NINO) in Layer 0,1,3-9 and Layer 2 is populatedby voltage sensitive Analog front end board (ANUSPARSH).

The discriminated signals are pass though the FPGA basedDigital-Front end. The event latch, time of muon arrival in each layeris recordedby the arrival of trigger from Trigger system.

The trigger is formed by the coincidence of 1-fold signals from anyfixed set of layers within 100 ns.

The recorded data is analysed in offline to study the performance ofthe RPC detector.

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Closed Loop Gas System

The RPC detector is operated in the avalanche mode by a continuous flowof gas mixture (C2H2F4 (95.2 %), iC4H10 (4.5 %), SF6 (0.3 %)) with adifferential bias voltage of ± 5 kV.

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Performance of the mini-ICAL Stack

The periodicmonitoring of theRPC detectors aredone by analysing thedata collected fromexperiment and thepreformance of thedetector is studied byoccupancy, stripmultiplicity,inefficiency, efficiency,position resolution,time resolution andetc,.

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Cosmic Muon Momentum Spectrum

The charge dependent cosmic muon spectrum is unfolded from theexperimental data. The unfolded momentum spectrum along withCORSIKA predictionare given below figure.

(GeV)µ

p3− 2− 1− 0 1 2 3

)­1

GeV

­1 s

r­1

s­2

(cm

φ 0

0.05

0.1

0.15

3−10×

Corsika

Data

(b)

Pethuraj S, Vivek M Datar and G.Majumder (TIFR-INO) Mini-ICAL 30/07/2019 14 / 17

Muon-Spin rotation

Figure: tµ − te distribution for µ+ andtµ − te distribution for µ−

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Conclusion

Mini-ICAL detector stack commissioned in IICHEP-Transit Campus,Madurai.

The magnetic field measurement is done using Hall probe sensors, themeasurd field values are comparable with simulation within ± 10 %.

The charge dependent cosmic muon spectrum is calculated andcompared with CORSIKA predictions.

The lifetime of the muon in iron was measured as (2.21 ± 0.01) µsand (0.27 ± 0.02)µs for µ+ and µ−. However, the modulation in thelifetime curve due to the µSR signal could not be measured.

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The End

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