five
FAST
minutes …
• Why FAST?
• measure the muon lifetime
t
m
to a precision of 1 ppm (~ 2 ps)
• measure the Fermi coupling constant GF to a precision of 1 ppm
• one order of magnitude improvement of the present world average
• How FAST?
Active scintillator target
Hight granularity
DC pion beam
p = 170 MeV/c
p+
1 ppm precision
1012 events
1012 x 9tm / 0.5 ~ 1.5 y
p+  m+
m+  e+
p+  m+  e+
(tp = 26.03 ns - PDG2002)
(tm = 2.197 ms - PDG2002)
estimated
efficiency
PARALLELISATION NEEDED
HIGH DATA RATE (1MHz beam rate)
~ 80 MB/sec
ONLINE ANALYSIS
FAST target: the story …
FAST target: the end of the story !
back view
PSI – 15 December 2003
tdcs
preamps
phomultipliers
ventilators
discriminators
RF frequency
~ 20 ns
time distribution
time resolution
with straight tracks
~ 1 ns
ANY serious
analysis on
these data
………
but it really
looks like a
lifetime plot
!!!
FUTURE PLANS :
1.
DECEMBER 2003:
trigger prototype (from CIEMAT – Madrid)
•Implement
•Test
•Take some data
2.
2004:
first real data taking run (from April on)
BUON NATALE
e
BUON ANNO !!!!