Get instance of AuthenticationManager Manually

I'm trying to implement the below, but my authenticationManager instance throws the below exception and is not autowired. How do I get an instance of it from Spring manually? I'm not using a spring controller, I'm using a JSF request scoped bean. I get the below exception at runtime when the container tries to autowire the authenticationManager. The requestCache comes in fine. I don't understand why I have two instances...

config:

<authentication-manager>
        <authentication-provider user-service-ref="userManager">
                <password-encoder ref="passwordEncoder" />
        </authentication-provider>
    </authentication-manager>

Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: protected org.springframework.security.authentication.AuthenticationManager com.dc.web.actions.SignUpDetail.authenticationManager; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No unique bean of type [org.springframework.security.authentication.AuthenticationManager] is defined: expected single matching bean but found 2: [org.springframework.security.authentication.ProviderManager#0, org.springframework.security.authenticationManager] javax.faces.webapp.FacesServlet.service(FacesServlet.java:325)

@Controller
public class SignupController
{

    @Autowired
    RequestCache requestCache;

    @Autowired
    protected AuthenticationManager authenticationManager;

    @RequestMapping(value = "/account/signup/", method = RequestMethod.POST)
    public String createNewUser(@ModelAttribute("user") User user, BindingResult result,  HttpServletRequest request, HttpServletResponse response)
    {
        //After successfully Creating user
            authenticateUserAndSetSession(user, request);

        return "redirect:/home/";
    }

    private void authenticateUserAndSetSession(User user,
        HttpServletRequest request)
    {
        UsernamePasswordAuthenticationToken token = new UsernamePasswordAuthenticationToken(
                user.getUsername(), user.getPassword());

        // generate session i开发者_StackOverflow社区f one doesn't exist
        request.getSession();

        token.setDetails(new WebAuthenticationDetails(request));
        Authentication authenticatedUser = authenticationManager.authenticate(token);

        SecurityContextHolder.getContext().setAuthentication(authenticatedUser);
    }

}

First, provide an explicit bean name for your AuthenticationManager

<authentication-manager alias="authenticationManager">
   ...
</authentication-manager>

Second, use qualifier when auto-wiring:

@Autowired
@Qualifier("authenticationManager")
protected AuthenticationManager authenticationManager;