Current Status of the Construction of the Angra Antineutrino Detector

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ANGRA Collaboration:

CBPF J.C. Anjos, G.L. Azzi, A.F. Barbosa, R.M.O. Galvão, H. Lima Jr, M. Vaz

Graduate Students: Marcelo Nascimento Souza (PhD) Thamys Abrahão (MSc) Marcio Nunes (MSc) Andre G. Oliveira (MSc) Rafael Gama (MSc) Wallace R. Ferreira (MSc) Aridio Schiapazza (MSc)

Vitor Ferraz (MSc)

Undergraduate Students: Upiratan Beatriz

Brazilian Institutions:

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The ANGRA Collaboration:

PUC-RJ Hiroshi Nunokawa

UNICAMP E. Kemp, T. Bezerra, L. F. González, T. Junqueira

UFBA Iuri M. Pepe Paulo Farias

UEFS Germano P. Guedes

UFABC Marcelo Leigui, R. Da Maceno, P. Chimenti

UFJF Luciano M. Andrade, Rafael A. Nóbrega, Augusto S. Cerqueira

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The ANGRA Collaboration: International group

A. Bernstein, N. Bowden

L. Villaseñor, E. Casimiro Linares D. Reyna

Walter Fulgione, M.Aglietta

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Neutrinos Angra Project

Development of new techniques for nuclear reactor monitoring

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DETECTOR STATUS

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Existing Infrastructure at ANGRA

-  Currently measuring background muon flux

-  Remote data acquisition from Angra-CBPF

-  Old 20´HC container placed next to reactor containment

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Top view of the container showing detector position

New container being prepared: size 40‘ High Cube model, for better shielding

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Central detector: Gd loaded water with 40 PMTs to detector Cherenkov radiation

external water shield

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Detector design (2011)

(detector + muon veto)

Central detector: Gd loaded water with 40 PMTs to detector Cherenkov radiation

Optimisation of number of PMTs:

Simulation with GEANT4 (2 MeV positrons at the center of the detector)

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Modeling of PMT fixture

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Prototype of the central detector   Mechanical Project of “Sarcophage”

]   External box: iron   Internal box: Polypropilene

PMT test setup

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Setup for testing efficiency of PMT photo-cathode

  Mounting of PMTs in the prototype tank

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Setup for testing efficiency of PMT photo-cathode

  Mounting of the prototype tank

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Setup for testing efficiency of PMT photo-cathode

  Mechanical project   ”PMT Hat” Mounting of the PMT “hat”

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Single Photoelectron Charge Spectrum Nu-DAQ

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Construction of a 50 l prototype for neutron detection in Gd loaded water ( 1 PMT)

•  252Californium source donated by CDTN / MG (2010);

•  Instalation of a small laboratory in the old CBPF linear accelerator tunnel;

•  Authorization to use the neutron source given by CNEN in 2011;

•  Some work still needs to be done

•  Instalation of water purification station concluded;

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Muon outer veto project

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Testing Setup to test the multi-anode PMT H7546B

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ELECTRONICS STATUS

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Muon electronics - conceptual diagram (2007)

Front-end electronics

VME bus

PMT

ADC 125 MHz

trigger logic

control and status registers

data builder

TDC 81 ps

28 bits stop

start*

time encoding

FPGAs

* trigger pulse from previous event

leading-edge discriminator

control data addr

signal conditioning

10 bits

FIFO

DC level-1 trigger

VII Encontro Neutrinos Angra – UFJF 1-3 de junho de 2011 Herman Lima Jr

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•  Lay-out of VME board developed in

collaboration with Brazilian industry

CADSERVICE

•  Ten units produced for tests

•  Components mounted by

CADSERVICE (Campinas, SP)

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Luciano M. de A. Filho (UFJF) Augusto Santiago (UFJF)

A. F. Barbosa (CBPF)

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Optimized Digital Detection for the Trigger System.

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Proposal

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 Digital  Filter  

Trigger  Decision  

Central  FPGA  of  NDAQ  

ADC

•  Digital  Filter  to  maximize  signal/background  ra8on  before  the  trigger.  

•  Implementa8on  →  Filter  FIR.  

•  Two  methods  tested  

1.  Joint  Filter.  

2.  Op8mized  Filter  for  amplitude  es8mate.  

•  Similar  results  for  both  filters.  

•  Op8mized  filter  has  advantage  of  output  in  Volts.  

Increase  signal/background  

ra8o  

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Optimal filter for amplitude estimate

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Signal  before  the  filter   Signal  aIer  the  filter  

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Results

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Peak/Valley  =  2.5   Peak/Valley  =  5.0  

Variance  of  the  measurement:  

Error  in  the  measurement:    

ANTES   DEPOIS  

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Detector Simulation Studies

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Simulation Software for photon propagation in the Central Detector

Rafael Antunes Nóbrega Universidade Federal de Juiz de Fora - UFJF

Faculdade de Engenharia Elétrica

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Event Generation

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UP

DOWN

FRONT BACK

Configuration 1

< 55 55 – 60 60 – 65 65 – 70 70 – 75 75 – 80 80 – 85 > 85

Hits/100 Ev./PMT

77  (+19%)  

Média / 100 Ev.

Detector Geometry Studies: With or without Winston cones?

Gustavo Valdiviesso (UFAlfenas)

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Conclusion of the Detector Geometry Studies

Geometric configuration of the 40 PMTs does not affect neutrino signal.

Final configuration to optimize muon rejection.

Better signal with Winston cones (16% more light), but technical difficulties to implement

(construction, cost... ).

Polyethilene Shielding generates at least the double of neutrons by spallation than water

Internal surface should be reflective but does not need to be polished.

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Data Analysis: simulation of expected signal and background

Signal and background Simulation:

•  Positrons (from neutrino interaction) •  Neutrons (from neutrino interaction) •  Cosmic Muons •  Cosmic Neutrons

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GEANT4: antineutrino signal

positron signal (prompt)

Neutron capture in Gd signal

Distribuition of total number of photo electrons (p.e.) observed

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GEANT4: muon background Cherenkov signal of a muon

in the target

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GEANT4: study of neutron shielding

Fluxo Experimental medido no LNGS (1000 m): En > 10 MeV

N_flux = 75 n/m2.s

Angra (nível do mar): redução 3x

N_flux = 25 n/m2.s

Atenuação da blindagem ( ~ 85% acima de 10 MeV)

N_flux = 4 n/m2.s ~ 5% de contaminação

10 MeV neutron

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µs

Counts

One day neutrino detection time

spectrum

Average ≈ 30µs

The time interval for both neutron capture in Gd and consecutive cosmic rays arrival

follow a Poisson distribution

The probability for an event to occur after a time interval ’t’ is:

1/λ = average time interval between events

1/λν ≈ 30µs = time average for n capture

1/λμ ≈ 1ms = time average for cosmic muons

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Data acquisition simulation

Simulated data for one day of data taking and data reduction by each selection criteria

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Data acquisition simulation

Simulated data for one day of data taking and data reduction by each selection criteria

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Data acquisition simulation

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Data acquisition simulation

Fit Result: Neutrino events estimated within ~ 8% uncertainty

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Conclusions •  Previous experiments demonstrated a good capability of using antineutrinos for nuclear reactor distant monitoring.

•  Neutrino laboratory already installed in Angra

•  Muon detection (background estimate) and remote data acquisition (CBPF-Angra link) working.

•  Simulation is running and guiding final detector design.

•  Electronics is ready for production phase

•  Expected data taking by beginning 2012

•  Good opportunity to develop experimental neutrino physics in Brazil and to contribute to new safeguards techniques.

•  Good opportunity to interact with local industry.

Thank you!