Could some one please help me out with rendering this in arnold?

As you can see the points have colours.I coloured them according to the velocity, but i'm not sure how to render them in arnold. In my shader i dropped down a user data node, entered the Cd attribute, i also tried entering v, then into a colour ramp, then plugged that into the surface shader and then out but the particles just come out white.
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render_help.zip
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Hi,
I am sure that you might have figured this out already. if not,

the shader was assigned to Arnold/Default properties, instead of that you need to assign it to Render/Material.

thanks
Anoop