Stopping rate of negative cosmic-ray muons near sea level

Abstract

A production rate of 0. 065 ± 0. 003 Ar atom/kg min of K at 2-mwe depth below sea level was measured by sweeping argon from potassium solutions. This rate is unaffected by surrounding the solution by paraffin and is attributed to negative-muon captures and the electromagnetic interaction of fast muons, and not to a nucleonic cosmic-ray component. The 37 39 Ar yield from K by the stopping of negative muons in a muon beam of the SREL synchrocyclotron was measured to be 8. 5 ± 1. 7%. The stopping rate of negative cosmic-ray muons at 2-mwe depth below sea level from these measurements and an estimated 17% electromagnetic production is 0.63 ± 0.13 |_i /kg min. Previous measurements on the muon stopping rate vary by a factor of 5. Our value is slightly higher but is consistent with two 37 previous high values. The sensitivity of the Ar radiochemical method for the detection of muons is considerably higher than that of the previous radiochemical methods and could be used to measure the negative-muon capture rates at greater depths. IntroductionUntil the experiments of the Utah cosmic-ray group [Bergeson et al., 1967], it was universally believed that cosmic-ray muons result solely from the decay of secondary pions and kaons from cosmic-ray interactions in the atmosphere. The Utah experiment raised the possibility for an additional source of muons. An explanation [Bjorken et al., 1969] of the Utah experiment has been proposed that requires an anomalous absorption of muons of negative helicity and unusual shape for the sea-level muon energy spectrum. This spectrum is often inferred from stopping rate versus depth measurements near sea level. Although the muon stopping rate has been 111-098 measured by three different methods, measurements by even the same method often disagree. Stopped muon rates have mainly been measured with nuclear emulsions and with scintillators at depths to 300 mwe (meters of water equivalent). Recent measurements by Bergamasco [1970] are a factor of 2-5 higher than previous ones. Additional measurements of the stopped negative-muon rate might be helpful in determining whether cosmic muons result solely from the decay of secondary IT and K mesons.Until now, because of restricted sensitivity, radiochemical methods for detection have yielded positive results to a depth of only 0.2 mwe. Winsberg [1956] Cl from rainwater produced by the Ar (|jt , v n) reaction. Rama and Honda [1961] extracted gold radioactivities from mercury at sea level and state that their result is 59 consistent with Winsberg's. Takagi and Tanaka [1969] observed a Fe radioactivity of 0. 35 ± 0.14 atom/kg min induced by cosmic-ray muons in cobalt at sea level. This is a lower limit for the stopping of negative muons because the yield of the reaction was not determined. A more sensitive radiochemical method with a measured yield is needed. -37The K ([i , v 2n)Ar reaction offers the possibility for extremely high sensitivity because it is possible to extract argon with almost 100% efficiency from large 37 volumes of potassium ...

Explicit simulation of environmental gas tracers with integrated surface and subsurface hydrological models

“…The flux of fast cosmogenic neutrons is exponentially attenuated with depth on a length scale, which is proportional to the density of the medium without of its elemental composition (Gosse and Phillips, 2001). Other production reactions, e.g., induced by muons or by neutrons from (α, n) reactions can be neglected in the depth range considered here (Spannagel and Fireman, 1972;Heisinger et al, 2002;Sramek et al, 2017). The depth dependent production rate 37 P (z)r in (atoms•yr −1 • cm −3 ) has been parameterized through a production function equation (Guillon et al, 2016) and can be described as follows:…”

Measurement of muon-induced26Al in terrestrial silicate rock

“…The resulting activites are very low, but in some favorable cases they exceed the detection limits of today's lowlevel counting methods. Some efforts havre been made during the last 20 years to detect muon-induced activities in terrestrial substances [Winsberg, 1956;Rama and Honda, 1961;Takagi and Tanaka, 1969;Spannagel and Fireman, 1972;Fireman and Steinbrunn, 1973].…”

Reviewing 39ar and 37ar Underground Production in Shallow Depths with Implications for Groundwater Dating

“…Muons were recently identified as significant contributors to 39 Ar underground production by the muon capture reactions on potassium [ 39 K(μ − ,γ) 39 Ar] in the context of Dark Matter research in deep underground laboratories (Mei and Hime, 2006). The 37 Ar production processes related to muon capture [ 39 K(μ − ,2n) 37 Ar] were also reported in early literature (Spannagel and Fireman, 1972). However, the importance of these processes for shallower groundwater dating applications was never recognized until now.…”