How to initialize an immutable array

[Sparsh Mittal]

I am making a program which accesses 1D array using for loop and 
then I am parallelizing this with foreach, TaskPool and parallel.

The array does not need to change, once initialized. However, the 
parallel version takes more time than serial version, which I 
think may be because compiler is trying to make sure that array 
is properly handled by different threads.

So, is there a way, an array can be made immutable and still 
initialized? Thanks a lot for your time.