SksMinus status

Hyperball collaboration meeting

2009/3/11

K. Shirotori

Reaction analysis :K1.8 + SksMinus

-ray detection : Hyperball-J⇒Reaction- coincidence

J-PARC E13 experiment

Hypernuclear -ray spectroscopy experiments on several light nuclei(4

He, 7Li, 10

B, 11B, 19

F)

(K-, - ) reaction @ pK = 1.5 GeV/c

SksMinus setup

SksMinus elements Particle tracking : SDC1~4 Time-of-flight : STOF Reaction ID : BAC, SAC (n=1.03) Veto counters

SMF : - from K- → - + SP0 : - from K- → - + 0

Target : Li2O, Teflon ((CF2)n),

Boron(10,11B) (~10 cm, ~15 g/cm2)

Liquid 4He (25 cm, 3.13 g/cm2)

_

Requirements for - of ~1.4 GeV/c Acceptance >100 msr, ~20o scattering angles Momentum resolution < 3 MeV/c (FWHM)

1 m

SksMinus

Contents

• Detector status– Drift chambers– Timing counters– Veto counters– Others

• SksMinus system status– SKS magnet problem– Detector placement

• Summary

Drift chambers

Drift chambers for SksMinus

• SDC3&4 : BD chamber ×2– Large DC camber : 2 m×1 m (x,

x,u,u,v,v)

• SDC2 : Old SKS chamber– Repair in Tohoku

• SDC1 : New construction– Not completely finish

the design work

Drift chambers status• BD chambers are almost ready.– ~300 m (rms) position resolution– 99% efficiency at counting rate of 100 kHz (w/ 90Sr

source)⇒To design and product frame

• Broken wires of SDC2 are finished to be repaired.– Signal check and TDC data taking– Frame design

• SDC1 is under construction.– How about design ? Almost finished⇒– Frame confliction to Hyperball-J frame

Timing counters

Timing counters for SksMinus

• STOF : Using SKS TOF scintillation counter– 2 m×1 m TOF wall– Present 15 segments + new 17 segments– Bought by KEK fund

• BH2 : Time zero counter– ~1 MHz counting rate

⇒1 segment counter ?

Timing counters status• STOF– New segments : Need 34 PMTs (H1949)– PMT check Finished : 71 PMTs– Light guide is ordered.

⇒Counter assembly and frame design

• BH2– Scintillator : Available one– PMTs : Booster PMT (old SKS BH2 PMT)

Veto counters

Veto counters for SksMinus

• SP0 : K-→-0 event veto– T. Otani working

• SAC & BAC : (K-, -) trigger– Aerogel cherenkov counter– M. Sato working

• SMF : K-→- event veto– Counter assembly

– Iron shield

SAC and BACAerogel cherenkov counters for the (K-, -) reaction ID

– Radiator (Aerogel) are bought by Kyoto Univ. fund.– Fine mesh PMTs are bought by Osaka RCNP fund.

• BAC1&2 : Beam PID counter– 160×57×4 mm3 radiator– 2 fine mesh PMTs

• SAC1 : - detection counter– 334×80×4 mm3 radiator– 5 fine mesh PMTs

• SAC2 : Combinational beam veto Aerogel counter– K- beam veto by SFV– Forward scattered - saved by Aerogel cherenkov counter

We can assemble all detectors after PMTs are arrived.⇒All detectors will be tested in LNS experiment

SP0 statusCounter production– Plastic scintillation counter : E559 Range counter– 4 mm thickness lead plate : Arrived– Frame design final check

Proto-type production⇒

Result of test experiment– LNS experiment : Response to electromagnetic shower

compared with simulation⇒Detection efficiency : 78.6 ± 1.5%(sys.)– CYRIC experiment : Neutron detection efficiency⇒~0.3 % of non-mesonic weak decay events detected

Enough performance for E13 experiment

SMF statusCounter production– Plastic scintillation counter :

BT(2m 1.2m cutting)⇒– Light guide for 2 segments

readout– Frame design

Iron shield– Barrow from KEK (Request

for support)

⇒Need to design iron shield frame (after finished BD and STOF frame)

100 cm×50 cm×50 cm

100 cm×50 cm×20 cm

Block-A

Block-B

Others

Other components status• Targets – 4He target was ordered. : ~\4,000,000

– Li2O : Company was found.

– 10B and 11B : modified old target used in BNL-E930 for the beam profile at K1.8

– 19F : Teflon ((CF2)n) or BeF2

– CH2 : SksMinus calibration run (12C and p(K-, -)+)

+ Design of target stage with BAC and SAC

• He target assembly and test• He target cell production

Summary○ SDC3&4 : Repair finished Frame⇒○ SDC2 : Repair almost finished Frame⇒× SDC1 : Design

○ STOF : Design and construction (by KEK ?)○ BH2 : Construction (scintillator + booster PMT)

○ SAC&BAC : Construction○ SP0 : Design finalize construction⇒× SMF : Iron shield borrow, frame, scintillation

counter cutting

△ Targets : Helium target assembly and test

To do• SDC3&4 : Frame design• SDC2 : Test Frame design⇒• SDC1 : Design and test

• STOF : Frame design and counter assembling• BH2 : To find scintillator + booster PMT

• SAC&BAC : Preparation for the LNS test experiment• SP0 : Design finalize Proto-type construction⇒ ⇒• SMF : Scintillation counter cutting, Iron shield frame design After ⇒

finishing BD and STOF frame design

• Targets : Helium target assembly and test• Target stage : W/ SAC and BAC design

• Rotation arm for SksMinus position

SksMinus system status

SKS magnet problemSKS magnet coil broken !• One of the coil segment was broken and removed.

⇒ Coil turn became 5/6.

Effects• Maximum magnetic field strength : 2.7 T 2.5 T⇒• Change of the shape of magnetic field (Cannot be measured)

What did we do ?• Change the SksMinus geometry

– Incident beam angel– Target position and around target

• Magnetic field map : Calculated map is enough for E13 experiment.

Acceptance : 118 msr 115 msr⇒Momentum resolution : 2.1 MeV/c 2.4 MeV/c⇒

SksMinus system is almost OK. The change of magnetic field shape is still a significant problem.

Change of the rotation angleOld : -27° +17°⇒New : -27° +12°⇒

Just only changing the rotation angle from SksZero configuration to SksMinus configuration

SKS moving ー Old SksMinusー New SksMinus

Acceptance : latest one118 ms ⇔ 115 msr

○ : 395A before× : 395A after□ : New geom

Momentum resolution

○ : 395A before× : New geom

2.1 MeV/c (2.7 T) 2.4 MeV/c (2.5 T)⇒

SKS magnet and detector positionSKS magnet position : FF + 600 mm⇒Enough space for Hyperball-J(Not determined the Q-magnet design)

Upstream detectors• Need minor change of positions with the realistic

detector size• To design suitable frame

Downstream detectors• Frame design in progress• Iron shield for SMF