E Experimental Setup and Condition

Transcription

1 C2C Rome E Experimental Setup and Condition Tomofumi Maruta Graduate School of Science, Tohoku Univ

2 Table of Contents Kinematics Experimental setup HKS Detector HES Detector Design Resolution Data summary 2

3 Progress of Spectroscopic by (e,e K + HallC E (2000): 12!B Splitter + SOS + Enge Resolution : 750keV(FWHM) A proof of principle E !B 440h x 0.66µA 3

4 Progress of Spectroscopic by (e,e K + HallC E (2000): 12!B Splitter + SOS + Enge Resolution : 750keV(FWHM) A proof of principle E (2005): 7!He, 12!B, 28!Al Splitter + HKS + Enge Resolution : 400keV(FWHM) Yield : 10 x E Optimization of eʼ acceptance (Tilt method) Establish the techniques E !B 440h x 0.66µA Resolution x 2 Yield x 10 S/N ratio x 4 E !B 120h x 24µA Preliminary 3

5 Progress of Spectroscopic by (e,e K + HallC E (2000): 12!B Splitter + SOS + Enge Resolution : 750keV(FWHM) A proof of principle E (2005): 7!He, 12!B, 28!Al Splitter + HKS + Enge Resolution : 400keV(FWHM) Yield : 10 x E Optimization of eʼ acceptance (Tilt method) Establish the techniques E !B 440h x 0.66µA Resolution x 2 Yield x 10 S/N ratio x 4 E !B 120h x 24µA E (2009): 7!He, 9!Li, 10!Be, 52!V New Splitter + HKS + HES Tilt method Precise study in the wide mass region Preliminary 3

6 Kinematics of the E Experiment Electron beam Momentum: 2.34GeV/c Target nucleus Scattered electron Central momentum: 0.844GeV/c Angular acceptance: 3 9! "+p#!+k + 1.5GeV "* p Coincidence measurement M.Q.Tran et al. PLB445 (1998) 20 K + Central momentum: 1.2GeV/c Angular acceptance :

7 Kinematics of (e, e K + ) programs E E E Mainz E" (GeV) W (GeV) Q 2 (GeV/c) Ebeam (GeV) 4.02/3.78/ Peʼ (GeV/c) 1.8/1.57/ θeʼ (deg) PK+ (GeV/c) θk+ (deg) M.Q.Tran et al. PLB445 (1998) 20 "+p#!+k + Q 2 (GeV/c) 2 Mainz E (E05-115: virtual photon oriented e distribution) E E

8 Continuous Electron Beam Accelerator Facility Bird view of CEBAF North Linac South Linac Accelerator specification Duty factor : 100%! comparable hypernuclear yield[/h] to ($ +,K + ) reaction (100 x σ(e,eʼk) < σ($,k)) Injector HallA HallC Beam energy spread : < 7 x 10-5 Bunch energy spread (σ) < 3 x 10-5 Energy stability (σ) < 3 x 10-5! Achievable to good energy resolution of a few 100keV Beam size (rms): < 100μm Beam configuration 0.5ps bunch in every 2ns time 2ns Δt=0.5ps CEBAF is unique facility for (e, e K + ) hypernuclear spectroscopy except for Mainz 6

9 Beamline at Hall-C E01-011:!Post-chicane configuration E05-115:!Pre-chicane configuration Merit : Combine dumps in both photon and beam. Demerit : Huge background around post-chicane area due to beam halo. Merit : Cleanly transport the beam. Demerit : Photon dump is necessary inside the Hall. To dump Target HKS HKS 2009年12月21日月曜日 New Splitter HES To beam dump Target HKS CHAPTER Photon line Beam 24 Beam The HKS Enge spectrometer Splitter 2.3 Enge The E hypernuclear spectroscopy system is establi olution for the Λ hypernuclear spectroscopy. It consists of the Enge split pole magnet (Enge) and the High resolution The incident electron ( 1.8 GeV) interacted with a target Enge Photon dump 7

10 E setup HES Introduction of Large acceptance electron spectrometer. HES detector Higher electron beam energy acceptable than Enge. e HKS New splitter K + HKS detector 2.344GeV e beam Target 8

11 E Setup HKS New SPL To Photon dump Beam To beam dump HES 9

12 HKS Spectrometer KD KQ2 KQ1 QQD configuration Momentum acceptance : 1.2GeV/c ±12.5% Solid angle : 11msr!p/p : 2 x 10-4 Angle acceptance : 1 13 deg Rate capability : 1.5MHz HKS Solid Angle Solid Angle (msr) Kaon Momentum (GeV/c) 10

13 HKS Detectors (Cherenkov Counters) HKS-D KDC1 KTF1Y KDC2 KTF2X KLC Singles Rate $ + 25 khz K + p 0.2 khz 16 khz Max. DAQ rate 2kHz 30μA, 12 C 100mg/cm 2 Based on E KTF1X KAC KWC KAC1/2/3 7-seg. Aerogel cherenkov Effective area 46 H x 169 W x 31 T (cm 3 ) Index KWC1/2 12-seg. Water cherenkov Effective area 35 H x W x 8 T (cm 3 ) Index 1.33 KLC 13-seg. Lucite cherenkov Effective area 42 H x W x 2 T (cm 3 ) Index 1.49 New New Cherenkov counters are for $/p rejection >99.9% $ rejection by AC >99.9% p rejection by WC AC WC LC $ + K + p Ncherenkov 1-1/(%n) 2 11

14 HKS Detectors (TOF Counters, DCs) KDC1 KDC2 KTF1Y KTF2X HKS-D KLC KTF1X KAC KWC KDC1/2 Planner drift chamber Effective area 30 H x 105 W x 3.5 T (cm 3 ) Layer config 6 (xxʼ, uuʼ, vvʼ) KTF1X 17-seg. plastic scinti Effective area 30 H x 125 W x 2 T (cm 3 ) KTF1Y 9-seg. plastic scinti Effective area 27.5 H x 125 W x 2 T (cm 3 ) KTF2X 18-seg. plastic scinti. Effective area 35 H x 170 W x 2 T (cm 3 )! TOF resolution of σ=75ps is required for $ + /K + 4σ separation! flight length 1.5m (KTF1X - 2X)! 1.35GeV/c $ + /K + ΔTOF = 300ps! σ=77ps achieved at test experiment at KEK-T1 12

15 HES Spectrometer ED QQD configuration Momentum acceptance : 0.844GeV/c±17% Solid angle : 7msr Angle acceptance : 3 9 deg δp/p : 2 x 10-4 (FWHM) Rate capability : 5MHz HES Solid Angle Solid Angle (msr) EQ2 EQ e Momentum (GeV/c) 13

16 HES detector package EDC1 Honeycomb, used in 2nd EDC2 EDC1 Effective area 12 H x 100 W x 32 T (cm 3 ) Layer config 10 (xxʼ, uuʼ, xxʼ, vvʼ, xxʼ) EDC2 Planner drift chamber Effective area 30 H x 105 W x 3.5 T (cm 3 ) Layer config 6 (xxʼ, uuʼ, vvʼ) EHOD1/2 29 seg. plastic scinti. e EHOD1 HES-D Effective area 30 H x 117 W x 1 T (cm 3 ) EHOD1 EDC1 EHOD1 EHOD2 EDC2 14

17 Momentum Correlation Momentum acceptance between K+ and eʼ are HES Pe '[ GeV / c ] decided! distribution to be diagonal. 1.1 E Pe ' vs PK Beam energy GeV ΛV Σ Λ g.s PK [ GeV / c ] HKS 350 Figure 5: Momentum correlation between kaon arm and electron arm for hyperons and hypernuclei production 2009年12月21日月曜日 reaction. 15

18 Tilt Method Optimization of Scattered electron acceptance Beam Energy : 1.8"2.34GeV Background electrons go more forward Beam current # S/N ratio # Brand-new e spectrometer, HES Enlarge acceptance # Virtual Photon Yield # EQ2 EQ1 signal Splitter y (mrad) yʼ (mrad) ENGE acceptance x (mrad) Red: Signal Green: B.G. Blue : B.G. E E background xʼ (mrad) 16

19 Tilt Method Optimization of Scattered electron acceptance Beam Energy : 1.8"2.34GeV Background electrons go more forward Beam current # S/N ratio # Brand-new e spectrometer, HES Enlarge acceptance # Virtual Photon Yield # EQ2 EQ1 signal Splitter 6.5 y (mrad) yʼ (mrad) ENGE acceptance x (mrad) Red: Signal Green: B.G. Blue : B.G. E E background xʼ (mrad) 16

20 Design Energy Resolution Target 7 Li 10 B 12 C 52 Cr HKS momentum (kev) HKS angle (kev) HES momentum (kev) HES angle (kev) Beam energy (kev) 160 Target (100mg/cm 2 ) Overall (kev)

21 Parameters of JLab (e, e K + ) programs Configuration E E E E SOS+ENGE +Splitter HRS+HRS +Septum HKS+ENGE +Splitter HKS+HES +New Splitter Beam intensity (μa) Target thickness (mg/cm 2 ) Hypernuclear yield ( 12!B g.s.) ( 16) ( 40) Resolution (kev) ( 3 400) Beam energy(gev) pk (GeV/c) peʼ (GeV/c) θk (deg) θeʼ (deg) ( ): Expectation 18

22 Data summary Beamtime: Aug./21 st Nov./2 nd /2009 Target Hypernucleus Thickness (mg/cm 2 ) Average beam current (ua) Total Charge (Coulomb) CH2 Water! & ! & Li 7! He Be 9! Li B 10! Be C 12! B Cr 52! V

23 Collaboration Pictures 20