DocumentCode :
3588505
Title :
Temperature effect and correction method for LHAASO KM2A timing synchronization node
Author :
Guanghua Gong ; Hongming Li ; Weibin Pan ; Jianmin Li
Author_Institution :
Key Lab. of Particle & Radiat. Imaging, Tsinghua Univ., Beijing, China
fYear :
2014
Firstpage :
1
Lastpage :
1
Abstract :
The Large High Altitude Air Shower Observatory (LHAASO) project aims to search the origin of galactic cosmic rays above 30TeV with high sensitivity and wide spectrum, it´s a dedicated instrument made by 4 sub-detector arrays. The square kilometer complex array (KM2A) consists 5635 scintillation electron and 1221 muon detectors covering the area of 1.2Km2. To guarantee the angular resolution of reconstructed air shower event, a 500ps (rms) timing synchronization must be achieved among the spread few thousand detectors. White Rabbit (WR), a recent emerging technology providing a cost-effective solution that combines sub-nanosecond precision timing transfer and gigabit Ethernet data transfer over the same fiber media, is the most attractive solution to solve the synchronization requirement for the LHAASO KM2A detector array. A compact universal timing endpoint based on write rabbit (CUTE-WR) been designed as timing synchronization interface card to provide synchronized clock and time information to each KM2A detect unit. The test results from a prototype network with 4 White Rabbit switches and 8 CUTEWR nodes shows a 200ps (rms) synchronization precision in different connection topologies. The LHAASO instrument locates at wild field with an altitude of 4300m a.s.l. According to the local meteorological record, the daily and yearly temperature variation can be about 25 and 50 degrees respectively. The temperature dependency of white rabbit key components like VCO and integrated optical modules could significantly degrades the synchronization precision. This paper presents the measurement results of delay and synchronization variation of the WR switch, the CUTE-WR node and the link fibers under wide temperature range. The temperature effect on fiber propagation velocity, laser spectral drift, fixed delay on PCB trace and device are separately studied. The fitting value are applied to an asymmetrical link model which consists dedicated components for uplink/d- wnlink media propagation delay and transmit/receive delay for both master/slave. According to the results, a quasi-linear temperature correction method is implemented for the KM2A timing synchronization node that reduce the synchronization variation from 300ps to 50ps in a temperature range of 50 degrees.
Keywords :
atmospheric temperature; cosmic ray apparatus; cosmic ray muons; cosmic ray showers; galactic cosmic rays; muon detection; scintillation counters; synchronisation; CUTE-WR; LHAASO KM2A timing synchronization node; Large High Altitude Air Shower Observatory; White Rabbit; altitude 4300 m; angular resolution; asymmetrical link model; compact universal timing endpoint; connection topologies; fiber media; fiber propagation velocity; fixed delay; galactic cosmic ray origin; gigabit Ethernet data transfer; laser spectral drift; muon detectors; quasilinear temperature correction method; reconstructed air shower event; scintillation electron; square kilometer complex array; subdetector arrays; subnanosecond precision timing transfer; temperature effect; temperature variation; time information; Detectors; Rabbits; Radiation imaging; Synchronization; Temperature distribution; Temperature measurement;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Real Time Conference (RT), 2014 19th IEEE-NPSS
Print_ISBN :
978-1-4799-3658-8
Type :
conf
DOI :
10.1109/RTC.2014.7097462
Filename :
7097462
Link To Document :
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