Transcript Document
The INO project
BARC-CU-DU-HRI-Hawaii-HPU-IITB-IMSC-IOP-PU-PRL-SINP-SMIT-TIFR-VECC
A brief introduction to neutrinos
Schematic of the tracking Resistive Plate Chamber (RPC)
Neutrinos were proposed by Pauli to save the laws of conservation of energy and angular momentum and statistics in nuclear beta
decay. It has zero electric charge, mass 0 and exists, as far as we know, in 3 varieties viz. e corresponding to the electron
and its heavier cousins the muon and tau lepton. Neutrinos interact only weakly with matter making them very hard to detect. For
example, a 1 MeV e has a mean free path in matter of about 108 km. Each neutrino has, if it is a Dirac particle, its antiparticle
partner. However it could also be its own antiparticle (Majorana particle). If so one should observe neutrinoless double beta decay.
Some pictures of the test setup
Two 2 mm thick float Glass
Separated by 2 mm spacer
2 mm thick spacer
Pickup strips
Sources of neutrinos
Atmospheric neutrinos - cosmic ray interaction in upper atmosphere produce and whose decay generates roughly two
for every e, E GeV, neutrino flux (e ) 105 m2 sec1
Solar neutrinos - E 0.1-15 MeV, (e ) 6 1014 m2 sec1
Neutrinos from man made sources such as nuclear power reactors - E 0.1-5 MeV, (e )
Geoneutrinos – from beta decays of
40K,
1013
m2
sec1 GWth1 at
Glass plates
1 km
U and Th chains (contributing 40% heat production in earth) E 0.1-2 MeV, (e )
Graphite coating on the outer surfaces of glass
Complete RPC
5 1010 m2 sec1
How does the RPC work
Supernova explosions in the cosmos where 99% energy released as neutrinos (total no. of neutrinos emitted over few secs 1058
Glass
Plates
1. SuperKamioka - anomalous ratio of /e for atmospheric neutrinos and solar e deficit confirming the results of the pioneering
37Cl experiment of Davis (fetching him the 2002 Nobel prize in Physics)
Graphite
Spacers
8 KV
Signal pickup (y)
Neutrino physics has witnessed an explosive growth following some landmark experiments :
Graphite
A passing charged particle induces an avalanche, which develops
into a spark. The discharge is quenched when all of the locally
available charge in an area 0.1 cm2 is consumed.
2. Sudbury Neutrino Observatory (deficit of solar e observed as other active species through the neutral current interactions)
Before
3. CHOOZ (no deficit of reactor anti-e over L 1 km) & KamLand (deficit of reactor anti-e over L 200 km)
After
++++++++++++++++++++
-------------------------
Atmospheric neutrinos were first detected in KGF (1965) by a TIFR group. The Indian Neutrino Observatory (INO) is an initiative
to revive underground experiments in this exciting field (see http://www.imsc.res.in/~ino). An MoU signed by participating DAE
institutes on 30th August, 2002 to work towards a proposal for INO.
Efficiency and timing of glass RPC
++++++
----------
++++++
-------
The discharged area recharges slowly through the high-resistivity
glass plates.
RPC gas mixture
Freon 134a : 62%
Argon
: 30%
Isobutane : 8%
All the above results with RPC in streamer mode. For
higher count rate capability and longetivity it could be
operated in the avalanche mode (lower HV, amplification
needed, better timing
After discussing various possibilities it was decided to work towards a 50-100 kT magnetized iron calorimeter (ICAL) with tracking
gas detectors for measuring the momenta of charged products following neutrino interaction with the detector material. The physics
goals of such a detector are:
Schematic of 50 kT magnetized iron calorimeter with tracking detector trays
The favored explanation of the results of neutrino
Because of the small neutrino event rates
experiments is that the neutrino flavour and mass
cosmic ray muons are the most important source
eigenstates are not the same, that at least two
of
background.
This
can
be
reduced
to
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++Precise
determination of
species
have
non-zero,
but
small
masses
and
that
manageable
levels
by locating
theatmospheric
neutrino neutrinos
neutrino
oscillation
parameters
using
matter effects cause resonant transformations of
detector deep underground (depth 1 km) in
)-N(
)]/[N(
)+N()] for sin2 2 0.05
neutrino
flavours
(MSW
effect)
Matter
for neutrinos and antineutrinos, observed via R(L/E)
= [N(
mineseffect
or tunnels
13
Oscillations (2 flavors)
Possible CP and CPT violation in leptonic sector (also if sin2 213 Neutrino
0.05)
Study of Kolar events, ultra high energy neutrinos and multimuon events
Neutrino flavor (e, ) & mass eigenstates (1,2)
could neutrino
be different,
in general
In future ICAL could be used as the end detector in a long baseline accelerator
experiment
for determining oscillation
e
cos allows
2 the
sin possibility
parameters at a higher precision. The geographical location at a latitude
of11.5N
of probing the earth’s
1
core using accelerator neutrinos from Fermilab, USA
1 sin 2 cos
In a weak process flavor eigenstates are
produced which propagate in time as
( t ) 1e
iE 1t
C e ( t ) e C f
P ( e f ; t ) sin
2
E 2 E1
cos 2 e
m 2 m1
2
2 sin [
2
2E
Dm
sin
A possible configuration of current coils and magnetic field lines and direction
f
1
2
2
iE 2 t
( E 2 E1 )t ]
2
2E
1 . 27 D m L
2
Cosmic muon flux versus depth
Schematic of atmospheric neutrino
transport through earth to detector
P ( e f ; L ) sin
2
2 sin
2
E
Disappearance of through
Of the two possible sites, Rammam near Darjeeling in West Bengal and
Pushep near Ooty in Tamilnadu, the latter has been chosen as the preferred
site on the basis of seismicity, proximity to industrial towns, equator,
connectivity etc.
Schematic of underground experimental cavern
2 (1.27
2 L/E)
up(
) / Ndown
) vs-L/E
1 - sin2 (2Q)Nsin
Dm(
sin2 (2Q) sin2 (1.27 Dm2 L/E)
(a simulation for ICAL)
Detector
Size of cavern : 150 m 22 m 30 m
Earth
Site & infrastructure detailed project report by March, 2007
Active collaboration from HEP and NP community is requested !
Panoramic view of Pushep site from TNEB guest house at
Masinagudi