1. Negative ion sources and Be ionisation studies Tania de Melo Mendonca on behalf of the TISD team EN-STI-RBS

2. TISD activities 2015 2 Multi walled carbon nanotubes for 8 B production Multi walled carbon nanotubes for 8 B production Negative ion beams: Nb and ThO 2 Negative ion beams: Nb and ThO 2 New UO 2 batch characterization New UO 2 batch characterization LIEBE target – reported by Melanie Delonca LIEBE target – reported by Melanie Delonca n-TOF sample preparation: Be ionisation studies n-TOF sample preparation: Be ionisation studies Yield database – ongoing updates and upgrade Yield database – ongoing updates and upgrade Molecular beams Molecular beams The team in 2015

3. Negative ion source units at ISOLDE (PSB) Nb foils + Ir 5 Ce pellet UC x + LaB 6 pellet 3 M. Menna et al., Nucl. Instrum. Meth. B 266 (2008) 4391 T. Stora et al., To be published Bromine release fraction Disadvantages of LaB 6 pellet as ioniser: Small interaction area Easy poisoning of surface Sticking of reactive halogens on the Ta tube Improved lifetimes and operational temperatures with tubular ionisers

4. Nb+GdB 6 Target unit #535: Nb foils (25 µm thickness) + GdB 6 tube ioniser Mass markers: NaF+NaCl, KI+NaBr Cs dispenser (counterbalance of excess electrons) Deflector 4 Br and I efficiencies (measured at the offline separator): 17% Target at 1900C, Line at 1730C

5. Nb+GdB 6 : on-line results 5 Courtesy of M. Delonca Chlorine isotopes (oven@35A) Bromine isotopes (oven@35A)

6. ThO+GdB 6 6 Courtesy of M. Delonca Target unit #540: ThO + GdB 6 tube ioniser Mass markers: KI, Au Cs dispenser (counterbalance of excess electrons) Deflector Iodine efficiency measured at the offline: 10% Following Nb results, ion source temperature was limited – optimal temperature: 1250C Problems at start of the run attributed to coating of the ion source with Cs Recovery of radioactive beam for ion source at 1600C (target at 1900C) Cs dispenser heating (A) Ion source temperature (C) Proton current (µA) 87 Br Yield (ions/µC) 4516000.31.3x10 4 4516000.39.0x10 3 45160011.1x10 4 45168018.0x10 3 45177819.4x10 2 45160019.3x10 2 45160022.6x10 3 48160024.8x10 4

7. ThO+GdB 6 Alike Nb target yields could not be reproduced. Electron deflector not connected! 7 127 I on FC490 without deflection 127 I on FC490: effect of deflector voltage IsotopeYield (/µC) Yield UC+LaB 6 (/µC) 38 Cl8.6x10 2 1.6x10 5 40 Cl1.2x10 4 4.3x10 4 78 Br6x10 5 - 85 Br5.7x10 5 9.6x10 5 85 Br (target 1800C) 5.5x10 4 - 87 Br6.8x10 4 2.1x10 5 137 I2.7x10 4 1.3x10 5 138 I2.1x10 3 4.7x10 4 203 At6.3x10 3 - 204 At1.9x10 4 - 204 At (target 1800C) 8.6x10 3 - Yields after deflector optimization (target 2000C, line 1600C, Cs disp: 35 A, deflector 200V) Effect of deflector voltage on 85 Br yield

8. Summary of negative ion source runs Nb+GdB 6 Beam not constant over time for steady operating conditions Difficult control of yields with Cs dispenser heating Influence of ion source temperature unclear Yields for Cl and Br isotopes are in general lower than 2006 run Possible ion source surface poisoning (Cs dispenser) ThO+GdB 6 Beam not constant over time After connecting the deflector: Significant electron deflector influence on yields 85 Br and 40 Cl yields closer to 2005 run Tests foreseen in 2016 to confirm advantages of negative ion sources on halogens yields 8

9. Be ionisation studies Preparation of 7 Be samples for n-TOF, SARAF and ILL (1 GBq each) Be source from irradiated targets at PSI (100 GBq total) Previous sample preparation performed using laser ionisation (U. Koester et al., Nucl Instrum Meth B 204 (2003) 343) Alternative using VADIS tested at the offline separator Unit #552 test of different arrangements of ion source efficiency estimation: 1x10 -5 % Further tests include molecular formation 9 Current (A) Thank you for the attention! 9 Be