Sks Minus status 19 HB meeting 2009206 Contents

Sks. Minus status 19 HB meeting 2009/2/06 白鳥昂太郎

Contents Ø Trigger rate study n In particular, S trigger (子熊とりがー)

Trigger candidate of E 13 experiment Ø (K-, p-) reaction : True trigger (積極的に検出) l Hypernuclear production : AZ(K-, p-)ALZ l Quasi-free : n(K-, p-)L, n(K-, p-)S 0, p(K-, p-)S+ p. K=1. 5 Ge. V/cでは、これらすべての反応がSks. Minusのacceptanceに入る l その他色々 : N(K-, p-)Y+p, N(K-, p-)Y+N+p, A(K-, p-)A*+Y. . . p. K=1. 5 Ge. V/cでは、ほぼSks. Minusのacceptance外か l K- beam decay (vetoed by SMF, SP 0) Ø 2 -body: K-→m-+nmbar, p-+p 0 Ø 3 -body: K-→ p-+p 0, p-+p++p-, m-+nmbar+p 0, e-+nebar+p 0 l Bema through (vetoed by BAC, SAC) Ø K- →KØ p- →pØ pbar, e-, m-とか

Expected trigger number : 10 cm 7 Li target (20 cm effective region) l (K-, p-) reaction : True trigger W/o S n(K-, p-)L : ~600 /spill (quasi-free main) l n(K-, p-)S 0, p(K-, p-)S+ : ? ? l N(K-, p-)Y+p, N(K-, p-)Y+N+p. . . : Smaller cross section and almost out of Sks. Minus acceptance ⇒ 600+S trigger l l K- beam decay vetoed by SMF, SP 0 2 -body: K-→m-+nmbar : 1400 ⇒ ~200 /spill Ø K-→ p-+p 0 : 400 ⇒ ~100 /spill Ø 3 -body: K-→ p-+p 0, p-+p++p-, m-+nmbar+p 0, e-+nebar+p 0 : 80 ⇒~10 /spill ⇒ W/o veto : 1400+80=2880 /spill ⇒ W/ veto : 200+10=310 /spill Ø l Bema through vetoed by BAC, SAC Ø Ø Ø K- →K- : 500 k/spill× 0. 01= 50 /spill p- →p- : 200 k/spill× 0. 01= 20 /spill pbar, e-, m-とか: とりあえず無視 (m-はp- と似たような数勘定になるが) Total w/o Ge hit : (600) + (200 + 10) + (50 + 20) + S trigger = 980 /spill + S trigger (w/o Ge hit : (600) + (1400 + 80) + (50 + 20) + S trigger = 2550 /spill + S trigger) w/ Ge hit : Total/2 = ~500 /spill + S trigger/2 w/ Ge hit : Reaction/2 + decay/3 + no-beam = ~400 /spill + S trigger/2 How much S trigger ? Ge trigger is essential !

L生成cross section @ 1. 5 Ge. V/c Quasi-freeだと変わるが、とりあえずこれで計算 : 0. 3 mbくらい (q<15°) ⇒~600 /spill (500 k/spill beam, 20 cm 7 Li target) (Sks. Minusのacceptanceを考慮)

S生成cross section p(K-, p-)S+ deferential n(K-, p-)S 0 total

L, S生成cross section Total cross section l n(K-, p-)L : ~2. 2 mb (exp. ) l n(K-, p-)S 0 : ~0. 5 mb (exp. ) l p(K-, p-)S+ : ~1. 2 mb (exp. ) Deferential cross section l n(K-, p-)L : ~0. 3 mb (exp. ) @ p. K=1. 5 Ge. V/c, q<15° l p(K-, p-)S+ : ~0. 2 mb (exp. ) @ p. K=1. 43 Ge. V/c, q<18° ( cos(q) > 0. 95での平均とした) ⇒S生成trigger数はL生成と同程度として多めに見積もって みる

Expected trigger number : 10 cm 7 Li target (20 cm effective region) l (K , p ) reaction : True trigger n(K-, p-)L : ~600 /spill (quasi-free main) l n(K-, p-)S 0, p(K-, p-)S+ : ~600 /spill (quasi-free main) l N(K-, p-)Y+p, N(K-, p-)Y+N+p. . . : Smaller cross section and almost out of Sks. Minus acceptance ⇒ 600+600 = 1200 /spill l l K- beam decay vetoed by SMF, SP 0 2 -body: K-→m-+nmbar : 1400 ⇒ ~200 /spill Ø K-→ p-+p 0 : 400 ⇒ ~100 /spill Ø 3 -body: K-→ p-+p 0, p-+p++p-, m-+nmbar+p 0, e-+nebar+p 0 : 80 ⇒~10 /spill ⇒ W/o veto : 1400+80=2880 /spill ⇒ W/ veto : 200+10=310 /spill Ø l Bema through vetoed by BAC, SAC Ø Ø Ø K- →K- : 500 k/spill× 0. 01= 50 /spill p- →p- : 200 k/spill× 0. 01= 20 /spill pbar, e-, m-とか: とりあえず無視 (m-はp- と似たような数勘定になるが) Total w/o Ge hit : (600 + 600) + (200 + 10) + (50 + 20) = 1580 /spill (w/o Ge hit : (600 + 600) + (1400 + 80) + (50 + 20) = 3150 /spill) w/ Ge hit : Total/2 = ~800 /spill w/ Ge hit : Reaction/2 + decay/3 + no-beam = ~700 /spill Ge hitの見積もりに依るが、Trigger rateは現DAQではギリギリ ⇒ Ge triggerをGe×PWOか？

各targetでのtrigger

4 He L 反応を羅列 l True : 4 He(K-, p-)4 LHe ⇒ 4 LHeのdecay Ø g-decay : 4 LHe*→ 4 LHe+g Ø Weak decay : 4 LHe→ 4 He+p 0, 3 He+n+p 0, 3 He+p+pl Quasi-free production 4 He(K-, p-)3 He+L : L decay 4 He(K-, p-)3 He+S 0 : S 0 decay 4 He(K-, p-)3 H+S+ : S+ decay 3 H*, 3 He*, 4 He(K-, p-) 3 N+Y, 2 N+N+Y, N+N+N+Yは無視 Ø Ø 特殊な条件 Ø 物質量が小さい : n(K-, p-)L : ~80 /spill Ø Targetが長い ⇒Mainにはbeam decayが効く

Expected trigger number : 25 cm 4 He target (40 cm effective region) l (K-, p-) reaction : True trigger n(K-, p-)L : ~80 /spill (quasi-free main) l n(K-, p-)S 0, p(K-, p-)S+ : ~80 /spill (quasi-free main) l N(K-, p-)Y+p, N(K-, p-)Y+N+p. . . : Smaller cross section and almost out of Sks. Minus acceptance ⇒ 80+80 = 160 /spill l l K- beam decay vetoed by SMF, SP 0 2 -body: K-→m-+nmbar : 2800 ⇒ ~400 /spill Ø K-→ p-+p 0 : 800 ⇒ ~200 /spill Ø 3 -body: K-→ p-+p 0, p-+p++p-, m-+nmbar+p 0, e-+nebar+p 0 : 160 ⇒~20 /spill ⇒ W/o veto : 2800+160=3760 /spill ⇒ W/ veto : 400+20=620 /spill Ø l Bema through vetoed by BAC, SAC Ø Ø Ø K- →K- : 500 k/spill× 0. 01= 50 /spill p- →p- : 200 k/spill× 0. 01= 20 /spill pbar, e-, m-とか: とりあえず無視 (m-はp- と似たような数勘定になるが) Total w/o Ge hit : (80 + 80) + (400 + 20) + (50 + 20) = 850 /spill (w/o Ge hit : (80 + 80) + (1400 + 80) + (50 + 20) = ~4000 /spill) w/ Ge hit : Total/2 = ~450 /spill w/ Ge hit : Reaction/2 + decay/3 + no-beam = ~300 /spill Decay vetoで大幅にtrigger rateを減らせる

Summary l S reaction triggerはLと同程度 eventでtrigger数が決まる ⇒単純な(K, p) triggerとGe triggerでも問題なし 7 Li, 10 B, 11 B, 19 F (+ 12 C, 16 O)実験ではGe triggerを l L L L 夫しないと若干厳しい l l l 4 LHe実験はdecay 1 k /spill程度のtrigger rateならば、安直に早いADC, TDCモジュールの導入が理想的 将来的に 10 M/spillのintensityが出たときにどうするか？ Ø 800 /spill (@500 k/spill)⇒ 16000 /spill !

E 930 trigger condition l KPi = Kin×Piout : 1. 1 k/spill Ø Ø l KPinon-bias= Kin×Piout : 2. 4 k/spill Ø l Kin = 200 k/spill Piin = 70 k/spill W/o Forward veto 2 nd level trigger : Ge hit Ø Ø Ge OR (one of Ge detector has hit) Vetoed : Overflow of all ADC data ⇒KPi trigger was reduced to 28%. ⇒Trigger rate : 0. 31 k/spill

48 D 48 acceptance l 60 msr