Nagoya Multi-Directional Muon Telescope
Cosmic-Ray Research Section,
Solar-Terrestrial Environment Laboratory,
Nagoya University, Nagoya, 464-8601 Japan

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CONTENTS
I. INTRODUCTION ......................................................................................................................................... 3
II. MULTI-DIRECTIONAL MUON TELESCOPE AT NAGOYA ................................................................... 4
a. Setting of the telescope ........................................................................................................................... 4
b. Electronic circuits .................................................................................................................................. 4c. Coincidence system and component telescopes ......................................................................................

6

d. Recording system ..................................................................................................................................

8e. Power supplies ....................................................................................................................................... 8
f. Overall stability of the telescope.............................................................................................................. 8III. REDUCTION OF DATA............................................................................................................................ 8
a. Adoption criteria for raw data to produce hourly counts (N).................................................................... 8b. Conversion to relative intensity (W) by means of Natural Logarithmic Representation ........................... 8c. Pressure correction and the barometer corrected relative intensity (WP) .................................................... 9d. Calculation of daily table ........................................................................................................................ 9e. Final data file .......................................................................................................................................... 9
IV. METHOD FOR ELIMINATING TEMPERATURE EFFECT ON COSMIC RAY MUON INTENSITY,
AND G- AND GG-COMPONENTS........................................................................................................... 10
V. DESCRIPTION OF DIAGRAMS ................................................................................................................ 11
a. Multi-directional hourly muon intensity ................................................................................................. 11
b. Solar rotation diagram of cosmic rays .................................................................................................... 11c. Multi-directional daily mean muon intensity .......................................................................................... 12
d. Suimmation harmonic diagram of cosmic-ray daily variation ................................................................. 12
App. I REPLACEMENT OF COINCIDENCE SYSTEM................................................................................ 13
App.II FOR USE OF DATA........................................................................................................................... 132

I. INTRODUCTION
Multi-Directional Cosmic-Ray Muon Telescope at
Nagoya was planned and constructed as a part of Japanese
program for the International Active Sun Year (IASY). The
construction of the telescope as well as the building for it, wasstarted in the summer of 1968. The building was completed
in March 1969, and the telescope was completed in autumn
of 1969. After careful check of the whole system, continuous
observation of the cosmic-ray intensities was started in
October 1970 and has been continued thereafter. This
telescope has an effective area of 36 m2 in which 9 m2 has therole as the muon monitor in Japan.
The geographical and geomagnetic coordinates of theobservation site are summarized in Table I. Average variations of the climate at Nagoya, such as the temperature andthe atmospheric pressure, are shown in Fig. 1. The building
which houses the telescope was built near the top of a hill in
the University campus beside the dome for a Cerenkov telescope built in 1959 as shown in Fig. 2. The building has anarea of 152 m 2 with a thin slate roof and heat insulation
structure as shown in Fig. 3. The telescope was constructed
inside a thermostatic chamber (7.2×7.2×4.3 m3 ) built in an
air conditioned room (117 m2 ).

Table I. Locality of observation site
Geographical Latitude; 35°09’N, Longitude; 136°58’E
Altitude; 77 m above sea level

Fig. 1. a) Average annual variations of the temperature and the atmosphericpressure at Nagoya for 1941-1970b) Average daily variations of the temperature and the atmosphericpressure at Nagoya for 1965

Geomagnetic Latitude; 24.7°N
Declination; 6.44°W, Inclination; 48.25°N

Fig. 2. Aerial view of STEL: The building for the multidirectional telescope is at the left side of the photograph,with dome for the Cerenkov telescope at the center, and thelaboratory office at right.

3

Fig. 3. Side view of the building for the multi-directional telescope showing thestructure of the roof and the side walls (top), and plan of the building showing thearrangement of the thermostatic chamber in the observa-tion room (right).

II. MULTI-DIRECTIONAL MUON TELESCOPE AT NAGOYA
b. Electronic circuits
The block diagram of the electronic circuits for the telescopeis shown in Fig. 5. Pulses from each phototube areamplified (~300) by a circuit, which is set in the phototube
box. Differential pulse height distribution from a detector
after amplification is shown in Fig. 6. The distribution of
signal (cosmic-ray) pulses has a maximum at a certain pulse
height (which is referred to as the peak pulse height) and canbe discriminated from that of the noises ((-rays etc.) bychoosing a proper discrimination bias. However, the discrimination bias voltage is fixed to a preset value (~0.5V) in
the present circuit, so the high tension voltage of each phototube is adjusted in turn. To compensate the differences inthe sensitivities of phototubes as well as the scintillation
efficiencies of detectors, the following procedure is taken for
the adjustment.
i) The high tension voltage of each phototube is adjusted
by inserting a proper resistor between the output of acommon High Voltage (H.V.) supply and the resister network of the phototube as shown in Fig.7, so that the peakpulse height for all the phototubes coincide among them-a. Setting of the telescope
The multi-directional muon telescope consists of 2 layersof 36 detectors as shown in Fig. 4. Two layers are separated
by 1.73 m in height by means of iron frames and Pb blocks of
5 cm thickness, which are placed just underneath the detectorsof the upper layer in order to absorb soft component of cosmic
rays. The detector consists of a 5 cm thick plastic scintillatorof 1 m2 area, which is set at the bottom of 1.6 mm thick ironplate box and viewed by a 5" phototube (Hamamatsu
Photonics R877). These detectors are placed in a square (6 H
6 m 2 ) on each layer, one side of which is set along thegeographical north-south direction. Each detector is called by
the number, attached in the figure, with initial U or L for theupper or lower layer (i.e. U1, U2, ..., U36, L1, L2, ..., L36).
Sometimes, the detectors with the initial U or L are called theupper or lower detectors. Multi-directional muon telescope isconstructed by a group of sets of 2-fold coincidence between
the upper and lower detectors. The selection rule of the sets isgiven in II-c.

4

Fig. 4. Setting of the detectors in the multi-directional telescope: Numbers attached tothe square denote the detector nos., and V, 30°N etc., specify the name of component,
relating to the upper detector in coinci-dence with L23 detector

Fig. 5. Block diagram of the electronic circuits of the telescope, showing the path of signals from the detectors to the outputs of the recorder system.

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Fig. 6. Differential pulse height distribution of output pluses from this amplifier:
Peak at right side is due to the cosmic-ray particles, while the rise in lower pulse
height region is mainly due to background gamma-rays

selves.
ii) The counting rate for various components (cf. II-c) was
obtained as a function of the common H.V. supply voltage,
as shown in Fig. 8.
iii) In order to get the best stability for continuous
observation, the voltage of the common H.V. supply should be
set at a point where the slope of the curve in Fig. 8 has theminimum value. However, as seen in the figure, such a value
is different for different component, and the median value forthe vertical component and the single counts (i.e. Upper andLower in Fig. 8) was taken as the value of the H.V. supply
voltage, as shown by a straight line in the figure.
Single counting rate of one detector corresponding to thissetting was about 1.1·104 c/min. in the upper layer and
0.9·104 c/min. in the lower, and the equivalent discrimination bias is shown by an arrow in Fig. 6. Temperaturedependences of the scintillation efficiency, the phototube
sensitivity, the gain of the amplifier and the discriminator bias

Fig. 8. Dependence of the counting rates of various components on the changeof H.V. supply voltage.

were studied. It was found that these dependences produce a
net change of B0.035% in the observed intensity for +1°C
change in temperature.
c. Coincidence system and component telescopes
Pulses from 72 detectors in the upper and lower layers
are properly fed into 992 sets of 2-fold coincidence circuits toconstruct 17 component of the telescope. Each component of
the telescope consists of all the possible sets of 2-foldcoincidence between any pair of upper and lower detectors
placed in relative positions, as specified below. Taking L23
as the position of the lower detector in Fig. 4, the relative
position of the upper detector for the specified component
such as Vertical, 30°W, 39°NW, 49°W or 64°W is defined bya square or dashed rectangle with the specified mark in the
figure. Relative position for other directions is easily foundfrom the figure. For large zenith angles, such as 49° and 64°,
the dashed rectangular area larger than 1 m 2 is adopted inorder to increase counting rate. It is noted, however, that thisarea is varied from 3 to 2 m2 for 49° and between 10 and 3
m 2 for 64° depending on the location of the lower detector,
an example of which as shown by the rectangle for 64°N in
Fig. 4.
Directional sensitivity of each component of the tele-

Fig. 7. Circuit to adjust the high tension voltage of phototube by vary-ing thevalue of resister between the common H.V. supply and the resister network of thephototube

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In the table, SS multiplied by the square of cosine of thezenith angle (z) is also shown for a crude estimate of thecosmic-ray flux for each component. It is noted that at large
zenith angles, the observed rates become larger than the
expected values, which is an indication of the contamination

scope,after summing up all the possible sets of coincidence, isshown in Figs. 9 and 10. The average counting rate, theeffective geomagnetic cut-off rigidity at the maximum sensitivity and the total solid angle multiplied by area (SS) are
shown in Table II, together with the number of sets of coincidence for each component. The effective cut-off rigidities
were determined in considering the effect of shadow cone ofcosmic-ray orbits in the geomagnetic field, which isapproximated by 6 order coefficients of spherical functions(Finch and Leaton, 1957).

Fig. 9. Directional sensitivity of Vertical component is shown by con-tour lines
of equal sensitivity in a polar diagram of zenith and azimuthal angles

Fig. 10. Directional sensitivities of 30°E, 39°NW, 49°S and 64°E components
are shown by contour lines of equal sensitivity in a polar diagram of zenith andazimuthal angles.xii

Table II. Geometical parametes and counting rates. Value of N0 is that fixed for periods after Jan. 30, 1971 (cf.II- c).
Component

Total solidangle
Harea (SS)(m2 sterad)

Vertical
30° North
30° East
30° South
30° West
39° NE
39° SE
39° SW
39° NW
49° North
49° East
49° South
49° West
64° North
64° East
64° South
64° West

9.93
5.23
5.23
5.23
5.23
2.94
2.94
2.94
2.94
3.37
3.37
3.37
3.37
1.50
1.50
1.50
1.50

Total

62.09

SSH cos2z

Averagecounts N0(*106 /hour)

Effective
geomagnetic
cut-off (GV.)

No. of2-foldcoin. sets

9.09
3.97
3.97
3.97
3.97
1.87
1.87
1.87
1.87
1.58
1.58
1.58
1.58
0.33
0.33
0.33
0.33

2.76
1.25
1.20
1.23
1.26
0.58
0.58
0.60
0.62
0.49
0.46
0.48
0.49
0.14
0.14
0.14
0.15

11.5
12.9
16.2
11.3
9.4
17.9
15.0
9.2
11.0
12.9
21.0
10.9
9.3
11.0
25.1
10.8
8.7

36
30
30
30
30
25
25
25
25
64
64
64
64
120
120
120
120

40.09

12.55

12.55

992

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DC power supplies for the amplifier and the discriminatorare also stabilized for the AC voltage change, but havetemperature dependencies of B10 and B2 mV/°C respectively.
The effect of changes in the supply voltages on the counting
rates was studied and it was found that the change of thepower supply voltage caused by +1°C changeof the room
temperature produces B 0.006% change in the observed
intensity.
As the logic circuits for the coincidence system as wellas the recorder system are not sensitive to the change of the
supply voltage, conventional stabilizers are used in the power
supplies for these systems.

by shower events in the observed counts. This is due to theinsufficient stopping power of 5 cm thick Pb blocks against
shower particles.
d. Recording system
The output pulses from the coincidence system are fed
into a recorder system (cf. Fig. 5). Each channel of therecorder consists of 10 bits binary scaler and 4 digits decimalcounter with 4 digits buffer memory. The scaling factor (K) of
the binary scaler is so adjusted that the counting rate of thedeci m a l coun t er becom es a bout 8000/ 10 m i n . T h eaccumulated counts in the decimal counter are transferred tothe buffer memory once every 10 minutes and then the
counter is cleared up for the next accumulation period. The
contents of the buffer memories as well as the universal time
(U.T.) code from an electronic clock are transferred by anautomatic scanning circuit to an PC via a serial output of
RS232C. Nineteen channels of the recorder are used to record
the counting rates of the cosmic-ray intensities from 17
directions together with the total single counts of the upperand lower layers. Another channel of the recorder is used toaccumulate pulse counts from a digital barometer by means ofa quartz crystal resonator. The room temperature as well as
the outdoor temperature are also measured by a digital electric
thermometer to record with the same recording system.

f. Overall stability of the telescopeHigh counting rate of the telescope as shown in Table II,
naturally reduces the statistical fluctuations due to the finite
counting rates. Then the change of counting rate due to otherreasons such as the change of the pulse height distribution
has much important effect on the stability of the observed
rate. Instrumental fluctuations in short time interval (lessthan a day), is mainly originated from the change of the room
temperature. In order to reduce this cause, the room
temperature of the observation room is air-conditioned to
20±1°C and the temperature variation in the thermostaticchamber containing the telescope is maintained within±0.1°C throughout the year. By this regulation of thetemperature change, the observed intensity has an overall
stability of ±0.01% for duration of a few days (cf. II-b, e).
The stability in longer time interval is mainly controlled
by the variation in the pulse height distribution due to thefatigue of the phototube as well as the change of the scintillation efficiency. As no compensation for these effects were
made, decrease less than 1% per year in the counting rate
was observed.

e. Power supplies
In order to avoid interruption of the observation due to theelectric failure, an AC-DC-AC converter system with a deckof floating batteries (9.2 KV AH) is used for the AC power
supply. This system can supply 500 VA power to the telescopefor 6 hours without AC power input. High voltage supply tothe phototube is highly stabilized (4·10 -4 % for 1V ACchange), but has a temperature dependence of B50 mV/°C.

III. REDUCTION OF DATA
multiplied by the scaling factor (K) of the binary scaler toobtain the total counts (N = n HK) for the particular hour.

a. Adoption criteria for raw data to produce hourly
counts (N)PC checks counts transferred for every 10 minutes
interval whether they are inside certain limits. These limits
are chosen to reject any variation of counting rates outsidesof +5% and B15% of the average counting rate. Then all
counts satisfying the criteria are summed up for hourly values if at least three 10 min. values pass this test, and normalized to hourly counting rates (n). Further, the counts are

b. Conversion into relative intensity (W) by means of
Natural Logarithmic Representation
Accumulated counts per hour (N) are then converted.into
the relative intensity (W) using the Natural Logarithmic
Representation (Wada, 1957) as follows:8

W= 102 H In (N/N0)+WL

in units of %variation (up to 3rd harmonics) is tabulated.

(1)e. Final data file
These hourly values of WP processed by Online PC areplotted regularly for every solar rotation period using thecomputer systems in the Laboratory and in Nagoya University
Computation Center. Careful check of the data was made,utilizing the hourly data tables and inspecting visually theplotted diagrams. These data are then edited to a final electric
data file to be opened in the Data Server of the Laboratory (cf.
App.II). In the course of the observation renewal and highvoltage readjustment of phototubes and repair of amplifiers
etc changed counting rates of related components. Such levelchanges are not adjusted.

where N0 is the average counting rate and WL (15.0%) isartificially added to make the values of Walways positive.
c. Pressure correction and the barometer corrected
relative intensity (WP )The counting rate (NP) of the digital barometer is converted into atmospheric pressure (P) by using a conversion
formula and a set of calibration coefficients (A, B, and C)
as,
P = A + B·NP + C· NP2

hPa.

(2)

Coefficients ($’s) for the barometer effect correction were
derived by a correlation analysis between P and W’s as tabulated in Table III. Then using the coefficient, the barometercorrected relative intensity (WP) is obtained by
WP =102 H(W B $ H(P B P0))

in units of 0.01%. (3)Table III. Coefficients for barometer effect correction.

The value of P0 is set to 1000.0 hPa for simplicity, though
the yearly average of the atmospheric pressure is 1010 hPa.
d. Calculation of daily table
Hourly values of WP, daily sum and average as well as
the 1st, 2nd and 3rd harmonic coefficients of the daily variation of cosmic-ray intensities are computed and tabulated ondaily basis. In the same table, the residual dispersion of thecosmic-ray intensities for one day after removing the daily

9Component

Coefficient $Vertical
30°N, E, S and W
39°NE, SE, SW and NW
49°N, E, S and W
64°N, E, S and W

B0.12%/hPa
B0.12%/hPa
B0.12%/hPa
B0.12%/hPa
B0.15%/hPa

IV. METHOD FOR ELIMINATING TEMPERATURE EFFECT ON COSMIC-RAY MUONINTENSITY, AND G- AND GG-COMPONENTS
1

diurnal variation indicates the presence of P2 (sinλ) typeanisotropy in the equatorial coordinate system ( 8, n ), due to1
a P2 (cosλ) type anisotropy in interplanetary space. It was
concluded that this anisotropy was produced by a pitch angle( P ) di st r i bution of cosm i c-r a y pa r t i cl es a bout t h einterplanetary magnetic field lines from a detailed study ofthe phenomena (Nagashima et al., 1972; Fujii, 1971).
In Fig. 12, the distribution of the daily values of G-component relative to the average over a solar rotation period isplotted for (a) the days when the polarity of the interplanetary magnetic field was towards the sun, and (b) the days
when the polarity was away from the sun. A marked difference between two distributions is an indication that the cosmic- ray anisotropy perpendicular to the ecliptic plane has acorrelation with the polarity of the interplanetary magnetic
field (Kondo et al., 1975). Fig. 13 shows the time variationof daily mean values of GG-component in a period of solar
rotation number 1939, which demonstrates good correlation
between the change of sign of GG-component and that of thepolarity of the interplanetary magnetic field. Several reasonsfor this phenomenon, such as the radial density gradient of
the cosmic-ray particles (cf. Swinson, 1969), and the tilt of
the magnetic field line relative to the ecliptic plane are undercritical examination.
For this convenient nature of the G- and GG-components, they are plotted in the diagrams together with othercomponents.

Correction for the atmospheric temperature effect was notapplied to the reduced data due to the lack of enough data
about the change of the temperature in upper atmosphere.
This disadvantage for the muon intensity in comparison with
the neutron can be eliminated easily if one takes differences
between the data of pairs of components, such as 30°NB30°E.
This difference method is particularly useful for the analysis
of cosmic-ray anisotropy, in which the lack of the knowledge
about the dailyvariation of the atmospheric conditions usuallycasts some doubt on the obtained results. Further, this method
eliminates the contamination due to the day to day intensity
variation in the analysis of cosmic-ray anisotropy.
Especially, if one takes the second order difference
G = (30°N B 30°S) + (30°N B 30°E)
GG = (49°N B 49°S) + (49°N B 49°E),(4)

the spurious variations from these sources are almost eliminated (Nagashima et al., 1972). Actually the intensity
variation of these G- and GG-components mainly reflects
change of difference between the intensity from north polar
direction and that from a direction parallel to the equatorial
plane. So it is a good index to study the North-South (orNorth-Equatorial) asymmetry of the cosmic-ray flux. As an
example of this characteristic, the annual change of thediurnal variation of G-component is shown in Fig. 11. A
significant annual change of the amplitude and phase of theFig. 11. Annual change of the diurnal vector of G-component observed in 1970-1972 is shown in (b). (a) is the prediction on the annual change of the diurnal vectorof G-component based on the pitch angle distribu-tion hypothesis, while (c) is that based on the density gradient hypothesis

10Fig. 13. Transition of N-S asymmetry of GG-component correlated with thepolarity of the interplanetary magnetic field during one solar rota-tion

Fig. 12. Distribution of the daily values of G-component relative tothe average over a solar rotation period, classified by the polarity of theinterplanetary magnetic field

V. DESCRIPTION OF DIAGRAMS
All data are plotted in the same scaling units as illustrated at left bottom corner of the diagram. In other words,
the distance between two adjacent level lines corresponds to
2.8% of intensity change. The level line for each compo-nent
expresses the average intensity of all the hourly values overthe solar rotation period, the value of which is written inunits of percent (i.e. WPH100) under the name of component
at the left side of the frame. At right side of the diagram, thestandard error ( ± N0 ) for hourly value of each component
is illustrated.

a. MULTI-DIRECTIONAL HOURLY MUON INTENSITY
Hourly values of WP for 14 components are plotted in
Diagrams, one for each of Solar Rotation Number. On eachdiagram, data of 13 components are plotted in the same frameby the following order: 64°E, N, S and W; 49°E, N, S and W;
30°E and N; Vertical; 30°S and W; and those of G-component(cf. IV) are in a separate frame. Data of 39° NE, SE, NW and
SW are omitted because of limited space. This ordering waschosen so that the effective rigidity for each component(considering the coupling coefficient) is higher for thecomponents plotted at higher position.
The name of the observation site, the reference level P0
for the pressure correction and the geographic coordinates are
written at left top corner of the diagram. Solar Rotation No.
for the particular diagram is written at the center of the
diagram, while the first and last dates of the period are written at right top corner. At the top of the frame, the day of therotation, starting from 1 and ending at 27 for every solar
rotation period, is written, while the day of the month iswritten at the bottom of the diagram together with the nameof the month. Time scale of the diagram is in U.T., and 0 hrof the local time corresponds to 15 hr U.T. of the previous
day.

b. SOLAR ROTATION DIAGRAM OF COSMIC RAYSThis diagram was prepared to emphasize the 27-dayrecurrence tendency in cosmic-ray intensity and its
anisotropy. The hourly values of WP of Vertical component
for the specified 14-solar-rotation period, covering about one
solar calendar year, are plotted against the day of the rotation
on each of Diagrams. At right top corner, the first and last
dates of the data in the diagram are written, while those foreach rotation period are written at the right side of the frame.
Level line for each rotation expresses the average intensity of
all hourly values over the particular rotation period, the valueof which is written in units of percent (i.e. WP H100) under
the solar rotation no. at the left side of the level line. Again

11

diagrams, grouped on the 14-solar-rotation basis. Vectors(CMi, SMi) for i-th rotation period are summed up in the diagram, so that j-th point in the diagram has the following
coordinates.

the scaling unit for the plotting is shown at the left bottom
corner of the diagram, and the distance between two adjacentlevel lines corresponds to intensity change.
Hourly values of WP of G-component in the same period
are plotted in Diagrams with the same format as for the
Vertical component. In the diagrams, the variations for Gcomponent are very small in comparison with those for
Vertical-component. This is due to the insensitivity of Gcomponent to the change of atmospheric condition as well as
the day to day modulation of primary cosmic rays as stated inIV.
Differences of hourly values VB64°E (=Vertical B64°E)
are plotted in Diagram with the same format. VB64°E is agood index to study the North-South asymmetry in conjunction with G and GG, as VB64°E reflects mainly change of theNorth-South asymmetry while G and GG reflect change of theNorth-South as well as the North-Equatorial asym-metry.
Daily mean of GG-component are plotted in Diagram as
an index of the polarity of the Interplanetary Magnetic Field(cf. IV).

∑    ⋅ ⋅ ⋅    = ∑     =   =

=



=

The scaling units of axes of summation diagrams are shownin the title of each diagram. The following symbols are used
to specify the name of components: ࿾; Vertical, ; 30°N,
H:30°E, +; 30°S, and ; 30°W, respectively.

Acknowledgements:
These data are published on one of projects to con-struct
data bases in Center for Joint Observations and Data
Processing, Solar-Terrestrial Environment Laboratory,
Nagoya University. The graphs are processed using thefacilities of Solar-Terrestrial Environment Laboratory andNagoya University Computation Center.

c. MULTI-DIRECTIONAL DAILY MEAN MUONINTENSITY
Daily averages of Wp for 14 components are plotted in
Diagrams. One each diagram, data of 13 components areplotted in a frame with the same order as in the hourly value
plot (cf. VI-a), and those for G-component are in a separate
frame. The first and last dates of the period covered by adiagram are written at right top corner of the diagram. At the
top of the frame, solar rotation numbers are written for each27-day period. All data except G-component are plotted in thesame scaling unit as illustrated at left bottom corner of theupper frame, and the distance between two adjacent level lines
corresponds to intensity change. The ordinate scale for Gcomponent is expanded twice, as the day to day variation of
G-component is quite small. The level line for eachcomponent expresses the average of daily means over thewhole period in the dia-gram, the value of which is written
under the name of com-ponent at left side of the diagram.
The annual variations of cosmic-ray intensity for the 13
components in the upper frame are mainly due to the effect of
the atmospheric temperature, while those for G-component isdue to the variation of the North-South (or North-Equatorial)asymmetry of primary cosmic rays (cf. IV).

References
Finch, H.P. and B.R. Leaton (1957): Mon. Not. Roy. Ast.
Soc. Geophys. Suppl., 1, 314.
Fujii, Z. (1971): Rep. Ionos. Space Res. Japan, 25, 242.
Kondo, I., Z. Fujii and K. Nagashima (1975): Proc. 14th Int.
Cosmic Ray Conf., Munich, 4, 1182.
Nagashima, K., K. Fujimoto, Z. Fujii, H. Ueno and I. Kondo(1972): Rep. Ionos. Space Res. Japan, 26, 31.
Swinson, D.B. (1969): J. Geophys. Res., 74, 5591.
Wada, M. (1957): J. Sci. Res. Inst., 51, 201..xvii

d. SUMMATION HARMONIC DIAGRAM OFCOSMIC-RAY DAILY VARIATIONFirst, second and third harmonic vectors of the daily
variation of 5 components (Vertical, 30°N, E, S and W),
averaged over each rotation period are plotted respectively in
Diagrams. Each diagram consists of three summation

12

App. I REPLACEMENT OF COINCIDENCE SYSTEM
Table V. Observed average counting rates after
replacement of coincidence system

In September 1979 telescope coincidence system was
replaced by a new system, to renew electronic circuits which
had been used since the start of observations. Observations
restarted on September 30, 1979.
The new coincidence system was designed, modifying theoriginal system to reduce number of sets of coincidence andto simplify electronic circuits. For components from Verticalto 39° North-West in Table II, the logic of new sys-tem is
identical with that of the original system. For Components
with zenith angles of 49° and 64°, sets of coin-cidence were
designed based on 6 m 2 detectors units in line on each layer.
In Fig. 15 examples of relative positions between upper andl ower t r a ys for t h e coi ncidence a r e sh own for t wo
representative components, 49° South and 64° South. It isnoted here that, by the change of coinci-dence system, thetotal solid angles of components with 49°and 64° zenith
angles are increased in comparison with those of the previous
system. Average counting rates for the components are shownin Table V. The geometrical para-meters will be reported in
the future publication.

Components

49° North
49° East
49° South
49° West
64° North
64° East
64° South
64° West

Data of Nagoya Multi-Directional Muon Telescope
published so far are available from Home Page of SolarTerrestrial Environment Laboratory (http://www.stelab.nag
oya-u.ac.jp) via network with forms of the graphs as well as
files of hourly value data, WP. One record of the hourly value
files (96 byte) consist of 24 data of 4 digits each shown
below.
Digit
1-4
5-8
9 - 12
13-16
17-20
21-24
25-28
29-32
33-36
37-40
41-44
45-48
49-52
53-56
57-60
61-64
65-68
69-72
73-76
77-80
81-84
85-88
89-92
93-96

coincidence are shown by broken and dashed rectangu-lars with symbol L1 ~ 6
and U13 ~ 18 for 49° South, and with symbol L1 ~ 6 and U19 ~36 for 64°
South. All combinations of coincidence for the components are as follows;

64°S

0.611
0.581
0.599
0.617
0.178
0.173
0.176
0.180

App.II FOR USE OF DATA

Fig. 14. Examples of relative positions between upper and lower detectors for theComponent
49°S

Average count no. (x106/hour)

Combination of coincidences(L1~ 6) H(U13 ~ 18) + (L7 ~ 12) H(U19~24) + (L13~ 18) H(U25 ~ 30) + (L19 ~ 24) H(U31 ~ 36)(L1 ~ 6) H(U19 ~ 36) + (L7 ~ 12) H(U25 ~ 36) + (L13~ 18) H(U31 ~ 36)

13

Data
Year
Day of Year
Hour and minute (start time of record)
Upper Single
Lower Single
Vertical
30° North
30° East
30° South
30° West
39° NE
39° SE
39° SW
39° NW
49° North
49° East
49° South
49° West
64° North
64° East
64° South
64° West
Pressure
G-component

You are welcome to use Nagoya Muon Telescope data
under the conditions: 1) to acknowledge Cosmic Ray Section,
Solar-Terrestrial Environment La boratory, Nagoya
University in any publised use of the data, 2) to send a copyof any paper using these data to:Z. Fujii
Solar-Terrestrial Environment Laboratory,
Nagoya University, Nagoya 464-8601 Japanfujii@stelab.nagoya-u.ac.jp

14