The HEAO-3 Heavy Nuclei Experiment is composed of ionization chambers above and below a plastic Cerenkov counter. The energy dependence of the abundances of elements with atomic number, Z, between 18 and 28 at very high energies where they are rare and thus need the large area x time are measured. The measurements of the Danish-French HEAO-3 experiment (Englemann,, et al., 1983) are extended to higher energies, using the relativistic rise of ionization signal as a measure of energy. Source abundances for Ar and Ca were determined

Binns, W. R.

Garrard, T. L.

Israel, M. H.

Jones, M. D.

Klarmann, J.

Stone, E. C.

Waddington, C. J.

English

NASA Technical Reports Server

OG 4. I-8
28
ENERGY SPECTRA OF ELEMENTS WITH 18 <_ Z _< 28
BETWEEN 10 AND 300 GeV/amu
Michael D. Jo_es a, J. Klarmann a, E. C. Stone b, C. J. Waddington c, W. R. Binns a,
T. L. Garrard , M. H. Israel a
a) Washington University, St. Louis, Me 63130, USA
b) California Institute of Technology, Pasadena, CA 91125 USA
c) University of Minnesota, Minneapolis, MN 55455, USA
1. Introduction. The HEAO-3 Heavy Nuclei Experiment (Binns, et aL, 1981) is
composed of ionization chambers above and below a plastic Cherenkov counter. We
have measured the energy dependence of the abundances of elements with atomic
number, Z, between 18 and 28 at very high energies where they are rare and thus need
the large area x time of this experiment. We extend the measurements of the Danish-
French HEAO-3 experiment (Englemann, et al., 1983) to higher energies, using the
relativistic rise of ionization signal as a measure of energy, and determine source
abundances for Ar and Ca.
2. Data Analysis. We confine this analysis to events in the 1.1 m2sr in which the
cosmic rays penetrate all six ionization chambers, and to the first 370 days of the flight,
when all six ionization chambers were functioning properly. These selections give the
highest possible ionization resolution. We select only events incident with geomagnetic
cutoff greater than 8 GV, so Z is determined by the Cherenkov signal. We further
require agreement between the means of the three ionization chamber signals above the
Cherenkov and those below, to eliminate most nuclear interactions inside the
instrument.
-- , ..... _00 v . , , • _" , • , ,
32 | Ni
J/ 20C28
Zi 26
m
'_ I002L
2C 0 i ....
I ' I ' i i I '20 22 4 26 2'8 25 26 27 28 _9
Zc Zc
Figure l Figure 2
Figure I is a schematic plot showing the locus of events for each element, 20 < Z
< 28. Zc is the square-root of the Cherenkov signal normalized so Zc _ Z at high
energy. Zi is the square-root of tile ionization normalized so Zi = Z at minimum-
ionizing. Figure 2 is a histogram of Zc for events with 29.3 < Zi < 29.5, the region
between the dashed lines in figure 1. This histogram includes Fe, Co, and Ni at about
130, 34, and 12 GeV/amu respectively. The abundance of each element in each of
eighty such histograms is determined by maximum-likelihood fitting.
 .1-8 
8 
NERGY ECTRA F EMENTS ITH  ~  ~ 8 
ETW EN 10 ND 300 eV/amu 
Michael D. Jo~esa, J. Klarmanna , E. C. Stoneb, C. J. WaddingtonC , W. R. Binnsa , 
. . arrard , . . Israela 
a) ashington University, St. Louis, O 63130, USA 
b) California Institute of Technology, Pasadena, CA 91125 USA 
c) University of innesota, inneapolis, N 55455, USA 
1. Introduction. The EAO-3 eavy uclei Experiment (Binns, et al., 1981) is 
composed of ionization chambers above and below a plastic herenkov counter. e 
ave easured the energy ependence f the abundances f elements ith atomic 
umber, , etween  a d  t ery igh e ergies here they are rare d thus eed 
the large area x time of this experiment. e extend the easurements of the anish-
French EAO-3 experiment (Englemann, et al., 1983) to higher energies, using the 
relativistic rise of ionization signal as a easure of energy, and determine source 
undances r r d a. 
2. Data Analysis. e confine this analysis to events in the 1.1 m2sr in which the 
c smic rays enetrate all six i nization c ambers, and t  t e first 0 ays f the flight, 
hen all si  ionization chambers ere f nctio ing roperly. hese selections ive the 
highest possible ionization resolution. e select only events incident ith geomagnetic 
cutoff greater than 8 , so  is determined by the herenkov signal. e further 
require agreement between the eans of the three ionization chamber signals above the 
herenkov a d t ose elow, to eliminate ost clear i teractions i side the 
nstrument. 
32 
30 ======)t~ 28 
Zi 2 
 . J ) ) 
 
: ! J J 2 
2 01-
20 22 2  26 28 
 
Figure 1 
'3 0 
Ni 
0 
III 
~ 
i! 
~ 
CD 
«1 0 
Figure 2 
Figure 1 is a schematic plot showing the locus of events for each element, 20 ~ Z 
< 28. Zc is the square-root of the Cherenkov signal normalized so Zc ~ Z at high 
energy. Zi is the square-root of the ionization nor alized so Zi = Z at minimum~ 
ionizing. Figure 2 is a histogram of Zc for events ith 29.3  Zi  29.5, the region 
between the dashed lines in figure 1. This histogram includes Fe, Co, and Ni at about 
130, 34, and 12 GeV /amu respectively. The abundance of each element in each of 
eighty such histograms is determined by maximum~likelihood fitting. 
https://ntrs.nasa.gov/search.jsp?R=19850025701 2020-03-20T18:05:30+00:00Z
29 OG 4.1-8
Corrections to these raw abundances were calculated to account for interactions
both in the lid in front of the first ionization chamber and in the Cherenkov counter
and other material between the ionization chambers. The latter calculation included
only charge changes of one or two charge units, other interactions having been
eliminated by the requirement for agreement between upper and lower ionization
chambers. The calculation assumed that at all energies the total cross-sections were
given by the formula of Westfall et al. (1979) and the partial cross-sections for changing
by n charge units were the same fraction of the total cross-section for any projectile as
was measured by Webber and Brautigam (1982) at 980 MeV/amu for Fe on C. These
calculated corrections lowered the raw abundance ratios by typically l0 to 30 percent.
3. Energy Scale. We used Zi/Z as a measure of energy, and derived an empirical
energy calibration by comparing our Fe observations with an Fe energy spectrum
derived from a compilation of previously published measurements (Webber, 1982). This
Fe spectrum was multiplied by an empirical geomagnetic transmission function which
represented the fraction of time when the geomagnetic cutoff permitted Fe of that
energy to reach the instrument; the product was the effective Fe spectrum at the
instrument, averaged over many orbits. This energy spectrum was then converted to a
Zi/Z spectrum using a trial form of the energy dependence of Zi/Z. Finally this
calculated spectrum was folded with the instrument's ionization resolution, and the
resulting Zi/Z spectrum was compared with tile data. The process was iterated, by
changing the assumed form of the energy dependence of Zi/Z, until the calculated and
observed spectra of Fe agreed.
The resulting energy dependence is consistent, between about l0 and 100
GeV/amu, with one derived independently for a different detector system by Barthelmy
et al. (1985, OG 4.1-7). Above about 200 GeV/amu, the shape of our calibration curve
depends upon the assumption we made that the Fe energy spectrum falls as a power-
law with exponent -2.7 at energies above those where it has been measured.
Abundance ratios derived from data in a particular Zi/Z histogram were plotted
at the mean energy from which those particles came, assuming the Fe energy spectrum
and the calibration curve described above. The energy resolution implied by our
ionization resolution of 0.40 charge units is comparable to the spacing of the points in
figure 3.
4. Results. Figure 3 gives the resulting abundances of several elements relative to Fe
as a function of energy. The X symbols are the results of the DF experiment
(Englemann, 1983), while the O symbols are the results of this experiment. In every case
our results are consistent with those of the DF experiment in the interval where both
experiments apply, l0 to 25 GeV/amu. At higher energies our data generally continue
the DF trend.
Our data above 10 GeV/amu suggest a Ni/Fe ratio slightly dependent upon
energy, with a best fit power law of exponent -0.050 q- 0.016. If we ignore this slight
variation with energy, then the mean value of the Ni/Fe ratio over our data is 0.054 4.
= 0.001.
For the secondary ratios, K/Fe, Sc/Fe, Ti/Fe, and V/Fe, our data indicate an
extension to about 100 GeV/amu of the same power law dependence as was indicated
. by the DF data. Figure 4 shows the best lit exponent for each of these ratios combining
the DF and our data. The steepening of the slope with decreasing Z is expected as
lower Z elements have greater contributions from tertiary nuclei.
9 OG 4.1-8 
o rections  ese aw undances re alculated  count r teractions 
oth  e   ont f e rst nization hamber d  e herenkov ounter 
d ther aterial tw en e nization hambers. he ter lculation cluded 
only eharge changes of one or t o charge units, other interactions having been 
eliminated by t e requirement for agreement between upper and lo er ionization 
hambers. he alculation sumed that t ll ergies t e t tal ro s-sections re 
given by the formula of estfall et al. (1979) and the partial cross-seetions for changing 
by n charge units ere the sa e fraction of the total cross-section for any projectile as 
was measured by ebber and Brautigam {1982} at 980 eV /amu for Fe on C. These 
lculated rrections l ered t e r  undance r tios  t pically 10 t   rcent. 
3. Energy Scale. e used Zi/Z as a easure of energy, and derived an e pirical 
nergy alibration  paring ur e servations ith n e ergy s ectrum 
derived from a co pilation of previously published easurements { ebber, 1982}. This 
Fe spectrum as ultiplied by an e pirical geomagnetic transmission function hich 
represented t e fraction f ti e hen the geomagnetic cutoff permitted e f t at 
energy to reach t e i strument; t e roduct as t e. effective e spectrum t t e 
instrument, averaged over any orbits. his energy spectrum as then converted to a 
Zi/Z spectrum using a trial form of the energy dependence of Zi/Z. Finally this 
calculated s ectrum as f lded ith t e i strument's i nization resolution, a d t e 
resulting i/Z spectrum as compared ith the data. he process as iterated, by 
changing the assumed for  of the energy dependence of Zi/Z, until the calculated and 
bserved s eetra f e a reed. 
he resulting energy dependence is consistent, between a out 10 a d 100 
GeV jamu, with one derived independently for a different detector system by Barthelmy 
et al. (1985, OG 4.1-7). Above about 200 GeV jamu, the shape of our calibration curve 
depends upon the assumption e ade t at the e energy spectrum falls as a po er-
la  ith exponent -2.7 at energies above those here it has been easured. 
Abundance ratios derived from data in a particular ZijZ histogram were plotted 
at the ean energy from which those particles ca e, assuming the Fe energy spectrum 
and the calibration curve described above. The energy resolution i plied by our 
ionization resolution of 0.40 charge units is comparable t  the spacing f t e points in 
figure 3. 
4. esults. Figure 3 gives the resulting abundances of several elements relative to Fe 
as a function of energy. he  sy bols are the results of the F experiment 
(Englemann, 1983), while the 0 symbols are the results of this experiment. In every case 
our results are consistent with those of the DF experiment in the interval where both 
experiments apply, 10 to 25 GeV jamu. t higher energies our data generally continue 
e  end. 
ur data above 10 eV /amu suggest a iJFe ratio slightly dependent upon 
energy, ith a best fit power la  of exponent -0.050 ± 0.016. If e ignore this slight 
variation ith energy, then the ean value of the i/Fe ratio over our ata is 0.054 ± 
. 01. 
For the secondary ratios, /Fe, Se/Fe, Ti/Fe, and V /Fe, our data indicate an 
extension to about 100 GeV Jamu of the sa e power law dependence as was indicated 
by the F data. Figure 4 shows the best fit exponent for each of these ratios co bining 
the F and our data. he steepening of the slope ith decreasing Z is expected as 
lo er  elements have greater contributions fro  tertiary nuclei. 
30 OG4.1-8
' I ' ' I ' '
0.2C , ' I ' ' I ' ' 0.I("''|IIsla At
tl. KIII I
- ' O.0_ 'I'I,
O IC '''il'l'_l' ! t t t t t
o 'I° I
o.o5 'I o.o: I
' t
O.O? , , I , t I , , O.O1 , , I , , I , i
O_CL ' ' i ' ' i ' ' O IC , ' I ' ' i '
Co Sc
' I 0.05
O.2C, ''',,,, . llll I
''.t',,, | l |l i l
' ',i I I'I_
OJO- - 0.02 tl I
tttO.Oe , , I , , I , , O.O1 , , I , , I , ,
0.20 , ' I ' ' I ' ' 0.I0_. , ' I ' ' I ' '
Ti ! tIlSSSt$ | II l V
0.I( - ,,,. - O.OFJI-- 'ill..
I',,,, l I O.O2_ I _Olo Io.o_ ' ,I,
-
I
0.0: , , I , , I ,I , 0011 , , I , , I ,
I I0 I00 I( DO.IO__ , ' I ' ' I ' '
ENERGY (GeV/omu)
, ,Ifoo5T,,,'", [ Figure 3
Abundances relative to Fe
i x Englemann, et al. (1983)
0.02 Ni • This work.
O.O1 , , I , ' I , ,
I0 I00 I000
30 
, Ar 
I I I I 
, I I , 
, 't - I • 
• t t I I 
t 
o. 
Co 
 
I I I 
I '., •••• 
, • t t t f I 
o. 
Ti 
I , •• 
" , 
't 
Ni 
OG 4.1-8 
. ,, , , 
• • •• K 
o. 't-t. 
.t. t 
t t 
Sc 
t t 
ttl 
H ; ~. J itt 
• f t 
, 
I "I V 
0. 
I I , I • _ 
t ", 
t t 
0.01 L--'----L_~-'----L__,..,!~-'----L~L_ 
I 10 
ENERGY (GeViamu) 
Figure 3 
Abundances relative to Fe 
x Englemann, et al. (1983) 
• This work. 
3 1 OG 4. I-8
Our data indicate a leveling of the Ca/Fe ratio above the energies of tile DF
experiment, as would be expected from an energy-independent primary component
becoming increasingly significant at higher energies as the secondary component I
becomes less abundant. We fitted the combination of the DF and our ratios to a
function aEP+b. With p = -0.295 + 0.010, interpolated from figure 4, the result is
primary Ca/Fe = 0.094 ± 0.004. A galactic propagation calculation on the DF data
(Lund, 1984) gives a source abundance of Ca/Fe = 0.065 + 0.019.
-0.22
-0.24F
Figure 4_-o.2_ _ Exponent of power law fit to
_i abundance of element Z
_-0.a( relative to Fe.
-0.3_
-0._ ' , _) _ ., ,18 19 I 22 23 :
Z
A similar fit to the energy dependence of Ar/Fe, but with p = -0.33 4- 0.01, gives
primary Ar/Fe = 0.026 4- 0.003. Propagation of the DF data (Lund, 1984) gives Ar/Fe
-- 0.032 ± 0.008. Source abundances inferred from such galactic propagations on
observed abundances 2.5 to 5 times higher must depend critically upon the adopted
fragmentation cross-sections, while our extension of observations above 100 GeV/amu
permits inference of source abundances without galactic propagation calculations.
5. Acknowledgement. This work was supported in part by NASA grants NAG 8-498,
500, 502, and NGR 05-002-160, 24-005-050, and 26-008-001.
6. References
Barthelmy, S.D., M.H. Israel, J. Klarmann, 1985, this conference OG4.1-7.
Binns, W.R., et at, 1981, Nucl. Instr. Meth., 185, 415.
Englemann, J.J., et al., 1983, 18th ICRC (Bangalore) 2, 17.
Lund, N., 1984, Adv. Space Res., 4, (No.2-3), 5.
Webber, W.R., 1982, Comp. Origin o/Cos. Rays, ed. M.M.Shapiro, 25.
Webber, W.R. and D.A. Brautigam, 1982, Ap.J., 260, 894.
Westfall, G.D., et al., 1979, Phys. Rev. C, 19, 1309.
1  .1-8 
Our data indicate a leveling of the Ca/Fe ratio above the energies of the DF 
experiment, as ould be expected fro  an energy-independent primary component 
becoming increasingly significant at higher energies as the secondary component 
becomes less abundant. e fitted the combination of the  and our ratios to a 
f nction a P +b. ith   - . 95 ± . 10, i terpolated fr  fi re 4, t e result is 
primary a/Fe  0.094  0.004.  galactic propagation calculation on the F data 
( und, 1984) gives a source abundance of a/Fe = 0.065 ± 0.019. 
.22 
-0.24r f 
§-o.26 Figure 4 
;a 
~ 28 r 
! 
Exponent of power law fit to 
ff  a undance f lement  
~-o.3C 
t relative to Fe. 
-0.32 
-0 ... · 
  20 21   24 
 
 si ilar fit to the energy dependence of r /Fe, but ith p = -0.33 ± 0.01, gives 
primary Ar/Fe = 0.026 ± 0.003. Propagation of the DF data (Lund, 1984) gives Ar/Fe 
= . 32  . 08. urce bundances i ferred fr  s ch alactic ropagations  
observed abundances 2.5 to 5 ti es higher ust depend critically upon the adopted 
fragmentation cross-sections, while our extension of observations above 100 CeV /amu 
permits inference of source abundances without galactic propagation calculations. 
5. Acknowledgement. This work was supported in part by NASA grants NAC 8-498, 
, , and CR -002-160, -005-050, a d - 08- 01. 
 ferences 
arthelmy, . ., . . Israel, J. larmann, , t is c nference C4.1-7. 
inns, .R., et l., 1, cl. l str. eth., 5, . 
Englemann, J.J., et al., 1983, 18th I RC (Bangalore) 2, 17. 
und, ., 1984, Adv. Space Res., 4, ( o.2-3), 5. 
ebber, .R., 1982, o po rigin 0/ Cos. Rays, ed. . .Shapiro, 25. 
e ber, .R. and . . rautigam, , p.J., 0, . 
estfall, C. ., et al., ]979, Phys. Rev. , 19, 1309. 


Energy spectra of elements with 18  or = Z or = 28 between 10 and 300 GeV/amu

Energy spectra of elements with 18 or = Z or = 28 between 10 and 300 GeV/amu

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