17 3.6 Energy spectrum of cosmic rays with taper derived from AGASA and HiRes and. Behavior of the ratio e/owith XN P (c) and RCP (d), the distribution of χik (e) and the dependence of the mean of lnP1.
Energy spectrum
Thus, lighter cosmic rays tend to be less charged and r is larger - they are less confined to the galaxy by its magnetic field. 1The transition means a reduction in the galactic component, not its disappearance, since galactic ultrahigh-energy cosmic rays can still hit Earth, although they are less confined to the galaxy.
Theoretical problems
Propagation
The main conclusion from Figure 2.2 is that regardless of the source energy, a proton cannot travel more than ~100Mpc [2] with energies according to GZK; in other words, the universe is opaque to protons with energies greater than GZK cuto. However, their cross sections are low compared to the pγCM B → pπ0 cross section, so the latter is the most important process in the case of protons.
Acceleration and production
There are higher-order diagrams for the νγ→νγ dispersion, but they have low amplitudes due to the multiple nodes present. But neutrinos can cause a GZK-like effect due to the existing cosmic neutrino background created by the expansion of the universe.
Relevance
Electromagnetic showers
From that moment on, the creation of new generations of particles stops and the cascade decreases. Equations (3.4) and (3.5) contain the two key predictions of Heitler's model: (a) the number of particles at the spray maximum is proportional to the primary energy and (b) the slant depth of the spray maximum shows a logarithmic increase with the primary energy .
Hadronic showers
Specifically, for each hadron in the cascade there are on average ~102 muons and neutrinos and ~104 electrons, positrons and photons [10]. As in the electromagnetic case, the hadronic shower reaches a maximum, characterized by Xmax and Nmax, when the charged pion energy drops below the energy at which decay and interaction occur with equal probability.
Indirect detection
Ground arrays
For example, it is not possible to carry out direct studies on the longitudinal development of the shower. Adequate first estimates about primary energy and shower direction are also advantages of the ground arrays [2].
Light detectors
AGASA studied most features of the UHECR, especially the far end of the cosmic ray spectrum. XR (400nmλ )4, where 1 and 2 refer respectively to the start and nal point of the trajectory. Furthermore, the analysis of the lateral distribution of this type of radiation can be used to estimate the maximum and primary energy of the shower.
First, the positions of the activated pixels are used to find the shower-detector plane (SDP), which contains both the detector and the shower axis. Finally, using the uorescence yield, the number of electrons in the shower is reconstructed as a function of the slope depth, Ne(X), this is the longitudinal prole, allowing Xmax and Nmax to be determined. Although the calculation of the missing energy is model dependent, Monte Carlo simulations show that it represents less than 10%.
Present status
- Surface Detector
- Fluorescence Detector
- Laser facilities
- Atmospheric monitoring devices
In this way, only the neutrino part (and eventually an unknown neutral, weakly interacting part) of the shower remains undetected. Between the diaphragm and the mirror is the 440 PMT camera (described below) that allows imaging of the shower profile. 4.2) where φt andαm= 16◦ are respectively the azimuth and elevation angles of the telescope axis and αc=.
There are two laser facilities at the Pierre Auger Observatory, both near the center of the array as represented in Figure 4.8: the Central Laser Facility (CLF), almost equidistant from the eyes of Los Leones, Los Morados and Coihueco and operating since July 2003, and the second Central Laser Facility (XLF), almost equidistant from Los Morados, Loma Amarilla and Coihueco sites and ended in January. The laser wavelength is ideal for the uorescence technique as it is approximately in the middle of the nitrogen uorescence spectrum;. Several other monitor devices are available and distributed around the site according to gur 4.8: CLF (as explained in the last section), backscatter LIDARs (Light Detection And Ranging), Horizontal Attenuation Monitors (HAMs), Aerosol Phase Function Monitors ( APFs), cloud cameras and star monitors.
Event reconstruction
Surface Detector
Fluorescence Detector
In monocular events, when only one eye is activated, pixel timing information is essential to accomplish this task. Assuming that a shower evolves along a line with the speed of lightsc, one would expect the central times of each pixel (see figure whereT0 is the time when the shower is at its closest distance to the eye, χi is the viewing direction of the projected pixel in SDP and χ0 is the angle of the shower axis within the SDP. However, some technical problems can arise when certain events - usually distant ones - produce short traces in the viewing angle [12].
It includes two phases: calculation of the light profile on the diaphragm as a function of time and determination of the number of charged particles in the shower as a function of the slant depth, i.e. reconstruction of the correct longitudinal profile using both proles (4.7) and the shower geometry as input data. At this point, we can matrix-match the dEdX profile of the shower and the three components of detected light: uorescence, direct Erenc light, and diffuse Erenc light.
Hybrid
As a final note, note that the energy calculated with (4.12) or (4.13) is about 10% less than the actual energy of the cosmic rays – remember the discussion about the missing energy in section 3.2.2. If, in addition to the FD, one SD tank is activated − as in Figure 4.10 −, the arrival time of the shower front on the ground,tgrd, limits the parameter T0 in the timing t to Eq. The restriction allows a more accurate reconstruction of Rp and χ0 or, in other words, of the shower geometry.
Moreover, this reconstruction works quite well even if the shower produces short tracks within the FD's angle of view. The results of the resolutions in Rpandχ0 are shown in Figure 4.14 and are quite impressive: the hybrid technique provides a geometry reconstruction with a ~10 times better resolution and no systematic drift. But perhaps the most important feature of the hybrid technique is the possibility to calibrate the S38 parameter of the SD analysis with the energy reconstructed by the FD, as shown in figure 4.15 for a specific set of hybrid data [25].
Future steps
- Southern site enhancements
- The northern site
- The 3D method
- Some applications
While each pixel of the FD camera corresponds to a direction on the sky, the third dimension—distance to the eye—is determined by timing information. The solid circles represent the center points of the volumes and the color code refers to the observation times. Visualization of the complex 3D output of the new geometry reconstruction is done using the map3d package [73], as shown in Figure 5.1 (b).
In addition to all volume vertices and center points, so-called nearby points can also be represented. In other words, events with χ0< π2 represent large, extended volumes containing parts of the shower axis − the 3D structure of such an event is shown in Figure 5.5. Note the difference between the reconstructed volumes here and those of the event presented in Figure 5.1(b).
Prole reconstruction
- The 3D shower prole
- Light at diaphragm
- Spot and mercedes
- Expected and observed signals
Then, Nvol·N1 points~r(q) are generated uniformly in the cylinder according to the element volumerdrdθdhand, as in equation (5.6), is the number of expected photons at the membrane coming from Vik. Following a similar reasoning as in the uorescence case, the density of Erenkov photons with λ∈[λ1, λ2] emitted at (X, R) and arriving directly at the detector is essentially Nevertheless, the erenkov emission is in principle very small at large angles compared to the emission in the parameterization range.
The first step in the calculation of this contribution by the telescopes is the construction of the beam of. A photon coming from a given volumeik can be misplaced in the PMT camera according to the location presented in Section 4.1.2 - the photon can jump into a pixel i0 6=i, which means it will be associated with a other volume i0k of the same timeslot. In the Monte Carlo integration, each of the randomly generated Nvol·N1 points~r(q) corresponds to a particular direction θ(q), φ(q) in the camera.
Validation
So, one should proceed with the likelihood function, which is the product of the observation probabilities Nγ,ik. Behavior of the e/o ratio with XN P (c) and RCP (d), the χik distribution (e) and the dependence of the mean lnP1. In order to perform a lateral shower pole measurement, it must first be ensured that no significant bias is introduced by the 3D reconstruction.
Referring to Figures 6.1(e) and 6.1(f), it is clear that using the KG parameters instead of the simulation parameters reduces the χ2/Ndf values. Dotted lines refer to expected signals calculated with the KG parameters, while solid lines represent the use of the simulated parameters. The behavior of the ratio e/o with XN P (c) and RCP (d), the χik distribution (e) and the χ2/Ndf values per event (f) are also shown for the same simulation set.
Lateral sensitivity
Data
Mantsch for Pierre Auger Collaboration, The Pierre Auger Observatory Progress and First Results, 29th International Cosmic Ray Conference, Pune, India, 2005. Perrone for the Pierre Auger Collaboration, Measurement of the UHECR energy spectrum from hybrid data of the Pierre Auger Observatory, 30th International Cosmic Ray Conference, Mérida, México, 2007. Matthews for the Pierre Auger Collaboration, A description of some ultra-high energy cosmic rays observed with the Pierre Auger Observatory, 29th International Cosmic Ray Conference, Pune, India, 2005.
Bertou for the collaboration of Pierre Auger, Performance of the surface array of the Pierre Auger Observatory, 29th International Cosmic Ray Conference, Pune, India, 2005. Bellido for the collaboration Pierre Auger, Performance of the Fluorescence Detectors of the Pierre Auger International Observatory29, Conference, Pune, India, 2005. Boniface for the collaboration of Pierre Auger, Angular Resolution of the Pierre Auger Observatory, 29th International Cosmic Ray Conference, Pune, India, 2005.
