Charge State Breeding for the. at TRIUMF

Transcription

1 CANADA S NATIONAL LABORATORY FOR PARTICLE AND NUCLEAR PHYSICS Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada Charge State Breeding for the Acceleration of Radioactive Ions at TRIUMF F. Ames, ISAC Science Forum, October 21, 2009 LABORATOIRE NATIONAL CANADIEN POUR LA RECHERCHE EN PHYSIQUE NUCLÉAIRE ET EN PHYSIQUE DES PARTICULES Propriété d un consortium d universités canadiennes, géré en co-entreprise à partir d une contribution administrée par le Conseil national de recherches Canada

2 Layout of the ISAC facility at TRIUMF F.Ames, October 21,2009 2

3 Charge state breeding at ISAC: Requirements: M/Q < 30 with additional stripping after first acceleration stage (150 kev/u) M/Q < (6)7 without additional stripping ion velocity: 2 kev/u transversal emittance: 30 π mm mrad Incoming beam: singly charged ions continuous beam typical emittance < 30 π mm 30 kev beam intensity: 1 > ions/sec F.Ames, October 21,2009 3

4 modified 14.5 GHz PHOENIX ECR ion source from Pantechnik 2 step deceleration for the injection of singly charged ions 2 step acceleration scheme + Einzel lens focusing for the extraction of the highly charged ions F.Ames, October 21,2009 4

5 charge breeder results from the test stand Measurements with ions from standard ISAC ion sources Element Mass Charge state with maximum efficiency (A/Q) Efficiency (%) rise time (90%) for charge state with maximum efficiency (ms) 1+ ion source Ar (5) ECR Kr (7) ECR Xe (7.6) ECR K (4.3) 2.1 surface Rb 85/ (6.5) surface Cs (6.7) surface + testsource emittance of Cs n+ measured < 20 π mm 15q kev F.Ames, October 21,2009 5

6 installation of the charge state breeder at ISAC F.Ames, October 21,2009 6

7 ion optical simulation for mass resolution after charge state breeding F.Ames, October 21,2009 7

8 urrent [A] c A/Q mass spectrum from residual gas ions out of the charge state breeder F.Ames, October 21,2009 8

9 na Cs + in background cur rrent [A] Cs Cs Cs 2 Cs 18+ Cs 17+ Cs 16+ Cs 15+ Cs A/Q charge bred Cs ions from test ion source F.Ames, October 21,2009 9

10 acceleration of charge bred 80 Rb November 11 measure γ radiation of 80 Rb 14+ after charge breeding ions per sec radioactive beam is accompanied by ~100 na 40 Ar 7+ inject beam into RFQ, accelerate to 150 A kev, drift through DTL, analyze energy with magnet γ measurement transmission for 40 Ar 7+ 33% measure γ radiation of 80 Rb 14+ after acceleration ions per sec (32%) γ spectrum after acceleration F.Ames, October 21,

11 efficiency [%] efficiency [%] charge state t deltav [V] charge state distribution of stable Cs from test ion source Efficiency for the production of Cs 17+ as function of the potential difference between the singly charged ion source and the charge breeder charge bred Cs ions from test ion source F.Ames, October 21,

12 charge bred radioactive ions efficiency [%] efficiency [%] charge state charge state charge state distribution of 124 Cs charge state distribution of 80 Rb T 1/2 = 30.8 s T 1/2 = 30 s Cs 1+ ions injected Rb 1+ ions injected Both isotopes have been produced in a tantalum target equipped with a surface ion source F.Ames, October 21,

13 transport of highly charged ions from teststand cross section for charge exchange at E=10-15 qkev: σ = ( q 1.01) cm transmission n theory 1e-7 T theory 3e-7 T theory 5e-7 T Cs res. gas transmission from CSB to RFQ (25 m) charge F.Ames, October 21,

14 Summary and Outlook charge breeding of stable ions mass to charge ratio A/q = 4.3 ( 39 K 9+ ) to A/q = 6.7 ( 133 Cs 20+ ) efficiency >3 % at test stand, 2 % on line, higher for noble gases breeding time x 100 ms charge breeding of radioactive ions test beam time November 2008 first acceleration of radioactive charge bred 80 Rb 14+ ions 1.4% efficiency for 124 Cs 20+ (A/q = 6.2) transport of highly charged ions vacuum in low energy beam line has to be improved plans for the future continue commissioning with radioactive ions from different elements further optimization of breeding efficiency and accelerator transmission at low A/q values (43% at A/q=5) injection of molecular ions into charge breeder beam purification F.Ames, October 21,