372596139

102

RIKEN Accel Próg. Rep. 24 (1990)

111-5-8. Performance of Isotopic Separation in RIPS

T.Nakamura, T.Kubo, S.Shimoura, H.Okuno, N.Inabe, K.Yoshida, H.Kumagai,

I.Tanihata, K.Asahi, and M.Ishihara

To study the performance of isotopic separation in a radioactive beam linę, RIPS,ⁿ we have carried out an experiment on the production of radioactive fragments ¹⁴B and ¹⁶C, using 100 MeV/u ¹⁸0 beams from RIKEN Ring Cyclotron. The target used was a 277 mg/cm beryllium piąte.

Fragments ¹⁴B and ^1<łC were selected according to the condition shown in Table 1. Particie identifi-

'1'able 1. The experimental condition for studying isotopic separation in RIPS. Bp,, the magnetic rigidity for the first stage, which is optimized for ⁿB; Bp-,, the magnetic rigidity for the second stage, which is optimized for “B and ^,ł’C; d^, the thickness of the degrader in the central ray; X, a parameter in the rangę formula; "T^,, ranges in the degrader.

2 dimcnv.or.iJ image jt I *

_{c c}-......gp--r£------

x :ic;

Magnets	Bpi	4.02	(T-m)
Magnets	Bp*	3.67	(T-m)
Degrader	do = 1.365 g/cra² Aluminum		A = 3.48
Isotope		“B	^iaC
	Ro(g/cm²)	5.15	4.81
	d₀/Ro	0.265	0.284

Fig. 1. 2-Dimensional profile of F2 detected by PPAC, tuned for ^1;>B (left) and ^1HC (right).

3000

2400

1800

1200

600

r 30 mm	■ i
¹1
- . I	L
f	\ FWHM lOmni
^,4B j	1
/v_	l^J

O 60 120 180 24C

X posilion

Fig. 2. Horizontal projection of the profile of F2 (Fig. 1), tuned for ^,r,B (left) and ^1(,C (right).

cation for these isotopes was performed by measur-ing the energy loss in a 400-pm Silicon detector at the achromatic focal piane (F2) and a time of flight between a PPAC (parallel piąte avalanche counter) located at F2 and RF signals of RIKEN Ring Cyclotron. Figurę 1 shows beam profiles at F2 and Fig. 2 the projection to the horizontal direction, which are observed by the PPAC. The left focusing image corresponds to ¹⁴B and the right one ¹⁶C. The dis-placement and the size of images (FWHM) of two images are also shown in Fig. 2. The displacement is consistent with the designed value of dispersion in the second stage in RIPS (described as D₂)_ywhich is 375 cm. The value of D₂ is used for deter-mining mass dispersion Z)_A by

dp/Ro 1~X 1 - d₀/R₀ X

The mass resolving power is thus obtained as

\A/AA\ = 1.1 x 10² (2)

We may conclude that resolving power A/AA \ > 100 is achieved without any second order correc-tion.

References

1) T. Kubo et al.: This Report p. 96.

2) K.-H. Schmidt, E. Hanelt, H. Gaissel, G. Muenzen-berg, and J.P. Dufour: Nuci. Instrum. Methods, A260, 287 (1987).