How to open a page in a new tab using ImageButton OnClick Event ASP.Net

HI

I have 1 image button and Linkbutton in my page below is code:

 <asp:ImageButton ID="ImageButton2" runat="server" ImageUrl="~/image/editpro.png"
                                    CssClass="DMPIMG" OnClick="ImageButton2_Click" OnClientClick="return ValidateRange()" />

and Linkbutton:

 <asp:LinkButton ID="LinkproM" runat="server" CssClass="Links3" OnClick="LinkproM_Click"
 CausesValidation="false">مدیریت محصولات</asp:LinkButton>

I want when I click on imagebutton it open page in new window so I wrote below code:

  <script type="text/javascript">
        function ValidateRange() {

            document.forms[0].target = "_blank";
            return true;
        }
    </script>

and I want when I click on linkbutton it doesn't open new window...

here when I click on linkbutton it doesn't  open new window it is correct but when I click on imagebutton and it opens new window and back to page and click on linkbutton it open linkbutton in new window...

I want when I click on link button it doesn't open new window any way...

best regards

Neda