1. The Monitoring System of the ARGO-YBJ Data Acquisition
S. Mastroianni
INFN sez. di Napoli
On behalf of the ARGO-YBJ Collaboration
8 Strips = 1 Pad
(56 ´ 62 cm2)
10 Pads = 1 RPC
(2.80 ´ 1.25 m2)
RPC carpet 99m 110 m
covering 5600 m2 1 2
Local
Station 3 4
Receiver 5 6
12 RPC = 1 cluster =
= 1 LS ( 5.7 ´ 7.6 m2 ) 7 8 9 10
Resolutions:
space 6.5 ´ 62 cm2 (1 strip)
time ~ 1ns
Big
Pad#0
ADC
High Altitude Cosmic Ray Laboratory (Tibet , 4300 m.)
Big
Pad#1
ARGO-YBJ is in stable data taking since Nov (d.c. > 90%) with the full central carpet (130 Cluster) + Guard Ring;
Low Multiplicity trigger with 20 fired pads on the central carpet  Trigger rate ~ 4 kHz;
Aims:
cosmic-ray physics (above ~1 TeV)
VHE γ-astronomy (above ~300 GeV)
to distribute timing-critical signals
to realize a hardware real-time control
without software penalities:
Physical goals
The ARGO-YBJ experiment is devoted to the study of many issues in g-astronomy and cosmic ray physics. These includes:
1)g-astronomy at few hundreds GeV threshold energy to monitor galactic and extragalatic point candidate sources and a diffuse g-astronomy from galactic plane and SNR;
2)the studies of the GRB over the full GeV-TeV energy range;
3)the primary proton spectrum in TeV region
4)the p/p* ratio not accessible to satellite
5)sun and eliosphere physics including cosmic ray modulation
The Monitoring
System
to monitor the dead time at each DAQ levels
to optimize the data acquisition
to troubleshoot the system in case of an error
to check the event number synchronization
Many front-end channels
High data transfer peak
Very large dynamics
DAQ request
May, 2009
S. Mastroianni - XI Pisa Meeting 2009, La Biodola, Isola d'Elba, (Italy)

2. The Monitoring system The Monitoring System Test results
Data are shifted from the LS propagating through
every FIFO element until they reach the L2 controller
Front-end busy
trigger
L1 busy
L2 busy LS
20MB/s
Cluster #1
L1Busy
Trigger
Farm
#1000
buffer
Busy
L1 C
L2 Busy
L1bus
L2 C
L2bus
Cluster #2
Total Dead Time
DAQ linear scheme and Busy generation Model
The fifo status depends upon the difference of the flow between the writing and reading!
1) LS Busy
2) L1 Busy
3) L2 Busy
On transfer
LS busy
Fifo on board
Data buffer’s ORed Busy
The Monitoring System
Fifo on board
study of the trend of Busy sources trigger by trigger
study the DAQ data fow in order optimize the overall performance
trigger on a complex Busy pattern by setting a reference range
It works like a logic-analyzer continuously measuring
all the Busy duty cycle and frequency for each trigger
and writing the results in a FIFO
Test results
L1 Busy duty cycle is linear behaviour
only one time for each trigger
A data frame generator, consisting of an average size of about 70 words, feeds 4 buffer 4kHz in order to reproduce the real experimental setup.
The Monitoring System is a control instrument essential to monitors continuously the dead time at different levels of the DAQ architecture for each trigger issued.
May, 2009
S. Mastroianni - XI Pisa Meeting 2009, La Biodola, Isola d'Elba, (Italy)