METU

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METU
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• Status and Preliminary Results

• Future Plans and Conclusion

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CsI(Tl) Crystal Array
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Z 0 cm
QR
Z 40 cm
208Tl
40K
FADC Readout 16 ch., 20 MHz, 8 bit
QL
137Cs
Region of Interest for SM ???ee)
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Period II Data Volume (186 kg in mass) Total
95 / 50 days ON/OFF Period III Data Volume (200
kg in mass) Total 190 / 40 days ON/OFF

• Energy resolution info
• ? 10 FWHM _at_ 660 keV
• Z-position resolution is
• ? ?(z) 2 cm _at_ 660 keV
• ? ?(z) lt2 cm _at_ higher energies

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• Get z-definition correction parameter f

Whats wrong
SEH, SCH
SEH, SCH
SEH, SCH
SEH, SCH
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Data Analysis Techniques - Calibration
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Event Selection
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Data Analysing Techniques - Defining Cuts
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Data Analysing Techniques - Defining Cuts
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P-II and P-III OFF CsI Energy Spectra with
Various Cuts
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ON and OFF Energy Spectra
36 Crystals (40 cm) Mass 57.6 kg Basic
cuts PSD 4 cm Z-cut
ON spectrum 0.5086 0.0093/day/kg in Period II
(5922 kg-day)
OFF spectrum 0.4502 0.0127/day/kg in Period
II (2786 kg-day)
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P-II and P-III OFF CsI Energy Spectra with
Various Cuts
Period-III
Period-II
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P-II P-III CsI Energy Spectra
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Background Understanding
B. Environmental Backgrounds

• IDEA multiple-hit analysis can give us very good
  understanding especially Tl-208 and cosmic
  related background in the region of interest.
• Cosmic
• - By comparing cosmic and not-cosmic
  multiple-hit spectra.
• - Tl-208
• - By examining multiple-hit spectra
  as well as simulation of Tl-208 decay chain
  energies to understand/suppress background in the
  region of 3-4 MeV.

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Intrinsic 137Cs Level
31.3 kgday of CsI(Tl) data was analysed.
137Cs contamination level in CsI was drived gt
(1.55 0.02 ) X 10-17 g/g
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Event Configuration

• Pulse shape (ß or a)
• Timing of event
• 50 ns per bin (20 MHz FADC)
• 10,000 bins (500 µs) per event
• 356 bins (17.8 µs) for following pulse

2050ns
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The Event Selection 238U chain
238U abundance (0.86 0.03) x10-12 g/g
238U abundance 0.82 0.02 x10-12 g/g
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The Event Selection 235U chain
(a) 223Ra(a)? 219Ra(a, 3.96 s)? 215Po
(b) 219Ra(a)? 215Po(a, 1.78 ms)? 211Pb

• Selection 3-a signature
• both time delay greater than 500 ms
• No signal
• DAQ Inactive

235U abundance lt 4.9 x10-14 g/g
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The Event Selection 232Th chain
232Th abundance (2.23 0.06) x10-12 g/g
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The Event Selection 232Th chain
232Th abundance (2.3 0.1) x10-12 g/g
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Delta Z Distributions
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Environmental Background Understanding
81 crystals including 2020 and 40 cm crystals in
PII was analysed.
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Simulation 4 MeV pair-production
511 keV
S1
S2
S3
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Background Understanding via Multi Hit
External Source(s)
511 keV
605 keV
2100 keV
796 keV
1173 keV
1332 keV

• Co-60 contamination
• 1173.2 keV 99.86 accompanied with 1332.5 keV
  99.98
• The background related to reactor. Mostly come
  from the dust.
• Tl Pair Production One escape peaks
• ( 2105 511 keV)

• Cs-134 (n 133Cs g 134Cs)
• 605 keV 97.6
• 796 keV 85.5

583 keV
External Source(s)
2614 keV
With the Q of beta decay at 2MeV
Internal Source(s)
2614 keV 99 accompanied with 583 keV 85 510.8
keV 23 860 keV with 13
860 keV

• Cosmic induced neutrons can be captured by the
  target nuclei 133Cs.

• Combination of Tl gammas can affect up to around
  4 MeV

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Background Understanding Due to Tl-208 and
Cosmic Inefficiency
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SH Prediction for Cosmic Background

• ? ON - OFF
• ? ON - (SH)pred.

where T1 (SH)not cos (SH)cos and
T2 (MH)not cos (MH)cos
d(SH)pred lt dOFF we win
with this alternative approach

• Single Hit Prediction is made by using ON period
  data. We can improve accuracy profoundly since we
  have more than 100 days ON data in PII and 200
  days in PIII and more for other periods

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Background Understanding Due to Tl-208
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Background Understanding Due to Tl-208
580 keV
510 580 keV
860 keV
860 keV
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Background Understanding Due to Tl-208
580 keV g 2614 keV g
860 keV g 2614 keV g
No z cut
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Tl-208 SH Estimation 3 - 3.5 MeV PIII-ON Period
Tl 2614 583 keV
No z-cut
4 cm z-cut
Best fit 0.0343 0.0025 c2 10.89/(nof8)
SH 471.11 34.34
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Tl-208 SH Estimation 3 - 3.5 MeV PIII-ON Period
Tl 2614 860 keV
No z-cut
4 cm z-cut
Best fit 0.002722 0.000199 c2 11.52/(nof8)
SH 38.17 2.79
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Tl-208 SH Estimation 3.5 - 4 MeV PIII-ON Period
Tl 2614 860 keV
No z-cut
4 cm z-cut
SH 18.29 1.69
Best fit 0.001305 0.000121 c2 11.011/(nof8)
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Background Expectation via PAIR PRODUCTION
3 - HIT
2 - HIT
q
p
q
q
p
SH
p
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Background Understanding via Pair-Pro
d lt 2 crys
K-40 950 keV
K-40 950 keV
Tl-208 2100 keV
Tl-208 2100 keV
Tl-208 2614 keV
Tl-208 2614 keV
1 cry d
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Background Understanding via Pair-Pro
850 keV K-40
1600 keV Tl -208
2100 keV Tl -208
2614 keV Tl -208
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Background Understanding via Multi-Hit
Cosmic-Ray Inefficiency

• Red Cosmic
• Blue not-cosmic

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OFF-BKG (Multi-Hit)
Period-III
Period-II
Sin2qW 0.0001 0.13
Sin2qW 0.00005 0.109
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SH Prediction via Multi-Hit for ON Data
Period-II
Period-III
Energy (MeV)
Single-Hit
Single - Hit
Prediction
Prediction
961 31
3 3.5
961 31
937.6 42.2
1747 41.8
1641.4 46.6
287.2 15.9
734 27.1
292 17.1
3.5 4
741.825.1
524 22.9
4 4.5
193 13.9
188.6 13.2
504.320.9
356 18.9
4.5 5
141 11.9
128.3 10.9
368.0 17.8
5 5.5
117 10.8
91.4 9.2
270.615.3
263 16.2
203 14.3
5.5 6
81 9
66.4 7.9
202.113.2
6 6.5
50.6 6.9
175 13.2
175.112.1
55 7.4
200 14.14
6.5 7
77 8.8
79.1 8.3
180.112.0
157 12.5
76 8.7
7 7.5
84.1 8.3
177.011.5
7.5 8
137 11.7
73 8.5
60.9 7.1
109.9 9.3
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sin2qW measurement for Period-II
ON-OFF
ON-(BKG)expec.
s (1.786 1.297) sSM
s (1.194 1.145) sSM
Sin2qW 0.328 0.137
Sin2qW 0.259 0.153
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sin2qW measurement for Period-II
ON-(OFF BKG)expec
s (1.454 1.859) sSM
Sin2qW 0.291 0.102
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sin2qW measurement for Period-III
ON-OFF
ON-(BKG)expec.
s (1.298 1.413) sSM
s (1.0004 0.8977) sSM
Sin2qW 0.272 0.179
Sin2qW 0.231 0.133
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sin2qW measurement for Period-III
ON-(OFF BKG)expec
s (1.01 0.77) sSM
Sin2qW 0.233 0.114
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sin2qW measurement for Period-II Period-III
ON-(BKG)expec.
s (1.207 0.577) sSM
Sin2qW 0.260 0.076
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Expected Accuracy with data size
sSin2qW 0.13 sSM
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TEXONO and World status
Characteristics of the previous and current n-e
scattering experiments
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Background Expectation via PAIR PRODUCTION
3 - HIT
2 - HIT
q
p
q
q
p
SH
p
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Conclusion
Sin2?W was observed but there is NO real
measurement for reactor neutrino YET.