A proportional drift chamber which consists of eight rectangular drift tubes with cross section of 10 cm x 5 cm, a sense wire of 100 micron phi gold-plated tungsten wire and the length of 6 m, was tested using cosmic ray muons. Spatial resolution (rms) is between 0.5 and 1 mm over drift space of 50 mm, depending on incident angle and distance from sense wire

Cho, C.

Higashi, S.

Hiraoka, N.

Maruyama, A.

Okusawa, T.

Sato, T.

Suwada, T.

Takahashi, T.

Umeda, H.

English

NASA Technical Reports Server

6§ HE 5.2-I I
PROPORTIONAL DRIFT TUBES FOR LARGE AREA MUON DETECTORS
C. Cho, S. Higashi, N. Hiraoka, A. Maruyama, T. Okusawa
T. Sato, T. Suwada, T. Takahashi and H. Umeda
Department of Physics, Osaka City University
Sugimoto, Sumiyoshi-ku, Osaka, Japan
ABSTRACT
A proportional drift chamber which
consists of eight rectangular drift
tubes with cross section of 10 cm x 5
cm, a sense wire of 100 _ gold-plated
tungsten wire and the length of 6 m, is
constructed and tested using cosmic ray
muons. Spatial resolution (rms) is
between 0.5 and I mm over drift space of
50 mm, depending on incident angle and
distance from sense wire.
I. INTRODUCTION
The large proportional drift chamber have been
constructed for muon identification in the TOPAZ experiment
at KEK to study e+e - interactions (I). A chamber contain
eight rectangular drift tubes with cross section of 10 cm x
5 cm, length of 6 m and a sense wire for each cell (Fig. I ).
Two adjacent planes of staggered tubes help to solve the
left-right-ambiguity. The
chamber with large area, verysimple structure and good
space resolution is also very ___._7_--_/
useful to study muons in
cosmic ray experiments,
specially to measure the
direction of muons for
. multiple muon study and
spectrogragh. In this paper,
we will describe the chamber 5500_/[_®°® ® ® ® ® _
. design, and cosmic ray test on
the three muon chambers
aligned vertically, filled A T
with mixture of Ar + 10% CH 4. I 400 1140u'_'
Reconstructions of tracks of unit mm
the cosmic ray in the chamber
determine the drift distance Fig. I
from sense wire as a function Sketch of the proportional
of the electron's drift time, drift tube chamber.
https://ntrs.nasa.gov/search.jsp?R=19850027774 2020-03-20T17:03:50+00:00Z
66
HE 5.2-11
the spatial resolution and the chamber efficiency.
2. CONSTRUCTION
A chamber consists of eight rectangular drift tubes with
cross section of 10 cm x 5 cm and the length of 6 m. A
chamber is made out of two four-cell structures which are
extruded separately from 6063-T5 aluminium and welded
together. The ends of the chamber are notched to allow
serial gas flow between cells. Aluminium end caps are
welded onto both ends of the four-cell structures to seal
gas, which also used to support sense wires. Aluminium
plates are welded onto both ends of the lower four-cell
structure to mount the chamber on the apparatus. A maximum
sagitta at the center of chamber is less than 3 mm, a
maximum lateral twist about the wire axis less than 3 ° and a
surface flatness for 400 mm wide less than 1.6 mm. The
extrusion is cleaned with 10% sodium hydroxide to take off
oil and nap on the aluminium surface. Each cell has a sense
wire of gold-plated tungsten of 100 _m in diameter to get
high electric field at the position far from the wire. The
wire is soldered to copper pins in the center of Delrin
plugs under the tension of 850 grams. Lids are attached to
both ends to provide mechanical protection for the wire and
electronics. Chambers can maintain a vacuum pressure of
less than 0.1 Torr, which is the limit of the pump used.
High voltage and preamplifier/discriminator PC boards
are mounted on the chamber. The wire is connected to the
high voltage supply through a 10 Megohm register, and the
preamplifier through a 500 pF coupling capacitor.
3. RESULTS
Fig. 2 shows a set-up of the chamber and read out system
to measure the drift time as a function of a drift space,
p_t0
_A ,C,NT,. mul,
LAY. -- Z7- A r-"-_r'_T'_--_
I" I" I" I ' I B-D--_/L_I iCONT_L_ , Fig. 2
2. I • I'.l start_-_ Schematic view of
I" I " I " I &,,l st_ll_JC I_ the set-up for
' stop
"1" I/ I" I'1 v stroll measuring the
_" I" I. I, _ _ ......] I'_MA_ 'II space resolution
-_B '_ __ "_ of the drift tubes
_-ON '_IIi" !V_il ' i" i PD_P- . with incidentI_ 11 I cosmic rays.o_ _ L___ ' ' '
_M_. _!_J h_IVER
_. =6.5_it)
67 HE 5.2-11
the spatial resolution and the detection efficiency. The
set-up consists of three chambers and two scintillation
counters with 10 cm width which are used to select cosmic
ray muons and to generate start pulse for TDC. The drift
times are digitized by 11 bit CAMAC TDC's with 2ns bins and
read out to micro PDP-11. The data are taken for track
angles 0o,28 ° and 45 ° with gas flow of 100 cc/min, high
voltage of 3.1KV and threshold of 500 pV. The analysis to
get spatial resolution is as follows. Data on tim_ about
Ixi0 4 events for a track angle are converted to drift
distance from the wire using a time-distance relation which
is assumed at first. • Assuming the wire positions, the
circular space contours are fitted with a straight line of a
track using the method of least squares, which gives time
new distance on the straight line. The mean of the
60............... .', ..... ........ 1.5 , , . , • ', • , •
2".: "°......:...._E 40 _" " ".'.o
E .-
"-" = 05
_. 30 //
20 _
lO 8
o 10 oo
0 500 1000 1500 _ •........ -.,05 " ..'"
Drift Time (nse¢)
Fig. 3 ........
Distance from the sense wire 10 20 30 40 50
versus measured drift time Oistonce from wire(mm)
for track angle 0°.
Fig. 4
Spatial resolution (rms)
VS distance from wire for
. track angles 0 °, 45 °.
. deviation from the straight line for each wire changes the
wire position. By calculating the mean of the time-distance
distribution, a empirical time-distance relation is
obtained, which is used for next straight line fit. These
calculations are continued until the width of the
experimental time-distance distribution is minimized.
Fig. 3 shows a scatter plot of the drift time VS the
distance of the track from the sense wire; time-distance
distribution for track angle 0°. At larger track angles the
68
HE 5.2-11
100 .......................
.-- 80
v
Fig. 5
u 60 Detection efficiencies forc
•_ I cosmic rays in the drift
40 _ tubes for track angles 0 °,
! 45°"
0o 45°
20 i
,I I m I
20 30 40 50
Distance from wire(mm)
time-distance distribution is almost the same. Fig. 4 shows
the spatial resolutions (rms) VS the distance at 0 ° and 45 °,
which are obtained from the time-distance distributions
(Fig. 3). The resolution is 0.5 mm at the center and about
0.8 mm at near to and far away from the wire for track angle
0 ° but gets worse at large track angle, _ I mm at 45 °
Fig. 5 shoes the single wire efficiencies VS position
distribution with a maximum collection time of 2 Us at 0 °
and 45 °. The efficiency is greater than 99.97% within 43 mm
but drops off rapidly near the ends.
4. CONCLUSION
Large area rectangular drift tube chamber with drift
space of 5 cm are constructed and tested. The spatial
resolution (rms) is better than I mm, and the efficiency for
detecting the passage of a particle is greater than 99.9%.
These characteristics are adequate for the purpose of a
large muon detector in cosmic ray experiments.
REFERENCE
I. R. Hayano et al (1983) TRISTAN PROPOSAL, TRISTAN-EXP-002
ACKNOWLEDGEMENT
We wish to thank all members of TOPAZ-group, in
particular, T. Kamae, S. Iwata and Y. Watanabe for there
encouragement.


Proportional drift tubes for large area muon detectors

Proportional drift tubes for large area muon detectors

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