Measurement of the cosmic ray antiproton/proton flux ratio at TeV energies with the ARGO-YBJ detector

Abstract

Cosmic ray antiprotons provide an important probe to study the cosmic ray propagation in the interstellar space and to investigate the existence of dark matter. Acting the Earth-Moon system as a magnetic spectrometer, paths of primary antiprotons are deflected in the opposite sense with respect to those of the protons in their way to the Earth. This effect allows, in principle, the search for antiparticles in the direction opposite to the observed deficit of cosmic rays due to the Moon (the so-called "Moon shadow''). The ARGO-YBJ experiment, located at the Yangbajing Cosmic Ray Laboratory (Tibet, P.R. China, 4300 m a.s.l., 606 g/cm(2)), is particularly effective in measuring the cosmic ray antimatter content via the observation of the cosmic rays shadowing effect due to: (1) good angular resolution, pointing accuracy and long-term stability; (2) low energy threshold; (3) real sensitivity to the geomagnetic field. Based on all the data recorded during the period from July 2006 through November 2009 and on a full Monte Carlo simulation, we searched for the existence of the shadow cast by antiprotons in the TeV energy region. No evidence of the existence of antiprotons is found in this energy region. Upper limits to the (p) over bar /p flux ratio are set to 5% at a median energy of 1.4 TeV and 6% at 5 TeV with a confidence level of 90%. In the TeV energy range these limits are the lowest available

4.5 Years of Multi-Wavelength Observations of MRK 421 During the Argo-Ybj and Fermi Common Operation Time

“…China. It is mainly devoted to γ-ray astronomy (Bartoli et al 2012a(Bartoli et al , 2012b(Bartoli et al , 2012c(Bartoli et al , 2013b(Bartoli et al , 2014(Bartoli et al , 2015 and cosmic ray physics (Bartoli et al 2012d(Bartoli et al , 2012e, 2013c. The detector consists of a carpet (∼74 × 78 m 2 ) of resistive plate chambers (RPCs) with ∼93% of active area, surrounded by a partially instrumented area (∼20%) up to ∼100×110 m 2 .…”

A possible explanation of the knee of cosmic light component spectrum from 100 TeV to 3 PeV

“…As mentioned above, the acceleration efficiency plays an important role for the cut-off energy of the spectrum in the model. KASCADE experiments [16] show that the observed H spectrum has a knee feature at a few PeV, which is not consistent with that observed by ARGO-YBJ experiment [7,25,26]. To reproduce the observed H flux by KASCADE experiments with our model, the acceleration efficiency ( i.e.…”

“…Here β + δ = 4.7 is used [24], so η He /η H ≈ 0.31K He H . Figure 3 shows the comparison of our model results with the H + He flux observed by ARGO-YBJ experiments [7,25,26]. The H + He spectrum has a knee feature of ∼ 700 TeV [7].…”

“…And the deviation at low energy may be due to solar modulation, and we did not consider the factor in our model. [7,25,26], AMS [27,28], PAMELA [29], CREAM [30], the hybrid experiment [26] below the knee, Tibet ASγ [31], and KASCADE [16][17][18] above the knee. Long dashed and short dashed lines represent predicted fluxes of H and He components, respectively, and the solid line is the flux sum of two components.…”

The Cosmic Ray p+He energy spectrum in the 3–3000 TeV energy range measured by ARGO-YBJ

“…As it is well known, since the development of a shower presents intrinsic fluctuations, the primary energy cannot be determined on an event-by-event basis. As widely described in [4,5], the determination of the cosmic ray energy spectrum from the spacetime distribution of charged particles at ground level is a classical unfolding problem that can be dealt with the bayesian technique [6]. In order to evaluate the conditioned probabilities needed in the unfolding procedure a detailed simulation of the development of the shower in the Earth's atmosphere and of the detector response has been performed.…”