Neutrino-Induced Muons Deep Underground

Abstract

Dividing both sides of (14) by {o P + o A ) E , it is straight forward to show (<J P + v A ) EV£ 0 \-l/2. ((°A> E r l/2 ]We define the unboundedness of the total cross sections as lim {o P J) B = «>.Hence if (o>) and (cr A > are both unbounded the rhs of (15) is zero which is the desired result [Eq.(1)]. Equation (14) shows that the same result holds if only one of the total cross sections is assumed to be unbounded; it then follows that the other cross section must be unbounded, too. From Eq. (1) or (10) it is also clear that there exists a set of points {£*}, ^j-* 00 , on which Aa/ (Op + a A )-~0; in particular, if Aoy^Op + oJ has a limit, this limit is zero.We should like to emphasize that inequality (14) is quite general; it is also valid if we replace (v P ) E and {o^) E by the corresponding elastic cross sections. If one is willing to make a strong assumption that o P , o A are bounded then the coefficient I on the rhs of (12) and (14) should be replaced by unity. In this case one gets a generalization the results of Roy and Singh. 6 For pion-nucleon scattering, if isospin invariance is assumed, a restriction on (Aa) £ in terms of the charge-exchange cross section ir~p -n°n can be similarly obtained. 1 U. Amaldi et al,, to be published; S. R. Amendolia et al., to be published.We report here the results of a measurement of the integral energy distribution of the neutrino-induced muon flux deep underground using the Utah neutrino detector. Five neutrino-induced muon candidates have been obtained from the approximately 10 6 muons which have passed through the detector during 603 days of live operation out of 830 days total elapsed time. By comparing the observed and expected energy distributions we are able to set lower limits on the saturation energy EQ of the total neutrino-nucleon cross section or, equivalently, on the mass M w of the intermediate vector boson if scale invariance of the inelastic structure function vW 2 is assumed. We find at the lcr, 2<r, and 3a levels of confidence E Q >320, 80, and 29 GeVorM w >10, 5, and 3 GeV, respectively.The observation of a muon flux induced by the interaction of cosmic-ray neutrinos in rock deep underground has been used to investigate the nature of the weak interaction. 1 " 4 Previous experiments have yielded values for the integral muon flux, but none thus far has analyzed the high-energy spectrum of the observed muons. In this communication, we report the results of a measurement of the spectrum of the underground neutrino-induced muon flux made possible by the unique University of Utah neutrino detector. 5 " 8 We compare the observed spectrum with those calculated for different assumptions concerning the high-energy (E v > 10 GeV) behavior of the neutrino-nucleon total cross section. 9 Comments are made on the scale invariance of the structure functions measured in inelastic neutrino-nucleon scattering, and a lower limit is placed on the 66

Observation of atmospheric neutrinos

“…The first atmospheric neutrino experiments observed these muons in the 1960s (Achar et al, 1965a(Achar et al, , 1965bReines et al, 1965Reines et al, , 1971Krishnaswamy et al, 1971;Bergeson, Cassiday, and Hendricks, 1973;Crouch et al, 1978). Then in the late 1970s a large-scale experiment using liquid scintillators was begun at Baksan (Boliev et al, 1981).…”

“…Another experiment was begun during the late 1960s (Bergeson, Cassiday, and Hendricks, 1973). Since this detector was located at a relatively shallow depth (about 1500 mwe), horizontally going particles, as well as the downward going particles, were dominated by cosmicray muons, and only upward going muons were selected as neutrino events.…”

Towards high-energy neutrino astronomy

“…The anomalies in muon depth-intensity which they reported in 1967-71 provided one of the initial motivations to build underwater detectors. In 1973, the Utah group reported also first results on neutrinos [Bergeson 1973]. Combining their energy spectra with those of the KGF group they concluded that the spectrum is consistent with a linear growth of the neutrino cross-section up to high energies and that the W-boson mass has to be large.…”

“Why Do We Do Physics? Because Physics Is Fun!”

“…This would be the case if the total neutrino-nucleon cross section rose linearly with laboratory neutrino energy. The rough prediction was equal numbers of events per factor of 10 in incident neutrino energy (16). And the energy resolution of Jack's detector extended up to hundreds of GeV.…”