Neutrino Oscillation Detectors:a (Re?)View

Where we are? Where are we going? How do we get there?

More questions than answers

Adam Para, FermilabNuFact 02,

Imperial College, LondonJuly 5 2002

Quark and Neutrinos Mixing (Kayser representation)

' ' '

1

1

1

tiny

tiny

small

small small

small

d

d s b s

b

Weak eigenstates are mixtures of mass(strong) eigenstates

1

2

3

e

sB B

B B B

B B B

Weak eigenstates are mixtures of mass eigenstates

Mixing pattern for quarks and leptons is very different. Curious…Very curious.. What is it telling us??

Completing the Neutrino Mixing Matrix

1

2

3

e

iseB B

B B B

B B B

2 2 2133 1 3

21

23

1s (in dei

1sins gree2

4s??in n

2)e es U

2

3 0.03eU CHOOZHow small is ‘small’?

Small, otherwise known as:

If ‘small’ is not too small, then:

• mass hierarchy

•CP violating phase

|S|<0.17

First step: determine/improve limit on sin2213

Please, please, please.. Can we settle on one convention? sin2213?

Roadmap I

Agreed (?):

e oscillation experiment

Conventional beams (they are super!)

NuMI (2005)

JHF (2007-8)

Sensitivity down to sin2213~0.003

we think it is worth ~300-400 M$ (50+50, 200+100) and 3000 man-years (physicist-years?)

~ results by 2015

Major branch point: positive outcome of MiniBoone experiment

Roadmap II (??)

e appearance observed Neutrino mass hierarchy CP violation NuMI OA, Phase II, new

proton driver JHF Phase II $1.5B (0.5 + 1) Results by 2025Major branch point: m2

12 very small ‘Cheap’ version of neutrino

factories technically feasible Somebody builds a gigantic

water Cherenkov/LA somewhere

e appearance not observed Improve sensitivity down to

sin2213~0.0003 NuMI OA, Phase II, new proton

driver JHF Phase II $1.5B (0.5 + 1) one? Both??? Results by 2025Major branch point: ‘Cheap’ version of neutrino

factories technically feasible Somebody builds a gigantic

water Cherenkov/LA somewhere Is it worth the money/effort? Are there more important

issues?

Roadmap III(???)

Ultimate limit on sin2213 , or Precision determination of CP violation in

leptonic sector Lepton number violation, new physics Precision measurements Life sciences Neutrino Factory Near detectors, intermediate detector, far

detector $2-3 B 2030

So, what about detectors?

Detectors are not generic. Their design depends on: Energy regime:

JHF – mostly quasi-elastics, 1 NuMI – few pions, range out NuFact – many pions, showers

Required performance: Detect/identify e interactions Reject NC/0

Detect wrong sign muons Detect electrons determine sign Detect taus, determine sign

JHF NUMI Nu Fact

Super-beams

Neutrio Factories

CC e / NC interactions

~ 2 GeV > 5 GeV

Fine grained, relatively simple tracking calorimeter ?

Sophisticated imaging calorimeter, or

Give up/ focus on muons

Beam-Detector Interactions

Optimizing beam can improve signal Optimizing beam can reduce NC backgrounds Optimizing beam can reduce intrinsic e

background Easier experimental challenge, simpler

detectors # of events ~ proton intensity x detector mass

Split the money to maximize the product, rather than individual components

e identification/background rejection: beam + detector issue

e background

NC (visible energy), no rejection

spectrumSpectrum mismatch: These neutrinos contribute to background, but no signal

e (|Ue3|2 = 0.01)

NuMI low energy beam

NuMI off-axis beam

These neutrinos contribute to background, but not to the signal

On the Importance of the Energy Resolution

• cut around the expected signal region too improve signal/background ratio•High energy tails of the resolution function very important

First oscillation minimum: energy resolution/beam spectrum ~ 20% well matched to the width of the structure

Second maximum: 20% beam width broader than the oscillation minimum, need energy resolution <10%. Tails??

First oscillation minimum: energy resolution/beam spectrum ~ 20% well matched to the width of the structure

Second maximum: 20% beam width broader than the oscillation minimum, need energy resolution <10%. Tails??

JHF-Kamioka Neutrino Project

~1GeV beamKamioka

JAERI(Tokaimura)

0.77MW 50 GeV PS

( conventional beam)

4MW 50 GeV PS

Phase-I ( Super-Kamiokande) Phase-II (Hyper-K)

Plan to start in 2007(hep-ex/0106019)

Detectors?

Water Cerenkov: good match for sub GeV region (JHF, SPL, BB)

~1 GeV beam for Quasi-elastic interactions Simple event topology High electron ID efficiency (~40%) Good energy resolution (kinematics)

E(reconstruct) – E (True) (MeV)

=80MeV

E(

reco

nst

ruct

)

E (True)

events

Super-Kamiokande

４０ｍ

４１

．４

ｍ50,000 ton water Cherenkov detector (22.5 kton fiducial volume)

Hyper-Kamiokande (a far detector in the 2nd phase)

~1,000 kt

Candidate site in Kamioka

Good for atm. proton decay

Water Cherenkovs in US?

Off-axis beams + 2 detectors

100kmFNAL BNL

Soudan

Homestake

WIPP

(hep-ex/0205040,0204037,hep-ph/0204208)

Det. 2

NuMI Beam: on and off-axis

Det. 1

•Selection of sites, baselines, beam energies•Physcis/results driven experiment optimization

An example of a possible detector

Low Z tracking calorimeter

Issues: absorber material (plastic? Water? Particle board?) longitudinal sampling (X0)? What is the detector technology (RPC? Scintillator?

Drift tubes?) Transverse segmentation (e/0) Surface detector: cosmic ray background? time

resolution? . . .

NuMI detector workshop: October/November Fermilab/Chicago

Constructing the detector ‘wall’

Containment issue: need very large detector. Recall: K2K near detector – 1 kton mass, 25 tons fiducial, JHF proposal – 1 kton mass, 100 tons fiducial

Engineering/assembly/practical issues

Solution: Containers ?

On the importance of being mobile:mammals vs dinosaurs?

Neutrino factory, somewhere? Here we come!

Sin2213=0.05

Detectors for a Neutrino Factory

An easy case: wrong sign muons e) magnetic detector

Light yield as a function of a position make module 2 times bigger (x and y)

Fully loaded cost of a MINOS supermodule is $11M/2.8 kt

50 kton magnetized detector ~ $200 M

Economy of scale ?

MINOS Spermodule I

e e-

-

-

e e+

e +

+

Full physics menu at the neutrino factory?

Electron/tau ID in complex high energy events:Imaging detector ( Liquid Argon TPC)

Liquid Argon TPC

Excellent pattern recognition capabilitiesHigh efficiency for electron identificationExcellent e/0 rejection identification via kinematics a`la NOMADLepton charge determination if in the magnetic field

The only detector capable of fully exploiting the physics potential of the neutrino factory

Challenges of the Liquid Argon TPC

Cost effective implementation Single large cryostat Argon purity in large volumes Long drift distance Very high voltage

Safety, safety,safety Data acquisition A case of a dog, which did not bark (Conan Doyle)

50 l prototype exposed to the WANF beam + NOMAD 300 ton prototype exposed to cosmic rays in Pavia No results (QE ? e? Angular distribution of CR muons?

Uniformity of the detector? Long term stability? Other?)

Small LAr TPC in a neutrino beam at KEK or Fermilab ? :

•Proof of principle as a reliable experimental technique

•Rich source of physics information about low E neutrino interactions

Conclusions

We have a detector for low energy superbeams. Just need a beam. Water Cherenkovs likely to dominate this line of experiments for next 25 years

We have a medium energy superbeam. Just need a detector(s). Good ideas and a lot of engineering necessary to exploit the physics reach. Room for new developments.

We have minimal solution for a detector for the neutrino factory. We will build it in due time.

We have a 20 years old and still promising new technology. This is a major challenge. Need more effort here.

We are living in interesting times. Let’s go and look for e appearance!

11 Greatest Unanswered Questions of Physics

What is dark matter ? What is dark energy ? How were the elements from iron to uranium

made? Do neutrinos have mass ? … Are protons unstable ? What is gravity ? Are there additional dimensions ? How did the Universe begin ? Discover

February 2002