1. KamLAND Update NuFact 05 Lauren Hsu June 21, 2005
Lawrence Berkeley National Laboratory
For the KamLAND Collaboration
Add a slide that discusses FIDUCIAL VOLUME?
Include picture of effective baseline?
Somewhere we need a slide(s) of how the analysis is done!

2. KamLAND KAMioka Liquid scintillator Anti-Neutrino Detector
Looking for disappearance of anti-neutrinos 1 km beneath Mt. Ikeyama
Inside the
Kamioka Mine
KamLAND is looking for disappearance of anti-neutrinos, located 1 km beneath a mountain in central Japan, shares the same mine as Super-
Surrounded by 53 Japanese Nuclear Reactors

3. Liquid Scintillator: 20% Pseudocume + 80% Mineral Oil + 1.5 g/l PPO
The KamLAND Detector
(1879)
~2.5 m thick
Do this fast! Most people will be familiar with this!
Spiel: 1 kTon detecting volume (LS), encased by thin nylon balloon, viewed by ~ and 20” PMT’s, separated from PMT’s by 2.5m thick layer of mineral oil.
Liquid Scintillator: 20% Pseudocume + 80% Mineral Oil g/l PPO
H:C ~2

4. Anti-Neutrino Signal Detection
Use coincident energy deposits of inverse beta-decay:
Signal Selection:
T = [0.5, 1000]s
R < 2m
rvertex < 5.5m
Eprompt = [2.6, 8.5] MeV
Edelayed = [1.6, 2.6]MeV
e + p  e+ + n
Prompt Energy: positron energy deposit
(K.E. + annihilation ’s)
Candidate Coincidence Events: T = [0.5, 1000]s
Coincidence events *suppress* background – i.e. distint from anything else that can happen.
Efficiency of all events is 89.8%
Neutron capture on H is 0.33 barns
Delayed Energy:
n-capture releases 2.2 MeV , ~200 s later -
e energy: E = Eprompt MeV

5. Uniform spallation products off-z
Energy Estimation
Evis/Ereal
Correcting for Nonlinearity of Energy Scale
60Co, 68Ge, 65Zn,
deployed along z
Uniform spallation products off-z
Ereal (MeV) -
Only observe e above 3.4 MeV
(Eprompt = 2.6 MeV)
Say precise energy estimation is important both for having well-defined cut efficiencies and for measuring the energy spectrum of the neutrinos….
Prl says ~3000 spallation neutrons per kTon*day.

6. Fiducial Volume Estimate
Events/bin
z deviation (cm)
z-axis (cm)
(R/6.5m)
Fiducial Volume Uncertainty
To determine how many neutrinos you would have observed in the case of no-oscillations…
Fiducial volume:
/ from flow meters
Measure position distribution of beta-decays of 12B and 12N (60 combined events per kton per day)
Gives /-0.006(stat)+/-0.006(sys) (number measured in fiducial volume compared to total – systematic error arises from reconstruction of events near balloon edge).
Additional 2.7% uncertainty comes from fact that energy is higher
Flow Meters: /
12B/12N spallation:   0.006
Energy Dependence: 2.7%
Total: 4.7%

7. Backgrounds 13C(,n)16O Prompt Energy
Uncorrelated Backgrounds from trace radioactive isotopes.
Fiducial Volume: R < 5.5m
Correlated 13C(,n)16O Background Troublesome and new!
’s produced indirectly through decay of 210Pb, a long-lived daughter of 222Rn
13C(,n)16O Prompt Energy
quenched n
~6 MeV
excited 16O
4.4 MeV
excited 12C
Prompt E (MeV)
Correlated Muon Spallation Backgrounds: fast neutrons or delayed-n -decay of 9Li
cylinder cut veto (2 s)
whole detector veto (2 s)

8. Reactor Flux 235U:238U:239Pu:241Pu = 0.563: 0.079: 0.301:0.057
Total reactor power uncertainty is 2% (conservative estimate)
Averaged Relative Fission Yields:
235U:238U:239Pu:241Pu
= 0.563: 0.079: 0.301:0.057
Say somewhere that the neutrinos are a by-produce of fission.
Instantaneous power generation, burn-up and fuel exchange records provided by Japanese power companies
Neutrino spectra measured this way from power company data has been tested to a few percent accuracy in previous reactor neutrino experiments (which ones?)
The nuebar spectrum per fiession and its error are taken from literature (which ones?).

9. Improvements Over First Result
First KamLAND Result
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 to 6%/E(MeV))
Reactor off-time  study correlation
of signal with reactor flux.
PRL 90 (2003)
State: The analysis is basically the same, but

10. Observation of Spectral Distortion
Measurement of Energy Spectrum Distortion Due to e Oscillation
(Latest KamLAND Result) -
PRL (2005)
What points do you want to make here?
Spectral distortions, background, point out when this is from
Make way for next slide.

11. Neutrino Oscillations Favored
0.7% goodness of fit
1.8% goodness of fit
Goodness of fit = confidence level? Probability of getting a worse X2.
Just another way to bin the data, shows the oscillatory behavior (washed out by the multi-baselines).
Simplified expression for two flavor oscillations in a vacuum:
P(ll’) = sin22 sin2(1.27m2(eV2)L(m)/E (MeV))

12. Unparalled Sensitivity to m12
Extract Oscillation Parameters and Combine with Solar Data
PRL (2005)
PRL (2005)
What difference did the alpha-n background make??
Say the words LMA-I favored and LMA-II disfavored (98% confidence).
Solar + KamLAND: m12 = 10-5 eV2, tan212 =0.4 2
+0.6
-0.5
+0.10
-0.07

13. 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

14. 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

15. A flexible tool for systematic studies.
More Improvements
A Muon Tracker
A Full-Detector Simulation
Include discussion on MC?
Gold-plated events
~200 events/day
x-y resolution of 2-3 cm.
A flexible tool for systematic studies.

16. 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
Possibly leave this out if there’s no time.
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.

17. 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
Th + U signal
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. -
reactor - e
background
Sorry, no results yet, but paper to be released soon!

18. Future KamLAND: 7Be Phase
Detect e from 7Be via elastic
scattering (not a coincidence signal)
Make sure how you understand the impact on the shape analysis – these uncertainty are for rate only?
KamLAND needs to reduce 210Pb
and 85Kr by 5-6 orders of magnitude!

19. Timeline for KamLAND Excavation of new purification chamber
started in April and nearly finished.
Mention what the timeline is for the reactor analysis and data-taking. How much data do we have, and how much more will we take before shutting down. (what did the last datset include?)

20. Summary
KamLAND has observed disappearance of reactor anti-neutrinos at
99.998% significance.
Latest results (PRL ) show evidence for spectral
distortion, combined solar and KamLAND results give the most precise
determination to date:
m2 = 10-5eV2 and tan2 = 0.40
Future KamLAND measurements to benefit from: full-volume
calibration, muon tracker, full-detector simulations, and purification.
Results coming soon on geo-neutrinos – the first limit or
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.
+0.10
-0.07
+0.6
-0.5 12 12
What is the balloon made out of?

21. 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

22. Looking for Correlations in Un-Oscillated Rate Changes
Datapoints correspond to areas of equal flux.
What’s the point here? – Leave it out?

23. Changes from Extra BG
What is the balloon made out of?