1. JLab Doping Protocol Exploration
Towards High Q0 and High Eacc
Pashupati Dhakal
Friday, July 19, 2019

2. Earlier Results 1.5 GHz single-cell fine-grain Nb cavity (RRR>300)
N-infusion: 800 °C/3h, N2 at ~25 mTorr at 290°C, cooling to hold temperature maintained for 48 h
P. Dhakal et al., Phys. Rev. Accel. Beams. 21, (2018)

3. Baseline measurements after EP + 120 C normal (magic) bake
This Phase
Three cavities were selected RDT-06, RDTTD-02 and H2 (LG), all received 40 um EP on top of previous surface treatments.
Baseline measurements after EP
+ 120 C normal (magic) bake
+ 120 C bake with Nitrogen (after furnace control upgrade)

4. RDTTD-02

5. RDTTD-02
36 MV/m

6. RDT-06

7. RDT-06

8. Summary
Two cavities showed Eacc>35 MV/m with Q0>1010 .
~80 C hold for 4 hours during 120 C baking didn’t appear to be beneficial over the conventional 120C bake.
Path Forward:
High temperature furnace controls upgrade.
Complete the third cavity baseline measurements.
120C baking in nitrogen.

9. RDTTD-02 Baking cycle