How Can I check if Page is single page of Custom Post Type in Wordpress

On the Homepage I have called the content of Custpm Post Type with Ajax with this code

jQuery(document).ready(function($){
   $.ajaxSetup({cache:false});
    $(".sector_item a").click(function(){
        var post_link = $(this).attr("href");
        $(".sector_item_content").html("<div class='load' style='position:relative;margin-top:50px;padding-bottom:50px;'><img src='<?php bloginfo("template_url"); ?>/images/ajax-loader.gif'></div>");
        $(".sector_item_content").load(post_link);
        return false;
    }); 
}); 

But In the single Page of this same Post Type I need to have another design with content so how I can detect the single page. I tried with Wordpess is_single() function but it doesnt work it displayed anyway in ajax.How Can I fix this?