如何使用c#在新选项卡中打开PDF文件

这里我有问题打开选定的PDF文件在浏览器的新选项卡。下面显示了我所做的代码。谁能帮我一下……请……

搜索按钮:

protected void Button1_Click(object sender, EventArgs e)
                {
                    ListBox1.Items.Clear();
                    string search = TextBox1.Text;
                    if (TextBox1.Text != "") 
                    {
                        string[] pdffiles = Directory.GetFiles(@"''192.168.5.10'fbar'REPORT'CLOTHO'H2'REPORT'","*"+ TextBox1.Text + "*.pdf", SearchOption.AllDirectories);
                        foreach (string file in pdffiles)
                        {
              ListBox1.Items.Add(new ListItem(Path.GetFileName(file), file));
                        }
                    }
                    else
                    {
    Response.Write("<script>alert('For this Wafer ID Report is Not Generated');</script>");
                    }
                }

PDF文件打开按钮:

            protected void Button2_Click(object sender, EventArgs e)
            {
                    try
                    {
                    string fileName = ListBox1.SelectedValue;
                    byte[] fileBytes = System.IO.File.ReadAllBytes(fileName);
                    WebClient User = new WebClient();
                    Byte[] FileBuffer = User.DownloadData(fileName);
                    if (FileBuffer != null)
                    {
             Response.ContentType = "application/pdf";
             Response.AddHeader("content-length", FileBuffer.Length.ToString());
             Response.BinaryWrite(FileBuffer);
                    }
                    }
                        catch(Exception ex)
                            {
         Response.Write("<script>alert('PDF File is not Selected');</script>");
                            }
                }
            }

Response.Write("<script>window.open('" + pdf_filepath + "','_blank')</script>");