The cosmic ray primary composition in the energy range between 10
15 and 10
16 eV, i.e., around the “knee” of the primary spectrum, has been studied through the combined measurements of the EAS-TOP ...air shower array (2005 m a.s.l., 10
5 m
2 collecting area) and the MACRO underground detector (963 m a.s.l., 3100 m w.e. of minimum rock overburden, 920 m
2 effective area) at the National Gran Sasso Laboratories. The used observables are the air shower size (
N
e) measured by EAS-TOP and the muon number (
N
μ) recorded by MACRO. The two detectors are separated on average by 1200 m of rock, and located at a respective zenith angle of about 30°. The energy threshold at the surface for muons reaching the MACRO depth is approximately 1.3 TeV. Such muons are produced in the early stages of the shower development and in a kinematic region quite different from the one relevant for the usual
N
μ−
N
e studies. The measurement leads to a primary composition becoming heavier at the knee of the primary spectrum, the knee itself resulting from the steepening of the spectrum of a primary light component (p, He) of Δ
γ=0.7±0.4 at
E
0∼4×10
15 eV. The result confirms the ones reported from the observation of the low energy muons at the surface (typically in the GeV energy range), showing that the conclusions do not depend on the production region kinematics. Thus, the hadronic interaction model used (CORSIKA/QGSJET) provides consistent composition results from data related to secondaries produced in a rapidity region exceeding the central one. Such an evolution of the composition in the knee region supports the “standard” galactic acceleration/propagation models that imply rigidity dependent breaks of the different components, and therefore breaks occurring at lower energies in the spectra of the light nuclei.
We present the final results obtained by the MACRO experiment in the search for GUT magnetic monopoles and nuclearites. Several searches were performed with different subdetectors, i.e. scintillation ...counters, limited streamer tubes and nuclear track detectors. No magnetic monopole or nuclearite candidates were found. The MACRO upper limit to the local flux of GUT magnetic monopoles is at the level of
1.4×10
−16
cm
−2
s
−1
sr
−1
.
Results are presented on the discovery potential for MSSM neutral Higgs bosons in the Mh-{max}scenario. The region of large tan beta, between 15 and 50, and mass between ~ 95 and 130 GeV is ...considered in the framework of the ATLAS experiment at the Large Hadron Collider (LHC), for a centre-of-mass energy = 14 TeV. This parameter region is not fully covered by the present data either from LEP or from Tevatron. The h/A bosons, supposed to be very close in mass in that region, are studied in the channel h/A -> mu+mu- accompanied by two b-jets. The study includes a method to control the most copious background, Zo -> mu+mu- accompanied by two b-jets. A possible contribution of the H boson to the signal is also considered.
Muon astronomy with the MACRO detector AHLEN, S; AMBROSIO, M; BEMPORAD, C ...
The Astrophysical journal,
07/1993, Letnik:
412, Številka:
1
Journal Article
A negative search using 1/12 of the eventual MACRO detector has yielded nuclearite flux limits of 1.1 x 10 exp -14/sq cm/sr/s for in between 10 exp -10 and 0.1 g, and 5.5 x 10 exp -15/sq cm/sr/s for ...m greater than 0.1 g. We have modified the formula of De Rujula and Glashow for the light yield of nuclearites to include the UV light absorbed and reemitted in the visible region, and proved that the MACRO sensitivity extends almost to the escape velocity of the earth. Our flux limit, therefore, can be used to address nuclearites that are possibly trapped in the solar system. (Author)
Multiwire drift tubes with jet-cell geometry for muon detection at LHC Bagnaia, P.; Barberio, E.; Beker, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/1995, Letnik:
360, Številka:
1-2
Journal Article
Recenzirano
Recent results from test measurements with cosmic rays of jet-cell chamber prototypes, developed and studied for the μ detector of the ATLAS apparatus, are reported.
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