Atmospheric Neutrinos Atmospheric neutrino detector at Kolar Gold Field –1965
2 More on KGF
KGF Proton Decay Experiment
3 INO Collaboration
B.S.Acharya, Sudeshna Banerjee, P.N.Bhat, S.R.Dugad, P.Ghosh, K.S.Gothe, S.K.Gupta, S.D.Kalmani, N. Krishnan, N. K Mondal, B.K.Nagesh , P.Nagaraj, Biswajit Paul, A.K.Ray, Probir Roy, B.Satyanarayana, S.Upadhaya, P.Verma Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai V.M.Datar, M.S.Bhatia, S.K.Kataria Bhabha Atomic Research Centre, Mumbai P. Bhattacharya, S.Bhattacharya, S. Chattopadhyay, A.Ghoshal, A.Goswami K. Kar, D.Majumdar, P.B.Pal, S. Saha, M. Sharan, S.Sarkar, S.Sen Saha Institute of Nuclear Physics, Kolkata S. Chattopadhyay, M.R.Datta Mazumdar, P.Ghosh, G.S.N.Murthy, T.Nayak, Y.P.Viyogi Variable Energy Cyclotron Centre, Kolkata Amitava Raychaudhuri Calcutta University, Kolkata M.V.N.Murthy, D.Indumathi Institute of Mathematical Sciences, Chennai A. Datta, R.Gandhi, S.Goswami, S. Rakshit, P.Mehta Harish Chandra Research Institute, Allahabad S.C.Phatak, D.P.Mahapatra IOP, Bhubaneswar Amit Roy 41 Experimentalists + Engineers Nuclear Science Centre, New Delhi 22 Theorists J.B.Singh, M.M.Gupta, V.Bhatnagar Panjab University, Chandigarh S.D.Sharma Himachal Pradesh University, Simla A.Joshipura, S.Rindani P.R.L., Ahmedabad A.Bhadra,B.Ghosh,A.Mukherjee,S.K.Sarkar North Bengal University S.Umasankar IIT, Mumbai S.K.Singh AMU
Scientific Advisors: G.Rajasekaran, Bikash Sinha, Ramnath Cowsik,V.S.Narasimham, H.S.Mani, Amit Roy 4 Current Initiative
• Two phase approach: • Phase I ~ 2 Yrs. – Detector R & D – Site survey – Human resource development through training and workshops • Phase II – Construction of the detector
• Detector Possibilities:
– Magnetised iron with RPCs or glass spark chambers. – Alternate detector design.
• Should be an international facility
5 Neutrino Oscillations For neutrinos, weak eigenstates may be different from mass eigenstates.
ν e =ν1 cosθ +ν 2 sinθ
ν µ = −ν1 sinθ +ν 2 cosθ
In a weak decay one produces a definite weak eigenstate ν (0) =ν e Then at a later time t
− iE 1t − iE 2 t ν (t ) = ν 1 e cos θ + ν 2 e sin θ
Ce (t)ν e + C fν f 1 P(ν →ν ;t) = sin 2 2θ sin 2[ (E − E )t] e f 2 2 1 m 2 − m 2 ∆m2 E − E = 2 1 = 2 1 2E 2E 1.27∆m2 L P(ν →ν ; L) = sin 2 2θ sin 2 e f E 6 Choice of Neutrino Source and Detector
• Neutrino Source – Need to cover a large L/E range • Large L range
• Large Eν Range – Use Atmospheric neutrinos as source
• Detector Choice • Should have large target mass ( 50-100 KT) • Good tracking and Energy resolution ( Tracking calorimeter) • Good directionality ( <= 1 nsec time resolution ) • Ease of construction – Use magnetised iron as target mass and RPC as active detector medium
7 Disappearance of ν µ Vs. L/E
The disappearance probability can be measured with a single L’ detector and two equal sources: θ N up(L/E) = P(νµ →νµ; L/E) N down(L’/E) L = 1 - sin2 (2Θ) sin2 (1.27 ∆m2 L/E) θ
8 Current Activities
• Detector Development. • Detector Simulation. • Physics Studies. • Data Acquisition System. • Site Survey. • International Collaboration.
9 INO Detector Concept
INO IRON CALORIMETER
RPC Trays
10 Construction of RPC
Two 2 mm thick float Glass Separated by 2 mm spacer
2 mm thick spacer Pickup strips
Glass plates
Complete RPC Graphite coating on the outer surfaces of glass 11 RPC Principles of Operation
Signal pickup(x) µ Graphite
Glass Spacers Plates 8 KV
Signal pickup (y) Graphite
A passing charged particle induces an avalanche, which develops into a µ spark. The discharge is quenched when all of the locally ( r ≈ 0.1 cm 2) available charge is consumed.
Before After
++++++++++++++++++++ ++++++ ++++++ ------
The discharged area recharges slowly through the high-resistivity glass plates. 12 Principles of Operation: Rate Capability
Each discharge locally deadens the RPC. The recovery time is approximately +++++++ +++++++ ------ ρ l κε 0 A τ = RC ≅ = ρκε 0 A l
Numerically this is (MKS units)
τ = (5 x 1010 ) x 4 x (8.85 x 10-12 ) = 2 s
Assuming each discharge deadens an area of 0 . 1 cm 2 , rates of up to 500 Hz/m 2 can be handled with 1% deadtime or less. This is well below what is expected in our application.
13 Pulse Height from RPC
In streamer mode of operation, pulses are large (~100 mV into 50 ohms) and fast (FWHM ~ 15ns)
14 Test of RPC
15 Glass Spark Chamber R & D
Schematic of the RPC test setup at TIFR µ
P3 Glass RPC under test P1 P2
P6 P4 P5
Muon Trigger = P1 • P2 • P3 • P4 • P5 • P6
16 Gas Mixing Unit
17 Bubble Counter as flow rate monitor
18 RPC Efficiency and Time resolution
Freon 134a : 62% Argon : 30% Isobutane : 8%
Fermi Lab measurement
19 RPC Efficiency Studies
20 RPC Timing Studies
21 RPC Charge distribution
22 RPC Mean Charge Vs. Voltage
23 RPC Noise Pulse rate
24 RPC Cross talk
Gas Mixture Slit Size C H F :C H : Ar Cross talk (%) 2 2 4 4 10 (mm) 62:8:30 10 6.8
62:8:30 15 6.7
62:8:30 20 6.2
57:8:35 20 6.5
52:8:40 20 5.9
46:8:46 20 6.3
25 Magnet Model at VECC
• A model of the INO magnet has been fabricated at VECC to understand – If the measured field agrees with calculation. Whether 2D calculation is OK To understand magnet energizing time
Expected field inside iron 14 KG
26 Detector and Physics Simulation
• NUANCE Event Generator: – Generate atmospheric neutrino events inside INO detector • GEANT Monte Carlo Package: – Simulate the detector response for the neutrino event • Event Reconstruction: – Fits the raw data to extract neutrino energy and direction • Physics Performance of the baseline INO detector. – Analysis of reconstructed events to extract physics.
These studies are going on at all the collaborating institutes
27 Physics Performance
28 Other Physics potential
• Cosmic ray studies using multiple muon + air shower on surface • Search for magnetic monopoles • Search for WIMPs • Additional studies on Kolar Events, Double core events, anomalous cascades • Neutrinos from factories
29 Possible INO sites
• PUSHEP (Pykara Ultimate Stage Hydro Electric Project) in South India or • RAMMAM Hydro Electric Project Site
30 Possible tunnel alignments at PUSHEP
4 possible allignments of INO tunnel at PUSHEP
31 PUSHEP
Action Items: • Stress measurement at depths of 1000m •Permissions to conduct tests and approval for locating INO at PUSHEP •Possibility of building exploratory tunnel
32 Location of Rammam
33 Possible tunnel alignment at Rammam
34 International Collaboration
• Such a facility has to be an international effort. • A small beginning in detector collaboration with Gran Sasso Laboratory and Fermilab. • Discussing with JHF proponents on a possible very long base line beam towards INO. Ultimate Long base line neutrino experiment should have a beam from USA to India. • US has long term commitment towards neutrino physics. India has started R & D effort in this direction. There are lot of scope for collaboration. • There are lot more to achieve – Detector R & D – Associated Electronics – Simulation software and event reconstruction
35