We review genetic programming principles, their application to FOCUS data samples , and use the method to study the doubly Cabibbo suppressed decay D + → K + π + π − relative to its Cabibbo favored counterpart, D + → K − π + π +. We find that this technique is able to improve upon more traditional analysis methods. To our knowledge, this is the first… (More)
We describe a silicon microstrip detector interleaved with segments of a beryllium oxide target which was used in the FOCUS photoproduction experiment at Fermi-lab. The detector was designed to improve the vertex resolution and to enhance the reconstruction efficiency of short-lived charm particles.
A precision measurement by AMS of the positron fraction in primary cosmic rays in the energy range from 0.5 to 500 GeV based on 10.9 million positron and electron events is presented. This measurement extends the energy range of our previous observation and increases its precision. The new results show, for the first time, that above ∼200 GeV the positron… (More)
Study of the decay asymmetry parameter and CP violation parameter in the Λ + c → Λπ + decay. Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement of the weak decay-asymmetry parameter α Λc in Λ + c → Λπ + decay. Comparing particle with antiparticle decays, we obtain the first measurement of the CP violation parameter A ≡
Knowledge of the precise rigidity dependence of the helium flux is important in understanding the origin, acceleration, and propagation of cosmic rays. A precise measurement of the helium flux in primary cosmic rays with rigidity (momentum/charge) from 1.9 GV to 3 TV based on 50 million events is presented and compared to the proton flux. The detailed… (More)
Precision measurements by the Alpha Magnetic Spectrometer on the International Space Station of the primary cosmic-ray electron flux in the range 0.5 to 700 GeV and the positron flux in the range 0.5 to 500 GeV are presented. The electron flux and the positron flux each require a description beyond a single power-law spectrum. Both the electron flux and the… (More)