Atmospheric Temperature Effect forμMesons Observed at a Depth of 846 m.w.e.

Abstract

The experiment reported was a measurement of the effect of variations in atmospheric temperatures on the intensity of ju mesons observed underground at a depth of 846 m.w.e. The average energy of these particles is known to be ^2X10 n ev. A total of ^1.2 X10 6 coincidences, between two large trays of Geiger counters located in a salt mine, was collected over a two-year period. The correlation between variations in counting rate and simultaneous variations in effective atmospheric temperature was analyzed. The effective temperature was determined from radiosonde measurements of atmospheric temperatures at pressure levels up to 20 millibars performed by a U. S. Air Force weather observation unit near the salt mine. The resulting temperature coefficient is 0.22±0.06 percent per degree and the correlation coefficient is 0.75. The results are compared with those obtained from similar measurements at 1574 m.w.e. and with the theoretical values of the temperature coefficient derived from various schemes describing the production of n mesons with high energies.

Observation of muon intensity variations by season with the MINOS near detector

“…Figure 10 shows the new MINOS ND results and all the known measured values of α T as a function of detector depth. The figure includes results from Barrett 1,2 [1], AMANDA [7], ICECUBE [10], MACRO [6], Torino [3], Hobart [4], Sherman [2], Baksan [5], Borexino [8] and the MINOS FD [12]. The data are fully consistent with the prediction that α T increases with detector depth (equivalent to increasing values of E th cos θ) and asymptotically approaches unity for very large detector depths.…”

“…Figure 7 gives the measured α T as a function of zenith angle when T eff is calculated using Eq. (2). The data are grouped into, and the values of α T calculated for, nine zenith angle bins.…”

“…Consequently, the muon flux from weak meson decays increases. This variation in the muon flux has been observed, and correlated with temperature changes, by a number of experiments [1][2][3][4][5][6][7][8][9][10][11], including the MINOS measurement at the far detector (FD) [12]. These experiments measure α T , the correlation coefficient between the muon flux and the atmospheric temperature.…”

Atmospheric muons: experimental aspects

“…The dashed curve is the prediction using the pion-only model (Ambrosio et al, 1997c). The points correspond (from top to bottom): Ambrosio et al (1997c), Bouchta (1999), Adamson et al (2010), Selvi (2009), Bellini (2012, Desiati (2011), Andreyev et al (1991, Cutler et al (1981), Sherman (1954), Barrett et al (1954).…”

“…The dashed curve is the prediction using the pion-only model Ambrosio et al (1997c). The points correspond (from top to bottom): Ambrosio et al (1997c), Bouchta (1999), Grashorn et al (2010), Selvi (2009), Bellini (2012, Desiati (2011), Andreyev et al (1991, Cutler et al (1981), Sherman (1954), Barrett et al (1954). temperature T eff , defined by the weighted average of temperatures from the surface to the top of the atmosphere, is useful to describe the situation. T eff approximates the atmosphere as an isothermal body, weighting each pressure layer according to its relevance to muon production in atmosphere.…”