sksminus status 19
DESCRIPTION
SksMinus status 19. HB meeting 2009/2/06 白鳥昂太郎. Contents. Trigger rate study In particular , S trigger ( 子熊とりがー ). Trigger candidate of E13 experiment. (K - , p - ) reaction : True trigger ( 積極的に検出 ) Hypernuclear production : A Z(K - , p - ) A L Z - PowerPoint PPT PresentationTRANSCRIPT
SksMinusstatus
19
HB meeting2009/2/06
白鳥昂太郎
Contents Trigger rate study
In particular trigger ( 子熊とりがー )
Trigger candidate of E13 experiment (K-, )reaction : True trigger ( 積極的に検出 )
Hypernuclear production : AZ(K-, )AZ
Quasi-free : n(K-, )n(K-, )p(K-, )
pK=1.5 GeV/c では、これらすべての反応が SksMinus の acceptance に入る その他色々 : N(K-, )Y+N(K-, )Y+N+A(K-, )A*+Y
pK=1.5 GeV/c では、ほぼ SksMinus の acceptance 外か
K- beam decay (vetoed by SMF, SP0) 2-body: K-→-+
bar, -+0
3-body: K-→ -+0+0, -+++-, -+bar+0e-+e
bar+0
Bema through (vetoed by BAC, SAC) K- →K-
- →-
pbar, e-, - とか
Expected trigger number : 10 cm 7Li target (20 cm effective region) (K-, )reaction : True trigger
n(K-, )00 /spill (quasi-free main) n(K-, )p(K-, ) N(K-, )Y+N(K-, )Y+N+Smaller cross section and almost out of SksMinus acceptance
⇒ 600+ trigger
K- beam decay vetoed by SMF, SP0 2-body: K-→-+
bar : 1400 ~200 /spill⇒ K-→-+0 : 400 ~100 /spill⇒ 3-body: K-→ -+0+0, -+++-, -+
bar+0e-+ebar+0 : 80 ~10 /spill⇒
⇒ W/o veto : 1400+400+80=2880 /spill ⇒ W/ veto : 200+100+10=310 /spill
Bema through vetoed by BAC, SAC K- →K- : 500 k/spill×0.01×0.01= 50 /spill - →- : 200 k/spill×0.01×0.01= 20 /spill pbar, e-, - とか : とりあえず無視 (- は - と似たような数勘定になるが )
Total w/o Ge hit : (600) + (200 + 100 + 10) + (50 + 20) + trigger = 980 /spill + trigger(w/o Ge hit : (600) + (1400 + 400 + 80) + (50 + 20) + trigger = 2550 /spill + trigger)
w/ Ge hit : Total/2 = ~500 /spill + trigger/2w/ Ge hit : Reaction/2 + decay/3 + no-beam = ~400 /spill + trigger/2
How much trigger ? Ge trigger is essential !
W/o
Reaction trigger for Ge hitElementally process (quasi-free reaction) n(K-, )→p+- (64%),n+(36%) n(K-, )→(100%)⇒→p+- (64%),n+(36%) p(K-, )→p+0(52%),n+(48%)
1 - や 0→2, が Ge に hit⇒ おおよそ生成量と Hyperball-J acceptance で量が決まる
HBJ acceptance ~30% 程度 (target 内部等方生成 ),(0→2 は必ず Ge に hit, - は acceptance を hit とした ) の場合 : 0.3*0.64 + 0.36 = 0.55 の場合 : 0.3*0.48 + 0.52 = 0.66
⇒Reaction trigger/2 はおおよそ妥当 ( か ? E930 data⇒ の再現 )2. p や n で周辺物質に励起状態の原子核ができ、 を出す3. Quasi-free 反応で標的の原子核に励起状態ができ、それがやややを出す⇒ これらのプロセスでも Ge hit は増加する(1 は simulation 可能。 2,3 は難しい… )
生成 cross section
@ 1.5 GeV/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 (<15°)⇒~600 /spill (500 k/spill beam, 20 cm 7Li target)(SksMinus の acceptance を考慮 )
生成 cross sectionp(K-, )deferential n(K-, )total
生成 cross sectionTotal cross section n(K-, )~2.2 mb (exp.) n(K-, )~0.5 mb (exp.) p(K-, )~1.2 mb (exp.)
Deferential cross section n(K-, )~0.3 mb (exp.) @ pK=1.5 GeV/c, <15° p(K-, )~0.2 mb (exp.) @ pK=1.43 GeV/c, <18° ( c
os() > 0.95 での平均とした )
⇒ 生成 trigger 数は生成と同程度として多めに見積もってみる
Expected trigger number : 10 cm 7Li target (20 cm effective region) (K-, )reaction : True trigger
n(K-, )00 /spill (quasi-free main) n(K-, )p(K-, )00 /spill (quasi-free main)
N(K-, )Y+N(K-, )Y+N+Smaller cross section and almost out of SksMinus acceptance ⇒ 600+600 = 1200 /spill
K- beam decay vetoed by SMF, SP0 2-body: K-→-+
bar : 1400 ~200 /spill⇒ K-→-+0 : 400 ~100 /spill⇒ 3-body: K-→ -+0+0, -+++-, -+
bar+0e-+ebar+0 : 80 ~10 /spill⇒
⇒ W/o veto : 1400+400+80=2880 /spill ⇒ W/ veto : 200+100+10=310 /spill
Bema through vetoed by BAC, SAC K- →K- : 500 k/spill×0.01×0.01= 50 /spill - →- : 200 k/spill×0.01×0.01= 20 /spill pbar, e-, - とか : とりあえず無視 (- は - と似たような数勘定になるが )
Total w/o Ge hit : (600 + 600) + (200 + 100 + 10) + (50 + 20) = 1580 /spill(w/o Ge hit : (600 + 600) + (1400 + 400 + 80) + (50 + 20) = 3150 /spill)
w/ Ge hit : Total/2 = ~800 /spillw/ 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
4He
反応を羅列 True : 4He(K-, )4
He ⇒ 4He の decay
-decay : 4He*→4
He+ Weak decay : 4
He→4He+3He+n+3He+p+
Quasi-free production 4He(K-, )3He+decay 4He(K-, )3He+decay 4He(K-, )3H+decay 3H*, 3He*, 4He(K-, ) 3N+Y, 2N+N+Y, N+N+N+Y は無視
特殊な条件 物質量が小さい : n(K-, )~80 /spill Target が長い⇒Main には beam decay が効く
Expected trigger number : 25 cm 4He target (40 cm effective region)
(K-, )reaction : True trigger n(K-, )0 /spill (quasi-free main) n(K-, )p(K-, )0 /spill (quasi-free main)
N(K-, )Y+N(K-, )Y+N+Smaller cross section and almost out of SksMinus acceptance ⇒ 80+80 = 160 /spill
K- beam decay vetoed by SMF, SP0 2-body: K-→-+
bar : 2800 ~400 /spill⇒ K-→-+0 : 800 ~200 /spill⇒ 3-body: K-→ -+0+0, -+++-, -+
bar+0e-+ebar+0 : 160 ~20 /spill⇒
⇒ W/o veto : 2800+800+160=3760 /spill ⇒ W/ veto : 400+200+20=620 /spill
Bema through vetoed by BAC, SAC K- →K- : 500 k/spill×0.01×0.01= 50 /spill - →- : 200 k/spill×0.01×0.01= 20 /spill pbar, e-, - とか : とりあえず無視 (- は - と似たような数勘定になるが )
Total w/o Ge hit : (80 + 80) + (400 + 200 + 20) + (50 + 20) = 850 /spill(w/o Ge hit : (80 + 80) + (1400 + 400 + 80) + (50 + 20) = ~4000 /spill)
w/ Ge hit : Total/2 = ~450 /spillw/ Ge hit : Reaction/2 + decay/3 + no-beam = ~300 /spill
Decay veto で大幅に trigger rate を減らせる
7Li, 10
B, 11B, 19
F (+ 12C,
16O) どれも 10 cm の target 長なので reaction trigger が
main になる 標的の核子数が多く、励起状態からの粒子放出が増
えるので、 Ge が鳴る割合が増える 放出 ⇒ による Ge trigger 核子放出 ⇒ 周辺物質からの background
Ge trigger にも依るが、ｔ rigger rate は現 DAQ ではギリギリ ⇒ Ge trigger を Ge×PWO でどの程度まで改善できるか ?
Summary reaction trigger はと同程度 4
He 実験は decay event で trigger 数が決まる⇒ 単純な (K, ) trigger と Ge trigger でも問題なし 7
Li, 10B, 11
B, 19F (+ 12
C, 16O) 実験では Ge trigger を工夫しないと若干厳しい
1k /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？ 800 /spill (@500 k/spill) 16000 /spill !⇒
E930 trigger condition KPi = Kin×Piout : 1.1 k/spill
Kin = 200 k/spill Piin = 70 k/spill
KPinon-bias= Kin×Piout : 2.4 k/spill W/o Forward veto
2nd level trigger : Ge hit 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
48D48 acceptance 60 msr