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Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
NOSTOS:NOSTOS: a spherical TPC a spherical TPC to detect low energy neutrinosto detect low energy neutrinos
Igor G. Irastorza Igor G. Irastorza CEA/SaclayCEA/Saclay
NOSTOSNOSTOS A new concept: the A new concept: the
spherical TPC.spherical TPC. A first prototype: the A first prototype: the
Saclay sphere.Saclay sphere. Results and prospects.Results and prospects. Additional physicsAdditional physics
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
e- e
NOSTOS experimentNOSTOS experiment
EEmaxmax=18.6 keV=18.6 keV
<E><E>~~14 keV14 keV GOAL: detection of GOAL: detection of
very low energy very low energy neutrinos from a neutrinos from a tritium sourcetritium source
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
NOSTOS experimentNOSTOS experiment Oscillations at Oscillations at
“room” scale…“room” scale…
G. Gounaris, CERN seminar 23-09-04G. Gounaris, CERN seminar 23-09-04““room-size” neutrino oscillationsroom-size” neutrino oscillations
Oscillation of a Oscillation of a 10 keV 10 keV ee
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA SaclayLarge TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
NOSTOS SchemeNOSTOS Scheme
Large Spherical TPCLarge Spherical TPC 10 m radius10 m radius 200 MCi tritium 200 MCi tritium
source in the centersource in the center Neutrinos oscillate Neutrinos oscillate
inside detector inside detector volume Lvolume L2323=13 m=13 m
Measure Measure 1313 and and more…more…
10m
E
Shield
HighVoltage
DriftGaseousVolume
TritiumSource
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
10m
E
Shield
HighVoltage
DriftGaseousVolume
TritiumSource
The spherical TPC conceptThe spherical TPC concept(I. Giomataris, J. Vergados, NIM A530 (04) 330-358 [hep-ex/0303045] )
Drifting charges
MICROMEGASreadout
(max E=1.27 keV)(max E=1.27 keV)
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
The spherical TPC concept: The spherical TPC concept: AdvantagesAdvantages
Natural focusing: Natural focusing: – large volumes can be large volumes can be
instrumented with a small instrumented with a small readout surface and few readout surface and few (or even one) readout (or even one) readout lineslines
44 coverage: better coverage: better signalsignal
Still some spatial Still some spatial information information achievable: achievable: – Signal time dispersionSignal time dispersion
Other practical Other practical advantages:advantages:– Symmetry: lower noise Symmetry: lower noise
and thresholdand threshold– Low capacityLow capacity– No field cageNo field cage
Simplicity: few Simplicity: few materials. They can be materials. They can be optimized for low optimized for low radioactivity. radioactivity.
Low costLow cost
The way to obtain large detector The way to obtain large detector volumes keeping low background and volumes keeping low background and
thresholdthreshold
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA SaclayLarge TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
SourceSource & Target & Target SourceSource: 200MCi (20 kg) Tritium: 200MCi (20 kg) Tritium TargetTarget: Several possibilities as target gas:: Several possibilities as target gas:
Detailed calculation/simulation in progress to Detailed calculation/simulation in progress to assess expected signal/sensitivity, taking into assess expected signal/sensitivity, taking into account atomic effects (Gounaris account atomic effects (Gounaris et al.et al. hep-ex/0409053)hep-ex/0409053)
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
Experimental challenges: Experimental challenges: within within
reachreach ThresholdThreshold easily achievable, to be easily achievable, to be
demonstrated with underground tests demonstrated with underground tests BackgroundBackground simulations planned, to be simulations planned, to be
demonstrated with underground testsdemonstrated with underground tests Radial resolutionRadial resolution being demonstrated being demonstrated
by Saclay sphereby Saclay sphere StabilityStability first results positive, more first results positive, more
plannedplanned Scaling upScaling up intermediate size prototypes intermediate size prototypes
being designedbeing designed ElectrostaticsElectrostatics some ideas being some ideas being
demonstrated by Saclay spheredemonstrated by Saclay sphere
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
First prototype: First prototype: the Saclay spherethe Saclay sphere
D=1.3 m D=1.3 m V=1 mV=1 m3 3
Spherical vessel Spherical vessel made of Cu (6 made of Cu (6 mm thick)mm thick)
P up to 5 bar P up to 5 bar possible (up to possible (up to 1.5 tested up to 1.5 tested up to now)now)
Vacuum tight: Vacuum tight: ~10~10-6-6 mbar mbar (outgassing: (outgassing: ~10~10-9-9 mbar/s) mbar/s)
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA SaclayLarge TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
First prototype: the Saclay First prototype: the Saclay spheresphere
Simple multiplication structure: Simple multiplication structure: small (10 mm small (10 mm Ø) Ø) spheresphere
Internal electrode at HVInternal electrode at HV Readout of the internal electrodeReadout of the internal electrode
10 mm10 mm
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
First tests: GainFirst tests: Gain
Ar + 10% COAr + 10% CO22
High gains High gains (>10(>1044) achieved ) achieved with simple with simple spherical spherical electrodeelectrode
No need to go No need to go to very high V to very high V (better for (better for minimizing minimizing absorption)absorption)
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
First tests: GainFirst tests: Gain
Ar + 2% IsobutaneAr + 2% Isobutane High gains (>10High gains (>1044) )
achievedachieved
No need to go to very No need to go to very high V even at high Phigh V even at high P
P up to 1.5 bar P up to 1.5 bar tested up to nowtested up to now
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
First resultsFirst results 5.9 keV 5.9 keV 5555Fe signalFe signal
• Very low electronic noise: low threshold
• Fit to theoretical curve including
avalanche induction and electronics: system
well understood
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
First resultsFirst results
Runs of Runs of 5555Fe, Fe, 109109Cd Cd and Cosmic Raysand Cosmic Rays
Better resolution Better resolution obtained in more obtained in more recent tests with recent tests with Isobutane Isobutane (analysis in (analysis in progress)progress)
55Fe55Fe 5.9 keV5.9 keV
Ar Ar escapeescape
5555Fe Fe spectrum spectrum
with Ar+COwith Ar+CO22
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
Pulse deconvolutionPulse deconvolution
Response function Response function including the ion including the ion induction + electronics induction + electronics effects associated to effects associated to one single point charge.one single point charge.
Remove the slow tail of Remove the slow tail of the pulsesthe pulses
Recover the time Recover the time (=radial) structure of (=radial) structure of the primary ethe primary e-- cloud cloud
This analysis will not be This analysis will not be needed when a fast needed when a fast readout (MICROMEGAS) readout (MICROMEGAS) will be availablewill be available
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
First resultsFirst results
Clear time Clear time dispersion effect dispersion effect observed in observed in deconvoluted deconvoluted pulses correlated pulses correlated with distance with distance drifteddrifted
60 cm drift
50 cm drift
40 cm drift
30 cm drift
20 cm drift
10 cm drift
Template pulses
(average of 20 sample
pulses)
In Ar+CO2
P=0.25 bar
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
First resultsFirst results Even with a very Even with a very
simple (and slow) simple (and slow) readout, we have readout, we have proved the use of proved the use of dispersion effects dispersion effects to estimate the to estimate the position of the position of the interation (at least interation (at least at ~10 cm level).at ~10 cm level).
Further tests are Further tests are under preparation under preparation to better calibrate to better calibrate (external trigger (external trigger from Am source )from Am source )
Average time dispersion of 5.9 keV deconvoluted events
VS.
Distance drifted
No s
ou
rce r
un
(c
osm
ics)
Ar+CO2P=0.25 bar
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
First resultsFirst results
Stability: Stability: – tested up to ~2 months.tested up to ~2 months.– No circulation of gas. Detector working No circulation of gas. Detector working
in sealed mode. (1 pass through an in sealed mode. (1 pass through an oxysorb filter)oxysorb filter)
No absorption observedNo absorption observed– Signal integrity preserved after 60 cm Signal integrity preserved after 60 cm
drift.drift.– Not high E needed to achieve high gain.Not high E needed to achieve high gain.
RobustnessRobustness
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA SaclayLarge TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Next stepsNext steps
ElectrostaticsElectrostatics
– Field shaping ringsField shaping rings
– More ambitious ideas in mind for the More ambitious ideas in mind for the future: charging systems without electrical future: charging systems without electrical contact contact (like the ones in electrostatic (like the ones in electrostatic accelerators)accelerators)
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA SaclayLarge TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Next stepsNext steps: : Micromegas as NOSTOS Micromegas as NOSTOS
readoutreadout Very fast signals: will allow to measure precisely time Very fast signals: will allow to measure precisely time
(and space) dispersion, i.e. radial coordinate of event.(and space) dispersion, i.e. radial coordinate of event.
Spherical MICROMEGAS (?) (or series of flat elements)Spherical MICROMEGAS (?) (or series of flat elements)
2 Typical MICROMEGAS
pulses
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
NOSTOS Additional PhysicsNOSTOS Additional PhysicsNeutrino magnetic momentNeutrino magnetic moment
Best limit from Best limit from the MUNU the MUNU experiment: experiment: e e < 10< 10-10-10BB
[MUNU coll., PLB 564 (03)][MUNU coll., PLB 564 (03)]
NOSTOS NOSTOS sensitivity could sensitivity could be down to 10be down to 10-12-12BB
McLaughlin & Volpe PLB 591 (04) 229
10-12B10-11B
NO MM
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
NOSTOS Additional PhysicsNOSTOS Additional PhysicsWeinberg angle at low energiesWeinberg angle at low energies
High accuracy measurement of the High accuracy measurement of the Weinberg angle at very low energyWeinberg angle at very low energy
e e
e e
e-e-
e- e-
w-
z0
G.’t Hooft, Phys. Lett. B37,195(1971)
d /dT 1.710 47(gL2 gR
2 (1 T /E )2 gLgRmeT /E2)
gL sin2W ,gR sin2W 1/2,T 2(E cos)2 /me,Tmax 1.27keV
For T<<1 keV d/dT = a(2sin4w+sin2w +1/4)
Important: Important: atomic effectsatomic effects
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
NOSTOS Additional PhysicsNOSTOS Additional PhysicsNeutrino-nucleus interactionNeutrino-nucleus interaction
≈ N2E2
[D. Z. Freedman, Phys. Rev.D,9(74)1389]
n
Recoil energy: Emax =(2E)2/2AM Emean=Emax/3
Could be measured by a miniNOSTOS close to a nuclear reactor
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
NOSTOS Additional PhysicsNOSTOS Additional PhysicsNeutrino-nucleus interactionNeutrino-nucleus interaction
1 m3 detector (present prototype!!)
(gas at 5 bar) at 10m from a reactor
after 1 year run (2x107s), assuming full detector efficiency:
Xe ( ≈ 2.16x10-40 cm2), 2.2x106 neutrinos int., Emax=146 eVAr ( ≈ 1.7x10-41 cm2), 9x104 neutrinos int., Emax=480 eVNe ( ≈ 7.8x10-42 cm2), 1.87x104 neutrinos int., Emax=960 eV
Challenge : Very low energy thresholdChallenge : Very low energy threshold We need to calculate and measure the We need to calculate and measure the quenching factorquenching factor
from nuclear reactor
miniNOSTOSminiNOSTOS– flux=1013/cm2/s – <E> ~ 3 MeV
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
NOSTOS Additional PhysicsNOSTOS Additional PhysicsNeutrinos from supernovae Neutrinos from supernovae
with a 4 m spherewith a 4 m sphere coherent neutrino-nucleus
interaction High cross sections and reasonable
recoiling energies:– For E=10 MeV: ≈ 2.5x10-39 cm2,
Emax = 1.5 keV – For E=25 MeV: ≈ 1.5x10-38 cm2 ,
Emax = 9 keV – (Xenon assumed)
For a a typical supernova explosion and the D=4 m spherical TPC detector:
Detection efficiency independent of the neutrino flavorDetection efficiency independent of the neutrino flavor The challenge is again at the low-energy threshold detectionThe challenge is again at the low-energy threshold detection
~ 100 events detected with Xe at 1 bar for a distance of 10kpc~ 1000 events at 10 bar pressure !!!
4m prototype4m prototype
Large TPC Workshop, ParLarge TPC Workshop, Paris, 20-21 December 2004is, 20-21 December 2004
Igor G. Irastorza, CEA SaclayIgor G. Irastorza, CEA Saclay
ConclusionsConclusions Spherical TPC concept introduced in the framework Spherical TPC concept introduced in the framework
of NOSTOS proposalof NOSTOS proposal Promising as a simple way to obtain large detector Promising as a simple way to obtain large detector
volumes, keeping low background and low volumes, keeping low background and low threshold threshold
First prototype already working in SaclayFirst prototype already working in Saclay First encouraging results: low threshold, stability, First encouraging results: low threshold, stability,
no absorption, dispersion vs. drift observed.no absorption, dispersion vs. drift observed. To be done next: optimize electrostatics, develop To be done next: optimize electrostatics, develop
more calibration systems, assess background (test more calibration systems, assess background (test underground)underground)
Highly exciting physics program could be done by Highly exciting physics program could be done by NOSTOS: neutrino oscillations, magnetic moment, NOSTOS: neutrino oscillations, magnetic moment, Weinberg angle, Neutrino-nucleus interaction, Weinberg angle, Neutrino-nucleus interaction, Supernova detection,…Supernova detection,…