Stockholm Skolors Kosmiska NÃ¤tverk Stockholm Educational Air ...

Stockholm Skolors Kosmiska Nätverk 

Stockholm Educational Air Shower Array 

(SEASA) 

Mark Pearce - KTH Stockholm - 

Mark Pearce, Department of Physics, The Royal Institute of Technology (KTH), Stockholm, Sweden 

Amsterdam, March 7th – 8th 2005



(SEASA) 

Part 1: Introduction 

Part 2: Technical details 




Orientation 

• KTH particle physics group 

– Astroparticle physics with balloons and satellites (PAMELA, GLAST) 

– Accelerator-based particle physics (ATLAS, D0) 

• Mark Pearce, lecturer (pearce@particle.kth.se) 

• Stefan Rydström, engineer 

• Petter Hofverberg, PhD student 


• ... and usually 1-2 final year undergraduate students (very 

important!). Four have written theses (20 weeks) so far. 2 

currently on-going. 

• Financing: none, (direct at least)


10 15 eV 

10 17 eV 

10 19 eV 

5 km

Photo: P. Walck 

Mark Pearce - KTH Stockholm -

~1 m 

• ’NE’ scintillator recycled from CP- 

LEAR 

• Wavelength shifter read-out 

• Hamamatsu R5900U PMTs 

(spares from PAMELA) 

• All of these will be changed in 

next phase... 

13 cm 


• Car roof boxes used to provide 

cheap and weatherproof 

housing 

• No temperature control

Per station: 

• 3 x scintillators + PMTs / HV 

• Programmable analogue front-end 

• Programmable logic array 

• GPS timing (PPS+100MHz+sawtooth) 

• Embedded Linux ’DAQ on a chip’ 

• Environmental sensors (Temp. etc.) 

Server (at AlbaNova) 

• MySQL database (Linux / Java) 


Viewer (web browser – where ever..) 

• Client-side Java applet

Web Viewer: ’Live Live’ Map 


Web Viewer: Monitoring 


Web Viewer: Administrator 


Present Status 

• Two stations running at AlbaNova University Centre 

• Proof-of-principle studies complete for basic design 

• Now in production stage for first cluster of stations 

• Showers seen! (~35 / hour / station; ~10 / day / both stations) 

• Many studies: Temperature, pressure effects. GPS position 

fixing and timing. Aires simulations. Detector spacing, 

threshold settings etc. etc. 


• Learnt many lessons during installation! 

– Weatherproofing detectors and securing against wind 

– Cabling

Two-station Showers! 

[120 hours / 78 triggers / 33 within 1 µs] 


[Random coincidences]


Education / Outreach 

• Contact established with 3 local ’gymnasium’ schools (pre-university) 

• Aim to involve students in detector construction, installation, testing, soldering 

electronics boards etc. 

• Web software allows students to monitor their station and access data 

• Cosmic ray telescope is an important bridging tool 

• Starting this programme is an important milestone for 2005 

[Brochure]

Future Plans 

• Scintillators / PMTs ordered for another 5 stations 

which will be deployed during 2005 (at least four of 

these at schools) 

– Single sheets of scintillator (1m x 30 cm x 1.5 cm) remove the 

need for (expensive!) wavelength shifting read out 

– Hamamatsu R5900U PMTs replaced with the much cheaper 

Hamamatsu R6094 (Ø 28 mm) / Photonis XP3314 (Ø 76 mm) 

– Electronics design fixed, but firmware will be updated 

– Viewer software will evolve (more features!) 

– Electronics will be packaged more attractively 


• Lack of funding is a major hinder to subsequent 

expansion – significant additional funding will also be 

sought in 2005




(SEASA) 

Part 1: Introduction 

Part 2: Technical details 




Now 

• ’NE’ scintillator recycled from CP-LEAR 

• Wavelength shifter read-out 

• Hamamatsu R5900U PMTs 

Future 


• Single sheets of scintillator (1m x 30 cm x 

1.5 cm) remove the need for (expensive!) 

wavelength shifting read out 

• Hamamatsu R5900U PMTs replaced with 

the much cheaper Hamamatsu R6094 (Ø 

28 mm) / Photonis XP3314 (Ø 76 mm)

School 1 

PPS 

GPS 

RS232 

Internet 

t 1 

Analog 

front-end 

t 2 

t 3 

Programmable 

Logic Array 

RS232 

Single Chip 

Computer 

(Linux) 

Analog 

Digital 

School 2 


Analog 

Digital 

~10ns 

V ref 

School 3 

School 4

[HV board not shown] 


RS232 to ’LOC’ 

and GPS software 

KTH Electronics Card 

PMT analogue 

electronics x 3 (DACs) 

To Motorola 

Timing 2000 

Antenna 

Power in 

Altera Cyclone 

PLA 

Motorola M12+ 

Oncore GPS 

receiver 


LVTTL 

Expansion 

ports 

JTAG 

Sensors 

HV control 

Pressure sensor

16 + 6 MB flash 

Axis Linux on a Chip (’LOC( 

LOC’) 

2 x serial port 

Etrax 100LX MCM 

100BaseT Ethernet 

• Sold as a ’development board’ 


(USB) 

• Strong user community (mail lists etc.) 

• Embedded Linux 2.4 

• In-built web-server 

• Also, SSH / (Telnet / FTP)

GPS Timing 


t(GPS 1) – t(GPS 2) t(GPS 1) – t(GPS 2) 


t(GPS 1) – t(GPS 2) 

t(GPS 1) – t(GPS 2) 

• As f(N sat 

) etc. 

Trigger no. Trigger no.

Data Flow 

EmLinux / C 

Linux / Java / MySQL 


Browser / Java Applets

Event Format 



Studying Enviromental Effects

Pulse Height Information 


V th

Calibration 

• No direct calibration (eg: 

via LEDs) 


• Threshold curves are 

produed automatically by 

DAQ system 

• Currently done by hand but 

will eventually be automated 

network-wide

Future Developments 

• The current system is fully tested and can be 

deployed at schools ’as is’ 

• Some improvements are foreseen in the near future: 

– GPS initialisation and site survey controlled by the LOC (being 

tested now) 

– Programming Altera PLA directly from the LOC 

– Automatic calibration curves 


– Programmable trigger window / widen (1 µs?) & count particles 

– Add more features to the viewer: GPS data / angles / pulse length 

/ real-time histogramming / chat (video?) function / SMS and e- 

mail alerts / integrate into project homepage (educational material)

Live Demonstration! 


[To the live demonstration]

Stockholm Skolors Kosmiska NÃ¤tverk Stockholm Educational Air ...

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