Dear Mayank,

this should be rather easy using the Bethe-Bloch formula. Here's a link to the review from the Particle Data Group:

http://pdg.lbl.gov/2015/reviews/rpp2015-rev-passage-particles-matter.pdf

Best regards,

Alexander

SRIM (Stopping and Range of Ions in Matter) employs an empirically calibrated ion-energy loss model and is relatively easy to use: http://www.srim.org/. One issue is that it's Windows only.

The LISE++ (http://lise.nscl.msu.edu/lise.html) Physical Calculator, described briefly here (http://www.euroschoolonexoticbeams.be/site/files/2013_10_ExoBeams13_OTarasov_LISE-PP.pdf) is an even easier to use tool.  It is Windows or Mac only, but the Windows version runs fine on Linux if you run it through Wine.

http://www.srim.org/

Thank you both for your kind suggestions. SRIM only calculated energy loss for monoenergetic charged particles. In my case, alpha particles are produced in the target due to (n,a) reaction. alpha will have energy distribution. Alpha will loose the fraction of its energy in the target. I need to reproduce the alpha particles spectrum from the measured one with silicon surface barrier detector like 

www.sciencedirect.com/science/article/pii/0168900295001468.