HAWC and HAWC-South : TeV all-sky gamma-ray experiments for the northern and southern hemispheres

Transcription

1 HAWC and HAWC-South : TeV all-sky gamma-ray experiments for the northern and southern hemispheres Michael DuVernois UW-Madison For the HAWC Collabora:on

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3 Brief take on the science HAWC Detector HAWC Preliminary Science HAWC-South Sketch/ Plausibility Backups: Milagro, Electronics, Building HAWC Offline: Let s chat southern sites, hardware, size, al:tude...

4 Why use Gamma-Rays? 4

5 Gamma-Rays Probe Accelerated Par:cles Electrons: Synchrotron Emission Probes Magne:c Field, Electron Energy Inverse Compton Sca6ering Probes Photon Field, Electron Energy Synchrotron Self Compton If photon field is synchrotron, then Electron Energies & Magne:c Field are determined Quadra:c rela:on between variability of TeV (IC) and X-rays (synch) Hadrons: p + p > π + + π o + > e + ν + γ + p + γ > π + + π o + > e + ν + γ + Inverse Compton Synchrotron 5

6 Nature s Par:cle Accelerators are Gamma-Ray Sources ExtraGalactic Galactic Pulsars Wind Nebula Active Galactic Nuclei Pulsars Starburst Galaxies Supernova Remnant Long Gamma-Ray Burst X-ray Binaries Short Gamma- Ray Burst 6

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8 Gamma-Ray Detectors: Strengths & Weaknesses Space-Based Tracking Detectors (Fermi LAT, AGILE, EGRET) + Wide field of view + Con:nuous Opera:on + Very Low Background - Small Area Limits Highest Energy - Moderate Angular and Energy Resolu:on Imaging Atmospheric Cherenkov Detectors (VERITAS, HESS, MAGIC, HEGRA, Whipple) + Best Angular Resolu:on + Large Area + Low Background - Pointed Observa:ons with small field of view - Low Duty Cycle Extensive Air Shower Detectors (HAWC, Tibet Asγ, ARGO, MILAGRO) + Wide Field of View + Con:nuous Opera:on + Large Area - Moderate Angular and Energy Resolu:on - Moderate Background Rejec:on 8

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10 Flux Sensi:vity Differential Sensitivity per Quarter Decade of Energy! 10

11 High Al>tude Water Cherenkov Detector m deep, 7.3m diameter Water Cherenkov Detectors 22,000 m 2 detector area 4100 meter site in Mexico 11

12 High Al>tude Water Cherenkov Detector m deep, 7.3m diameter Water Cherenkov Detectors 22,000 m 2 detector area 4100 meter site in Mexico 12

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14 HAWC Site Loca:on in Mexico High Altitude Site of 4100 m a.s.l. with temperate climate and existing infrastructure 17 R.L. of atmospheric overburden vs. 27 R.L. at sea level Latitude of 19 deg N HAWC Large Millimeter Telescope (50m dia. dish) Pico de Orizaba 5600 m (18,500 ) 14

15 Angle Reconstruc:on Photons convert to e+e- in the water 15

16 HAWC-30: Engineering Test of full detector HAWC-111: Operations Begins: August 2013 (283 days) HAWC-250: November, 2014 (~150Days) HAWC-300: March 2015 Present : >95% uptime HAWC Inauguration, HAWC-300: March,

17 HAWC Day TeV Sky Survey Mrk σ Geminga* - 6σ Mrk σ Crab Nebula - 38σ Galactic Plane 0σ 17 Sta:s:cal Significance 6σ

18 More data & HAWC Pass 4 reconstruc:on coming soon with 2x the sensi:vity of the previous maps! HAWC records ~ 2 TBytes of data each day. Reprocessing past data is taking ~1 months. New reconstruc:on algorithms are tested on the smaller subset of data from near the Crab. Pass 3 3.1σ/sqrt(day) Pass 4 5.5σ/sqrt(day) Pass4: 80σ on the Crab with 211 days 18

19 Pass 4 Angular Resolu:on and Background Rejec:on Data from the Crab (preliminary) Bins 7-9 Gammas Angular resolu:on for large events: Gaussian sigma ~ 0.15 o 68% containment: 0.24 o Achieving proposed resolu:on PINC Parameter for Iden:fica:on of Nuclear Cosmic Rays. Reject >99.9% of hadronic background for large events while retaining >50% of gamma rays. 19

20 HAWC: Photon-Rich Datasets Above 10 TeV! > 85 % of PMTs Hit With Strong Photon Cut Isotropic Diffuse Particle Measurements/Limits Crab Nebula 1 in 10 4 Events Kept 25% Efficiency for Photons Isotropic TeV Cannot Exceed Off-Crab Observations 20

21 Galac:c Gamma-Ray Sources Pulsar Wind Nebula Do PWN produce the positrons we detect at Earth? Supernova Remnants Does the spa:al and spectral morphology prove that SNRs accelerate hadronic cosmic rays? X-ray Binaries Does the discovery of an XRB with gamma-rays imply more binaries to discover? Pulsars Does the detec:on of TeV gamma rays imply different accelera:on mechanisms? 21

22 HAWC-111 Galactic Plane Source Finding! (ApJ in press: arxiv: )! HAWC-111 Data HAWC-111 Model 11 Point Sources Residual 22

23 Geminga: A Nearby Particle Accelerator! Contributor to the Positron Excess?! Milagro - Point Search HAWC- Point Search Positron Frac>on Yuksel, Kistler & Stanev. PRL. (2009). 1 Deg Search 1 Deg Search 23

24 Extragalac:c Gamma-Ray Sources Ac:ve Galac:c Nuclei Do blazars (AGN with jets pointed at us) accelerate the > 1 Joule cosmic rays? Starburst Galaxies Does the excess rate of SNR tell us that SNR s also accelerate the cosmic rays in our galaxy? Gamma-Ray Bursts Can these gamma rays be detected with ground based detectors? 24

25 Time Variability: Mrk 421 (HAWC-250)! 1 Week Bins 25

26 Time Variability: Mrk 501 (HAWC-250)! 1 Week Bins 26

27 Time Variability: Crab Nebula (HAWC-250)! Crab HAWC-250! 1 Week Bins 27

28 Gamma-Ray Bursts: Expect 1-2 Per Year in HAWC-300 (extrapola:ng from Fermi) Gilmore & Taboada, NIM A 2013 Null Hypothesis Burst Search Significances 2 search methods: 1) Follow up rapidly on alerts from satellites (mostly GBM). 2) Search HAWC in real :me for GRBs -> Issue GRB and fast transient alerts. ~4 sec 18 Swift-triggered reconstruction GRBs latency visible in HAWC-111 No detections yet. 28

29 Simulated HAWC lightcurve for Fermi GRB HAWC effective area ~100m 2 at 100GeV and grows rapidly with energy. Assume spectrum extends to 125 GeV and attenuation with EBL model of Gilmore. HAWC: 200 events from GRB if near zenith with ~20 background events HAWC Simulated 29

30 Probing Fundamental Physics with Astrophysical Gamma Rays Cosmology What does the measurement of the ayenua:on of gamma-rays by infrared photons tell us about the evolu:on of the universe? Lorentz Invariance Do photons of different energy travel at different speeds from distant astrophysical transients? Dark Mayer Is the dark mayer composed of WIMPs (Weakly Interac:ng Massive Par:cles) that annihilate or decay into gamma-rays? 30

31 Cosmological Infrared Extragalac:c Background Light (EBL) EBL constrains galaxy and star forma:on history High energy gamma rays pair produce with the infrared extragalac:c background light (EBL) EBL not well constrained by direct measurements due to zodiacal light e - ~TeV γ e + ~ev γ Kneiske, et al A&A

32 Dark Mayer Targets Galac:c Center (GC) Close By Large DM Content Astrophysical Backgrounds Dwarf Galaxies (DSphs) No Astrophysical Backgrounds Close By (~10 s kpc) High M/L Galaxy Clusters Distant Large DM Content Many are extended Astrophysical Background (?) Uniden:fied Gamma- Ray Sources Poten:ally Nearby DM Subhalos? Not iden:fied Op:cally (yet?)

33 HAWC Sensi:vity to Dark Mayer HAWC has sensi:vity to higher mass WIMPS Sommerfeld enhancement due to heavy boson coupling by non-rela:vis:c DM significantly increases the cross sec:on Wide field of view allows searches for all known dwarf spheroidals, galaxy clusters, M31, Galac:c Center Extended sources such as Virgo and M31 Non luminous sub halos Abeysekara, Phys. Rev. D,

34 What s Next Imaging Atmospheric Cherenkov Telescopes Cherenkov Telescope Extensive Air Shower Detectors Wide Field HAWC upgrade with sparse outrigger array LHASSO construc:on in China soon Southern array at higher al:tude? 34

35 Cherenkov Telescope Array Interna:onal project with both a Northern and Southern site Operated as a facility with Guest observer program Possible layout of southern CTA 35

36 CTA is major increase in sensi:vity 36

37 Upgrading HAWC - HAWC Sparse Outrigger Array to Enhance Sensi:vity above 10 TeV - Accurately determine core posi:on for showers off the main tank array. - Increase effec:ve area above 10 TeV by 3-4x - Funded by LANL/Mexico/MPI Heidelberg liter tanks: 1/80 th size of HAWC tanks. 37

38 LHAASO in China 38

39 Beyond HAWC: Even Lower Energy Same detector at a higher al:tude has increased sensi:vity especially at lower energies Factor of 4 increase in sensi:vity between ALMA and HAWC al:tude Sensi:vity for one year of observa:on of an array of 900 tanks with 900 PMTs at different al:tudes 39

40 Beyond HAWC: Southern Site Discovering rare transient events requires full sky coverage WCD proven technology TeV Source finder for CTA south Galac:c Center Alto Chorrillo Argen:na 4800m 40

41 Physics: Al:tude Effects Higher al:tude leads to lower energy threshold Higher in the air shower Improves ability to cross-check with IACTs EBL cutoff becomes negligible at lower energy Beyer to determine spectral shape Higher backgrounds & s:ll on the exponen:al decay of the showers Need to be able to deal with rates Simulate a strawman/simple water Cherenkov detector at differing al:tudes Want a good part of 10x acceptance of HAWC to act as finder for CTA Show this is plausible with real sites 41

42 Strawman detector Unit detector below (could use 1.5x or 2.0x this for site plan) 30 x 30 dense pack of 3m diameter, 1.5m tall RM-HDPE (9.5kton & m^2 with 60% packing) 10 35% QE PMT, facing up Local digi:za:on, pass :mes & npe for small npe, waveform for large npe & calibra:on (feature extrac:on) Boyom layer of scin:llator, or isolated water for muon detec:on, or other More details later 42

43 Moving detector around 43

44 5400m HAWC Milagro PeV p shower 44

45 Site plausibility: From Wikipedia 45

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47 Back in

48 General area Logis:cs include easy import, skilled workers, observatory infrastructures 48

49 Climate map 49

50 Also Chacaltaya, with long cosmic ray history 50

51 Drive the tanks+pmts up the hill, then fill 51

52 Electronics synergy with Next Genera:on IceCube & PINGU New PDOM electronics are being produced These are fairly general purpose, digital readouts with feature extrac:on, good for all environments, closely coupled to a 10 PMT, could be decoupled as well (electronics outside the tank) Power consump:on <2W (could be <0.5W in another year) FPGA with hard and so cores, local storage possible Built in communica:ons, capable of 1Mbps over random wire + Ethernet FADC with >100MHz bandwidth & >14b resolu:on Timing to <5ns either cabled or via Ethernet/White Rabbit Full self-calibra:on and built-in test equipment (BITE) FLASHCam electronics another op:on 52

53 Not exactly conclusions Going higher is possible, quite desirable, and plausible for a Southern Hemisphere experiment using WCD, want 10x HAWC acceptance Probably needs a different construc:on technique than HAWC, build lower and bring units up, tanks more like Auger perhaps Electronics could have significant synergies with Next Genera:on IceCube and/or other experiments, prototypes via outriggers CTA is building in the Southern Hemisphere first, finder-scope possibili:es here including collabora:on, significant CTA interest 53

54 Thank You hyp://webcamsdemexico.com/webcam-pico-de-orizaba 54

55 Milagro 2630 m altitude Pond: 80 m x 60 m 8 m deep 175 outriggers

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59 The HAWC Site La:tude: 18 o 59.7 N Longitude: 97 o 18.6 W 59

60 Tanks 60

61 Light-:ght bladder HAWC Design 3 Hamamatsu R5912 (8 ) 1 Hamamatsu R7081 (10 ) 61

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65 Current (Baseline) PDOM Block Diagram -HV Supply +5V Serial DAC HV Ctrl Comms ADC/DAC PSU To Surface PMT Base PCB Cal Pulser Pulse shaping & offset &possibly compression OSC f (sample) ~250MHz A/D 14 Bit Local Time Counter Pre-trigger Buffer Hit Packaging &Compression Write enable Hit Buffer R7081 High QE PMT Main Board Cal Flasher SDRAM FLASH Magnitude Comparator Threshold Register FPGA & ARM CPU 65

66 Save here Dominated by Fancy FPGA Save here $ PMT 66

67 PMTs Inves:ga:ng HZC Photonics Photonis produc:on line + Photonis engineering Seem to be doing the right thing, and easy to talk to (US business experience) Currently all Chinese labor + French parts Transi:oning to all Chinese materials as well Each is intended to reduce price by factor of ½ Example tube is the Auger 35% QE 9 low gain XP

68 Muon detec:on & higher gain ideas Idea = hadronic shower detec:on via percola:on neutrons from the shower, back of envelope simula:on seems to work, 1ms late, but search in :me and shape/distribu:on space, feed into gamma-hadron, needs good sims Do this with a Li diffused scin:llator layer, massive neutron cross sec:ons Scin:llator gain from Brownian diffused CdTe quantum dots (now available commercially at the 100mg level) Muon layer with water or plas:c or liquid scin:llator (or more q-dots) 68

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70 Other technology bits Hitachi 6TB He-filled, herme:c HDD, available on NewEgg. Works in vacuum. Works in a bucket of water. White Rabbit now has commercially available PHYs, open source designs, ~1ns :ming over >10km of fiber HVM HV supply, $100, <50mW All are taking advantage of mass markets for otherwise fantas:cally expensive engineering 70

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72 DDC2 Front End INPUT Single-Differen:al and Pulse Shaping COMPRESSOR ADC Input and DC Bias An:-Alias 72

73 DDC2 ADC Circuitry 73

74 Strawman Compression Calibra:on Or maybe put it here: Passive Compressor Uses op'cal excita'on: - Accurate waveshape. - No interference with signal path. - Possible extension to detector calibra'on? R7081 PMT & Base - HV + K A Toroid MSPS ADC Fiber end stuck In gel near PMT or Just radia:ng into sphere Fiber Op:c Ayenuator e.g. 10^6 Average Serial Slow ADC Average Light Output Flasher Amplitude e.g. SPE/ SPE Serial DAC LTC2601 Pulser e.g. 1kHz # Photons Narrow Pulse Width Time 74