A search for deeplybound kaonic nuclear states by
A search for deeply-bound kaonic nuclear states by in-flight 3 He(K-, n) reaction at J-PARC S. Ajimura, G. Beer, H. Bhang, P. Buehler, L. Busso, M. Cargnelli, J. Chiba, S. Choi, C. Curceanu, D. Faso, H. Fujioka, T. Fukuda, Y. Fukuda, C. Guaraldo, T. Hanaki, R. S. Hayano, A. Hirtl, M. Iio, M. Iliescu, T. Ishikawa, S. Ishimoto, T. Ishiwatari, K. Itahashi, M. Iwasaki, P. Kienle, J. Marton, Y. Matsuda, Y. Mizoi, O. Morra, T. Nagae, H. Ohnishi, S. Okada, H. Outa, A. Sakaguchi, F. Sakuma, M. Sato, M. Sekimoto, D. Sirghi, F. Sirghi, S. Suzuki, T. Suzuki, H. Tatsuno, D. Tomono, A. Toyoda, E. Widmann, T. Yamazaki, H. Yim, and J. Zmeskal E 15 : Stage 2/Day-1 採択
KN interaction 2 p AR E D 1 s -8. 6 ke. V PRL 94(2005) 212302 X Kp M. Iwasaki et al. , PRL 78 (1997) 3067 1997 KEK-PS Kp. X (precision measurement of 2 p->1 s x-ray energy in Kaonic hydrogen atom ) G = 407 e. V DE = -323 e. V only Coulomb int. 2005 2 p->1 s x-ray in Kaonic hydrogen have been measured again at DAFNE @DEAR ; repulsive! These results are now understood as strong attractive force between K and N Evidence(? ) for existence of 1 s KN bound state! Now, lets assume L(1450) as a candidate of KN bound state
L(1405) to Kaonic nucleus Construct K-N potential to reproduce measurements Energy shift of 1 s state Kaonic hydrogen (results of Kp. X measurement) Mass of L(1405) (Strong attraction in I=0 KN system ) Extension to light nucleus: Prediction of Kaonic nucleus deep binding energy narrow width Y. Akaishi & T. Yamazaki, PRC 65 (2002) 044005.
Search for Kaonic nuclear bound state The situation is still controversial! OBELIX We need to answer the basic question, whether the deeply bound state really exists? Taken from OHP at Trento WS 2006 KEK E 548 Taken from OHP at Trento WS 2006 Phys. Rev. Lett. 94 212303 (2005) E 549 FINUDA GSI FOPI
A search for deeply bound kaonic nuclear states Goal for the new experiment n To answering the basic question : whether the deeply bound state really exists? n Direct production of K-pp clusters via 3 He(in-flight K-, n) reaction n K- 3 He Reaction ? ? ? K-pp cluster Decay neutron ss a m y g n cop i s s Mi ctros n o r e t p S eu n via
Possible K-pp decay modes 2370 Me. V K-pp fit region K -pp ? ? 2275 Me. V 2267 Me. V p+ S- p p- S+ p Phys. Rev. Lett. 94 , 212303 (2005) FINUDA K-pp B. E. = 115 Me. V L p decay mode p L p- 2131 Me. V S 0 p 2054 Me. V Lp cluster Dominant Decay mode = YN p S 0 p decay mode g p p- Invariant mass reconstruction L p
Experimental Principle • 3 He(K-, n) reaction 3 He K- Reaction Mode to decay charged particles L pp p K-pp cluster Decay neutron ss a m y g sin scop s i M ctro n o r e t Sp neu via This mode allows us to investigate K-pp bound state in both ss Missing mass spectroscopy a m t n n and o a i i t r c a u v r Invariant mass reconstruction In nst o c e r
Signals from K-pp and “Two nucleon absorption” forward neutron n 3 He(K-, n) K- 3 He K-pp formation neutron K-pp reaction cluster ~ 1. 3 Ge. V/c @ 1 Ge. V/c K- and B. E. = 100 Me. V n K- Two nucleon absorption 3 He reaction p (spectator) ~ 1. 5 Ge. V/c @ 1 Ge. V/c K- L neutron
Detector concept 3 He K- H reaction D C cluster t C CD K- K-pp ne g a M d oi n le So neutron. Decay Mode to decay charged particles L p pp Cylindrical Detector system Decay particle detector (Decay particle detector) around target region neutron Neutron TOF counter
Cylindrical Drift Chamber Basic concept ; • Cell structure has been chosen as Hexagonal • 15 readout layers AA’A UU’ VV’ AA’ UU’ VV’ AA • 1800 readout channels in total • He based chamber gas will be used (to reduce material budget) Garfield simulation done by Dr. F. Sakuma • Design work for CDC is in progress
Detector construction status Solenoid Magnet Constructed; 2006 March CDC prototype complete Trigger hodoscope (designed almost complete) Neutron Counter (ready for installation) 3 He target Under construction Cylindrical Drift Detector (design completed, under construction)
Expected signal; Theoretical calculation We are going to measure only this components ( L required in final state )
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