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Ideas and opportunities for a 2 nd generation detector

Ideas and opportunities for a 2 nd generation detector. Argo and beyond Roma Tor vergata Jul 20 2011 By R. Santonico. The scenario. In the next 6 years, during the Lhaaso construction, Argo will be the only experiment running in the YBJ laboratory

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Ideas and opportunities for a 2 nd generation detector

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  1. Ideas and opportunities for a 2nd generation detector Argo and beyond Roma Tor vergata Jul 20 2011 By R. Santonico

  2. The scenario • In the next 6 years, during the Lhaaso construction, Argo will be the only experiment running in the YBJ laboratory • Outside of YBJ, Hawk will become in about 3-4 years, his main competitor. Lhaaso in turn could compete with Hawk by equipping in a shorter time one of his 4 pools • The opportunities offered by this scenario should be oriented in two directions • To complement the present Lhaaso project, mainly based on water Cerencov, scintillation and imaging Cerenckv detectors, with some other sub-detector based on a strong new idea • To improve the present Argo detector in order to fully exploit its potential and to produce results of excellence in competition with Hawk • In the long term Argo could become the “low energy” pole of Lhaaso • The main reason of this talk (and this workshop) is to stimulate ideas to take this opportunity

  3. What is Argo • It is a full coverage array of RPCs, a detector with a 2 mm thick gaseous target at 0.6 bar pressure • A few numbers • central carpet area 5772 m2 • guard ring 996 m2 • Number of pads 18360 • Number of strips 146880 • Minimum energy required to penetrate up to the gas few hundred keV • It has been running 4 years in the present configuration (plus 2 more years in a reduced configuration) • Negligible maintenance at the moment • 17 Chambers off out of 1836. • A gas recirculation/purification system would make its running cost negligible thus creating the best conditions to continue the data taking for many years more

  4. time resolution ~1-2 ns (pad) space resolution = strip CentralCarpet: 130 Clusters 1560 RPCs 124800 Strips 99 m 74 m 8 Strips (6.5 x 62 cm2) for each Pad 10 Pads (56 x 62 cm2) for each RPC 1 CLUSTER = 12 RPCs (5.7  7.6 m2) Gas Mixture: Ar/ Iso/TFE = 15/10/75 HV = 7200 V 78 m 111 m Single layer of Resistive Plate Chambers (RPCs) with a full coverage (92% active surface) of a large area (5600 m2) + sampling guard ring (6700 m2 in total)

  5. The ARGO-YBJ Resistive Plate Chambers Gas mixture: C2H2F4/Ar/iC4H10 = 75/15/10 Operated in streamer mode Time resolution ~ 1.5 ns P. Camarri - Workshop di Dipartimento - Roma "Tor Vergata" - 8 giugno 2011

  6. Upgrade of the analysis • Present event reconstruction methods require 1 year with (specify computing power) to reprocess 3 years data. This limits the possibility to test new ideas and new approach to the analysis • Great benefit from a more powerful approach to the event reconstruction: more manpower, new programs computers, storage • Try to optimize the shower front reconstruction (for a non usual detector) in order to improve angular resolution • Try to find some discriminating factor hadron/gamma • Conical shower front with variable angle (instead of fixed angle)  correlation with the hadron/gamma nature of the shower • Non conical shower fronts? • Search for gamma-hadron discriminating parameters

  7. Lead on top of the existing carpet • According to the project and the relative MoU the Argo central carpet should have been covered with 5 mm (1 X0) Pb • Its effect would be to convert the photons which constitute >80% of the e.m. shower component. • According to the existing simulations this would increase the significance of the observed gamma sources by a factor 1.5 at least • It requires some 300 t of lead

  8. Muon detection • Although there are no muons at 1 TeV a muon detector can be extremely helpful to discriminate hadronic showers in the energy range above 5 TeV which contains anyway about 20% of the statistics (some 700 Hz trigger rate) of the recorded Argo events • Two possibilities can be considered • An array of water Cerenkov detectors around the Argo laboratory • A muon detector installed inside small tunnels excavated below the laboratory

  9. CR physics with Argo • Although Argo is optimized for low energy showers, the use of the analog read out offers the unprecedented opportunity to study the core of a 1 PeV shower at the 1 m distance scale • This focuses the importance of Argo for CR studies and the need to optimize it as a hadron shower detector

  10. Analog read-out Is crucial to extend the dynamics of the detector for E > 100 TeV, when the strip read-out information starts to become saturated. Max fs: 6500 part/m2 0 4000 0 3500 3000 2500 ARGO event 2000 1500 1000 500 Fs: 4000 -> 1300/m2 P. Camarri - Workshop di Dipartimento - Roma "Tor Vergata" - 8 giugno 2011

  11. Neutron detection • The detection of the neutron component is crucial to study hadron showers. This offer the opportunity for a very interesting R&D finalized to the neutron detection • Special scintillators (presented at the Lhaaso 2011 workshop • Gaseous detectors with the surface treated to convert the neutron

  12. M-C Yu.V. Stenkin, Beijing'2011

  13. Detection of quasi horizontal showers • The detection of quasi horizontal showers can be used as the signature of the production and decay of a τleptonfrom a ντinteraction • Horizontal showers detection can be improved with vertical chambers along the perimeter of the laboratory. • Two chambers with a 1 m concrete block in between would also give a signature of the muon component

  14. Improving present RPC detector • Revision of the RPC signal pick up • A single large area pad (56x61 cm2) instead of 8 strips, with a substantial reduction of front end electronics channels • Amplitude recorded by ADCs which would substantially improve the amount of information • 1 TDC + 1 ADC per pad • Avalanche operation (instead of streamer) • Lower operating current  lower gas consumption • Larger dynamic range • Allows to resolve a pair e+e- at a few mm distance • Calorimetric structure : 2-3 detector layers interleaved with 1 X0 of Pb would supply a relevant information about energy of the e.m. component • A relevant investment of simulation is crucial to test different ideas of optimization

  15. Conclusions • Argo has still a relevant physics potential to express. To stop it at the end of 2012 as foreseen in the MoU long time ago, would be a big scientific mistake • The possibility to improve it to compete with Hawk should be seriously considered by a large Italian collaboration • In the longer term it could become the “low energy pole” of the big Lhaaso • Some original idea in the direction of Lhaaso would be very important for a qualified participation to this experiment

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