Stability of the IMS Radionuclide Detector Network and Lessons - PowerPoint PPT Presentation

Stability of the IMS Radionuclide Detector Network … … and Lessons Learned for Exotic Physics Searches Robert Lee, PhD, Maj, USAF Physics Department, USAF Academy Colorado Springs, CO Dan “Animal” Javorsek, PhD, Maj, USAF Air Force Test Center Edwards AFB, CA D. Brent Morris, PhD, Col, USAF Defense Threat Reduction Agency Ft Belvoir, VA

Overview • Unusual oscillations in the RASA “check source” photopeaks mimic reports of Decay Anomalies • Dark Matter & Decay Anomaly Reports rely on stability of a single detector • RASA diagnostics and mult. geographic locations offer unique capability to characterize oscillations • Our analysis supports conventional explanation for oscillations w/ implications for Anomaly Searches IMS Check Source Data Is Used To Investigate Anomalous Decays

Background • Nuclear decay rates are constant? 134 Cs 755 dN & − λ ≡ = − λ t N ( t ) N e 754 0 dt Days 753 • Many ways to perturb decay rates 752 – Chemical comp, pressure, E & B field… 751 Lagoutine Dietz Houtermans Unterw eger • Literature shows many discrepancies 109 Cd 465 – Dark Matter Searches 464 463 – Unexplained Periodicities (Neutrino Interactions?) 462 Days 461 460 459 458 457 456 Vaninbrouckx Lagoutine Schrader Unterw eger Martin Measured Half-lives for 134 Cs and 109 Cd

Background • Nuclear decay rates are constant? dN & − λ ≡ = − λ t N ( t ) N e 0 dt • Many ways to perturb decay rates – Chemical composition, pressure, E & B field… • Literature shows many discrepancies – Unexplained periodicities – Dark Matter Search 134 Cs 755 754 Days 753 752 751 Lagoutine Dietz Houtermans Unterw eger 109 Cd 465 464 463 462 Days 461 460 459 458 457 456 Vaninbrouckx Lagoutine Schrader Unterw eger Martin Measured Half-lives for 134 Cs and 109 Cd

New Interest in Anomalies 25 Nuclides, 8 Detector Types: All show 1 yr -1 Periodicities

RASA Check Source Measurements • Daily 10-15 min “check source” measurement • Check source includes – Cobalt ( 60 Co) – Cesium ( 137 Cs) – Europium ( 152 Eu) • Secondary Diagnostics – Crystal Temperature – Room Temp / Humidity – Blower Speed – Power Consumption – Mostly unreported, but valuable! Small Count Rates, But Many Years Worth of Daily Measurements

Analysis Basics Photopeaks utilized for the analysis were: 152 Eu Nuclide Decay Branching Analyzed Ratio Peak Energy [keV] β - E.C. 72% 60 Co β - 100% 1173.2, 1332.5 28% 137 Cs β - 100% 661.7 122, 245, 964, ε 72.2% 1086, 1112, 1408 152 Eu β - 27.8% 344.3, 778.9 Analysis includes: – Lomb-Scargle Power Spectrum – Shuffle Tests on Oscillations – Likliehood Analysis 152 Sm – Nelder-Mead Phase and Amplitude Fit 152 Gd – Frequency stability analysis w/ 1 yr window Annual Changes in 152 Eu Branching Ratio Might Suggest New Physics

Analysis Methodology 1) Determination of Residuals from Fit 6 x 10 2.69 2.68 2.67 Net Count 2.66 2.65 2.64 2.63 2010.432 2010.434 2010.436 2010.438 2010.44 2010.442 2010.444 2010.446 Year 2) Spectral Analysis 3) Significance Estimates Actual Data 10,000 shuffled trials

Preliminary Analysis • All stations certified at different times • Calibrations are performed periodically – Initially only 60 Co and 137 Cs, later 152 Eu – Detector swaps limit check source continuity – As a result, the longest continuous data set between detector swap is used Station Location Dates Analysis Dates USP 71 Sand Point, AK 1/1/07-4/5/13 4/17/09-4/5/13 USP 73 Palmer Station, Antarctica 3/3/06-4/5/13 6/22/09-4/5/13 USP 74 Ashland, KS 1/1/04-4/5/13 2/23/10-4/5/13 USP 76 Eielson AFB, AK 8/1/02-4/5/13 3/21/07-4/5/13 Daily RASA Operations & Diagnostics Provide a Unique Dataset

USP 73 – Palmer Station, Antarctica Search for Annual Oscillations Shuffle Prob Phase [ φ φ ] Nuclide Energy Freq Power Amp φ φ [%] Eu 121.8 0.98±0.22 4.2 0.0019 -10.2±15.8 3.7 Eu 244.7 1.14±0.14 1.5 0.0020 4.0±15.4 49 Eu 344.3 0.82±0.27 2.5 0.0014 35.3±15.6 22.7 Cs 661.7 0.87±0.15 4.4 0.0011 16.2±15.3 3.9 Eu 778.9 0.99±0.14 6.5 0.0051 6.3±15.4 0.5 Eu 964.1 0.75±0.40 5.2 0.0038 24.6±15.8 1.8 Eu 1085.9 0.96±0.25 4.9 0.0062 1.4±14.55 2.1 Eu 1112.1 0.98±0.15 10.2 0.0076 6.6±15.2 0.01 Co 1173.2 0.98±0.26 15.3 0.0037 3.5±15.8 4.60E-05 Co 1332.5 1.04±0.18 10.9 0.0030 -23.9±15.9 0.01 Eu 1408 1.04±0.18 7.0 0.0044 3.1±16.2 0.7 Annual Oscillations in a Few Peaks, but Low Significance

USP 73 – Palmer Station, Antarctica Detail of 60 Co 1173keV Peak • Small Annual Periodicity Nomalized Photopeak Data • Periodicity gets stronger in second half of data • No other spectral features Annual Peak Power Power Frequency (yr -1 )

USP 73 – Palmer Station, Antarctica 152 Eu Branching Ratio Power Power Frequency (yr -1 ) 75% Probability of Random Occurrence Frequency (yr -1 ) Count Power Detectors do not show Annual Oscillations in 152 Eu Branching Ratio

Combined Results - Frequency 2 1.8 1.6 Frequency [year-1] 1.4 1.2 1 USP71-SandPoint 0.8 USP73-Palmer 0.6 USP74-Ashland USP76-Eielson 0.4 0.2 0 0 200 400 600 800 1000 1200 1400 1600 Energy [keV] Annual Oscillations (+ Others) Found in All Detectors Studied

Combined Results - Phase 250 200 150 φ [deg] 100 φ φ Phase, φ 50 USP71-SandPoint USP73-Palmer 0 USP74-Ashland USP76-Eielson -50 -100 0 200 400 600 800 1000 1200 1400 1600 Energy [keV] Phase of Annual Oscillations Reveals a Seasonal Effect

Combined Results – Power 40 35 30 Spectral Power 25 20 15 Power Linear (Power) 10 y = 0.0068x + 1.8035 R² = 0.1884 5 0 0 200 400 600 800 1000 1200 1400 1600 Energy [keV] Strength of Oscillations are Greater at Higher Energies

State of Health Data • Many RASA Diagnostics Show Oscillations • Changes in Centroid Location Indicate Gain Shift USP71 Crystal Temperature Data Freq (yr -1 ) Outdoor Temperature 1.00 ± 0.10 Room Humidity 1.01 ± 0.12 Room Temperature 0.97 ± 0.09 Crystal Temperature 0.96 ± 0.12 Centroid Location ( 137 Cs 661keV) 0.96 ± 0.14 152 EU Total Br Ratio none Variations in Crystal Temp ( ± 2°) May Explain Periodicities

Conclusions (1/2) • Several statistically significant frequencies observed in RASA check source photopeaks – Annual (~1 yr -1 ), Rieger (~2 yr -1 ), Synodic (~10-15 yr -1 ) – Consistent w/ previous Nuclear Anomaly experiments • Photopeaks do not always show consistent signals – Low counts rates impede statistics • Phase results not consistent with previous Nuclear Anomaly experiments – Antarctica φ avg < Alaska φ avg Oscillations in RASA Check Source Data are Confirmed

Conclusions (2/2) • 152 Eu β-/E.C. Branching Ratio is Constant – Does Not Support Claims of New Physics Phenomena • Annual Periodicities Correlate with Crystal Temperature and other State of Health data – High frequency content (~10-15 yr -1 ) is harder to explain • RASA State of Health Data – Unique Time-Series Analysis Provides New Diagnostic Utility – Further Study on Crystal Temperature Variations Worthwhile Oscillations in RASA data are not “New Physics,” but the method provides unique info about IMS RASA operations!

Thank You! Jim Mattila, Laura Comes, Robin Orth Steve Huber and the entire General Dynamics Team Peter Sturrok, Ephraim Fischbach, Jere Jenkins, Tom Gruenwald Air Force Office of Scientific Research (FA9559-12-1-0027-DEF) Disclaimer The views expressed here do not necessarily reflect the views of the United States Government, the United States Air Force, or the Defense Threat Reduction Agency.