1. 32nd International Cosmic Ray Conference, Beijing
Observation of solar neutrons by using a very sensitive cosmic ray detector
Mt. Sierra Negra, Mexico
Yutaka Matsubara
August 11, 2011
32nd International Cosmic Ray Conference, Beijing

2. List of Authors
Y. Matsubara1, Y. Nagai1, Y. Itow1, T. Sako1, D. Lopez1. G. Mitsuka1,
K. Munakata2, C. Kato2, S. Yasue2, M. Kozai2, M. Tsurusashi2, Y. Nakano2,
S. Shibata3, H. Takamaru3, H. Kojima4, H. Tsuchiya5, K. Watanabe6,
T. Koi7, J. F. Valdés-Galicia8, A. Hurtado8, O. Musalem8, E. Ortiz8,
L. X. González9
1Solar-Terrestrial Environment Laboratory, Nagoya University, Japan
2Department of Physics, Shinshu University, Japan
3College of Engineering, Chubu University, Japan
4Faculty of Engineering, Aichi Institute of Technology, Japan
5High-Energy Astrophysics Laboratory, Riken, Japan
6Institute of Space and Astronomical Science, Japan Aerospace
Environment Agency, Japan
7SLAC National Accelerator Laboratory, USA
8Instituto de Geofisica, Universidad Nacional Autónoma de México, México
9Institoto de Astrofisica, Óptica y Electrónica, Tonanzintla, México

3. Observation of solar neutrons
charged particles
Earth
Sun
neutral particle: neutron
Magnetic field 太陽
M. A. Lee 1991 太陽
Study on particle acceleration by using
solar neutrons which come straightly
Neutrons are produced by accelerated ions

4. World-wide network of solar neutron telescopes
4600m
2770m
3135m
2003年3月・11月に設置作業。
4200m
4300m
5250m
3200m
started by Muraki et al. and
operated since November 2003
24 hour observing

5. Observation by different energies
Geotail
>50keV
September 7, 2005
Observation by different
energies
>30MeV
30min
Neutrons were observed for longer time than X-rays.
neutron
>60MeV
Sako et al. 2006
30min
Bolivia (SNT, NM)
Mexico (SNT, NM)

6. Typical solar neutron telescope (SNT)
Proportional counter
neutron
particle ID
Scintillator: 30 to 40 cm
（Energy）
direction
proton

7. SciCR 1.7m 3m KEK→FNAL 3m Scintillator bars 2.5cm x 1.3cm x 3m
116×64×2＝14848
We use SciBar （3m x 3m x 1.7m） for the cosmic ray observations at Sierra Negra. SciBar was used for the accelerator experiments.
SciBar has much better sensitivity than the current solar neutron telescope and can measure the track of particles.
Particle identity. Better energy and directional resolution.

8. INAOE The proposed plan Mexico city Sierra Negra Puebla
Transport the SciBar from FNAL to the
National Institute of Mexico (INAOE)
at 2150m above sea level.
(2) Measure cosmic rays at INAOE
and complete data taking system.
(2011 to 2012)
(3) Transport the detector to Sierra Negra,
4600m a.s.l. and start observing solar
neutrons. (2012 to 2013)

9. Preliminary experiment using mini-SciCR in 2010
20cm
20cm
successful !
Test of the power supply and electronics for SciCR
Measure cosmic ray backgrounds at Sierra Negra
　　　 determine trigger condition of the experiment
and calculate the expected efficiency of SciCR

10. Prepare data acquisition system in Japan
On-going !!
 Should be ready for shipping in September

11. Work at FNAL in February and March 2011
Inside the experimental hut
Remove fibers and pack scintillator bars and fibers
Two planes (X and Y) make one unit

12. Work at FNAL in February and March 2011

13. The detector arrived at INAOE in April 2011

14. The work until the end of 2011
(1)
To redirect the detector
(2)
To insert fibers
has already started and will finish soon.
is expected to finish in October 2011.

15. We measure cosmic rays in INAOE in 2011
All the hardware and on-line software should be confirmed before Sierra Negra.
(after October 2011 )

16. Comparison with the current SNT
16σ
Upper: Solar neutron event on September 7, 2005 (black),
Simulation assuming the instantaneous emission for the SNT (red)
SciCR
Ⅰ2σ
Lower: Simulation for the
SciCR assuming the same
Flare as above.
57σ
16σ: current SNT, 57σ for the SciCR

17. Summary
SciCR (SciBar for the Cosmic Ray Observations) is a sensitive experiment using 15,000 scintillator bars.
It works as
a super sensitive solar neutron telescope, and
a cosmic ray muon detector.
The progress of the project is as scheduled:
Observation of cosmic rays will start in the end of 2011 at INAOE (2,150m a.s.l. ) in Mexico.
The observation of neutron will start in the late 2012 on Sierra Negra (4,600m a.s.l.). Solar maximum will be 2013 !
The aurhors thank the SciBar and SciBooNE group for allowing them to use SciBar for the cosmic ray experiment,
and INAOE to give space to do cosmic ray experiment.
See the posters: ID26 (Y. Nagai et al.) as a solar neutron telescope
ID 373 (Y. Nakano et al.) as a muon detector

19. We put it on Mt. Sierra Negra (4,600m a.s.l.)
LMT

20. Preliminary experiment using mini-SciCR in 2010
Trigger board
VME
DAQ board
64ch MAPMT
Front-end board
slide from Y. Takubu

21. SciCR will start in 2012
Some minor problem will be solved in one year