Spawning particles around x,y on a particular Z plan

SpawnStars.cs

using TouchScript.Gestures;
using UnityEngine;
using System.Collections;

public class SpawnSparkle : MonoBehaviour
{
    public Transform Container;
    public GameObject ParticlePrefab;
  
	[Range(0.0f, 100)]
	public float zPosition;
	
	[Range(0.0f, 500)]
	public float factor;

	
    private void Start()
    {
        GetComponent<PressGesture>().StateChanged += HandleStateChanged;
    }

    private void HandleStateChanged(object sender, TouchScript.Events.GestureStateChangeEventArgs e)
    {
        if (e.State == Gesture.GestureState.Recognized)
        {
            var gesture = sender as PressGesture;
            RaycastHit hit;
            gesture.GetTargetHitResult(out hit);
			
			      Vector3 camPos = Camera.main.transform.position;
    		    Ray ray = new Ray(camPos, hit.point - camPos);
			
					
            var particleSpark = (GameObject)Instantiate(ParticlePrefab, transform.localScale, Quaternion.identity);
			       particleSpark.transform.parent = Container.transform;
            particleSpark.name = "Sparkle-" + gesture.ActiveTouches[0].Id;
            particleSpark.transform.position = ray.GetPoint(zPosition);

        }
    }
}