K. Johns

Measurement of the atmospheric neutrino flavour composition in Soudan 2

Abstract The atmospheric neutrino flavour ratio measured using a 1.52 kton-year exposure of Soudan 2 is found to be 0.72 ± 0.19−0.07+0.05 relative to the expected value from a Monte Carlo calculation. The possible background of interactions of neutrons and photons produced in muon interactions in the rock surrounding the detector has been investigated and is shown not to produce low values of the ratio.

Study of cosmic ray composition in the knee region using multiple muon events in the Soudan 2 detector

Deep underground muon events recorded by the Soudan 2 detector, located at a depth of 2100 m of water equivalent, have been used to infer the nuclear composition of cosmic rays in the ``knee`` region of the cosmic ray energy spectrum. The observed muon multiplicity distribution favors a composition model with a substantial proton content in the energy region 8{times}10{sup 5}{endash}1.3{times}10{sup 7} GeV/nucleus. {copyright} {ital 1997} {ital The American Physical Society}

The SOUDAN 2 detector: The design and construction of the tracking calorimeter modules

SOUDAN 2 is a 960-ton tracking calorimeter which has been constructed to search for nucleon decay and other phenomena. The full detector consists of 224 calorimeter modules each weighing 4.3 tons. The design and construction of the modules are described. The modules consist of finely segmented iron instrumented with 1 m long drift tubes of 15 mm internal diameter. The tubes enable three spatial coordinates and dE/dx to be recorded for charged particles traversing the tubes.

Measurement of the Omega - magnetic moment.

A sample of 24 700 {Omega}{sup {minus}} hyperons was produced by a prolarized neutral beam in a spin-transfer reaction. The {Omega}{sup {minus}} polarizations are found to be {minus}0.054{plus minus}0.019 and {minus}0.149{plus minus}0.055 at mean {Omega}{sup {minus}} momenta of 322 and 398 GeV/{ital c}, respectively. The directions of these polarizations give an {Omega}{sup {minus}} magnetic moment of {minus}(1.94{plus minus}0.17{plus minus}0.14){mu}{sub {ital N}}

Production polarization and magnetic moment of Xi -bar+ antihyperons produced by 800-GeV/c protons.

The polarization of {bar {Xi}}{sup +} hyperons produced by 800-GeV/{ital c} protons in the inclusive reaction {ital p}+Be{r arrow}{bar {Xi}}{sup +}+{ital X} has been measured. The average polarization of the {bar {Xi}}{sup +}, at a mean {ital x}{sub {ital F}}=0.39 and {ital p}{sub {ital t}}=0.76 GeV/{ital c}, is {minus}0.097{plus minus}0.012{plus minus}0.009. The magnetic moment of the {bar {Xi}}{sup +} is 0.657{plus minus}0.028{plus minus}0.020 nuclear magneton.

Search for direct CP violation in non-leptonic decays of charged Xi and Lambda hyperons

A search for direct CP violation in the nonleptonic decays of hyperons has been performed. In comparing the product of the decay parameters, alpha(Xi)alpha(Lambda), in terms of an asymmetry parameter, A(XiLambda), between hyperons and antihyperons in the charged Xi-->Lambdapi and Lambda-->ppi decay sequence, we found no evidence of direct CP violation. The parameter A(XiLambda) was measured to be 0.012+/-0.014.

The observation of underground muons from the direction of Cygnus X-3 during the January 1991 radio flare

Abstract Muons recorded in the Soudan 2 underground nucleon decay detector from January 1989 to February 1991 have been examined for any correlation with the radio flares of Cygnus X-3 observed during this period. On two nearby days during the radio flare of January 1991 a total of 32 muons within 2.0° of the Cygnus X-3 direction were observed when 11.4 were expected.

Measurement of decay parameters for Xi- --> Lambda pi- decay.

Based on 1.35 x 10(6) polarized Xi(-) events, we measure the parameter phi(Xi) to be -1.61 degrees +/-2.66 degrees +/-0.37 degrees for the Xi(-)-->Lambda pi(-) decay. New results for the parameters beta(Xi) and gamma(Xi) are also presented. Assuming that the CP-violating phase difference is negligible, we deduce the strong phase difference between the P-wave and S-wave amplitudes of the Lambda pi final state to be 3.17 degrees +/-5.28 degrees +/-0.73 degrees, reducing the uncertainty in estimating the level of CP violation in Xi-hyperon decay.

Precise measurement of the magnetic moment

With 4.36{times}10{sup 6} events, spin precession in a magnetic field has been used to measure the magnetic moment of the {Xi}{sup {minus}} hyperon as {minus}0.6505{plus minus}0.0025 nuclear magnetons.

Precise measurement of the Xi - magnetic moment.

With 4.36{times}10{sup 6} events, spin precession in a magnetic field has been used to measure the magnetic moment of the {Xi}{sup {minus}} hyperon as {minus}0.6505{plus minus}0.0025 nuclear magnetons.