Although the SCIN-MAGIC experiment has, like all ASTROMAG and most other Attached Payload experiments, been 'deselected' from Space Station, it is expected that ultimately such emulsion chambers will be flown on the Station. Some brief studies are described which were made in support of the design efforts for such a program being conducted at NASA Marshall

Gregory, J. C.

Takahashi, Y.

English

NASA Technical Reports Server

"Spectra, Composition, and Interactions of Nuclei above 10 TeV
using Magnet-Interferometric Chambers"
Final Report
P.O. # H-11203-D
Nov. 1, 1990 - Jul. 31, 1991
and
F
P.O. # H-11286-D '/
May 20, 1991 - Nov. 20, 1991
DrDe.p.Cartn_Gteog?&ePrintr_ipal Investi_lator
Dr./Y. Takahashi, Co-Principal Investigator
DelSartment of Physics
College of Science
The University of Alabama in Huntsville
Huntsville, Alabama 35899
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ABSTRACT
Although the SCIN-MAGIC experiment has, like all ASTROMAG and most other Attached
Payload experiments, been "de-selected" from Space Station, we expect that ultimately such
emulsion chambers will be flown on the Station. This report describes some brief studies made in
support of the design efforts for such a program being conducted at MSFC.
3INTRODUCTION
This report constitutes the first year effort by the UAH in support of the SCIN-MAGIC
Experiment to fly on the US Space Station ASTROMAG facility in, or around, the year 2000.
We proposed to fly an experiment in the Astromag Facility to measure the composition and
spectra of the cosmic ray nuclei above 1014 electron volts and to study with the magnetic field the
characteristics of particles produced in nucleus-nucleus interactions above 1012 eV/amu. The
proposed interaction studies are intimately connected with high energy cosmic ray studies since
analysis of data from air showers and "ionization calorimeters" depend upon the behavior of the
interactions.
The chemical composition will be measured for all elements from hydrogen to iron with
sufficient statistics to deduce spectra for the abundant primaries (H, He, CNO, NeMgSi, and the
Fe group) in the energy region where the principal models of cosmic ray acceleration and
propagation predict major composition and spectra changes. A measurement of the electron
spectrum above 1 TeV will also be made.
The experiment will also measure the transverse momenta of charged particles and photons
from a number (>100) of heavy ion central collisions that are expected to exceed 2 x 104s GeV/m3
energy density in the interacting complex. At those densities calculations based on quantum-
chromo-dynamics (QCD) predict a phase change in nuclear matter from bound nucleons to a quark-
gluon plasma (OGP) and a chiral symmetry phase. This experiment is designed to use the
Astromag field to measure exceptional characteristics of the produced particles that are predicted to
signal these phase changes. A larger sample of data will be available in which the produced
particle number distribution, rapidity distributions, angular correlations, charged/neutral ratio, etc.,
will be measured.
The experiment will be carried out with passive detector instruments (emulsion chambers)
very similar to those flown on balloons and used recently with heavy ion beams at CERN. The
emulsion chambers will be in two configurations. One (EMCAL) will be similar to those
frequently used in balloon borne composition studies. The other (MAGIC) contains a low density
4targetsectiondesignedsothat the high field of Astromag can be used to measure the signs and
transverse momenta of charged particles produced in the interactions.
The proposed apparatus contains eight blocks (chambers) which contain nuclear track
emulsions, CR39 plastic, X-ray film, lead or tungsten plates, and other inert materials. The
apparatus is in two pallets of four chambers (two each of EMCAL and MAGIC); each pallet
weighing ~ 1200 kg. Thermal control is achieved with coatings, insulation blankets, and electrical
heaters. Two 90 day exposures of the two-pallet configuration are proposed, the first as soon as
practical in the Astromag high field region.
Essentially all the techniques required for this investigation have had extensive exercise in
balloon and accelerator experiments which have been carried out by the UAH Co-lnvestigators.
The dynamic range and position-resolution of emulsion chambers make them particularly
appropriate as the detector system for the first systematic direct measurements in the 1014 - 1015
eV per particle regime. The same emulsion system is used to measure protons and Fe and to
measure the characteristics of interactions with secondary multiples of 1000 or more. The capacity
of emulsions to record the passage of all ionizing particles, with exceptionally high spatial
resolution, is a distinct asset in an investigation in a new realm of high energy nuclear physics.
Desi_,n Studies for SCIN-MAGIC
1) The scientific design effort of the SCIN-MAGIC was supported by the UAH science team
(JCG, YT and TH) at several science reviews held at MSFC. Some specific studies were
undertaken.
a) Direct Tracking of Primary_ and Secondary Partiqles in a MagnetiC Field
We have been conducting a series of interaction studies wilhhighly relativistic nuclei
at CERN, Geneva, using emulsion techniques for particle tracking. A recent run in August
1990 with sulphur-32 at 300 GeV/c used an electromagnet with a 1.8 Tesla field. A
significant finding from these studies is a demonstration of the capability for tracking nuclei
in an emulsion chamber system in a magnet field. Precision tracking of singly-charged
particles in emulsion chambers has been achieved using accelerator nuclear beams (Fi_. la
and lb).
The momentum resolution for secondary tracks with the latest design of MAGIC
telescope (Magnetic-Interactive-Emulsion-Chamber) is
A p/p (%) = 5 + 0.25 (p/GeV/c),
for a magnet field of 1.8 Tesla. This was confirmed by a MAGIC experiment performed at
CERN in August, 1990. A suppression of multiple scattering was achieved by reducing a
number of emulsion plates in the telescope.
For the purpose of a momentum measurements of primary (beam) nuclei, we
designed a BEAM TELESCOPE (BT). Figure 2 shows a new emulsion chamber system
with a BT in a planned solenoid magnet; Magnetic bending of primary nuclei is also
illustrated. Table I gives magnetic displacements of a nucleus track in the coordinate (x)
perpendicular to the magnetic fields (z). A unique identification of a heavy nucleus track is
much easier than that of singly-ionizing tracks that are often too many. Therefore, a large
spacing (5 era) between tracking layers can be used for BT, which improves momentum
resolution and measurable upper-end of momentum. Electromagnetic scattering is
drastically reduced by using only several layers of thin (30 microns) emulsions and thin
(300 micron) CR39 plates. The BT has an integrated field length of 1.2T X 0.2m = 0.24
Tesla.m for a vertical path length, and the maximum detectable momentum should be 2
TeV/n for a 1.2 micron resolution of relative coordinates measured from reference tracks.
The provision of straight-line fiducial marks is crucial to the application of this
technique in cosmic ray experiments.
Our existing effort produced effective tracking software, and we have built an
automatic microscope, CAVIA (Computer-Assisted-Visual-Image-Analysis). By using
them, we realized that the system and software allowed precision tracking of CR39 etch-
pits as well. Reconstruction of nuclear tracks in CR39 plates was made with a precision of
1.5 microns. A BT telescope with the emulsion calorimeter will allow such direct rigidity
measurements of nuclei with a similar precision, because very high energy nucleus events
(above 2 TeV/n) give a perfect set of straight lines (in-flight fiducial) for reconstruction of
coordinates. It is a unique virtue of an emulsion chamber with EMCAL (Emulsion
Calorimeter). No telescopes can maintain microscopic precision without independent
detection of these high energy tracks.
6The expectedaccuracy of momentum measurementsis a function of the primary
momentum,
A p/p (%) = 0.1 + 0.05 (p/GeV/c),
Consequently, the maximum detectable momentum (MDM) is about 2 TeV/c/n for a field
strength of 1.2 Tesla.
These new findings indicate that an emulsion chamber method in a magnet field is
more versatile than initially considered, allowing observation of cosmic ray nuclei in an
unprecedentedly wide energy band, 1 GeV/n - 1,000 TeV/n. This bandwidth observable
by the same detector system is nearly ideal for a detailed study of cosmic ray composition
and energy spectra.
SNERGY (GeV/N)
_)ELTA X (microns)
(A/Z =1) 1 10 100 1000
=2) 0.5 5 50 500 1000
7199 719 72 7.3 3.6
2O0O
(FOR B= 1.2 T, L= 20 CM)
TABLE 1
Magnetic deflection (microns) of x-axis for 20 cm-long
BT in a 1.2 Tesla magnet field.
b) Up_ading of the Automatic Miqroscope for Large-Area Experiments
Further work on beam tracking of nuclei in a large area Beam telescope can be
accomplished within a few years by upgrading auto-scan equipment. A small-stage (6" x
6") automatic microscope (CAVIA) is in operation, and upgrading of it to a larger (16" x
20") version can be accomplished with commercially available equipment. A digitized and
motorized large stage microscope will be assembled in less three years using existing
software for automatic scanning and analysis. We plan to replace a desk-top IBM PC 386
with a Workstation (SUN SPARC 1+ GX) to handle large object data from a large-area
scanning. Until its completion, an examination of beam tracking accuracies in automatic
7scanningwill be madewith small-size(4" x 5") emulsionand CR39 platesexposedto
oxygenandsulfur beamsin amagnetfield at 200GeV/n. Assumingthe availability of a
trackanalysissystem,a testballoonflight experimentcanbeginin 1993or 1994with a 1.2
Teslasuperconductingsolenoid magnet. Constructionof a superconductingsolenoid
magnet(1.2 Tesla field), suitable for emulsion chambersand a 10day flight, has just
started at National Laboratory for High Energy Physics (I(EK) in Japan (Fig. 4a and 4b).
We have obtained a permission to use it for balloon flight experiments for about ten years.
We are anticipating a delivery of a complete solenoid magnet and cryogenics system from
Japanese collaborators by early 1993.
Desi_an Studies in Support of SCIN-MAGIC
The UAH team has been concurrently involved in the detailed thermal and mechanical
design and analysis of the Emulsion Chamber Technology Experiment (ECI). This OAET-
sponsored technology development project will place a full size emulsion chamber weighing
approximately 500 lbs. on the STS for a 7 to 10 day evaluation. The project is seen as an ideal
precursor to the much larger exposure of SCIN-MAGIC or similar arrays on the Space Station.
The UAH engineering team including Dr. Francis Wessling (Chief engineer), Reinhold
Freiseis (stress analysis), Ron Eakes (mechanical design), Lisa Hughes (thermal analysis) and the
PI attended several engineering reviews at MSFC where the SCIN-MAGIC requirements were
discussed and the findings of the ECT analysis presented and discussed. Copies of the ECT
engineering analyses both from the PRR and the PDR have been delivered to MSFC and are not
reproduced here.
As a result of a development shake test of a full scale model of ECT at Marshall several
improvements have been made to the final design. These are included in the CDR report package
which has also now been delivered.
FIGURES:
la)
lb)
Polar angle resolution
Azimuth angle resolution
2) MAGIC Chambers in a Super-conducting Magnet Solenoid
3) MAGIC Momentum Resolution
4a)
4b)
Superconducting solenoid magnet being built at KEK
Cross sectional views of the solenoid
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Spectra, composition, and interactions of nuclei above 10 TeV using magnet-interferometric chambers

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