Search results for "MSS"

New results on kaon decays from NA48

2007

We report on recent results on rare and semileptonic kaon decays from NA48 and NA48/2. Using data from a minimum bias run in 1999 we present a new measurement of the CP violating decay K L → π + π − with over 40000 selected events. We measured the ratio Γ ( K L → π + π − ) / Γ ( K L → π ± e ∓ ν ) = ( 4.835 ± 0.038 ) × 10 −3 leading to the precise determination of the CP violation parameter | η + − | = ( 2.223 ± 0.013 ) × 10 −3 . From the same data we selected over 2 × 10 6 K L → π ± μ ∓ ν decays. Preliminary results from a dalitz plot fit yield the values for the form factors λ + = 0.0260 ± 0.0007 s t a t ± 0.0010 s y s t and λ 0 = 0.0120 ± 0.0008 s t a t ± 0.0015 s y s t . In one month of …

First observation and branching fraction and decay parameter measurements of the weak radiative decay Xi0 -> Lambda e+ e-

2007

The weak radiative decay Xi0 --> Lambda e+e- has been detected for the first time. We find 412 candidates in the signal region, with an estimated background of 15 +/- 5 events. We determine the branching fraction B(Xi0 --> Lambda e+e-) = [7.6 +/- 0.4(stat) +/- 0.4(syst) +/- 0.2(norm)] x 10^{-6}, consistent with an internal bremsstrahlung process, and the decay asymmetry parameter alpha_{XiLambdaee} = -0.8 +/- 0.2, consistent with that of Xi0 --> Lambda gamma. The charge conjugate reaction Xi0_bar --> Lambda_bar e+e- has also been observed.

Ion beam development for the needs of the JYFL nuclear physics programme

2008

The increased requirements towards the use of higher ion beam intensities motivated us to initiate the project to improve the overall transmission of the K130 cyclotron facility. With the facility the transport efficiency decreases rapidly as a function of total beam intensity extracted from the JYFL ECR ion sources. According to statistics, the total transmission efficiency is of the order of 10% for low beam intensities (I(total)or =0.7 mA) and only about 2% for high beam intensities (I(total)1.5 mA). Requirements towards the use of new metal ion beams for the nuclear physics experiments have also increased. The miniature oven used for the production of metal ion beams at the JYFL is not …

Unpolarized and polarized beam sources

1991

The cross sections of photon-induced nuclear processes were usually studied with the aid of a bremsstrahlung beam produced by fast electrons hitting a suitable radiator. Such bremsstrahlung radiation contains photons of all energies from zero up to the kinetic energy of the incoming electrons and so the desired cross section had to be deduced from the integral yield by taking the bremsstrahlung spectrum of the photon beam from the theory. In this section we shall show that this method can produce significant systematic errors in the absolute value of the cross sections due to the lack of a precise knowledge of the bremsstrahlung spectrum.

Investigation of the ββ decay of 116Cd into excited states of 116Sn

1994

Abstract The double-beta decay of 116Cd into excited states of 116Sn is experimentally and theoretically investigated. From an inclusive experiment, using an external source of isotopically enriched Cd, new most stringent limits for the allowed and non-standard-model decays into excited states are derived. It is further investigated whether the bremsstrahlung emitted by the ββ electrons can be used to derive information on the ground-state decay. For the two-neutrino-decay mode a calculation, using the quasiparticle random-phase approximation, shows that the disadvantage in phase space, in comparison to the ground-state decay, is partially compensated through the nuclear-matrix element. Exp…

Future Experimental Developments for Few-Body Physics at Mainz

1986

The racetrack microtron MAMI B [1] now under construction at Mainz will provide a high-intensity electron beam with energies up to 840 MeV. The 100% duty factor, high-quality beam is considered to be ideal for the investigation of the nucleus in the medium energy region. Coincidence experiments with the detection of the scattered electron and the hadronic reaction products will become possible in a wide kinematical range yielding the information about the response of the nucleus to the transferred energy and momentum. By the method of bremsstrahlung tagging intense secondary photon beams with high monochromacity and well known fluxes will be available for photonuclear research work. Further…

Measurement of photon showers in lead produced by electrons of 150 MeV

1976

Abstract The photon energy spectra induced by 150 MeV electrons in lead were measured in the energy range from 40 MeV up to the primary electron energy. The target thickness was varied between 0.1 and 2.5 radiation lengths X 0 . The photons were analyzed by use of a technique based on deuteron photodisintegration. Differential and integral shower spectra are presented and compared with Monte Carlo calculations of Nagel and Messel et al., both interpolated to our primary energy of 150 MeV. The measured spectra show good agreement with these Monte Carlo calculations for the thickest target of 2.5 X 0 and with calculated bremsstrahlung spectra for the thinnest target of 0.1 X 0 . Considerable …

Langevin approach to collisional bremsstrahlung in a magnetic field

1994

Heavy isotopes of actinium: 229Ac, 230Ac, 231Ac and 232Ac

1973

Abstract By irradiation of 232Th with 150-MeV bremsstrahlung and with 14-MeV neutrons, three new neutron-rich isotopes of actinium, 230Ac, 231Ac and 232Ac, were produced and identified and the previously reported isotope, 229Ac, was confirmed. The actinium isotopes were chemically isolated by a fast procedure based on elution with α-hydroxyisobutyric acid from cation exchange resins. For 229Ac, a half-life of 62·7 ± 0·5 min and a β-ray energy of 1·14 ± 0·15 MeV were found; 35 γ-rays were observed, the strongest ones with the following energies and relative intensities: 135·3(34), 146·4(35), 164·6(100), 252·2(24), 261·9(39), 317·0(23), 539·9(20), 569·1(91), and 605·2 keV(23). For 230Ac, a ha…

Photoproduction of $ \pi^{0}$ -pairs off protons and off neutrons

2015

Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of $\pi^0\pi^0$ pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557~MeV, which produced bremsstrahlung in thin radiator foils. The tagged photon beam covered energies up to 1400~MeV. The data from the free proton target are in good agreement with previous measurements and were only used to test the analysis procedures. The results for differential cros…