1 / 33

RPCs in the ARGO-YBJ experiment

RPCs in the ARGO-YBJ experiment. P. Camarri (University of Roma “Tor Vergata” and INFN Roma 2) for the ARGO Collaboration Workshop on Physics with Atmospheric Neutrinos and Neutrinos from Muon Storage Rings Mumbai, August 1-2, 2005. The ARGO-YBJ Collaboration. Collaboration Institutes:

benedict-green
Download Presentation

RPCs in the ARGO-YBJ experiment

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. RPCs in the ARGO-YBJ experiment P. Camarri (University of Roma “Tor Vergata” and INFN Roma 2) for the ARGO Collaboration Workshop on Physics with Atmospheric Neutrinos and Neutrinos from Muon Storage Rings Mumbai, August 1-2, 2005

  2. The ARGO-YBJ Collaboration • Collaboration Institutes: • Chinese Academy of Science (CAS) • Istituto Nazionale di Fisica Nucleare (INFN) Spokesman: Z. Cao Spokesman: B. D’Ettorre Piazzoli INFN and Dpt. di Fisica Università, Lecce INFN and Dpt. di Fisica Universita’, Napoli INFN and Dpt. di Fisica Universita’, Pavia INFN and Dpt di Fisica Università “Roma Tre”, Roma INFN and Dpt. di Fisica Università “Tor Vergata”, Roma IFSI/CNR and INFN, Torino IFCAI/CNR, Palermo and INFN, Catania IHEP, Beijing Shandong University, Jinan South West Jiaotong University, Chengdu Tibet University, Lhasa Yunnan University, Kunming Zhenghou University, Henan

  3. The YangBaJing High Altitude Cosmic Ray Laboratory Longitude 90° 31’ 50” East Latitude 30° 06’ 38” North 4300 m above the sea level 90 Km North from Lhasa (Tibet) Astrophysical Radiation with Ground-based Observatory

  4. The ARGO-YBJ site

  5. Outline • Introduction Ground based g-ray astronomy • The ARGO-YBJ experiment Detector layout and RPC details Physics goals and sensitivity Present status and first measurements • Conclusions

  6. Why ground-based detectors ? Satellite measurements are limited by the E-  ( = 2 ÷ 3) law for g-ray flux CRAB (>500 GeV)  6 · 10-11 photons/(cm2 s) 1 m2 detector needs  5 · 104 hours of observation to collect 100 photons CRAB (>1 TeV)  2 · 10-11 photons/(cm2 s)  1.4· 105 hours VHE -astronomy possible only by ground-based detectors exploiting the amplification effect of the Extensive Air Showers (EAS)

  7. Air Cherenkov Telescopes EAS arrays High energy threshold ( 50 TeV) Moderate bkg rejection ( 50 %) Modest sensitivity ( Fcrab) Modest energy resolution High duty-cycle (> 90 %) Large field of view (~ 1-2 sr) Very low energy threshold ( 60 GeV) Good background rejection (99.7 %) High sensitivity (< 10-2Fcrab) Good energy resolution Low duty-cycle (~ 5-10 %) Small field of view D < 4°- 5° Detecting Extensive Air Showers

  8. The Goal • Low energy threshold < 500 GeV • Increase sensitivity ΦΦcrab 10-1 Φcrab The Solution • High altitude operation • Secondary photon conversion • Increase the sampling (~1%  100%) Improves angular resolution Lowers energy threshold A new generation of EAS arrays

  9. ARGO-YBJ Physics Goals • g-ray astronomy Search for point-like galactic and extra-galactic sources at few hundreds GeV energy threshold • Diffuse g-rays from the galactic plane and SNRs • GRB physics (full GeV / TeV energy range) • Cosmic ray physics • ratio at TeV energy • Spectrum and composition around the “knee” (E >10 TeV) • Sun and heliosphere physics (E > 10 GeV)

  10. The ARGO detector: bakelite Resistive Plate Chambers operated in streamer mode Graphite layer Bakelite plate Gas gap Bakelite plate Graphite layer PET spacer thickness of the gas volume : 2mm Gas mixture: Ar/ i-C4H10 /C2H2F4 = 15/10/75 Operating voltage = 7.2 kV (10.2 kV at sea level) Single RPC absorption current @ 7.2 kV = 3- mA Single RPC count rate @ 7.2 kV = 4 kHz

  11. ARGO RPC details (1) Bakelite plate Read-out strip panel Front-end board

  12. ARGO RPC details (2) High-voltage connection Closed ARGO chamber Low-voltage connection

  13. RPC performance in the ARGO preliminary test • Altitude effect • Efficiency TFE/ iBUT=97/3 TFE/Ar/ iBUT=75/15/10 • Time resolution Gas mixture: Ar/ i-C4H10 /C2H2F4 = 15/10/75 Operating voltage = 7.2 kV (10.2 kV at sea level) Single RPC absorption current @ 7.2 kV = 3-4 mA Single RPC count rate @ 7.2 kV = 4 kHz

  14. 12 RPC =1 Cluster ( 5.7 ´ 7.6 m2 ) 78 Clusters 99 m 74 m 78 m 111 m Detector Layout 8 Strips = 1 Pad (56 ´ 62 cm2) 10 Pads = 1 RPC (2.80 ´ 1.25 m2) Central Carpet: 130 Clusters, 1560 RPCs, 124800 Strips Layer of RPCs covering 5600 m2 (  92% active surface) + 0.5 cm lead converter + sampling guard ring time resolution ~ 1 ns space resolution = 6.5 ´ 62 cm2 (1 strip)

  15. ARGO-YBJ Experimental Hall Cluster RPC chamber

  16. Trigger and Data Acquisition • Shower mode a minimum Pad multiplicity is required on the central detector, • with space/time consistency as for a shower front • Scaler mode measurement of the Pad rate from each Cluster (integration time: 0.5 s) • Aim - detection of unexpected increases in CR flux (GRB, Solar flares …) Pad Multiplicity info Local Station (basic unit of distributed DAQ System) • Central Station • Trigger • Data storage DATA Trigger

  17. BIG PAD Read-out of the charge induced on “Big Pads” ADC RPC Detector Control System (DCS) and Analog Charge readout DCS • High voltage control and monitoring • Monitoring of environmental parameters (indoor and outdoor temperature, atmospheric pressure) • HV fine tuning (to be implemented soon) • RPC current monitoring • RPC counting rate (for detailed diagnostics: to be added soon) The DCS is crucial for detecting anomalous detector behaviours and performing the required actions to protect the system. Analog Charge Readout

  18. Opening angle Zenith angle q < 40°  4.3 h/day CRAB Whipple E-2.49 Glast Milagro 0.55 TeV s≈ψ/ 1.58 ARGO Whipple Hegra ~ 1 TeV ~ 2 TeV ~ 5 TeV Veritas Sensitivity to the Crab and angular resolution Minimum Detectable Flux (5  in 1 y) N(>1 TeV) ~ 10 T5 (>1 TeV) ~ 3 months ARGO: without any /h discrimination ! Af = 80  80 m2 ARGO can observe, in 1 year, a Crab-like source of intensity 0.7 Crab units at energies E > 0.5 TeV, with a significance of 4 standard deviations.

  19. g-hadron discrimination • Development of an effective off-line procedure • Multiscale image analysis has been showed to provide an efficient tool for gamma/hadron discrimination • Results are encouraging and allow to nearly double the detector sensitivity. • The best response is obtained in the few TeV range. • The study is now being extended to all event categories • The measurement of the muon content of the shower allows hadron background rejection at higher energies

  20. Summary of the main detector features and performance • Resistive Plate Chambers (RPC) as active elements • Space information from Strip (6.5 × 62 cm2 ) • Time information from 8-strip pads (resolution 1 ns) • Large area ( 10000 m2 ) and full coverage (5600 m2 ) • High altitude (4300 m a.s.l.) • pointing resolution (≤ 0.5 °) • detailed space-time image of the shower front • detection of small showers (low threshold energy) • large fov and high “duty-cycle” • continuous skymonitoring (-10° <  < 70°)

  21. Status of the experiment • 16 clusters (~ 700 m2)in stable data taking for 10 months (Jan 2004 till October 2004) • gas mixture optimization • fine tuning of electronics parameters • long term test of the input-stage protection of the FE electronics, necessary to avoid damages due to high energy showers (tests at Roma 2 and in Tibet): fully successful • monitoring of RPC efficiency • time calibration operations • check of the reconstruction algorithms • 42 clusters (~ 1900 m2) in data taking since the end of 2004 • detecting area large enough for Solar Flare and GRB searches. • 100-110 clusters (~ 4500 m2) in data taking at the end of 2005 • Completion of the central carpet in spring 2006

  22. Trigger rates (threshold N > 60 pads)

  23. Shower Front on 42 Clusters (41 x 46 m2)

  24. Event reconstruction with 42 clusters (PRELIMINARY) Zenith angle distribution Direction cosine distributions <l> = -0.016 <m> = 0.025

  25. DCS: HV monitoring (16 clusters, 10/02/2005)

  26. DCS: RPC current monitoring (16 clusters, August 2004) • Average Total RPC current • Average barometric pressure • Average hall temperature

  27. doubles single pad Counting rate as a function of time 4 Clusters during 3.5 days All Clusters react homogeneously to external changes

  28. ~30 part/m2 ADC Counts on each big-pad Graphical elaboration Analog Charge Readout: event on 4 Clusters (180 m2) at YBJ (PRELIMINARY) Full scale = 4000 ADC counts = 300 mV 1 m.i.p = 2 mV

  29. 4000 ADC counts ~ 90 p/m2 Very big shower !! Some events…

  30. More events…

  31. Conclusions • The detector performance is turning out to be as good as expected • All the subsystems (DAQ, DCS, ACR) are fully operational; further improvements are foreseen on the DCS for redundancy • The analysis of the data collected on a ~ 1900 m2 carpet is in progress: early results are going to be presented at ICRC 2005 • The installation is in progress and will be completed in 2006 • Most important, a stand-alone RPC apparatus is turning out to be a crucial tool for cosmic-ray astrophysics, apart from its already established applications as a muon-trigger detector in experiments at colliders

More Related