The study of the cosmic ray abundances beyond 20 GeV/n provides additional information on the propagation and containment of the cosmic rays in the galaxy. Since the average amount of interstellar material traversed by cosmic rays decreases as its energy increases, the source composition undergoes less distortion in this higher energy region. However, data over a wide energy range is necessary to study propagation parameters. Some measurements of some of the primary cosmic ray abundance ratios at both low (near 2 GeV/n) and high (above 20 GeV/n) energy are given and compared to the predictions of the leaky box mode. In particular, the integrated values (above 23.7 GeV/n) for the more abundant cosmic ray elements in the interval C through Fe and the differential flux for carbon, oxygen, and the Ne, Mg, Si group are presented. Limited statistics prevented the inclusion of the odd Z elements

Derrickson, J. H.

Gregory, J. C.

Parnell, T. A.

Watts, J. W.

English

NASA Technical Reports Server

OG 4.1-6
20
A MEASUREMENT OF THE COSMIC RAY ELEMENTS C TO Fe
IN THE TWO ENERGY INTERVALS 0.5-2.0 GeV/n AND 20-60 GeV/n
J.H. Derrickson, T.A. Parnell, and J.W. Watts
Space Science Laboratory, NASA, Marshall Space Flight
Center, USA
J.C. Gregory
Department of Chemistry, University of Alabama Huntsville,
Huntsville, Alabama
Introduction. The study of the cosmic ray abundances beyond
20 GeV/n provides additional information on the propagation
and containment of the cosmic rays in the galaxy. Since the
average amount of interstellar material traversed by cosmic
rays decreases as its energy increases, the source com-
position undergoes less distortion in this higher energy
region. However, data over a wide energy range is necessary
to study propagation parameters. We present some measure-
ments of some of the primary cosmic ray abundance ratios at
both low (near 2 GeV/n) and high (above 20 GeV/n) energy and
compare them to the predictions of the leaky box model. In
particular, the integrated values (above 23.7 GeV/n) for the
more abundant cosmic ray elements in the interval C through
Fe and the differential flux for carbon, oxygen, and the
Ne,Mg,Si group will be presented. Limited statistics have
prevented the inclusion of the odd Z elements.
Instrument and the Exposure. The instrument has been
previously described [I] and will be briefly reviewed here
with the exposure parameters. The apparatus consists of a
freon -12 gas Cerenkov detector (index of refraction =
1.001) for differential energy measurements between 20 and
60 GeV/n. Two banks of six 5-inch photomultiplier tubes
viewed the freon gas which was contained in a thin
fiberglass tank lined with millipore paper. The pulse
height information from each set of tubes allowed correction
for those cosmic ray events where a particle passage or
delta rays obviously affected one bank of tubes. Two solid
Cerenkov radiators (teflon and lucite) were included for
charge identification. The teflon (effective index = 1.36)
and pilot 425 (effective index = 1.52) radiators were placed
in individual white boxes coated with BaSO 4 paint and each
was observed by eight 5-inch photomultiplier tubes.
 . -6 
0 
 EASUR MENT F E SMIC Y LEMENTS   e 
I  E O ERGY I ERVALS .5-2.0 eVln ND 0-60 eVln 
. . errickson, . . arnell, d . . watts 
Space Science aboratory, ASA, arshall Space light 
enter, SA 
J. . regory 
epartment f hemistry, niversity f labama untsville, 
untsville, labama 
I troduction. he st dy f t e smic r  undances eyond 
20 eVln provides additional information on the ropagation 
a d ntainment f t e smic r ys i  t e alaxy. ince t e 
average a ount of i terstellar aterial tra ersed by cosmic 
r s ecrea es s it  ergy i creases, t e urce c -
osition undergoes less istortion in t is higher energy 
region. owever, data over a ide energy range is necessary 
t  st dy ropagation arameters. e resent so e easure-
ents f so e f the ri ary c smic r  undance r tios t 
both lo  (near 2 eV/n) and high (above 20 eV/n) energy and 
co pare the  to the predictions of the leaky box odel. In 
articular, the integrated values (above 23.7 eV/n) for the 
ore a undant c smic ra  ele ents i  t  i terval  t r ugh 
e  t  i ferential fl  f r rbon, xygen, d t e 
e,Mg,Si group ill be resented. i ited statistics have 
revented t e i clusion f t e odd  ele ents. 
Instrument and the Exposure. The instru ent has been 
prev iously described [1] and ill be briefly reviewed here 
i th t  posure aram ters. he paratus c ns ists f a 
freon -12 gas erenkov detector (index of refraction  
1.001) f r ifferential energy easurements bet een 20 and 
 eV/n. o anks f i  -i ch hotomultiplier t es 
vie ed the freon gas hich as contained in a t in 
fi erglass tank li ed ith illipore aper. he ulse 
height information fro  each set of tubes allo ed correction 
for those cos ic ray events here a particle passage or 
delta rays obviously affected one bank of tubes. Two solid 
erenkov diators fl n  cite) ere l ded r 
charge identif ication. The teflon (effect i ve index = 1. 36) 
and ilot 425 (effective index = 1.52) radiators ere placed 
in individual hite boxes coated ith BaS04 paint and each 
was observed by eight 5-inch photomultiplier tubes. 
• 
https://ntrs.nasa.gov/search.jsp?R=19850025699 2020-03-20T18:05:33+00:00Z
OG 4.1-6
21
To further aid in event selection, two dual gap ion
chambers filled with Xenon and a plastic scintillator (NE
102) were included. The scintillator was also housed in a
light collecting box viewed by four tubes. An eight plane
multi-wire hodoscope was used to determine the particle tra-
jectory through the instrument. The track information was
used in correcting the pulse height information for path
length variations and for nonuniform response in the detec-
tors, and it was an effective tool in removing background
events such as showers, fragmentation events, and events
outside the defined geometry of the experiment. For the
detector arrangement, refer to Figure 2 in reference [i].
This instrument was flown from Pierre, South Dakota in
Septembe K of 1978 at an average depth in the atmosphere o_
3.6 g/cm z. The collection factor for the flight was 2.8 M
ster.hrs.
Corrections to the Data. The track fitting routines
screened the majority of atmospheric showers, some interact-
ing events, and events that missed one or more of the detec-
tors. The detector signals were corrected for the path
length difference and the nonuniformity in detector
response. Pulse height consistency criteria were then
applied to eliminate remaining background events, mainly
those interacting in the instrument. The energy calibration
of the freon-12 Cerenkov counter was accomplished by isolat-
ing the elements and finding saturation values (8 = I). For
oxygen, close to 150 photoelectrons were collected. Eight
percent of this saturation signal was a scintillation com-
ponent due to various effects including energetic delta
rays. With this information, the energy measurement was
unfolded following the method found in the appendix of
reference [2]. The charge of the events above 20 GeV/n was
determined by summing the saturated signals of the lucite
and teflon Cerenkov detectors. The charge resolution (_)
obtained for events with kinetic energy >25 GeV/n was
slightly better than 0.25. The separation into charge
groups was done as suggested in both references [2] and [3].
The even integer charge is defined as Zeven ± 0.625, and the
odd integer charge is Zod d ± 0.375. The charge deconvolu-
tion or overlap corrections for C, N, and O are respectively
0.98, 1.09, 0.99 for energies greater than 25 GeV/n.
Finally nuclear fragmentation corrections for both the
instrument and overlying atmosphere were performed according
to the method outlined in reference [4] with the fragmen-
- tation cross-sections taken from reference [5]. The cross-
sections were evaluated in the asymtotic region (E = 2
GeV/n) and applied to the 25 to 60 GeV/n energy interval
with the assumption that the scaling correction is minor.
Results and Conclusions The results of the 1978 flight are
listed in Tables I and II. The errors quoted are based on
counting statistics only.
 . -6 
1 
o rther i   vent election, t o ual ap  
chambers fill d ith enon and a lastic cintillator (  
02) ere i cluded. he cintillator as l o oused i   
li ht collecting box vie ed by four t bes. n eight plane 
ulti-wire odoscope as sed t  etermine t e article tr -
jectory through the instrument. The track information as 
sed i  orrecting t  ulse eight i f rmation f r ath 
length ariations and for nonuniform response in the detec-
t rs, a d it as a  ffective t ol i  re oving ackground 
vents ch  owers, mentation vents, d ents 
utside t e efined geometry f t e experiment. or t e 
detector arrangement, refer to Figure 2 in reference [1]. 
his str ment as n  ie re, outh akota  
septembe2 of 1978 at an average depth in the atmosphere o~ 3.6 /cm. he collection factor f r the fli ht as 2.8  
t r.hrs. 
orrections t  t e ata. he t ck itti g utines 
s reened t  ajority f t ospheric s owers, so e i teract-
i~g events, and events t at issed one or ore of the detec-
t rs. he etector si nals ere c rrected f r t e ath 
length difference and the nonuniformi ty in detector 
r sponse. ulse eight nsistency riteria ere t en 
applied t  eli inate re aining background e ents, ainly 
t se i teracting i  t  i strument. he ergy alibration 
of the freon-12 erenkov counter as accomplished by is lat-
i  t e ele ents and fi ding s turation alues (S  1). or 
oxygen, close to 150 photoelectrons ere collected. ight 
ercent f t is s turation si nal as a intillation co -
ponent due to various effects including energetic delta 
rays. wi th this information, the energy easurement was 
unfolded follo ing the ethod found in the appendix of 
reference [2]. The charge of the events above 20 eV/n as 
determined by su ming the saturated signals of the lucite 
d t fl n erenkov etectors. he arge r solution «J) 
obtained f r events ith inetic energy >25 eV/n as 
sli htly etter t an . 5. he s paration i to c arge 
groups as done as suggested in both references [2] and [3]. 
The even integer charge is defined as Zeven ± 0.625, and the 
odd integer charge is zodd ± 0.375. The charge deconvolu-
ti  r verlap rrections f r , , a  0 r  r spectively 
. 8, . 9, . 9 f r ergies reater t n  eV/n. 
inally nuclear fragmentation c rrections for both the 
instrument and overlying at osphere ere performed according 
t  the ethod utlined i  reference [4] ith the frag en-
ti n r s-sections en  ference ]. he ro s-
ctions ere aluated i  t  s mtotic r ion (    
e  /n) and appl ied to the 25 to 60 e  /n energy i terval 
ith t  ass mption t at t  s aling rrection is inor. 
esults and onclusions The results of the 1978 flight are 
list d in ables I and II. The errors quoted are based on 
counting statistics only. 
22 OG 4.1-6
Table I
(EK > 23.7 GeV Per nucleon)
Integrated Flux
in particles/(M2"Ster'Secs) Ratios _
C (5.2 • 0.3) x i0-2 0.98 ± 0.08
N (1.2 ± 0.i) x 10-2 0.23 _ 0.02
O (5.3 ± 0.3) x 10 -2 1.00 ± 0.08
Ne (i.i ± 0.i) x 10-2 0.21 ± 0.02
Mg (1.2 ± 0.i) x 10 -2 0.23 ± 0.02
Si (8.8 ± 1.3) x 10-3 0.17 ± 0.03
MnFeCo (5.9 ± i.i) x 10 -3 0.ii ± 0.02
• Normalized to Oxygen
Table II
Differential Flux
in particles_(M2"Ster'Secs'GeV per nucleon)
(N ± AN) -m _ (N ± AN) x I0 -m
Kinetic Energy
(GeV/n) Carbon Oxygen NeMgSi
25.8 (3.6 ± 0.3)-_ (3.6 ± 0.4)-2 (2.3 ± 0 3) -3
33.9 (1.6 ± 0.2)-_ (1.7 ± 0.3)-2 (8.3 ± 1 9.)4
50.6 (1.9 ± 0.4)-4 (2.3 ± 0.5)-4 (1.6 ± 0.5 )4
61.8 (4.6 ± 0.8) -4 (3.7 ± 0.8) -4 (2.5 ± 0.7) -4
The data is in general agreement with previous balloon
results. A comparison of the ratios in Table I with the
French-Danish experiment on HEAO-3 [6] is within one to two
sigma of their values at 25 GeV/n except for the ratio Ne/O.
In Table III, we have selected some key primary to
primary cosmic-ray abundance ratios at two widely separated
energies. The lower energy values were taken from a 1976
balloon flight experiment that is fully described in
reference [7].
Table III
'76' Experiment This Experiment
Ek = 1.2 GeV per nucleon Ek > 23.7 GeV per nucleon
O/C 0.91 • 0.02* 1.02 ± 0.08
_e/O 0.086 ± 0.006 0.iii • 0.022
Si/Fe 2.08 ± 0.16 1.49 ± 0.35
• Statistical error only
22 OG 4.1-6 
Table I 
(EK > 23.7 GeV Per nucleon) 
Integrated Flux 
in particles/(M2 'Ster'secs) 
C 
N 
0 
Ne 
Mg 
Si 
MnFeCo 
* Normalized 
(5.2 ± 0.3) x 10-2 
(1.2 ± 0.1) x 10- 2 
(5.3 ± 0.3) x 10-2 
(1.1 ± 0.1) x 10- 2 
(1.2 ± 0.1) x 10-2 
(B.B ± 1. 3) x 10- 3 
(5.9 ± 1.1) x 10-3 
to Oxygen 
Table II 
ifferential Flux 
Ratios ... 
0.9B ± O.OB 
0.23 ± 0.02 
1.00 ± O.OB 
0.21 ± 0.02 
0.23 ± 0.02 
0.17 ± 0.03 
0.11 ± 0.02 
in particles/(M2 'Ster'Secs'GeV per nucleon) 
(N ± ~N)-m = (N ± ~N) x 10-m 
Kinetic Energy 
(GeV/n) Carbon Oxygen NeMgSi 
25.8 (3.6 ± 0.3)-~ (3.6 ± 0.4)-~ (2.3 ± 0.3)-3 
30.0 (2.7 ± 0.3)-3 (2.3 ± 0.3)- (1.4 ± 0.2)-3 
33.9 (1.6 ± 0.2)- (1.7 ± 0.3)-3 (8.3 ± 1.9)-4 
39.8 (7.2 ± 1.1) -4 (9.3 ± 1. 3)-4 (4.4 ± 1.0)-4 
50.6 (1.9 ± 0.4)~4 (2.3 ± 0.5)-4 (1.6 ± 0.5)-4 
61.8 (4.6 ± 0.8)-4 (3.7 ± 0.8)-4 (2.5 ± 0.7)-4 
The data is in general agreement wi th previous balloon 
resul ts. A comparison of the ratios in Table I wi th the 
French-Danish experiment on HEAO-3 [6] is within one to two 
sigma of their values at 25 GeV/n except for the ratio Ne/O. 
In Table III, we have 
primary cosmic-ray abundance 
energ ies. The lower energy 
balloon flight experiment 
reference [7]. 
selected some key primary to 
ratios at two widely separated 
values were taken from a 1976 
that is fully described in 
Table III 
'76' Experiment This Experiment 
Ek = 1.2 GeV per nucleon Ek > 23.7 GeV per nucleon 
O/C 0.91 ± 0.02* 1.02 ± 0.08 
Pe/O 0.OB6 ± 0.006 0.111 ± 0.022 
Si/Fe 2.08 ± 0.16 1.49 ± 0.35 
* Statistical error only 
OG 4.1-6
23
These ratios seem consistent with the Dhenomenological
leaky box model for cosmic-ray propagation described in
reference [8]. Specifically we compared our O/C data to the
theoretical prediction plotted on figure 15 of reference
[8]. Taking note of the uncertainty in our data, we find
good agreement with this propagation model that uses the
source abundances of Shapiro, Silberberg, and Tsao [9].
References
i. Gregory, J.C. and Parnell, T.A., Proc. 16th Intl. Cosmic-
Ray Conf., Kyoto, 12, 355, (1979).
2. Juliusson, E., Ap.J., 191331, (1974).
3. Caldwell, J.H., Ap.J., 218, 269, (1977).
4. Hagen, F.A., Ph.D. Dissertation, University of Maryland
(1975).
5. Silberberg, R. and Tsao, C.H., Astrophysical J.
Supplement Series, 25, 315 and 335, (1973).
6. Engelmann, J.J., Goret, P., Juliusson, E., Koch-Miramond,
L. Masse, P., Soutoul, A., Byrnak, R., Lund, N., Peters, B.,
Rasmussen, I.L., Rotenberg, M., Westergaard, N.J., Proc.
18th Intl. Cosmic-Ray Conf., Bangalore, 2__,17, (1983)
7. Derrickson, J.H., Ph.D. Dissertation, University of
Alabama in Huntsville (1983)
8. Simon, M., Spiegelhauer, H., Schmidt, W.K.H., Siohan, F.,
Ormes, J.F., Balasubrahmanyan, V.K., and Arens, J.F., AD. J.
239, 712, (1980)
9. Shapiro, M.M., Silberberg, R., and Tsao, C.H. Proc. 14th
Intl. Cosmic-Ray Conf., Munich, 2, 532, (1975)
G .1-6 
3 
hese tios  cons istent ith t e phenomenolog ical 
leaky box odel for cosmic-ray propagation described in 
r ference [ ]. pecifically e compared ur /  ata t  t e 
t eoretical rediction lotted n fi ure  f r ference 
[8] • aking note of the ncertainty in our ata, e fi d 
good agreement ith t is propagation odel that uses the 
urce bundances f hapiro, ilberberg, d sao ]. 
eferences 
1. regory, J. . and arnell, .A., Proc. 16th I tI. osmic-
Ray Conf., Kyoto, 12, 355, (1979). 
2. Ju1iusson, E., p.J., 191 331, (1974). 
3. Caldwell, J. ., p.J., 218, 269, (1977). 
. agen, F.  •. , h. . issertation, niversity of aryland 
( 975) • 
5. ilberberg, R. and Tsao, .H., strophysical J. 
Supplement Series, 25, 315 and 335, (1973). 
. ngelmann, .J., oret, ., J liusson, ., och-Miramond, 
. asse, ., outou1, ., yrnak, ., und, ., eters, ., 
asmussen, I. ., otenberg, ., estergaard, .J., roc. 
18th I tI. osmic-Ray onf., anga1ore, ~, 17, (1983) 
. errickson, J. ., h. . issertation, university f 
labama i  untsville 83) 
. i on, ., piege1hauer, ., chmidt, .K.H., i han, ., 
rmes, J. ., a1asubrahmanyan, .K., and rens, J. ., p. J. 
239, 712, (1980) 
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A measurement of the cosmic ray elements C to Fe in the two energy intervals 0.5-2.0 GeV/n and 20-60 GeV/n

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