I. Angelov UN/ESA/NASA/JAXA Workshop on the International Heliophysical Year 2007 and Basic Space Science 2-6 June 2008, Sozopol, Bulgaria Muon Telescopes

I. Angelov UN/ESA/NASA/JAXA Workshop on the International Heliophysical Year 2007 and Basic Space Science 2-6 June 2008, Sozopol, Bulgaria

Muon TelescopesMuon Telescopes at Basic Environmental Observatory at Basic Environmental Observatory

Moussala and Moussala and South-West University - BlagoevgradSouth-West University - Blagoevgrad

I. Angelov, E. Malamova, J. Stamenov

INRNE – BAS, SWU “N. Rilski”

Presenter : I. Angelov


Institute for Nuclear Research and Nuclear Energy, BAS

Basic Environmental Observatory – Moussala

42°11’N , 23° 35’E , 2925 m a.s.l.

South West University “N. Rilski” Blagoevgrad

Department of Physics

42°01’N , 23° 06’E , 383 m a.s.l.

Observation sites


Outline

1) Description of the instruments.

2) Main characteristics of the telescopes.

3) Examples of experimental data.

4) Summary

5) Future plans.


Detectors setup

Moussala – 1 m2 , 2x2

configuration, 1m between detectors planes

Blagoevgrad – 2.25 m2 , 3x3 configuration, 1.5 m between detectors planes

Both telescopes use water cherenkov detectors


Detectors setup

• Mirror container 50x50x12.5 cm• 10 cm distilled water as radiator• 2.5” , 12 dynodes photomultiplier FEU-110, FEU-139

• PMT in single electron counting• 300 Ohm anode load• 90 MHz bandwidth amplifier with gain x50• discriminator threshold 15 – 50 mV• 60 ns ( 45 ns ) TTL pulses formed


Coincidence circuits and data acquisition system


1200 1300 1400 1500 1600 1700 1800 1900 2000

0

20

40

60

80

100

120

140

160

180

D1U-D1D D2U-D2D D3U-D3D D4U-D4D

CO

INC

IDE

NC

E C

OU

NT

S P

ER

15

SE

CO

ND

S

HIGH VOLTAGE, V

Detectors adjustment :

• plateau in the counting characteristics

• fixed thresholds are selected – 28 mV for Moussala

– 22 mV for Blagoevgrad

• optimal HV is chosen for each detector

Dependance of the count rate – vertical coincidences on the HV for the four pairs of detectors of the telescope at BEO

Detectors adjustment


Direction Angular interval, deg

Number detector pairs

Count-rate, min-1

Statistical error for 1h

Vertical +18.4 -18.4 9 878 0.44%

NS 0 - 33.7 6 438 0.61%

SN 0 - 33.7 6 438 0.61%

WE 0 - 33.7 6 455 0.6%

EW 0 - 33.7 6 455 0.6%

Direction Angular interval, deg.

Number detector pairs

Count-rate, min-1

Statistical error for 1h

Vertical +25.6 -25.6 4 2387 0.27%

NS 0 - 45 2 814 0.45

SN 0 - 45 2 704 0.49%

WE 0 - 45 2 756 0.47%

EW 0 - 45 2 734 0.48%

Angular directions and count rates

SWU telescope count rates =>

BEO telescopecount rates =>


BEO telescope :

• 40 cm concrete above the detectors; 5 cm Pb ;

• ~ 0.45 GeV energy threshold for CR muons

SWU telescope :

• 160 cm concrete above the detectors; 5 cm Pb ;

• ~ 1 GeV energy threshold for CR muons

the MMC (Muon propagation Monte Carlo) software was used for calculation (Chirkin and Rhode, 2004, 2005)

Energy thresholds and response to primary protons

BESS spectrometer at mount Norikura – 2770 m a.s.l. , Rc=11.2 GV. (Sanuki et al., 2003) kinetic energies ~ 0.48 – 106 GeV I0 0.0105 cm-2s-1ster-1

Count rate 580 min-1 - Moussala telescope 2925 m a.s.l. , Rc=6.3 Gv,corresponds to I0 0.0188 cm-2s-1ster-1


10 100 10000.00

0.04

0.08

0.12

0.16

0.20

0.24

0.28

0.32

Rel

ativ

e p

art

of

the

tota

l m

uo

n f

lux

Energy of primary protons, GeV

10 100 10000.00

0.04

0.08

0.12

0.16

0.20

0.24

0.28

0.32

Rel

ativ

e p

art

of

the

tota

l m

uo

n f

lux

Energy of primary protons, GeV

Energy thresholds and response to primary protons

Results from simulations with PLANETOCOSMICS code

Response to primary protons generated muons – BEO telescope

90% of the counted muons generated from protons with energies above 10 GeV

Response to primary protons generated muons – SWU telescope

90% of the counted muons generated from protons with energies above 15-20 GeV

Rc6.34 GV

Rc6.24 GV


680 690 700 710 720 730 740 750-8

-6

-4

-2

0

2

4

6

8

10

12

Ver

tica

l f

lux,

%

pressure, hPa

940 950 960 970 980 990 1000-10

-8

-6

-4

-2

0

2

4

6

8

10

Ve

rtic

al

flu

x, %

pressure, hPa

Meteorological corrections

Barometric effect for CR muons SWU muon telescope

= -0.1245 / % hPa

Barometric effect for CR muons BEO muon telescope

= -0.2845% / hPa


-0.12

-0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

2015105

27

Va

ria

tio

n o

f C

R

,

VE

RT

ICA

L c

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1

Date, 27 October - 21 November 2003

Forbush decrease October – November 2003, SWU telescope

FD in october – november 2003

(HALLOWEEN SPACE WEATHER STORMS OF 2003)

<= SWU telescope, pressure corrected 1h data.

<= Athens NM data


Forbush decrease December 2006, BEO telescope

FD in December 2006

(after the GLE of 13 December)

<= BEO telescope, pressure corrected 1h data.

<= Athens NM data


Summary

• Two operational muon telescopes in BG ( Rc6.3 GV )

at ~380 m. a.s.l., 2.25m2 detectors , 1 GeV energy threshold, 0.45% statistical error for 1h intervals (after reconstruction since November 2007)

at ~2925 m. a.s.l., 1m2 detectors, 0.45 GeV energy threshold, 0.27% statistical error for 1h intervals, (since August 2006)

• Detectors of original construction, easy to build and cost effective.


Future plans

• Coincidence circuits and counters controller upgrade, using FPGA - all combinations of UP and Down detectors

• A possibility to upgrade to higher number of detectors at South West University exists – enough room space ;


Thanks for the attention !

The BEO muon telescope was constructed and funded as a part of the FP6 BEOBAL project - BEO Centre of Excellence Research Capacity Improvement for Sustainable Environment and Advanced Integration into ERA.

Questions, comments and ideas are WELCOME.


Basic references

Hamamatsu Photonics K. K. Photon counting using photomultiplier tubes, 2005 http://sales.hamamatsu.com/assets/applications/ETD/PhotonCounting_TPHO9001E04.pdf

Chirkin D., Rhode W., All Lepton Propagation Monte Carlo, Proceedings of the 29th ICRC, Pune, 2005, http://icrc2005.tifr.res.in/htm/Vol-Web/Vol-19/19093-usa-chirkin-D-abs2-he21-poster.pdf

Chirkin D., Rhode W., Muon Monte Carlo: a high-precision tool for muon propagation through matter, 2004, http://arxiv.org/PS_cache/hep-ph/pdf/0407/0407075v1.pdf

Sanuki T., Fujikawa M., Abe K. et al, Measurements of atmospheric muon spectra at mountain altitude, 2003, http://arxiv.org/PS_cache/astro-ph/pdf/0205/0205427v3.pdf

Desorgher L., PLANETOCOSMICS Software User Manual, 2005,

Documents

I. Angelov UN/ESA/NASA/JAXA Workshop on the International Heliophysical Year 2007 and Basic Space Science 2-6 June 2008, Sozopol, Bulgaria Muon Telescopes