“Construction of a cosmic stand, using scintillating
tiles to study Micro Pattern Gaseous Detectors”
Olga Zormpa
Annual Meeting 14-15/11/2019
NCSR Demokritos
Institute of Nuclear and Particle Physics
Introduction
This thesis was carried out within the framework of the postgraduate program "Physical and Technological Applications" (N.T.U.A.) and was carried out entirely at theInstitute of Nuclear and Particle Physics of the NCSR "Demokritos".
In the context of this thesis, the study and construction of a device (Cosmic Stand, CS), aimed at the detection of cosmic muons, was based on the technique of coincidence. The ultimate goal was to study the MicroMeGaS detectors by using this apparatus as a triggering system.
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Hamamatsu H10682-210
o Photon counting head device consisting of ametal package photomultiplier tube, alongwith a high-speed photon counting circuitand a high-voltage power supply circuit.
o Over light detection
o Effective area: 8 mm
o Peak Sensitivity Wavelength: 400 nm
o Max Dark Count: 100 Hz
o Output pulse Width: 10 ns
o Output pulse Height: ~2 V
o The high voltage supply for photomultipliertube and the discrimination level are presetto optimum values
Dark Current
Rate (Hz)
PMT1 3.07 ± 0.53
PMT2 13.4 ± 3.36
PMT3 3.41 ± 0.61
PMT4 9.75 ± 1.82
Photomultipliers
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Scintillators
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Design
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Rate R (Hz)
δR
SeparatelyB 37.49 0.47C 42.11 0.40A 5545.32 69.05
Coincidence
B+A 2.20 0.02C+A 2.17 0.05B+C 3.82 0.05
B+C+A 0.58 0.02
Noise Calculations
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3.600
3.700
3.800
3.900
4.000
4.100
4.200
6/6 7/6 12/6 13/6 14/6 18/6 20/6 21/6 25/6 27/6R
ate
(Hz)
Dates
Muon DistributionDates Rate (R) δR
6/6/19 3.940 0.033
7/6/19 3.930 0.033
12/6/19 3.922 0.033
13/6/19 3.869 0.033
14/6/19 3.948 0.033
18/6/19 3.950 0.033
20/6/19 3.933 0.033
21/6/19 3.889 0.033
25/6/19 3.957 0.033
27/6/19 4.127 0.033
Daily Distribution of muons
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Callibration with Fe-55: Channel 351 → 5.9 keV
Landau MPV: channel 75 → Emu=1.26 keV
{𝜒2 =FCN
ndf=
667.556
509= 1.3/df}
2.44 keV/cm→ Emu,th=1.22 keV
FCN=667.556 FROM MIGRAD STATUS=CONVERGED 111 CALLS 112 TOTAL
EDM=2.58823e-007 STRATEGY= 1 ERROR MATRIX UNCERTAINTY 2.0 per cent
NO. NAME VALUE ERROR STEP SIZE DERIVATIVE
1 Constant 1195.360000 9.686580 -0.275756 0.000120
2 MPV 74.530200 0.488637 0.005695 -0.000465
3 Sigma 32.518700 0.257339 0.000014 0.280630
Cosmic Stand + Micromegas Detector
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Final Cosmic Stand
• 2 levels of 16 scintillators
• Connected by four with Hamamatsu Photonics R580-12
photomultiplier tubes
• Dimensions 84 cm × 92 cm
• 2 intermediate levels able to move in x-y plane (Micromegas
detectors or scintillators-pmts)
Expected frequency
𝑓ℎ ≈ 100 𝐻𝑧
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Conclusion
• The final Cosmic Stand is designed and all the components (photomultiplier tubes and
scintillators) have been tested. As soon as technical issues are resolved we can start the
construction.
• In the meantime the 2 small modules (pairs of scintillators-PMTs) can be used as a trigger to
the Micromegas detectors
• Further studies of the Micromegas detectors.
• The 2 small pairs of scintillators-PMTs have already been used to trigger the Micromegas
detector and help us adjust the SRS.
• It can be used for cosmic muon detection under neutron irradiation.
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Thank you for your attention
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12
24 PMTs Hamamatsu Photonics
R580-12
o Spectral response range : 300-
650 nm
o Number of stages : 10
o Useful photocathode diameter :
34 mm
o Photocathode type : bi-alkaline
o 𝑉𝑖𝑛 = 18 𝑉 − 24 𝑉o 𝑉𝑝𝑚𝑡 = 1200 𝑉 − 1600 𝑉
o 𝑄𝐸 = 12 ~ 17% for 𝜆 =520 𝑛𝑚
Final Cosmic Stand-PMTs
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Dark current measurements for 11 out of 23 PMTs.
Left plot shows exponential reduction of the dark current rate, as the threshold increases.
Right plot shows the dark current for the 11 operative PMTs. The grey band indicates the
acceptable values as defined by Hamamatsu.
Final Cosmic Stand-Dark Current
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𝜆1 = 405 𝑛𝑚𝜆2 = 450 𝑛𝑚𝜆3 = 520 𝑛𝑚o Activation using square pulse:
• 𝑉 = 2𝑉• Δ𝑡 = 500 𝑛𝑠• 𝑓 = 1 𝑀𝐻𝑧
o Use of filter, to achieve different transparencies
o Use of optical fibre to connect LASER, filter
and ΡΜΤ
Final Cosmic Stand-Tests using LASER
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Experimental data after connecting the PMTs with pulse LASER. On the left plot, is shown the
response of the PMT as transparency changes. On the right plot, is shown the response of the PMT
as LASER frequency changes.
Final Cosmic Stand-Tests using LASER
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