Charm Physics at Fermilab E791

TL;DR

Fermilab E791 experiment collected a large charm particle dataset using advanced silicon detectors and high-speed data acquisition, enabling detailed studies of charm decays and rare processes.

Contribution

The experiment achieved high-statistics charm data collection with innovative detector and data acquisition systems, facilitating new measurements of charm decays.

Findings

Observation of D0 --> K- pi+ decays

Observation of D+ --> K- pi+ pi+ decays

Preparation for studying rarer charm decays

Abstract

Experiment 791 at Fermilab's Tagged Photon Laboratory has just accumulated a high statistics charm sample by recording 20 billion events on 24000 8mm tapes. A 500 GeV/c pi- beam was used with a fixed target and a magnetic spectrometer which now includes 23 silicon fixed target and a magnetic spectrometer which now includes 23 silicon microstrip planes for vertex reconstruction. A new data acquisition system read out 9000 events/sec during the part of the Tevatron cycle that delivered beam. Digitization and readout took 50 uS per event. Data was buffered in eight large FIFO memories to allow continuous event building and continuous tape writing to a wall of 42 Exabytes at 9.6 MB/sec. The 50 terabytes of data buffered to tape is now being filtered on RISC CPUs. Preliminary results show D0 --> K- pi+ and D+ --> K- pi+ pi+ decays. Rarer decays will be pursued.