Basu, Basudhara

Bhattacharyya, D P

Biswas, S

Majumdar, Rena

Mitra, Mala

Pal, Pratibha

Rakshit, Ruma

Saha, S

IACS Institutional Repository

N O T EIndian J. Phys. 69A (2), 295 -  298 (1995)I .) P t “ .an international journalEstimation of total charge changing cross section in 197Au + 27A1 interactions at 0.930 GeV/nD  P Bliattadiaryya, S Saha, Basudhara Basil, Pralibha Pal,Ruma Rakshil, Rena Majumdar and Mala MuraDepartment of Theoiclical Flysics, Indian Association loi the Cultivation ol Silence. Jadavpur, C."alcutla-70<) 032. IndiaandS BiswasCosmic Kay and Space Physics Division, Tata Institute of Fundamental Research, Colaha, Hombay-4(X) 005, IndiaR e i e i v e d  2 S  D e i  e m b e r  l b 9*/, a u e p t e d  IK J a n u a r y  I b b 4Abstract : The total charge changing cross section ol v>! Au projectiles at HhVALAC energy 1,015 GeV/n in 27AI target has been studied using a stack consisting ol CK- *9 (J)OP) plastic track detectors and the target Hie measuied total cross section lor An + Al interactions has been found comparable with flic extrapolated BFVALAC data ol Bums e t  a l  and oui earlier results on yHU- jons in 27Al target al relativistic energies TTic esUmnled value of the total charge changing cross section has been found to be (3150 ± 134) mb which is close to the expected result from the lit alter Binns e ta l .Keywords : Au + Al interactions, BHVALAC beam, total charge changing cross section PACS Nos. : 25 75 +r, 96 40 DcThe study o f  nuclear interaclion phenomena at relativistic energies is necessary for understanding the heavy ion projectile interactions with nuclear matter under conditions oi high pressure and temperature.The com parison o f the observed data on nucleus-nucleus interactions with the expected result yield the interaction picture of the hadron structure. An accurate inJormation on the fragmentation cross section in nucleus-nucleus interactions is important lor  understanding the ultra heavy nuclei composition of cosmic rays. This may exhibit some idea on the galactic cosm ic ray exposure behind the shielding in the space flight pointed out earlier by Townsend [1].©  1995 1ACS2 % l)  P Bhattacharyya el alIn the present work, w e have used C R -39  (O O P) so lid  state nuclear track detector to determ ine die total charge changing cross section lor the production ol Iragrnenls of charge ZF in c o llis io n s  o l |1J7Au heiun at 0 .9 3 0  CieV/n d elec ted  on  the C R -3 9  (D O P ) sla ck  after  traversing 2 cm  thick - 77 Al target sand w itched betw een  C R -39  (D O P ) sheets. F requencies o f  the etch  pit co n es o! the lt,7Au p rojectiles in the p lastic  plates both above and below  the A l target have been m easured to estim ate the total charge changing cross section  and the result has been com pared w ith  the experim ental results of B inns e ta l  [2] for Kr, X c, H o and An along w ith ours tor V  interactions with A l target [3], The expected  results from  the fit after  Dudkin el a l |4 |  have a lso  been considered in the present survey. |Tublr 1. Muence ol Au projcuilc.s iiicnlcnt al energy 0930 (icV/n on a 2 cm V  Ai target s.imlwiidied hy ( ’R-3‘) (DOP) pl.islic shoe Is and of those emerging through it at energy 0 717 (ieV/n \lnculcnl Number ol Number ol I’olal 4 0U1I chargeprojectile An nuclei An nuclei mean flee path dungingdiaigc / lllLlcIlMl emerging of flu Au projei cross-on ihc Irom llie 1 lies in Al sectionlargL-l target A, O f(jvi nir) (jxt enr) (j'/fin') (mb)/9 40 IS 2749 14 22 + 0 94 • 4 ISO+134W e used C R -39 (l)(  )P) Pershore plastic plates with thickness ol about 4 5 0  p m  and o f  area 25 cm - each and a 7tAl target, 2 cm  thick. There are 1 0  sheets o f  p lastics above the target and 5 sheets below  it. The stack w as irradiated at an angle 3 0 “ w ith the ^ A u  nuclei at 1 015  ( ie V /n  en ergy  from  the L aw rence B erk eley  Laboratory B F W A L A C  The en erg ies  o l the surviving 7 / Au nuclei w ere cstim aled-and lound to be 9 3 0  M eV /11 and 717  M eV /11 at the lop  and tiie bottom  o l the target respectively. The sheets were etched for 3 hours in 6 .25  N  NaOH  so lu tion  at (7 0  + 0 .1 ) C. The bulk etch rate ( VG) o f  the p lastic  m aterial w as found to be o f  value (1 .3 6  ±  0 .0 5 ) pm /h  T he cone lengths o f  the etch pits on both die surfaces o f  the plastic  plates above  and b e lo w  the target, were m easured by a L eitz  m icro sco p e  w ith  a X 1 5  filar  m icrom eter eyep iece  and a X 2 4  dry objective, l l ic  f inest d iv ision  o f  the filar m icrom eter scale  w as 0 .3  p in . F requencies o l the etch  pit con es corresponding to on ly  Au projectiles, w ere  m easured on the sam e tw o plates and the results w ere analysed  to determ ine the total charge  changin g  cross section . The num ber o f  co n e s  per c m 2 o f  ultra h eavy  ions in the p lastics  adjacent to the 2 cm  A l target are d isp layed  in the T ab le  1. T he m easu red  c o n e  len gth  distribution o f  the Au projectiles o f  Z//J = 95 .7  111 die plate just adjacent dow n to the target has been used to calculate die charge sensitiv ity  (V 'f/V G) o f  the C R -39  (D O P ) so lid  state nuclear  track detector. The response V j V q o f  the C R -39 (D O P ) p lastic  detector for A u -ion  detection  has been found to be 4 1 .6 9  for Z/f5 =  95 .7  w hich is  com parable to the result as exp ected  from  die g lob a l survey d isp layed  in F igure 1. The fit to the global data [3 ,5 -9 1  as d isp layed  in the  figure fo llo w s an exponential relation o f the formv r / v c  =  A  ex p  I B ( Z /P ) i ( 1)Estimation o f  tatol charge changing cross section etc 297£> 10 -10T-//9 . o f  f h e  p r o j e c t i l eFigure I. The etch rate distribution V j l v ( t  has been displayed as a function of Z/ ( i  lor VII ions inCR V) detectors . . 0 45 GeV/n 84 Kr in GR-39 (MA ND) Bhattacharyya c i a l \ 5 \ .  ▼ I 70(ieV/n * ’Po. •  1 45 (ieV/n WKr. ^  1 28 CieV/n n n [J.i> f J KleV/n ‘t)7Au m GR-39 (J)OP)Salomon et a l [61. 1 88 C,l V / ii vT e  m GR-39 (DOP) Bh.itidiharyya et a l |7 |,  ■ 1 015 GeV/n1 j7Au in C R -19 (DOP) Bhaliacluryya e t  til |8 | ,  ▲ 0  927 (ieV/n in CR PI (DOP)Bhalljcharyya e ia l  |9], .. 0 930 GeV/n 147Au in CR-39 (DOP) Presexil Work Pull curve showsthe exponential I’ll lo llie data obtained from global survey for different projectiles in ('R-39  detectorFigure 2. Total charge changing cross section in Al target is plotted as a function of projectile charge. •  - 1.419 GeV/n H*Kz, 1.155 GeV/n 13IXe, 1 022 GeV/n ,65Ho, 0932 GeV/n 197 Au B i n n s e i a l  [2], ■ -  0.927 GeV/n 23Hl r Bhattacharyya v t a l  [3], ▲ 0 930 GeV/n 197Au presentwork. Full and broken curves are the expected results from the fits after Binns e t  a t  [ 2 ]  and Dudkin e i a l  [4] L, respectively.69A(2)-14298 D P Bhattacharyya et alwhere the num erical values o f  the fitting param eters are found to be A =  0 .4 0 5 1 1 4  and B  =  0 .0 4 8 5 5 4 , resp ectiv e ly . T he total cross section  for the A u +  A l in teraction s has been  estim ated from the m easured number o f  tracks per c m 2 in the plastic sheets adjacent to the A l target. Table 1 sh ow s the detail o f  the cone length frequency m easurem ents for the estim ation  o f  the m ean free path o f  Au in Al target at 9 3 0  M eV /n  energy. T he estim ated  total charge  changing cross-section  has been com pared with the em pirically fitted results o f  B inns e ta l  [2 | along  w ith our earlier result w ith U + Al interactions [3] The em pcrica lly  fitted results o f  D udkin el a l  [4] are a lso  d isp layed  in die F igure 2. It is  ev id en t from  the plot that the total charge changing cross section  o f  ultra heavy nuclei has a projectile  charge d epend en ce  for a particular target. ^A cknow ledgm ent \Ih e authors are thankful to P ro f 11J Crawford and Lawrence B erkeley B l-VAI^AC group lor providing beam  exposure facility  for die present experim ent.References[1] l. W Townsend N A S A  T e c h t i  M e m o r a n d u m  4386 (1992)[2] W R Binns. T L Garrard, M U Israel, M P Kert/mann, J KI ami an n, E C Slone and C J Waddington P h  v sR e v  C36 1870(1987) •[3] D P Bhattacharyya. R Rakshit. B Basu, P Pal, S Biswas and N Durgjprasad N u n v o  (  i m  15C 341 (1992)f4] V E Dudkin, K E Kovalev, N A Nefedov, V A Antonchik, S D Bogdanov, V F Kosnuch, A Yu Likhachev. J 1 (assail. H V Benton and H J Crawford Nu < l  P h y s  A568 900 (1994)[5] D P Bhullacharyya, B Basu, P Pal, R Rakshit. S Chakrabarty and 1 Hitnyadi N lh l e n t  l u s t r u m  M c t h  B61 197(1991)[6] M H Salamon. P B Puce, M Tmcknell, Shi Lin-Guo and G Tarlc N u i l e a r  l u s t r u m  M e t h  B6 504 (1985)[7] D P Bhullacharyya, B Basu, P Pal, R Rakshit, S Chakrabarty, S Biswas and N Durgaprasad N u o v o  C i m  15C 11 (1992)18) D P Bhattacharyya, S Chakrabarty, R Rakshit, B Basu. P Pal and S Biswas Nu< l  l u s t r u m  M e t h  B73 308(1993)[9] D P Bhattacharyya, R Rakshit and P Pal F l ' / J K A  (in press) (1995)

Estimation of Total Charge Changing Cross Section in 197Au + 27Al Interactions at 0.930 GeV/N

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Estimation of Total Charge Changing Cross Section in 197Au + 27Al Interactions at 0.930 GeV/N

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