From svd_ml-request@bsunsrv1.kek.jp Thu Dec 9 16:39:45 1999 Received: from uhhepi.phys.hawaii.edu (uhhepi.phys.hawaii.edu [128.171.11.8]) by uhheph.phys.hawaii.edu (8.9.1a/8.9.1) with ESMTP id QAA23127 for ; Thu, 9 Dec 1999 16:39:44 -1000 (HST) Resent-From: svd_ml-request@bsunsrv1.kek.jp Received: from bsunsrv1.kek.jp (bsunsrv1.kek.jp [130.87.224.2]) by uhhepi.phys.hawaii.edu (8.9.1a/8.9.1) with ESMTP id QAA18692 for ; Thu, 9 Dec 1999 16:39:41 -1000 (HST) Received: (from list@localhost) by bsunsrv1.kek.jp (8.8.8/3.6Wbeta7) id LAA19335; Fri, 10 Dec 1999 11:35:46 +0900 (JST) Resent-Date: Fri, 10 Dec 1999 11:35:46 +0900 (JST) X-Authentication-Warning: bsunsrv1.kek.jp: list set sender to svd_ml-request@bsunsrv1.kek.jp using -f Old-Return-Path: tsuboy@kek.jp To: svd_ml@bsunsrv1.kek.jp Subject: Large doses in the beam study 2-8 December 1999 From: Toru Tsuboyama X-Mailer: Mew version 1.93 on Emacs 20.3 / Mule 4.0 (HANANOEN) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: <19991210113527T.tsuboy@kek.jp> Date: Fri, 10 Dec 1999 11:35:27 +0900 Sender: TSUBOYAMA Toru X-Dispatcher: imput version 980905(IM100) Lines: 36 Resent-Message-ID: <"N7k_53.0.xj4.wR6Ku"@bsunsrv1> X-Mailing-List: archive/latest/1412 X-Loop: svd_ml@bsunsrv1.kek.jp Precedence: list Resent-Sender: svd_ml-request@bsunsrv1.kek.jp Content-Transfer-Encoding: 7bit Status: RO X-Status: Dear colleagues, As D.Zonter showed in yesterday's SVD meeting, there were three moments with extremely high dose rate while the high-emittance run of KEKB was prepared. SVD has suffered radiation 0.2 to 0.4 krad, depending on the radfet position. Only F-90 sensor, which is put on Beryllium pipe, suffered 1.3 krad in a few minutes. The F-VA1 sensor which is placed at F-90 position, behind 300 um gold plates, suffered about 0.6 Krad. It seems that the 300 um gold, together with the slight larger distance from the beam center could reduce the radiation level by 1/3. 1) December 2 16:20 Since the injection to LER was poor, LER movable masks were fully opened. SVD issued beam abort at LER current of 4 mA. 2) December 5 17:20 Since the injection to LER was poor, LER movable masks were fully opened. SVD issued beam abort at LER current of 20 mA. 3) December 8 19:58 When vacuum leakage happened. Beam is aborted by SVD. Graphs were read out by eyes. Dec.2 Dec.5 Dec.8 Sensor 16:20 17:20 19:59 F 0 degrees on Be tube 0.6 0.3 0.4 F 90 degrees on Be tube 0.05 0.1 0.1 F 180 degrees on Be tube 0.05 0.1 0.05 F 90 degrees close to VA1 0.1 0.15 0.15 B 180 degrees on Be tube 0.05 0.1 0.1 ============================================================= Best regards, Toru (KEK)