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Manuscript Title: A program for calculating spectroscopic amplitudes for two-nucleon transfer reactions by projecting angular momentum.
Authors: T. Takemasa
Program title: SPECTO
Catalogue identifier: ACDX_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 36(1985)79
Programming language: Fortran.
Computer: FACOM M-380.
Operating system: IV/F4.
Program overlaid: yes
RAM: 118K words
Word size: 64
Peripherals: disc.
Keywords: Nuclear physics, Nilsson, Deformation, Onishi-yoshida method, Projection, Direct reaction, Bcs, Ground state, Amplitude spectroscopic, Adiabatic, Pairing, Rotational band, Two-nucleon transfer.
Classification: 17.11.

Nature of problem:
The program SPECTO calculates the spectroscopic amplitudes for two- nucleon transfer reactions on axially symmetric permanently deformed nuclei. The wave function is constructed by projecting a Nilsson and BCS wave function onto a definite angular momentum state. Nilsson states are obtained for any quadrupole, hexadecapole and sextupole deformations. The deformation difference between an initial nucleus and a final one is exactly taken into account in the calculation of the spectroscopic amplitude. Specto also calculates the spectroscopic amplitudes for the two-nucleon transfer reactions in the Bohr-Mottelson adiabatic hypothesis.

Solution method:
The single-particle Hamiltonian is diagonalized in solving the Nilsson wave functions and eigenvalues. The BCS equation is then solved with the strengths of the pairing force which are chosen to get fits with the experimental energy gap. The ground state (g.s.) rotational band members for initial and final nuclei are constructed by the projection method of Peierls and Yoccoz using the Nilsson and BCS intrinsic states. Using these wave functions, the spectroscopic amplitudes for the two- nucleon transfer reactions are evaluated by the Onishi-Yoshida formula.

Three major shells N are allowed for photon and neutron states and an allowable maximum shell is N=7. Mixing between major shells is not allowed. Protons and neutrons do not interact. The deformations are restricted to Y20, Y40, and Y60 shapes. The vanishing pairing force strength is not allowed. The states of initial and final nuclei are restricted to members of the g.s. rotational band in doubly even nuclei and the spin of the g.s. rotational band is permitted up to 8 h. The program permits one to calculate the spectroscopic amplitudes for thirty different transfer processes of two like nucleons between initial and final nuclear states.

Running time:
The test case requires 18 s to run on the FACOM M-380 computer at Kyushu University.