Status of the ANAIS experiment - UCLA · ANAIS EXPERIMENT ANAIS is a project aiming to set up, at the new facilities of the Canfranc Underground Laboratory (Spain), a potassium-purified

Status of the ANAIS experiment

J. Amaré, S. Cebrián, C. Cuesta, E. García, M. Martínez, M. A. Oliván, Y. Ortigoza, A. Ortiz de Solórzano, J. Puimedón, M. L. Sarsa , P. Villar and J. A. Villar.

ANAIS EXPERIMENT

ANAIS is a project aiming to set up, at the new facilities of the Canfranc Underground Laboratory (Spain), a potassium-purified NaI(Tl) experiment to look for dark matter.

MotivationStudy of the annual modulationDAMA/LIBRA positive signal.

Technical aspects:

• 9 NaI(Tl) crystals of 12.5 kg.

• Coupled each one to 2 PMTs.

• Shielded from external radiation.

Experimental goals:

• Energy threshold < 2 keVee.

• Background at low energy as low as possible.

• Very stable operation conditions.

C. Cuesta 2

APPROACH

C. Cuesta 3

ANAIS-0

ANAIS-25

ANAIS-37ANAIS-112

NaI(Tl) CRYSTALS

9 ultrapure NaI(Tl) crystals of 12.5 kg each.

Produced by Alpha Spectra Inc., CO following low radioactivity protocols.

C. Cuesta 4

NaI(Tl) CRYSTALS



• D0, D1 and D2 taking data at ANAIS-37.Radioactivity measured at LSC used to improve Alpha Spectra procedures:

C. Cuesta 5

(*)40K 238U 210Pb 232Th

D01.4 mBq/kg

(45 ppb K)10 Bq/kg 3.15 mBq/kg 3 Bq/kg

D11.1 mBq/kg


D21.1 mBq/kg

(34 ppb K)3 Bq/kg (*) 0.7 mBq/kg

1 Bq/kg (220Rn-216Po)

<0.5 Bq/kg (212Bi-Po) (*)

NaI(Tl) CRYSTALS



• D0, D1 and D2 taking data at ANAIS-37.Radioactivity measured at LSC used to improve Alpha Spectra procedures:

• D3 travelling to LSC, will arrive in February 2016. Improvement in radiopurity expected (<20 ppb K measured in powder).

• D4, D5 and D6 under preparation at Alpha Spectra, will arrive to LSC in Spring 2016.

• D7 and D8 will be prepared next.

C. Cuesta 6

(*)40K 238U 210Pb 232Th

D01.4 mBq/kg


D11.1 mBq/kg


D21.1 mBq/kg

(34 ppb K)3 Bq/kg (*) 0.7 mBq/kg

1 Bq/kg (220Rn-216Po)

<0.5 Bq/kg (212Bi-Po) (*)

PHOTOMULTIPLIERS

• Ham R12669SEL2.

• Selected after R&D considering low background + quantum efficiency + dark current rate.

• Characterization at University of Zaragoza: SER, dark counts, quantum efficiency

• Radioactivity screening at LSC. Average (mBq/PMT):

• Voltage dividers in CuFlon PCB

• PMTs housing made at LSC with electroformed copper

• Light collection in ANAIS-37:

• Available at LSC

C. Cuesta 7

Detector Phe-/keV

D0 15.26 ± 0.10

D1 14.44 ± 0.09

D2 16.31 ± 0.56

232Th 238U 262Ra 40K

20.7 0.8 157 8 82.5 0.8 111 5

PHOTOMULTIPLIERS

• Ham R12669SEL2.


• Characterization at University of Zaragoza: SER, dark counts, quantum efficiency.






C. Cuesta 8

Detector Phe-/keV

D0 15.26 ± 0.10

D1 14.44 ± 0.09

D2 16.31 ± 0.56

232Th 238U 262Ra 40K

20.7 0.8 157 8 82.5 0.8 111 5

M.A. Oliván PhD Thesis arXiv:1601.07312

http://arxiv.org/abs/1601.07312

PHOTOMULTIPLIERS

• Ham R12669SEL2.








C. Cuesta 9

Detector Phe-/keV

D0 15.26 ± 0.10

D1 14.44 ± 0.09

D2 16.31 ± 0.56

232Th 238U 262Ra 40K

20.7 0.8 157 8 82.5 0.8 111 5

PHOTOMULTIPLIERS

• Ham R12669SEL2.




• Voltage dividers in CuFlon PCB.




C. Cuesta 10

Detector Phe-/keV

D0 15.26 ± 0.10

D1 14.44 ± 0.09

D2 16.31 ± 0.56

232Th 238U 262Ra 40K

20.7 0.8 157 8 82.5 0.8 111 5

PHOTOMULTIPLIERS

• Ham R12669SEL2.





• PMTs housing made at LSC with electroformed copper.



C. Cuesta 11

Detector Phe-/keV

D0 15.26 ± 0.10

D1 14.44 ± 0.09

D2 16.31 ± 0.56

232Th 238U 262Ra 40K

20.7 0.8 157 8 82.5 0.8 111 5

PHOTOMULTIPLIERS

• Ham R12669SEL2.








C. Cuesta 12

Detector Phe-/keV

D0 15.26 ± 0.10

D1 14.44 ± 0.09

D2 16.31 ± 0.56

232Th 238U 262Ra 40K

20.7 0.8 157 8 82.5 0.8 111 5

PHOTOMULTIPLIERS

• Ham R12669SEL2.







• Available at LSC.

C. Cuesta 13

Detector Phe-/keV

D0 15.26 ± 0.10

D1 14.44 ± 0.09

D2 16.31 ± 0.56

232Th 238U 262Ra 40K

20.7 0.8 157 8 82.5 0.8 111 5

SHIELDING

Shielding Materials for the full experiment available at LSC.

C. Cuesta 14

40 cm neutron shielding

Active vetoes

Anti-Rn box10 cm ancient lead

20 cm lead

SHIELDING

Shielding Materials for the full experiment available at LSC.

C. Cuesta 15

40 cm neutron shielding

Active vetoes

Anti-Rn box10 cm ancient lead

20 cm lead

Muon-tagging system on-site and tested.

DATA ACQUISITION

• DAQ system:

– Individual PMT signals fully processed.

– Trigger at phe level each PMT signal.

– AND coincidence in 200 ns window.

– Redundant energy conversion by QDC in different ranges.

– Trigger in OR logical mode among modules.

C. Cuesta 16

DATA ACQUISITION

• DAQ system:






• Front-end modules available.

• DAQ software designed and tested.

C. Cuesta 17

DATA ACQUISITION

• DAQ system:






• Front-end modules available.

• DAQ software designed and tested.

• Slow control system operative:

– Monitoring:

o External Rn, H, P, T

o T inside the shielding

o N2 flux and PMT HV.

– Stability checks: gain, trigger level, coincidence window, trigger rate.

C. Cuesta 18

DATA ANALYSIS

C. Cuesta 19

External calibration source data (109Cd / 57Co)

Energy calibration

Determination of cut efficiency

DATA ANALYSIS

C. Cuesta 20

Background data

Coincidences with HE

Energy Calibration

Determination of trigger efficiency

Checking cut efficiency


Energy calibration

Determination of cut efficiency

DATA ANALYSIS

C. Cuesta 21

Background data

Coincidences with HE

Energy Calibration

Determination of trigger efficiency

Checking cut efficiency

Building filtered background


Energy calibration

Determination of cut efficiency • Application of cuts

• Efficiency correction

• New AS improved module 12.5 kg – D2 installed together to D0/D1 (ANAIS-25 ones).

ANAIS-37 DATA ANALYSIS

C. Cuesta 22


• Data taking since March 2015.


C. Cuesta 23


• Data taking since March 2015.

• Goals:

– Evaluate background after implementation of improvements at AS procedures.

– Confirm threshold below 2 keVee.


C. Cuesta 24


C. Cuesta 25

1 10 100

1

10

100

ANAIS37-D0 D1,D2

counts

/keV

/kg/d

ay

Energy (keV)

D0 (total)D1 (total)D2 (cosm. activated)D2 (after 3 month underground)D2 (after 5 month underground)

• Very promising reduction under 20 keV.


C. Cuesta 26

1 10 100

1

10

100

ANAIS37-D0 D1,D2

counts

/keV

/kg/d

ay

Energy (keV)



• D2 cosmogenic lines still decaying.


C. Cuesta 27

1 10 100

1

10

100

ANAIS37-D0 D1,D2

counts

/keV

/kg/d

ay

Energy (keV)




• 210Pb clear reduction with respect to ANAIS-25 modules.


C. Cuesta 28

1 10 100

1

10

100

ANAIS37-D0 D1,D2

counts

/keV

/kg/d

ay

Energy (keV)





• Background below 2 counts/keV/kg/day down to 6 keV.


C. Cuesta 29

1 10 100

1

10

100

ANAIS37-D0 D1,D2

counts

/keV

/kg/d

ay

Energy (keV)






• Background below 10 counts/keV/kg/day down to 1.5 keV:- Filtering protocols still under optimization.- Limited by acceptance below 2 keVee still working to understand PMT origin events (Blank Module measurements ongoing).


C. Cuesta 30

1 10 100

1

10

100

ANAIS37-D0 D1,D2

counts

/keV

/kg/d

ay

Energy (keV)







1 10 100

1

10

100

ANAIS37-D0 D1,D2

counts

/keV

/kg/d

ay

Energy (keV)


C. Cuesta 31

D0 (170 d LT)D1 (170 d LT)D2 ( d LT)D2 ( d LT)D2 (last 30 d LT)

0 2 4 6 8 100.0

0.2

0.4

0.6

0.8

1.0

Cu

ts E

ffic

iency

Energy (keV)

D0

D1

D2

Underestimate of acceptance efficiencies is suggested by the study of coincident events among detectors

Raw coinc. spc.After cutsAfter cuts eff. corr.Rejected by cut (I)Rejected by cut (II)

(Bkg)







C. Cuesta 32

1 10 100

1

10

100

ANAIS37-D0 D1,D2

counts

/keV

/kg/d

ay

Energy (keV)

D0 (170 d LT)D1 (170 d LT)D2 ( d LT)D2 ( d LT)D2 (last 30 d LT)

Goal: accumulate a population of pure PMT events and testing the filtering protocols

Filtering protocols seem to reject most of the PMT events

Blank Module measurements

Blank module rawPassing cutsPassing cuts eff. corr.Rejected by cuts

(Bkg)

SIMULATIONS – D0 and D1 in ANAIS-25

C. Cuesta 33

0 2 4 6 8 10 12 14 16 18 200

1

2

3

4

5

6

Co

un

ts /

keV

/ k

g/ d

ay

Energy (keV)

Data D2

Simulation

0 10 20 30 40 50 60 70 80 90 100

100

101

Co

un

ts /

keV

/ k

g/ d

ay

Energy (keV)

Data D2

Simulation

SIMULATIONS – D2 in ANAIS-37

C. Cuesta 34

200 400 600 800 1000 1200 1400

10-1

100

Co

un

ts /

keV

/ k

g /

day

Energy (keV)

Data D2

Simulation

SIMULATIONS – ANAIS with liquid scintillator veto (LSV)

C. Cuesta 35

3x3 detectors with ANAIS-25 features inside the LSV:• Vessel: stainless steel cylinder, 5-mm-thick.• Reflector: 0.5 mm reflector Lumirror.• Liquid scintillator medium: Linear AlkylBenzene(LAB). • PMTs: Ham. R5912, 8’’ diameter borosilicate glass

40K fromcrystals

22Na fromcrystals

PMTs all

No LSV (%) 70.3 60.2 64.2 89.1

LSV 500 keV th. (%) 19.1 5.5 31.3 73.9

LSV w/o th. (%) 15.5 1.1 9.1 71.0

Background reduction in the 1-10 keV region (Anticoincidence among cristals):

60 cm

0 2 4 6 8 10 12 14 16 18 200

1

2

3

4

5

6

cou

nts

/keV

/kg/

d

Energy (keV)

Total

No LSV

LSV 500 keV threshold

LSV w/o threshold

• ANAIS experimental proposal:

• 112.5 kg (3×3 crystal matrix) of NaI(Tl) taking data along 2016.

• Shielding, electronic front-end, DAQ and software, slow control ready for the full experiment.

CONCLUSIONS

C. Cuesta 36




• Good quality NaI(Tl) detectors from Alpha Spectra have been fully characterized:

• Outstanding light collection improving energy resolution and triggering 1 keVee.

• D2 background: 34 ppb K and 0.7 mBq/kg 210Pb, next modules should be better in both isotopes.

CONCLUSIONS

C. Cuesta 37




• Good quality NaI(Tl) detectors from Alpha Spectra have been fully characterized:

• Outstanding light collection improving energy resolution and triggering 1 keVee.

• D2 background: 34 ppb K and 0.7 mBq/kg 210Pb, next modules should be better in both isotopes.

• Good sensitivity prospects for exploring the DAMA/LIBRA signal in a model independent way.

CONCLUSIONS

C. Cuesta 38

1-6 keVee region / 100 kg / 5 years

ANAIS-25 bkg with 210Pb observed in D2

90% CL positive signal in 90% of the carried out experiments

Discovery potential!

Documents

Status of the ANAIS experiment - UCLA · ANAIS EXPERIMENT ANAIS is a project aiming to set up, at the new facilities of the Canfranc Underground Laboratory (Spain), a potassium-purified