Is it possible to declare an array as readonly in c#?

is it possible to make one array readonly. such that set value to array will not be allowed.

here what i have tried with readonly keyword for declaring the array. Then i am checking if that array is readonly by using IsReadOnly property. but it never returns true.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace PrivateExposeConsoleApp
{
    class Program
    {
        private static readonly int[] arr = new int[3] { 1,2,3 };

        static void Main(string[] args)
        {
            // Create a read-only IList wrapper around the array.
            IList<int> myList = Array.AsReadOnly(arr);

            try
            {
                // Attempt to change a value of array through the wrapper. 
                arr[2] = 100;
                Console.WriteLine("Array Elements");
                foreach (int i in arr)
                {
                    Console.WriteLine("{0} - {1}", i + "->", i);
                }
                Console.WriteLine("---------------");
                Console.WriteLine("List Elements");
                foreach (int j in myList)
                {
                    Console.WriteLine("{0} - {1}", j + "->", j);
                }
                // Attempt to change a value of list through the wrapper. 
                myList[3] = 50;
            }
            catch (NotSupportedException e)
            {

                Console.WriteLine("{0} - {1}", e.GetType(), e.Message);
                Console.WriteLine();
            }



            //if (arr.IsReadOnly)
            //{
            //    Console.WriteLine("array is readonly");
            //}
            //else
            //{
            //    for (int i = 0; i < arr.Length; i++)
            //    {
            //        arr[i] = i + 1;
            //    }

            //    foreach (int i in arr)
            //    {
            //        Console.WriteLine(i);
            //    }
            //}

            Console.ReadKey();
        }
    }
}

Here see my commented parts. if i uncomment this my arr never becomes readonly. at the declaration i explicitily defined arr as readonly with the data as {1,2,3}. i don't want this value to be rewitten . it should be always 1,2,3 only.