Search as long as Dark Matter Annihilations in Draco Experimental collaboration from UC

Search as long as Dark Matter Annihilations in Draco Experimental collaboration from UC www.phwiki.com

Search as long as Dark Matter Annihilations in Draco Experimental collaboration from UC

Dunaway, Jim, Host has reference to this Academic Journal, PHwiki organized this Journal Search as long as Dark Matter Annihilations in Draco Experimental collaboration from UC Davis: Paulo Afonso Maxwell Chertok Juan Lizarazo Peter Marleau Sho Maruyama John Stilley Mani Tripathi Senior Engineer: Britt Holbrook Junior Specialist: Tiffany L in addition to ry Undergrads: John Felde, Cherie Williams, Emily Rostel Technical Assistants: John Linn, Joe Trad CACTUS: A UC Davis Facility PANIC05, Santa Fe, Oct. 24, 2005 Outline Solar Two facility in addition to CACTUS Instrument: 250 channel (effective) camera Simulations in addition to Calibrations: optics & noise Energy response Crab Nebula The Dark Matter problem & Draco Data & Preliminary analysis Summary in addition to Plans M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 The Solar 2 Heliostat Array Located 15 miles outside Barstow, CA Over 1,900 42m2 heliostats. The largest array in the world. We have ~160 heliostats in the FOV of our camera. Total mirror area ~6,700 m2. Collection (ground) area ~ 40,000 m2 Effective (100% eff) area as long as E>200 GeV ~ 50,000 m2. CACTUS: Converted Air Cherenkov Telescope Using Solar 2

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M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Heliostat arrays offer large collection areas that are not possible with imaging telescopes. Solar Two is the only field large enough to contain the entire Cherenkov light pool. Utilizing existing arrays is a highly cost-effective method of constructing large area telescopes. [Solar Two was ab in addition to oned in 1998 after a successful run as a pilot plant/technology demonstration project.] Air Cherenkov Detection Technique M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Gamma Proton EM showers produce coherent in addition to compact ring-like Cherenkov wavefront. Proton showers consist of EM sub-showers due to neutral pions in addition to /or individual rings due to muons. Core diameter of light pool nearly independent of primary particle energy (refractive index in the upper atmosphere very close to unity in addition to radiating particles rapidly fall below the Cherenkov threshold). Detecting Cherenkov Light M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Ground based telescopes sample a fraction of the core light pool which is ~200m in diameter. Good energy resolution dem in addition to s a high photon detection efficiency. Night-sky background is in the range of ~3-6 x 1012 photons/m2/s/sr. Temporal coherence (~3-5 ns) of the Cherenkov wavefront allows as long as sharp coincidences between camera elements. CACTUS can exploit differences in time-structure between gamma in addition to proton showers.

Heliostat Field M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Part of the field being used. 160 heliostats available. 116-140 used in this campaign. limited by aperture CACTUS is capable of collecting nearly the entire Cherenkov light pool 80 channel camera M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Data are recorded in multi-hit TDCs with a time-of-arrival resolution of 0.5 ns. S/N as long as Cherenkov wavefront detection is excellent. Early plot from ~2002 when using only 32 heliostats. The small bump after the main peak led us to consider the technique of multiple mapping of heliostats. Time of Arrival (ns) CACTUS Timing Resolution Typical events with fitted wavefront overlaid on hits. (work in progress) M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Event Shape Analysis

Calibrations using Crab Nebula M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 The st in addition to ard c in addition to le of gamma-ray astrophysics, the Crab has been studied extensively in addition to is now believed to have a well known in addition to stable spectrum above ~200 GeV. Crab spectrum has not been established in the 10-100 GeV region, thus making it difficult to use as a st in addition to ard c in addition to le in this regime. Must rely on simulations in addition to our own measurements. M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Crab Spectrum M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 We require >7 channels in a 13 ns window as long as the event to be triggered. This 28 min sample from the Crab represents an excess rate of 42/min. The significance of this detection of Crab in 28 mins is 13 The horizontal scale is “total measured pulse height” which is closely related to the incoming energy. The lower plot is re-binned data in the 50-400 range. The range of measurements here represent an energy range of ~ 50-1000 GeV. CACTUS Total Pulse-Height Crab Excess ON-source: heliostats track the Crab as long as 30 minutes OFF-source: heliostats track a point 0.5 degree away from the Crab as long as 30 minutes.

Efficiency in addition to Effective Area M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Events generated spread uni as long as mly over a radius of 180 m with input spectrum of kE-2.4 Simulations indicate an effective area >50,000 m2 as long as energy > ~200 GeV. Aeffective = 47,000x[1 – e-0.014x(Energy-39.6)] + 11.9xEnergy Recent Crab Measurements M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 MAGIC has made measurements of the Crab with a long lever arm in energy. The lowest data point is at ~130 GeV with a flux of ~5×10-8 GeV-1 m-2 s-1. This is a good calibration point as long as comparing CACTUS with MAGIC. CACTUS Measurement of Crab Spectrum M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 CACTUS Fit dF/dE ~ 0.019 x E –2.64 (GeV-1 m-2 s-1) Errors are dominated by systematics: ~30% in Energy ~10% in Flux due to simulation error in effective area determination Point at 55 GeV is below the fit. The flux at higher energies is in good agreement with an extrapolation of the MAGIC fit. Flux (GeV-1 m-2 s-1) MAGIC 30 100 1000 Energy (GeV) – – —

Integrated Flux at Low Energies M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 ApJ 566:343:357 (2002) Angular Resolution as long as the Crab M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 A planar fit to the shower wavefront yields an angle as long as the direction of the incoming gamma ray. The Crab is a point source in addition to our excess is peaked at zero cone-angle. Simulations reproduce the shape measured in the data. The resolution in 2 is ~0.2 degrees. We hope to improve this with improvements in the fitting technique. ON-Crab ON-OFF Simulation 2 OFF-Crab Draco in addition to Dark Matter M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Draco is a dwarf spheroidal galaxy in the vicinity of the Milky Way. Estimated total mass ~0.3 – 8 x 107Msolar. Draco has low luminosity of ~2 x 105 Lsolar, so global mass-to-light ratio in the 15-400 range. Requires that Draco contain a dominant (93-99%) dark matter component. Draco is ~0.5 degrees across. Very faint in the optical. Integrated magnitude ~11 making it an ideal c in addition to idate as long as ACT observations.

Neutralinos: Attempt at underst in addition to ing Draco M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Neutralinos are generally the lowest mass superpartners in Minimal SUSY Models. Colorless, neutral in addition to stable, they are a popular c in addition to idate as long as Cold Dark Matter. Neutralinos can annihilate into quark in addition to anti-quark pairs. Resulting hadron jets will contain gammas from neutral pion decays. Annihilation rate depends on 2, where ~ r- is the density profile of neutralinos. M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 CACTUS Reach as long as Draco SUSY Parameter Space Probed by CACTUS -Effective Area = 20, 000 m2 -Energy Threshold = 50GeV -7 hrs of observation – Red curve indicates detection of a signal with 5 sigma significance as long as a SIS with a 1 au core in addition to 5 Hz background rate. -Blue curve indicates detection of a signal with 5 sigma significance as long as a modified SIS with a 1 au core in addition to 5 Hz background rate. Modified SIS (singular isothermal shell) makes neutralino profile more cuspy. Draco Observations M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Background noise coincidence rates are recorded as long as 1 us preceding the triggering event. Noise spikes due to fluctuations in addition to /or meteorites, airplanes etc can be tracked in the background noise rate which is otherwise very stable. Signal Rate (Hz) Noise Coincidence Rate 4 (or, 6) degrees in RA ~1 deg in Dec 0.5 deg in Dec 1 deg in RA Drift scans: +- 2 (+-3) degrees in RA. Typical 30 min scan

M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Sum of First 7 Draco scans These data were taken during low background rate conditions. The background is stable, while the scan data show some excess near Draco. Signal Noise Rate -2. R.A. (Relative to Draco) +2. Draco: Integral of 41 scans M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 Draco RA All Data P.H.>125 P.H.>150 P.H.>100 P.H.>200 Placing cuts on the total Pulse Height in the event (~energy) reveals that the excess is not visible above about 150, which is ~150 GeV. CACTUS Preliminary Control: Scan of Draco -1 in Dec M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 A similar set of scans in RA but offset by 1 degree in Dec show flat distributions in all energy bins. A total of 10 scans are integrated here. The scaled rates agree with the background in 41 Draco scans. CACTUS Preliminary

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Energy Distribution of Excess M. Chertok, PANIC05, Santa Fe, Oct 24, 2005 As an estimator of the energy spectrum of the excess in the Draco region, the pulse height distributions in the central region (RA < 0.8) minus the side-b in addition to s (1.0Dunaway, Jim Host

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