The results of a new balloon borne cosmic ray detector flown from Palestine, TX in Sept., 1982 are discussed. The exposure of 62 square meter-ster-hr is sufficient to prove the concept of using gas ionization chambers as energy measuring devices in the relativistic rise region. The abundances, relative Fe-26, of the pure secondaries Cr-22 and Ti-24, the pure primary Ni26, and the mixed primary and secondary Ca-20 between 6 and 70GeV/amu were measured

Barthelmy, S. D.

Israel, M. H.

Klarmann, J.

English

NASA Technical Reports Server

0G-4.1-7
24
Relative Abundances of Elements (20 < Z < 28) at Energies
up to 70GeV/amu Using Relativistic Rr[se irn Ion Chambers
S.D. Barthelmy i, M.H. Israel, J. Klarmann
Physics Department and McDonnell Center for the Space Sciences
Washington University, St. Louis, Missouri 63130, USA
1. Introduction This paper reports on the results of a new balloon borne cosmic ray
detector flown from Palestine, TX in Sept 1982. The exposure of 62 m_-ster-hr is sufficient
to prove the concept of using gas ionization chambers as energy measuring devices in the
relativistic rise region. We have measured the abundances, relative to 20Fe, of the pure
secondaries 22Cr and 24Ti, the pure primary 2sNi, and the mixed primary and secondary 20Ca
between 6 and 70GeV/amu.
2. Instrument The instrument, Figure 1
shown in figure 1, is composed of 1.0cm r / H
NEll4 plastic scintillator(S), and 0.6cm i................................................. t s
Pilot 425 plastic Cherenkov(P), detectors { j i
in light diffusion boxes. These two detee- [ J t
tors determine the charge of the cosmic _(U) (_ _ _5_ _ s
rays. Interspaced around the S and P {' J J
i
detectors are pairs of 10cm dual gap P-10 H
gas ionization chambers(I). In addition s
to being the energy measuring devices P
they are also used for identification of I [ t
nuclear interactions in S and P detec- [ ] i
tors. At thebottomofthestackisaone c(_(_) (_) (_) (_) (_) _)_)[-_
atmosphere COs gas Cherenkov(G), L r 0
whose nominal threshold energy is , ,,_
34.8GeV/amu. This detector provides
the energy calibration of the relativistic
rise region of the ion chambers. The two
layers of x-y multiwire ionization hodoscopes(H) provide the trajectory information which
allows for the path length correction and for correction to the areal variations of the vari-
ous detectors. The stack, 160cm x 160cm x 190cm, with the electronics is flown inside a
one atmosphere pressure vessel.
3. Data Reduction Figure 2 is a plot of the mean ionization signal(I) versus the plastic
Cherenkov signal(P). The dashed lines are the charge tracks for the even Z elements 20 to
28. The vertical pairs of lines mark the 8=1 saturation of P, the events of interest in this
experiment. With I and P alone it is impossible to separate, say, relativistically risen
charge 24 from low energy charge 26. To remove this ambiguity a third dimension,
scintillation(S), is added.
I Presently at Goddard Space Flight ('enter. Greenbelt. Maryland 20771, USA
O -4.1-7 
2  
Relative undances of Elements ( Z<28) at Energies 
u  t  7 eV /amu Using elativistic Rise in Io  C ambers 
S.D. Bart l  1, M.H. Israel, J. Kl r n 
Physics Depart ent and Mc onnell Center for the Space Sciences 
ashington University, St. Louis, issouri 63130, S  
1. Introduction This paper reports on the results of a ne  balloon borne cos ic ray 
t ctor fl  fr  l stine,  i  S t 19 .  sure f  2- t r-hr is s ffi ient 
to prove the concept of using gas ionization cha bers as energy easuring devices in the 
r l tivistic ris  r i n.  h  sured t  a nces, rel ti e t  6 e, f t  r  
secondaries 22 r and 24Ti, the pure pri ary 2s i, and the ixed pri ary and secondary 20Ca 
een    /amu. 
. strument  i trument, 
sho n in figure 1, is co posed of 1.0c  
NE114 plastic scintillator(S}, and 0.6cm 
ilot  stic renkov(P}, t ctors 
 ht f sion s. ese  c-
rs termine e arge  e ic 
ys. t rspaced und  an   
detectors are pairs of IOc  dual gap P-lO 
s i nization a bers(I}. I  dition 
 ing e ergy easuring vices 
ey e lso d r entification f 
clear teractions  a   tec-
t rs. t t e b tt m of the stack is a one 
at osphere 2 gas herenkov(G}, 
whose no inal threshold energy is 
4.8GeV /amu. his etector rovides 
the nergy alibration f the lativistic 
rise ion f the n chambers. he o 
Figure 1 
1·········· .. ·· .. ···· .. ·········· .. ··· .. ·· .. ······, 
~--------------~llm 
H 
H 
5 
I 
H 
H 
p 
G 
layers of x-y ultiwire ionization hodoscopes(H) provide the trajectory information hich 
allows for the path length correction and for correction to the areal variations of the vari-
ous detectors. he tack, 60cm x 60cm  90cm, ith the lectronics is flo n inside  
one atmosphere pre sure ve sel. 
3. ata eduction Figure 2 is a plot of the ean ionization signal(l} versus the plastic 
herenkov signal(P}. The dashed lines are the charge tracks for the even  elements 20 to 
28. The vertical pairs of lines ark the (3=1 saturation of , the events of interest in this 
experiment. ith I and P alone it is impossible to separate, say, relativistically risen 
charge 24 from low energy charge 26. To remove this ambiguity a third dimension, 
scintillation(S), is a ded. 
I Pre~ntly at Go dard Spare Flight Center. Gr enbelt. Maryland :!Oi7I. r A 
https://ntrs.nasa.gov/search.jsp?R=19850025700 2020-03-20T18:05:28+00:00Z
25 0G-4,1-7
Figure 3 is a plot of the same events for S versus P. The energy dependence is almost
entirely in the P dimension. The relativistic events pile up at the right side of the cluster
and lower energy events trail off towards the left. The superposed boxes are the S and P
cuts used to select events that will be used to form abundance spectra. We observe that S
has negligible (less than 0.5%) relativistic rise at 100GeV tamu, so the S cuts do not intro-
duce a significant energy dependence.
Figure 2 Figure 5
600 500
"=,.
• • • I I
L_J
., .. _.,_.,,,;.. _ .,.:_,_: ,_,.:
%%
.:LJ
t
G"" ¢°
2002 [arb. units] 550
°O P [arb. units] coo P
The S cuts are asymmetric about the charge tracks. This is because almost all the
contamination from adjacent charges into a given charge selection box is from the lower
energy next higher charge. The P cuts are symmetric about the _-----1track of the given
charge. Both the $ and P cuts are made in constant sigma units for each charge. This
insures a constant fraction of the desired charge to be included within the S-P box cuts.
Taking the events within these cuts, histograms were formed in I/Imi n. Ratios of these his-
tograms to that for iron are the abundance ratio spectra that are discussed in section 5.
4. Energy Calibration Figure 4 is a
plot of I vs G for the events satisfying Figure 4
the S and P cuts in figure 3 for iron. 1600
The line through the data is a result of a
least-squares fitting with the semi-
empirical model described by equations 1. .:,
t=&l.(E) + B 0a) %. .:
c=K(,- ' !"
2)+ D (lb) =
I is the ratio of the I signal over the ri
I- " _ ..
minimum value (at 2.4GeV/amu). The o
D term represents the scintillation emis- 0 _.,:.'.:_., : •sion from the reflective paint coating on %,....
the inside of the G light diffusion box. ._-, • ,
The fitting was done in two steps. _:_.i"
° ,
" The first attempt only fit the events 0 .l
between the G values of 450 and 1100. 300 I [arb. units] 600
Using this fit a swath through I and G
 OG-4.1-7 
Figure 3 is a plot of the sa e events for S versus . he energy dependence is al ost 
entirely in the P di ension. The relativistic events pile up at the right side of the cluster 
a  l er e ergy e ents trail ff t ards t e left. e s erposed es are t e a   
ts s  t  s l ct nts t at ill  s  t  f r  ndance s ctra.  serve t at  
has negligible (less than 0.5 ) relativistic rise at lOO e  ja u, so the S cuts do not intro-
ce a si ificant e ergy e endence. 
i r   
0r-----------~--------~--~ 
.--. 
(f) 
~ 
c: 
~ 
-e 
o 
...... 
0'-------------------' 
 [ r . its] 600 
figure 3 
500 ..-----------'~----------..., 
D 
P [arb. units] 550 
The S cuts are asymmetric about the charge tracks. This is because al ost all the 
contamination fro  adjacent charges into a given charge selection box is fro  the lo er 
energy next higher charge. The P cuts are symmetric about the f3=1 track of the given 
charge. Both the Sand P cuts are ade in constant sigma units for each charge. This 
insures a constant fraction of the desired charge to be included ithin the -P box cuts. 
Taking the events ithin these cuts, histograms ere for ed in IjImi • atios of these his-
tograms to t at for iron are the abundance ratio spectra t at are discussed in section 5. 
4. nergy alibration Figure 4 is a 
plot of I vs G for the events satisfying 
the and P cuts in figure 3 for iron. 
he line through t e ata i   esult f  
least-squares fitting ith the s i-
empirical model described by equations 1. 
I=Imln(E) + B 
G =K(l - Etlres/a/E2)   
(la) 
(lb) 
I is the ratio of the I signal over the 
inimum value (at 2.4GeV jamul. he 
D term represents the scintillation emis-
sion from the reflective paint coating on 
the inside of the  light diffusion box. 
The fitting as done in t o steps. 
The first attempt only fit the events 
between the G values of 450 and 1100. 
Using this fit a swath through I and G 
Figure 4 
I [arb. units] 600 
26 0G-4.1-7
space was made to allow for the inclusion of events down beside the paint emission clump
and to extend the high end to include the fl=l events in the G detector. The sharp thres-
hold in G can be seen and it is the I value at this Eth,esh that provides one well defined cali-
bration point. Given the limited number of events the slope (Im) was very poorly deter-
mined from this I vs G comparison, and so we instead determined the slope by comparison
between our iron data and the iron spectrum from previous experiments (summarized by
Webber[l]).
For various values of Im, with B selected to give the previously determined I(Eth,sh ),
we convolved the Webber spectrum with equation 1 and with the resolution function of the
detector. We then determined the value of Im which gave the best least-squares fit to our
observed I-spectrum for iron. The final values of the parameters in equation l are Im ----
0.0738 4- 0.0023, B ---- 0.8889 4- 0.0019, K ---- 1220.0 4- 15, and D ---- 207.0 4- 4.0. The
numerical values of the parameters for equation la apply to an I scale in which minimum-
ionizing iron gives I=l.000, and this equation is taken as applicable for energies greater
than 5.0 GeV/amu.
5. Results Even with the tight S cuts near the Z+I charge track, there is still some con-
tamination. While these contamination events are of low intrinsic energy, their I mimics
relativisticly risen events because they have a greater charge. The upper S cut was fixed by
requiring that the contamination to any of the five charges never be more than 20% of the
charge of interest at the appropriate I/Imi, value. Subtractions were made for these con-
taminations. After producing the number versus I/Imin spectra, they are binned into three
differential points, one integral point, and using similar S and P cuts, a point at I,,,
(2.4GeV/amu).
Our results are listed in table I and plotted (points with error bars) in figure 5. In the
energy interval 6 to 25 GeV/amu our results are consistent with those of Englemann[2]
(their data has been propagated through 4.1 g/cm _ of air). Above 25 GeV/amu our results
indicate an energy dependence of relative abundances which continues the trend observed
by Englemann, et al.
TABLE 1 - Abundance Ratios to Iron for Ti, Cr, Ca, and Ni
Energy Range Element
Lower Upper Ti Cr Ca Ni
,'-_1.45 ,_3.35 0.158 5=0.007 0.161 5=0.007 0.217 5=0.009 0.055 5=0.004
5.90 11.62 0.129 5=0.013 0.124 5=0.013 0.225 -I-0.018 0.052 + 0.008
11.62 22.87 0.101 4- 0.023 0.086 4- 0.021 0.178 4- 0.032 0.037 4- 0.014
22.87 45.02 0.059.5= 0.023 0.074 5=0.026 0.092 -t-0.029 0.034 5=0.017
45.02 co 0.070 5=0.023 0.075 4- 0.024 0.126 5= 0.032 0.043 4- 0.018
8. Acknowledgements We are grateful to W. R. Webber for valuable suggestions regarding the
design of this experiment, and to John Epstein and John Vogel for essential contributions to the con-
struction of the instrument. This work was supported in part by NASA grant NGR-26-008-001.
References:
[1] Webber, W.R, 1982 Erice NATO Conference, 1983, Reidel, pp 25-45
[2] Englemann J.J., et al, 1983, ICRC, Bangalore, India, OGI-9, pp 17
6 OG-4.1-7 
space was made to allow for the inclusion of events down beside the paint emission clump 
and to extend the high end to include the {3=1 events in the G detector. The sharp thres-
old i   an e seen nd it is the  alue t this Et rts  that rovides ne ell efined ali-
bration point. Given the limited number of events the slope (1m) was very poorly deter-
ined fro  this I vs  comparison, and so e instead determined the slope by comparison 
etw en ur iron ata nd the ir n spectrum from revious xperiments (summarized y 
Webber[ 1]). 
For various values of 1 , ith  selected to give the previously determined I(EthrtSh ), 
we convolved the ebber spectrum with equation 1 and with the resolution function of the 
detector. e then determined the value of 1  hich gave the best least-squares fit to our 
observed I-spectrum for iron. The final values of the parameters in equation 1 are 1m = 
.0738 ± .0023,  = .8 89 ± .0019,  = 20.0 ± , and  = 07.0 ± .0. he 
nu erical values of the parameters for equation la apply to an I scale in which inimum-
ionizing iron gives 1= 1.000, and this equation is taken as applicable for energies greater 
than 5.0 e  lamu. 
6. esults Even ith the tight S cuts near the Z+ 1 charge track, there is still so e con-
ination. hile ese ntamination vents re f  trinsic nergy, eir  imics 
relativisticly risen events because they have a greater charge. The upper S cut was fixed by 
requiring that the contamination to any of the five charges never be more than 20  of the 
charge of interest at the appropriate Illmin value. Subtractions ere ade for these con-
ta inations. fter producing the number versus Illmin spectra, they are binned into three 
differential points, one integral point, and using similar Sand P cuts, a point at Imin 
(2.4GeV lamu). 
Our results are listed in table 1 and plotted (points with error bars) in figure 5. In the 
energy interval 6 to 25 GeV jamu our results are consistent with those of Englemann[2] 
(their data has been propagated through 4.1 gjcm2 of air). Above 25 GeV lamu our results 
indicate an energy dependence of relative abundances which cont.inues the trend observed 
by Englemann, et al. 
LE 1 - bundance atios to Iron for i, r, a, and i 
Energy Range Element 
Lower Upper Ti Cr Ca Ni 
....... 1.45 ......,3.35 .  ± .  .  ± .  .  ± .  .  ± .  
5.90 11.62 0.129 ± 0.013 0.124 ± 0.013 0.225 ± 0.018 .  ± .  
.  .  .  ± .  .  ± .  .  ± .  .  ± .  
.  .  .  ± .  .  ± .  .  ± .  .  ± .  
45.02 00 .  ± .  .  ± .  .  ± .  .  ± .  
8. cknowledgements e are grateful to . . ebber for valuable suggestions regarding the 
design of this experiment, and to John Epstein and John Vogel for essential contributions to the con-
struction of the instru ent. This work was supported in part by NASA grant NCR-26-008-ool. 
ferences: 
[II Webber, W.R, 1982 Erice NATO Conference, 1983, Reidel, pp 25-45 
[21 Englemann J.J., et ai, 1983, ICRC, Bangalore, India, OCI-9, pp 17 
Figure S
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1l
o- I I I I I _o- I I I I I
1.00 I/Imla 1.0.5 1.10 1.15 1.20 1.00 _ 1.06 I.I0 1.15 1.20
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I "= : ' 1" = I
0 I I I I I , i i i 0 I I i , I I I I i100 1 100ENERGY[_V/omu] m_.GY[CeV/amu]
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0.4 0.4 
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e I I I e I I I .00 1/! In 1.05 1.10 1.15 1.20 1.00 I/lmIn . 5 1.10 .  1.20 ~ ~ •  • • II I , 
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Relative abundances of elements (20 or = Z or = 28) at energies up to 70 GeV/amu using relativistic rise in ion chambers

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