ArgoYBJ: further steps for the next thfuture

WAPP 2009Bose Institute, Mayapuri, Darjeeling

Dec 12th 2009By R. Santonico

Argo is an unprecedented combination of:

• Large detection area (about 7000 m2 of RPCs)• Full coverage (92%)• High granularity (about 150000 read out strips)• High time resolution (2 ns)• High altitude (YBJ 4300 m asl)

His purpose is to image the shower front and to lower the threshold energy to a few hundreds GeV

10 Pads = 1 RPC (2.80 1.25 m2)

Gas Mixture: Ar/ Iso/TFE = 15/10/75

78 m

99 m

74 m

111 m

RPC 5600 m2 ( 92% active surface)• sampling guard-ring

Central Carpet:130 Clusters

1560 RPCs

124800 Strips

BIGPAD 1

ADC

RPC

Read-out of the charge induced on

“Big-Pads”

12 RPC =1 Cluster ( 5.7 7.6 m2 )

8 Strips = 1 Pad (56 62 cm2)

BIGPAD2

The ARGO-YBJ detector

Main improvement items: on the analysis

An unprecedented detector requires an unprecedented approach to the analysis

• Shower front reconstruction:- Usually made by fitting the shower front with a conical surface- Can we do better eg using a parabolic surface o fit the front? - Crucial improvement for a good direction reconstruction of very

low energy primaries (20-30 hits below 1 TeV)• Gamma-hadron discrimination- Not implemented so far in the analysis- Crucial for the γ-ray astrophysics- A strong effort has to be invested to exploit the potential of

Argo for the γ/h discrimination

Galactic plane

HESS J1841-055

CRAB

MGRO J2031+41

PSR J2021+4026

542 days

2007 day 311–2009 day 220

nhit > 40 Smoothing window radius = 1.3°

Percent variation542 days

2007 day 311–2009 day 220

Moon shadow: all data (2006+2007+2008)

N > 6043 s.d.

9 standard deviations / month

PSF of the detector

2063 hours on-source

θ < 50°

Main improvement items: on the detector

• Analog read out- Allows to study the shower core details in the meter

scale- Extends the multiplicity measurements up to densities

of several thousend particles per m2• Use radio wave detecting antennas- to complement the information supplied by the RPC

carpet with radio signals emitted by cosmic showers-

E 100 TeV

Strip Big Pad

E 1000 TeVStrip

Big Pad

A radio wave antenna for Argo

• Radio wave signals generated by Extensive Air Showers are random signals of limited duration and wide frequency band

• They are not easy to be detected by standard “resonating” antennas

• “Progressive wave” antennas being intrinsically wide band seem to be particularly suitable for their detection

• A prototype antenna of this kind was tested at YBJ

Argo “big pad” signal vs Antenna signal and its FFT

Next steps

• The noise below 20 MHz is now well filtered in the prototype antenna

• A trigger channel searching for coincidences with the RPC carpet will be stably implemented at the beginning of 2010

• Crucial to understand what role the antenna can have for a low energy oriented detector like Argo

Conclusions

• An improvement of the analysis methods will allow Argo to fully express its scientific potential

• The multiplicity analog read out is extremely promising to study dense shower cores in detail

• The complementation of the RPC carpet with a radio wave antenna might open a new horizon