References - Bogoliubov Laboratory of Theoretical Physics - JINR

field P ≈ +1. If we add the transition 2 → 6 after the second sextupole, we produce pure
state 6 with F =3/2, mF = −3/2 andP ≈−1 after ionization.
So, for the polarized metastable 3 He atomic beam, we need two weak field transition
units that should be placed between and after the sextupole magnets.
It is interesting to note that the pure states of 3 He(2S) may be transferred into the
pure states of 3 He + after stripping one electron in 2S-state. The results of Slobodrian [5]
tentatively confirm this point. In their scheme the adiabatic transition in a weak magnetic
field (mF →−mF ) transforms components 1-2 by turns into 3-6. In a magnetic field the
wave function of the hyperfine substate 3 of the 3 He(2S) atom is
ψ(F =1/2,mF = −1/2) = − sin αψ +
h ψ−
J +cosαψ−
h ψ0 J
⇒ ψ−
h ψ0 J .
With B =0.2 T,(x =0.8309) cos α =0.8564 and sin α =0.5164.
It can be easily shown that if the second ionization is effected in zero magnetic field
the expected value of P for the pure state of 3 He + would be P = −0.68, and for the mixed
state 3 He + P = −0.44 . The measured value is P = −(0.6 ÷ 0.8).
A tapered electromagnet produces a static magnetic field Bz(x) perpendicular to the
beam path with a field gradient dBz/dx along x = vt.
Bz(x) =B0 + dBz
dx x, Bx(x) =B1(x)sinωx. (10)
We accepted that some parameters have the same values as in the paper by Oh [2]:
B0 =1.17 × 10 −3 T, dBz/dx = −1.4 × 10 −2 T/m for a negative static field gradient
(or B0 =4.7 × 10 −4 T, dBz/dx =1.4 × 10 −2 T/m for a positive gradient), l =5× 10 −2
m, ω =9.63 × 10 7 rad/s for the 2 → 6 transition and ω =1.93 × 10 8 rad/s for the 1 → 3
transition. The atomic beam velicity v =1.2 × 103 m/sec. The RF amplitude B1(x)
is a quadratic function of x with zero values at x =0andx = l; Bmax 1 = B1(l/2) =
(1 − 2) × 10−4 T.
The results of the computer calculations for an atom velocity of 1200 m/s give practically
100% probability of the transition.
4 Conclusion
Some aspects of developing a polarized helion source for JINR Accelerator Complex was
discussed. The possibility to get positive and negative values of the helion polarization by
using two types of the weak field transitions in the metastable helium-3 atom is shown.
References
[1] E.P. Antishev, A.S. Belov, Proc. of the 12 Int. Workshop on Polarized Ion Sources,
Targets and Polarimetry, PSTP2007, AIP Conf. Proc. V.980 (2008) 263.
[2] S. Oh, Nucl. Instr. & Meth. 82(1970) 189.
[3] J.P.M. Beijers, Nucl. Instr. & Meth. A536 (2005) 282.
[4] H. Hasuyama, Y. Wakuta, Nucl. Instr. & Meth. A260 (1987) 1.
[5] R. J. Slobodrian et al., Nucl. Instrum. & Meth. A244 (1986) 127.
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