The Reaction 7Li(pi+,pi-)7B and its Implications for 7B

The reaction 7Li(pi+,pi-)7B has been measured at incident pion energies of 30-90 MeV. 7Li constitutes the lightest target nucleus, where the pionic charge exchange may proceed as a binary reaction to a discrete final state. Like in the Delta-resonance region the observed cross sections are much smaller than expected from the systematics found for heavier nuclei. In analogy to the neutron halo case of 11Li this cross section suppression is interpreted as evidence for a proton halo in the particle-unstable nucleus 7B.Comment: 4 pages, 4 figure

Search for the Hypothetical pi -> mu x Decay

The KARMEN collaboration has reported the possible observation of a hitherto unknown neutral and weakly interacting particle x, which is produced in the decay pi -> mu + x with a mass m(x) = 33.9 MeV. We have searched for this hypothetical decay branch by studying muons from pion decay in flight with the LEPS spectrometer at the piE3 channel at PSI and find branching ratios BR(pi- to mu- anti-x) < 4e-7 and BR(pi+ to mu+ x) < 7e-8 (95\% C.L.). Together with the limit BR > 2e-8 derived in a recent theoretical paper our result would leave only a narrow region for the existence of x if it is a heavy neutrino.Comment: 10 pages, TeX (uses epsf), 3 Postscript figures uu-encode

New skills for new classrooms: training tutors to teach languages online

While online teaching in post-compulsory education is the focus of much research today, the training of online tutors has been largely neglected. Most papers do not go beyond dealing with the technical skills that are needed to teach in an online environment. This article outlines a framework for tutor training, starting with a brief overview of benefits and challenges for online language tutors. On the basis of several years’ experience with teaching languages using a synchronous online environment and training tutors for online language courses, we suggest a pyramid of skills necessary for successful online teaching. These include the more general skills of dealing with the technology and using its advantages, the social skills of community building, language teaching skills, and the skills to teach creatively and develop a personal teaching style in an online medium. The article then suggests how these skills can be implemented in a training programme, which includes both pre-course training and on-going staff development