How to rotate particle 2d based on the collision position

Godot Version

<stable 4.2>

Question

<How do you rotate particle 2d to be instantiated at opposite direction of collision position.

right now, hit effect somehow appears downward when bullet collided at up side.
and appears upward when bullet collided at down side. with this code:

func knock_back(source_position: Vector2) -> void:
	$HitEffect.restart()
	hit_effect.rotation = get_angle_to(source_position) + PI

ezgif-1-ea968dc910

I want to make hit effect to be appeared at upward when bullet collided at upper part, and downward when bullet collided at bottom