1. Lauren Hsu Lawrence Berkeley National Laboratory
KamLAND Update
June 17, 2005
LEPP Journal Club
Lauren Hsu
Lawrence Berkeley National Laboratory
Other things to add:
Find neat pictures of trucking in the detector parts
Steal the physics scale figure
Talk about livetime, more on detector specs, more pictures of what the detector looks like?
Talk about electronics?
Show plot of correlation with reactors turning off (what’s the story? – steal Nickolai’s picture?)
What is the alpha-n background
How do we measure fiducial volume?

2. KamLAND Update - Lauren Hsu
Outline
Introduction
Role of Reactor Experiments in Neutrino Oscillations
II. KamLAND Overview and Results on 2nd Reactor Analysis
III. The Future of KamLAND Reactor Measurements
IV. Other Future Measurements: Geo-neutrinos and Be7
2nd results came out last year
KamLAND Update - Lauren Hsu

3. KamLAND KAMioka Liquid scintillator Anti-Neutrino Detector
Detecting reactor anti-neutrinos 1 km beneath Mt. Ikeyama
Inside the
Kamioka Mine
Very Basics of kamLAND, where is it and what does it detect?
What is the basic detector layout – 1 kton of LS
Maybe some history (when it turned on, when it was conceived, first results)
1 km below peak of Mount Ikenoyama (Gifu prefecture).
Surrounded by 53 Japanese Nuclear Reactors

4. Physics Reach of KamLAND
Point out that KamLAND has potential for multi-disciplinary research (though oscillations are probably the most well-known result).
KamLAND Update - Lauren Hsu

5. The KamLAND Collaboration
Tohoku U.
LBNL
Stanford
CalTech
KS State U.
U. of TN
U. of AL
TUNL
Drexel
U. of NM
U. of HI
IHEP
CENBG
What is TUNL?
~1/2 is from Tohoku, rest is mostly U.S.
~70 members
KamLAND Update - Lauren Hsu

6. KamLAND Update - Lauren Hsu
Role of Reactor Experiments in Neutrino Oscillations
KamLAND Update - Lauren Hsu

7. Neutrino Oscillations Review
Like quarks, neutrino flavor and mass eigenstates are not the same:
cos12 sin12 0
-sin12 cos12 0
cos23 sin23
sin23 cos23
cos e-isin13
-e-isin cos13  
UMNSP =
Solar and KamLAND
Atmospheric
Future reactor or
accelerator
e-i/2 0
e-i(/2+) 
Majorana phases
Say something about spectral distortions.
Jarlskog invariant
What do I want to say?
Say something about theta13 and the other parameters? – i.e. what’s the point of showing the ugly matrix?
Measuring oscillations of difference flavors, at different energies and baselines gives information about mixing matrix and mass splittings.
Oscillations through matter can discriminate between whether v1 is more nue than nux.
Matter enhanced oscillations are called “Large Mixing Angle MSW” effect? – required to explain deficit of solar neutrinos (cannot get less than 50% nue without it).
Explain on the slide what LMA-MSW is?
Simplified expression for two flavor oscillations in a vacuum:
P(ll’) = sin22 sin2(1.27m2(eV2)L(m)/E (MeV))
oscillations imply neutrinos have mass!
KamLAND Update - Lauren Hsu

8. Sampling of -Oscillation Experiments
By no means comprehensive!
Reactor
(KamLAND)
m23 & sin223
v (?) disappearance
Energy: ~ GeV
Baseline: ,000 km 2
tan12 & m 12
e disappearance
+ appearance
Energy: ~5-15 MeV
Baseline: 1.5108 km 2
m23 & sin223
vu (?) disappearance
Energy: ~ GeV
Baseline: 250 km 2
m12 & sin212
e disappearance
Energy: few MeV
Baseline: 180 km 2 -
Q: How do we know nmu goes to nutau and not nue?: ruled out by short baseline nuebar?
Q: Why isn’t there an oscillation on nue seen by atmospheric neutrinos? – is the energy too high?
Super-K (2 analyses)
Atmospheric: Looked for zenith angle (cosTheta) deviations from expected flux. Found none for nue, but did see a dip in numu (deficit in the negative cosTheta values)
Solar: B8 nue flux, observed significant deficit from expected SSM value, also looked at day/night asymmetries and seasonal variations (null results put strong constraints on oscillation parameters).
SNO: Latest results are from salt phase. Measure complete flux of all neutrinos coming from B8 spectrum.
K2K: Essentially a confirmation of the atmospheric results (shorter baseline, and with a man-made source of numu. Near detectors at KEK measure energy and flux. Presented first evidence for energy spectrum distortions last summer (beat kamland by just a few months!).
LSND (in case anyone asks): Beam of numu and nmubar directed at the detector. Looked for appearance of nuebar and nue (don’t quite understand this one). Energy range is ~100 MeV, baseline is 30 m (very short baseline accelerator experiment).
KamLAND Update - Lauren Hsu

9. Neutrino Mass Heirarchy? e  
0.0
m21
m22
m23
m12
m23
Normal or
Inverted? 2
= (1-3)10-3 eV2
atmospheric 2
= (7.90.06)10-5 eV2
Say something about sterile neutrinos?
Normal vs. inverted
M2 vs m1?
What does further precision on neutrino mass splittings tell us?
Solar and KamLAND
KamLAND Update - Lauren Hsu

10. Reactor Anti-Neutrino Experiments
Basics
Disappearance Experiment
Detect anti neutrino via inverse beta-decay
Energy range ~few MeV
Reactor anti-neutrino experiments performed since 1950’s
Detector relatively simple and basic design unchanged
Why a Reactor Neutrino Experiment?
Possibly list triva about first reactor experiment??
No matter effects
Man-made source
Opportunity to study anti-neutrino vs neutrino oscillations
KamLAND Update - Lauren Hsu

11. Anti-Neutrino Production in Reactors
235U + n  X1 + X2 + 2n
Anti-neutrinos produced in beta decay of daughter isotopes resulting from
fission
Production of anti-neutrinos well understood theoretically and fission yields
precisely monitored by power companies (to 2% uncertainty)
No need for a near detector to monitor flux!
Averaged Relative Fission Yields:
235U:238U:239Pu:241Pu = 0.563: 0.079: 0.301:0.057
Relevant isotopes (that fission?) U235, U238, Pu239, Pu241 = 0.563:0.079:0.301: (averaged relative fission yields – i.e. % ratio that neutrinos come from?).
Fission rates are a function of the power output.
Calculated neutrino spectrum (convoluted reactor spectrum w/ cross-section) verified to 2% accuracy in past reactor experiments
Net thermal power output by all Japanese Nuclear Reactors is 200 GW.
KamLAND Update - Lauren Hsu

12. Un-Oscillated Reactor Neutrino Spectrum
Verified to 2% accuracy by earlier generation of reactor anti-neutrino experiments
Say what prompt energy deposit this corresponds to and how you go between the two!
KamLAND Update - Lauren Hsu

13. Why KamLAND? KamLAND Optimizations:
More Overburden: Avoids Cosmogenic Backgrounds
Long Baseline – optimizes sensitivity to oscillations
Large (1 kTon!) – combats
1/R2 drop-off in intensity
Remove nu_atm and nu_sol - its confusing!
KamLAND sees ~1 anti-neutrino event/day at an effective baseline of 180 km.

14. The First KamLAND Result
PRL 90 (2003)
Before KamLAND
Make sure you know enough about this – based on how many days of data? Tonnage, what was the actual result?
Based on live days (7 months of data), 162 ton-year exposure. Expected 86, observed 5?
180 km effective baseline -
KamLAND is the first reactor experiment to observe e disappearance!
KamLAND Update - Lauren Hsu

15. Physics Implications for the First Result
Solar experiments have little sensitivity to DeltaM^2 due to matter effects.
Here, explain what LMA is?
Point out how sensitive KamLAND is to deltaM^2
Why aren’t solar experiments as sensitive?
Point out significance of tan^2?
KamLAND Update - Lauren Hsu

16. KamLAND Update - Lauren Hsu
III. KamLAND Overview and Results on 2nd Reactor Analysis
KamLAND Update - Lauren Hsu

17. KamLAND Update - Lauren Hsu
The KamLAND Detector
(1879)
What is the balloon made out of?
KamLAND Update - Lauren Hsu

18. KamLAND Update - Lauren Hsu
The Target Volume
Liquid Scintillator:
Serves as both the target and the
detector, > 1031 protons
20% Pseudocume + 80% Mineral Oil
+ 1.5 g/l PPO
Optimal light yield while maintaining
long attenuation length (~20 m).
Welding the Balloon
Balloon:
Separates target LS volume from
buffer oil
135 m Nylon/EVOH
(ethylene vinyl alcohol copolymer)
Supported by kevlar ropes
Date the picture!
*SAY* balloon is tear-dropped shaped
KamLAND Update - Lauren Hsu

19. KamLAND Photo-Multipliers
PMT and acrylic panel installation
” tubes
554 20” tubes (since
2/03)
Transit time spread
< 3 ns
Separated from inner
buffer by acrylic
panels
200 17” hits for 1 MeV
energy deposit
2000, 2002 (Jan is start of continuous data-taking)
KamLAND Update - Lauren Hsu

20. KamLAND Update - Lauren Hsu
The Outer Detector
3.2 kT water Cerenkov detector (~200
PMT’s)
Detects 92% of muons passing through
inner detector
Buffers inner detector from spallation
products and radioactivity in rock.
Explain what a spallation product is!!
How many OD PMT’s?
OD probably most useful for detecting muons that pass near but not through the id.
KamLAND Update - Lauren Hsu

21. Anti-Neutrino Signal Detection
Coincident energy deposits are a distinct signature of inverse beta-decay:
e + p  e+ + n
Prompt Energy: positron energy deposit
(K.E. + annihilation ’s)
Delayed Energy:
n-capture releases 2.2 MeV , ~200 s later
Coincidence events *suppress* background – i.e. distint from anything else that can happen.
Neutron capture on H is 0.33 barns
KamLAND Update - Lauren Hsu

22. Selecting Candidate Events
Apply Time and Spacial Cuts to Obtain Candidate Coincidence Events
Candidate Coincidence Events: t = [0.5, 1000]s
What point do you want to make here?
e energy obtained from E = Eprompt MeV -
KamLAND Update - Lauren Hsu

23. Basic KamLAND Data Reconstruction
How much energy deposited and where?
Energy Reconstruction:
Energy  Number of Hit PMT’s
Correction for Vertex Position
Corrections for Quenching and
Cerenkov
Vertex Reconstruction
Determined by Very Precise Timing of Hits (~ few ns):
Inherent Detector Resolution ~15cm.
Based on push-pull minimization algorithm.
Basically we want to know “How much energy was deposited in the detector and where?”
Energy and Vertex fitter Calibrated w/ Co60, Ge68, Zn65, and AmBe deployed along the z-axis.
KamLAND Update - Lauren Hsu

24. KamLAND Update - Lauren Hsu
Energy Calibration
What is the balloon made out of?
KamLAND Update - Lauren Hsu

25. KamLAND Update - Lauren Hsu
Energy Estimation
Correcting for Nonlinearity of Energy Scale -
Only observe e above 3.4 MeV
(Eprompt = 2.6 MeV)
What is the balloon made out of?
KamLAND Update - Lauren Hsu

26. Rate of Muons hitting KamLAND is ~1 Hz
Muon Tracking
Rate of Muons hitting KamLAND is ~1 Hz
Reconstruction of Tracks:
Pattern recognition based on
expected timing of inner
detector hits
Good agreement with
simulation of muons passing
through detailed mountain
topography
Don’t forget to mention why we are so concerned about muons!!
Roughly describe how the tracker works

27. Uncorrelated Backgrounds
Lots of steel in the chimney region!
Uncorrelated backgrounds:
From radioactive isotopes
in detector and surrounding
material.
Activity concentrated near
balloon
Fiducial volume cut defined
at r = 5.5m
KamLAND Update - Lauren Hsu

28. Correlated Cosmogenic Backgrounds
Muons interacting with material
produce neutrons and delayed
neutron  - emitters
Spallation Products
He8 is the other, thought to consist of very little of the actual delayed beta emitter bg.
Li9 beta decays and then the resulting nucleus emits a neutron – mimics the signal
Rate of events in muon shield is used to estimate rate in surrounding rock (of neutrons)
He8 thought to be a negligeable contribution
KamLAND Update - Lauren Hsu

29. KamLAND Update - Lauren Hsu
13C(,n)16O Background
low energy
Explain what the nuclear notation means!
What’s the story? – not detected in our first analysis.
The 4.4 MeV peak is from neutrons scattering off of C12 and exiting it (emits a 4.4 meV gamma).
~6 MeV is two gammas from two exited states of O16
~6 MeV
4.4 MeV
Background Prompt E (MeV)
KamLAND Update - Lauren Hsu

30. KamLAND Update - Lauren Hsu
KamLAND Reactors
Total reactor
power uncertainty
in analysis is 2%
(conservative estimate)
What’s the point of this slide?
KamLAND Update - Lauren Hsu

31. Dip in Nuclear Power Output
KamLAND
no-osc rate e events/day
Fix label on plot.
Add an arrow
Falsified saftey records prompted shutdown of several nuclear power plants
KamLAND Update - Lauren Hsu

32. Looking for Correlations in Un-Oscillated Rate Changes
Datapoints correspond to areas of equal flux.
KamLAND Update - Lauren Hsu

33. What Were Improvements?
More Statistics: live days compared to live days.
13C(,n)16O background discovered and included in analysis
Better Optimized Cuts (fiducial volume increased from 5m
to 5.5m)
Addition of 20” tubes (improved energy resolution from
7%/E(MeV) to 6%/E(MeV))
Reactor off-time allowed for study of correlation of signal
with reactor flux.
What is the balloon made out of?
Second results includes re-analysis of same data-sample used in first
KamLAND Update - Lauren Hsu

34. Observation of Spectral Distortion from Neutrino Oscillations
Measurement of Energy Spectral Distortion Due to Oscillation: PRL (2005)
258 events observed
365 expected
Say something about the cut at 2.6 MeV?
Say something about spectral distortions
Accidentals are the uncorrelated backgrounds
258 observed, when expected
KamLAND Update - Lauren Hsu

35. Looking for Oscillatory Behavior
0.7% goodness of fit
1.8% goodness of fit
Goodness of fit = confidence level? Probability of getting a worse X2.
Simplified expression for two flavor oscillations in a vacuum:
P(ll’) = sin22 sin2(1.27m2(eV2)L(m)/E (MeV))
KamLAND Update - Lauren Hsu

36. Unparalled Sensitivity to m12
Extract Oscillation Parameters and Combine with Solar Data
PRL (2005)
PRL (2005)
Results!
Solar + KamLAND: m12 = 10-5 eV2, tan212 =0.4 2
+0.6
-0.5
+0.10
-0.07
KamLAND Update - Lauren Hsu

37. KamLAND Update - Lauren Hsu
IV. The Future of KamLAND Reactor Measurements
KamLAND Update - Lauren Hsu

38. Future Improvements: Reactor Analysis
Further Improvements Require Reducing Systematic Uncertainty!
Systematic Unc. on Rate %
Fiducial Volume
4.7
un-oscillated e spectrum (theor.)
2.5
Energy Threshold
2.3
Reactor Power
2.1
Cut Efficiency
1.6
Fuel Composition
1.0
Cross Section
0.2
Livetime
0.06
Total
7.1
Make sure how you understand the impact on the shape analysis – these uncertainty are for rate only?
Compare to statistical uncertainty: 6.7%
Better understanding of 13C(,n)16O will also improve shape analysis
KamLAND Update - Lauren Hsu

39. Full Volume Calibration
A new full-volume calibration device
Off-axis calibration to improve energy and vertex estimation
Reduce fiducial volume uncertainty
Testing 4 at LBNL
Make sure how you understand the impact on the shape analysis – these uncertainty are for rate only?
Source placement uncertainty of 2 cm will measure fiducial volume to 2-3% uncertainty
KamLAND Update - Lauren Hsu

40. KamLAND Update - Lauren Hsu
A Muon Tracker
Gold-plated muon events will
cross-check the muon track-
reconstruction.
Three layer tracking chamber
prop tubes
~200 events per day in
coincidence with inner detector
x-y resolution of 2-3 cm.
assembled by graduate
student(s) at LBNL.
What is the balloon made out of?
KamLAND Update - Lauren Hsu

41. A Full-Detector Simulation
Geant4 visualization of KamLAND
Goal: A Tuned Full-Detector Simulation
Construction was 5 years (fast!).
Helps to reduce systematic uncertainty
for next analysis and increase understanding of detector
KamLAND Update - Lauren Hsu

42. A Change in Effective Baseline?
Shika upgrade will be complete in 2006.
Impact on baseline will depend on the oscillation parameters!
(sin212, m2) 12
What are the LMA parameters? And why does it have such a huge variation?? – from first KamLAND result? (Inoue had it at the beginning of this talk).
CLARIFY the (lefthand) y-axis.
KamLAND Update - Lauren Hsu

43. Projected Future Sensitivity
KamLAND will continue
to make the most sensitive
measurements on m2 for the forseeable future 12
What improvements do we assume?
KamLAND Update - Lauren Hsu

44. KamLAND Update - Lauren Hsu
V. Other Future Measurements: Geo-neutrinos and Be7
KamLAND Update - Lauren Hsu

45. KamLAND Update - Lauren Hsu
Geo-Anti-Neutrinos -
surface heat flux measurements
First search for geologically produced e!
16 TW of Heat predicted from decay of
238U and 232Th concentrated in earth’s crust
Total Heat radiated by Earth is ~44 TW
What is the source of heat and antineutrinos?
Never been measured before!
Say wha y anti neurtinos have to do with all this (measure u an Th).
No one has done this before, so whether or not kamland sees anything, we will at least put the first upper limit on this.
KamLAND Update - Lauren Hsu

46. A Measurable Spectrum Below 2.6 MeV
Geo-neutrino analysis is
very sensitive to quenched neutrons
from 13C(,n)16O background
Th + U signal
What is the balloon made out of?
reactor - e
background -
KamLAND Update - Lauren Hsu

47. Be7 Phase: 2nd KamLAND Phase
KamLAND Update - Lauren Hsu

48. An Ambitious Purification Project
Detecting e
Via elastic Scattering
(no coincidence to
suppress radioactive
backgrounds)
What is the balloon made out of?
KamLAND Update - Lauren Hsu

49. KamLAND Update - Lauren Hsu
Purification R&D
Current R&D shows promising results.
Kr removal is through He
bubbling and Kr trap
~10-4 achieved
What is adsorptions exactly
Talk about yellowing of scintillator?
RGA (Residual gas analyzer).
$10 million must be spent this year
Construction of Purification Hall already begun
3 Distillation towers will be installed.
KamLAND Update - Lauren Hsu

50. Post Purification Goal
What is the balloon made out of?
KamLAND Update - Lauren Hsu

51. KamLAND Update - Lauren Hsu
Timeline for KamLAND
Mention that we intend to continue taking data for reactor phase!
Excavation of new purification chamber
started in April and nearly finished.
KamLAND Update - Lauren Hsu

52. KamLAND Update - Lauren Hsu
Summary
KamLAND is the first experiment to observe disappearance of reactor
anti-neutrinos (99.998% significance).
Latest results (summer 2004) show evidence for spectral distortion.
combined solar-experiment and KamLAND results give:
m2 = 10-5eV2 and tan2 = 0.40
Future reactor measurements will benefit from full-volume calibration, a
muon tracker, full-detector Monte Carlo, and purification.
Expect results soon on geo-neutrinos – the first limit ever for
observation of anti-neutrinos produced from the earth.
Phase II of KamLAND: 7Be neutrinos from the sun. Purification stage
is already beginning, and measurements to start in 2007.
+0.6
-0.5
+0.10
-0.07 12 12
What is the balloon made out of?
KamLAND Update - Lauren Hsu

53. Acknowledgements
Almost all pieces of this talk borrowed liberally from
my KamLAND colleagues
Reference:
KamLAND Update - Lauren Hsu

54. KamLAND Update - Lauren Hsu
Mozumi 4/05
KL Control Room
to Kamioka Mine
KamLAND Update - Lauren Hsu