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?

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

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

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

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

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

Neutrino Oscillations Review Like quarks, neutrino flavor and mass eigenstates are not the same: cos12 sin12 0 -sin12 cos12 0 0 0 1 1 0 0 0 cos23 sin23 0 -sin23 cos23 cos13 0 e-isin13 0 1 0 -e-isin13 0 cos13   UMNSP = Solar and KamLAND Atmospheric Future reactor or accelerator 1 0 0 0 e-i/2 0 0 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

Sampling of -Oscillation Experiments By no means comprehensive! Reactor (KamLAND) m23 & sin223 v (?) disappearance Energy: ~ GeV Baseline: 15 -13,000 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

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

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

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 = 0.563:0.079:0.301:0.057 (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

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

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.

The First KamLAND Result PRL 90 (2003) 021802 Before KamLAND Make sure you know enough about this – based on how many days of data? Tonnage, what was the actual result? Based on 145.1 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

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

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

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

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

KamLAND Photo-Multipliers PMT and acrylic panel installation 1325 17” 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

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

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

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 + 0.8 MeV - KamLAND Update - Lauren Hsu

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

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

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

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

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

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

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

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

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

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

What Were Improvements? More Statistics: 515.1 live days compared to 145.1 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

Observation of Spectral Distortion from Neutrino Oscillations Measurement of Energy Spectral Distortion Due to Oscillation: PRL 94 081802 (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 365.2 expected KamLAND Update - Lauren Hsu

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

Unparalled Sensitivity to m12 Extract Oscillation Parameters and Combine with Solar Data PRL 94 081802 (2005) PRL 94 081802 (2005) Results! Solar + KamLAND: m12 =7.9 10-5 eV2, tan212 =0.4 2 +0.6 -0.5 +0.10 -0.07 KamLAND Update - Lauren Hsu

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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 = 7.9 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

Acknowledgements Almost all pieces of this talk borrowed liberally from my KamLAND colleagues Reference: http://www.ba.infn.it/~now2004/talks/12_09_04/plen/KamLAND.pdf KamLAND Update - Lauren Hsu

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