Target mainly by T. Nakadaira, Y. Hayato, A.K.Ichikawa Here, I will report about the present status on target R&D.

Current main member around target Construction group leader T. Kobayashi Convener of target and horn system : A.K.Ichikawa Convener of target station : Y. Yamada Target design : T. Nakadaira et. al Target FEM calculation : Y. Hayato et. al Radiation damage study : Y. Hayato et. al International collaboration Horn, especially on 2 nd horn with E.Zimmerman and L.Bartoszek Target : start discussion with RAL

Thermal Stress J/gK degree Z R Temperature rise of the target due to the radiation w/ 1 pulse cal. w/ MARS 2.6MJ in 5  s Aluminum cannot withstand. Only low-Z material such as graphite or beryllium. Thermal stress 6.8 MPa (safety factor ~3 against fatigue strength)

Water cooling Water Temp. 25 o C Heat transfer rate 5kW/m 2 K confirmed by cooling test Flow rate 20 l/min

Case (container) Target (Graphite) Gap o C 2dpa -> -0.5% Effect of J-PARC  0.26dpa/year

Effect of irradiation on graphite Damage by neutron irradiation o C … Change of dimension +0.14% Thermal conductivity -98% o C … … Change of dimension % Thermal conductivity -75%

Coaxial cooling pipe : Ti or Graphite

Time evolution of temperature (assuming specific heat at constant pressure) 780 ℃ 660 ℃ ~430 ℃ ~620 ℃ 380 ℃ 25 ℃ ~80 ℃ Condition (example)  flow velocity 170m/s

Prototype design of Target system Prototype design for He cooling pipe is in progress. Entrance of He Exit of He graphite Target Graphite Cap Inner Pipe t=2.0mm Graphite or t=0.3mm Ti (Ti-6Al-4V) Outer Pipe t=0.3mm Ti-6Al-4V

baffle

Temperature rise with nominal beam 理想的なバッフル ターゲット外径 = バッフル内径 水冷の場合 配管 Al 0.8mm

Temperature rise with mis-directed beam

Baffle –other possibility-

One of the Concept of Horn support Rod for position measurement Adjusting bolt vertical alignment rods frame A (fixed) frame B (vertical motion) frame C (horizontal motion) xy-stage by S.Koike

Another Concept of Horn support ~4m ~1m ~1.5m くらい か 支持基準 支持基準を 100  m で 調整できれば、 ~1mm は達成でき る？

Other R&D items -Remote Maintenance- Side View Top View Disconnect Horn and it’s support structure including strip-lines. Is this realistic? Residual radiation level should be checked. Anyway, we need remotely connectable/dis-connectable cuppling For strip-lines and water pipes.

comments The target is a critical part of the project and the relation to the 1 st horn is rather complicated. I feel that careful discussion is necessary before the real collaboration on the target to make clear situation.

Supplement

Target Nu-TAC 以後の進展 Graphite の熱応力の再評価 (S. Ueda) 比熱の温度依存性の update & bug fix 等価応力 [MPa ] 安全率 東洋炭素 IG 東海カーボン G 等価応力 [MPa ] 安全率 安全率  ３ は満たされている。 東洋炭素 ISO-88 についても安全率を評価 等価応力 [MPa ] 引張強度 [MPa ] 安全 率 東洋炭素 ISO

内側配管の温度勾配 / 応力分布 Al 合金 (0.8mm 厚 ),Ti 合金 (0.3mm 厚 ) ~200 ℃ 動径方向応力 <10kPa 円周方向応力 < ２Ｍ Pa 軸方向応力 < ４Ｍ Pa 等価応力 < ３Ｍ Pa 安全率 横軸 : 0= 最内面 1= 最外面

Ｈｅ冷却管のプロトタイプの設計 He の流量、除熱能力を試験したい。 KEKB/Belle の衝突点チェンバー冷却用の He システムを使ったテストの検討中。 最大ゲージ圧 0.1MPa, He 流量 400 [l/min] カウンターホール への移設可 電源 : 200V15A 冷却水 10-50[l/min] 冷却配管を設計中 絶縁材の材質を検討中