1 / 12

GAW G amma A ir W atch A Large Field of View Imaging Atmospheric Č erenkov Telescope

GAW G amma A ir W atch A Large Field of View Imaging Atmospheric Č erenkov Telescope. Giancarlo Cusumano Ist. Astrofisica Spaziale e Fisica Cosmica, Palermo, Italy on behalf of the GAW Collaboration. 32nd International Cosmic Ray Conference , Beijing , China.

cybille
Download Presentation

GAW G amma A ir W atch A Large Field of View Imaging Atmospheric Č erenkov Telescope

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GAW Gamma Air Watch A Large Field of View Imaging Atmospheric Čerenkov Telescope Giancarlo Cusumano Ist. Astrofisica Spaziale e Fisica Cosmica, Palermo, Italy on behalf of the GAW Collaboration 32nd International Cosmic Ray Conference, Beijing, China

  2. GAW: Gamma Air Watch GAW is R&D experiment to test the feasibility of an Imaging Atmospheric Čerenkov Telescopes characterized by large field of view and adequate sensitivity. Sky surveys Transient sources Extended sources Increasing the statistics at several decades of TeV Why it is important a large field of view at TeV energies 32nd International Cosmic Ray Conference, Beijing, China

  3. 213 cm Ø 47 cm 25 cm Ø 47 cm GAW and its Optics System GAW uses a non-commercial Fresnel lens as light collector. Advantages: no shadow small thickness good transmittance easy replication The lens is composed by a central core surrounded by an intermediate corona of 12 petals and an outer corona of 20 petals. A spider support will maintain all the pieces together. The lens design will be optimized to a spatial resolution suitable to the requirement of the Čerenkov imaging and as much as possible uniform up to +/- 7°. 32nd International Cosmic Ray Conference, Beijing, China

  4. GAW and its Optics System a b The diffractive and the refractive patterns are superimposed on the same side of the lens. The performance is the superposition of the diffractive and of the refractive lenses performance. Focal variation vs. wavelength for a diffractive (a) refractive (b) patterns The dispersive nature of the diffraction is opposite to that of the material, resulting in chromatic error compensation. 32nd International Cosmic Ray Conference, Beijing, China

  5. GAW: the Focal Camera MAPMT R7600-03-M64 peculiarities (related to the electronics requirements): small pixel size (~3×3 mm2 4x4 arcmin2), and fast response (< 10 ns) to follow the very short Čerenkov light time duration. The focal detector is formed by a grid of MultiAnodePhotoMultiplierTubes, MAPMT Hamamatsu R7600-03-M64, 8×8 pixels each (baseline). The number of active channels (order of 104) constituting the detector at the focal surface makes it basically a large UV sensitive digital camera with high resolution imaging capability. Hamamatsu R7600-03-M64 32nd International Cosmic Ray Conference, Beijing, China

  6. GAW Detector Working Mode Requirement: small pixel size, to minimize the probability of photoelectrons pile-up within intervals shorter than the given sampling time (10 ns in GAW). single photoelectron counting mode Method: Well-established technique that gives a binary information of the pixel content. The MAPMT R7600-03-M64 chosen as baseline for GAW satisfies such a requirement. Outcome: The electronics noise and the PMT gain differences are kept negligible and it is then possible to strongly reduce the minimum number of photoelectrons, pe, required to trigger the system in spite of the relatively small dimension (2.13 m Ø) of the lens Instead of the usual charge integration method, GAW front-end electronics design is based on “single photoelectron counting mode” 32nd International Cosmic Ray Conference, Beijing, China

  7. GAW: performance The detection trigger rate for a Crab-like spectrum peaks at ~0.8 TeV. GAW 32nd International Cosmic Ray Conference, Beijing, China

  8. GAW: Gamma Air Watch alt-azimuth mount Slewing sped up to 1.0 deg/sec A cover on the top will protect the lens from dust 32nd International Cosmic Ray Conference, Beijing, China

  9. GAW: Gamma Air Watch Site: Calar Alto Observatory Spain, ~2150 m a.s.l. 32nd International Cosmic Ray Conference, Beijing, China

  10. GAW: Gamma Air Watch The GAW Collaboration Istituto di Fisica Spaziale e Fisica Cosmica di Palermo, IASF-INAF, Palermo Italy Instituto de Astrofisica de Andalucia, Granada Universidad de Sevilla, DFAMN-US, Sevilla Universidad de Huelva, Huelva-Spain Spain Portugal Laboratório de Instrumentação e Fisica Experimental de Partículas, LIP, Lisbon 32nd International Cosmic Ray Conference, Beijing, China

  11. GAW: Gamma Air Watch Summary and timetable GAW will test the feasibility of a Imaging Čerenkov telescopes with large Field of View using: Fresnel lens as refractive collector, single photoelectron counting mode as detection working method The main goal of GAW is to demonstrate the feasibility of refractive optics for Cerenkov observations (much large FoV (±30°) can be realised with with two double sided curved Fresnel lenses as the JEM-EUSO). Planned time schedule: Autumn 2011: assembling of the Telescope in Calar Alto, 2012: engineering and calibration phase 32nd International Cosmic Ray Conference, Beijing, China

  12. GAW baseline GAW Baseline 32nd International Cosmic Ray Conference, Beijing, China

More Related