Speaker
Monica Tecchio
(University of Michigan)
Description
The goal of K0TO experiment at J-Parc is to discover and measure the rate of the rare decay of the neutral KL into a neutral pion, a neutrino and an antineutrino, for which the Standard Model predicts a branching ratio of (2.8+/-0.4)x10E-11.
The experiment is a follow-up to E391 at KEK with a completely redesigned beamline, a new Cesium Iodide calorimeter with increased granularity and reduced shower leakage, and a new readout electronics, trigger and data acquisition system.
The physics requirements are for a pipelined readout and trigger electronics with no deadtime, 14-bit dynamic range on the energy measurement and time resolution of 1 nsec. These requirements are accomplished via a frontend 125 MHz FADC board and a two-tiered trigger electronics.
The FADC board injects the analog differential inputs from up to 16 channels into a 10-pole Gaussian/Bessel low pass filter before digitization. The digitized shaped pulses are stored inside a 4 usec deep
pipeline while awaiting for the trigger decision. A first level trigger compares the time aligned energy sum over the whole calorimeter to a programmable threshold. Upon a first level trigger decision, the data are buffered to a second level trigger which can implement clustering and shape fitting for further trigger rate reduction. The communication between the FADC board and each of the trigger boards is done via 2.5 GBPS optical link. Data accepted by the second level trigger board is read out
via a front panel 1Gb Ethernet port into a 40-node computer cluster through a 48-port network switch using UDP protocol.
The 8 nsec system clock is generated by a Master Control module which supervises the integration of frontend, trigger, readout and external accelerator signals. Control signals are distributed to the whole K0TO data acquisition system either via the VME backplane or a custom-designed Fanout boards.
The pulse shaping circuit on the 125 MHz FADC board is optimized depending on whether it receives analog signals from the about 3000 channel of CsI calorimeter or from the roughly 1000 channels of upstream, downstream and beam hole veto detectors. The harsh background conditions for
some of the veto detector have required the development of a 4-channel 500 MHz version of the FADC board. The trigger electronics for these vetoes detectors, aiming at integrating the timing of the veto signals with the calorimeter energy sum, is under design.
The first K0TO physics run is planned for Spring 2012.
Author
Monica Tecchio
(University of Michigan)
Co-authors
Angela Steinmann
(Stetson University)
Craig Harabedian
(University of Michigan)
Duncan McFarland
(Arizona State University)
Jiasen Ma
(University of Chicago)
Joe Comfort
(Arizona State University)
Jon Ameel
(University of Michigan)
Mircea Bogdan
(University of Chicago)
Myron Campbell
(University of Michigan)
Shumin Li
(University of Michigan)
Yau Wah
(University of Chicago)
