Comments on the Fe-group track density and track length distribution in different meteoritic and moon crystals

0191-278X/86 $3.00+.00 Pergamon Journals Ltd.

Nuclear Tracks, Vol. 12, Nos I-6, pp. 403-405, 1986. Int. J. Radiat. Appl. Instrum., Part D Printed in Great Britain.

OOMMENTS O N THE Fe-GROUP TRACK DENSITY AND TRACK LENGTH DISTRIBUTION IN DIFFERENT M ~ O R I T I C A~TD M ~ O N CRYSTALS A.P. Sharma, V.P.Perelygin*,

L.L°Kashkarov**

Department of Physics, K u r u k s h e t r a University Kurukshetra-132119 (India) *Joint Institute of Nuclear Research(JINR) Dubna, Moscow (USSR) **Vernadsky Institute of ~eochemistry Analytical Chemistry USSR A c a d e m y of Science(USSR)

and

ABSTRACT The results of investigations length distribution

of Fe-group

in olivine

locations of several

different

The density of Fe-group

tracks

meteoritic

crystals.

crystals

and at

tracks density and track

crystals picked up from various

and moon crystals

are presented.

is found to v a r y from l.lxl0 5 t/cm 2 to

1,83xi0 7 t/cm 2 for olivine crystals pyroxene

nuclei

and pyroxene

and 1.5x10 4 t/cm 2 to 3,9xi0 7 t/¢~ 2 for

The track length spectrum peaks

-~ 10-14/~m in pyroxene

at

~

7-10~/m in olivine

crystals.

K ~I~OR DS Meteorite;

olivinet

pyroxene,

etching

INTRODUCTION The studies of heavy and superheavy useful

information

galactic

objects,

nuclei of galactic

about the processes heavy nuclei

tion in charge composition,

of nucleosynthesis

acceleration

intensity

cosmic rays reveal in different

and transport in galaxy, varia-

and energy spectra of heavy nuclei.

The present method makes use of the detection of tracks of stopping galactic nuclei of Z >/ 20 recorded for several space in the extraterrestrial The advantages fo i lows (i)

of using silicate They register

tens and hundreds of million years in

silicate minerals crystal

nuclei

from meteorites

are as

with Z 7/ 20 (VH nuclei)

(ii) They are exposed in free space hundreds

of various meteorites°

detectors

for several

tens and

of million years,

(iii)They are less prone to annealing which may occur during their lifetime To study the Fe-group tic and moon crystals, (meteorites)

in space.

track density

and track length distribution

in meteori-

we have surveyed about 20 stony iron Pallasites

and moon crystals (Luna 16 and Luna 24).

403

404

A.P. SHARMA et al.

S X P ~ I MENTAL The big crystals(size ~/ 2ram) and small crystals(size

~

Imm) were picked up

separately from the mixture of all types of crystals obtained by breaking a portion of meteorite~

The crystals were mounted in epoxy(Polymer's

optimum conditions being 60 ° for 1 hour) Modified WO 4 solution(PH=7o95) 1971) °

and then grinded ar~ polished~

has been used for etching(Krishnaswami

et al,

The olivine crystals are etched at a temperature of 100°C for 20-30

hours in a hermetically closed voltn~e while pyroxene crystals are etched in NaOH solution(6 gm NaOH in 6 cc H20) in teflon containers at r~ 140°C for few hours(Lal et al, 1968).

The tracks devolop~d after proper etching have been

measured for their densities and lengtl~s under optical microscope, tracks of lengths

~

The

20/urn are grouped as V H tracks pertaining to Fe-group

nuclei, The lengths ~/ 30//m ar~ counted for ~v"JH track density measurements. Their abundance is ~ery small, W H / $ H r ~ 10--3-10 -4 . The Fe- group track length spectrum has been measured in olivine as well as in pyroxene crystals for different meteorites by using TINT end TINCLE method(Lal,

1969),

RESULTS AND DI SCUSSION Table-I compares the fossil Fe-group track length peaks with the accelerated from cyclotron

Fe-ion track length caused by heavy ion- Fe--beam(monoenergetic)

Table-i Fe-jroup track density variation measured in different me teo rites

Met

rites

atia-

Track densi

t/on Olivine age Crystal (M Yrs)

Tugalin Bulean Marj alahti

Patwar Eagle Station

7

(2, I-4,8) xl0 6 (8 locations)

176

(0°7.6. i) xl0 6

70-90 36

(I, 3-18, 3) xl0 6 (29 locations)

.... 7oTE Pyroxe ne crys ta is,

(3°4-8,2) xl0 6 (3 locations)

(2,0-39,0) xl0 6 (9 locations)

(i,6.16.0) xl0 6

220

(Io3-7,2) xl0 6 (30 locations)

10-12~m

7~m

-

i0 ~ m

Soko Bahia

40

(3,5--7°7) xl0 6 (30 locations)

Yamysheva

40

(0o11-1,4) xl0 6 (27 locations)

.5/urn

(,015-6. i) xl06 (20 locations) _

-ion

18-24/urn (pyroxene Cry'.) 12-14 A/m (Clivine Crvs ta is )

i~-12

~m 10,5

-

Lup

9o5~m

/um. Lipovsky Khutor

-A-

track length (acceDeak in lerated Olivine Pyroxene from c~-ystal crystals cyclotron tre&G ie n ~ .

8Q 5~m

12--14/urn (Olivine cL'ystals)

Fe - GROUP TRACK DENSITY

in olivine

and pyroxene crystals.

columns A and B indicates all meteorites

in crystals.

ling of latent tracks.

tracks

This can be attributed

The shortening

for different meteorites

are shortened in

to some sort of annea-

of fossil tracks is found different

which can b e explained

due to their being in differ-

in space with respect to the position of the sun,

Fig. l shows the Fe-group Luna-24),

The comparison of track length peaks in

that the fossil Fe-group

as compared to fresh Fe-ion tracks produced b y cyclotron b e a m

and impregnated

ent orbits

405

track length spectra

In this case also,

for lunar crystals(Luna-16

the peak falls at 9 , 5 ~ m .

LUNAR OLIVINE

and

This also confirms

CRYSTAL

(Total number of measured tracks • 120) IB!

In

~c

12 8

o

S

uJ w

~

Z z

~ 0

0

2

F[

& I II 10 12 I& I$ 18 20 22 TRACK LENGTH ( ~ m l -{>

Fig.1 The track length spectrum of VH track in lunar olivine crystal. ~ac

c~

~ossil tracks in olivine crystals

fresh Fe-tracks

due to heavy ion beam from cyclotron.

to high moon temperature( some annealing from I. 2, 3,

~

are shortened in comparison

~

120°C)

8.10/urn(about

This may b e attributed

during day time, which might have caused

and hence have contributed

12-14/urn to REFERE~ES

to the

to the shortening

of track lengths

34~).

Krishnaswami S.~ Lal, D,, Prabhu N, and Tamhane AoS, SCo(1971), 174, p0287-91, Lal D,, Murali A.V, t Rajan R.S,, Tamhane A,S.Lorin J.C. and Pellas P., Earth Planet, Sci. Lett,(1968) 5, 111-19, Lal, D., Space Sc, Rev,(1969), 9 w 623-50.