ATLAS Intensity and Efficiency Upgrade ATLAS USERS MEETING Speaker: Mike Kelly Physics Division May 15, 2014

2 CARIBU 4. Split-ring cryomodules 109 MHz Energy Upgrade cryomodule The Present ATLAS Accelerator Cryomodules 8 Cryomodules, 47 SC Accelerating Cavities MHz RFQ PII Cryomodules MHz Module MHz Module

3 Clean Assembly (left) and Cryogenics Assembly (right) for ATLAS Intensity Upgrade Cryomodule (2013) Jan June 2013 Clean room assembly (south side of beamline) Assembly stand (north side of beamline)

Charged Particle Acceleration in a 2-gap Accelerating Cavity z 4 q

5 RF Surface: (Simplified) Niobium Surface, T c =9.2 Kelvin Superconductivity ~40 nm

Electropolishing System for Low-beta Cavities A unique ANL technical capability to electropolish cavities as the final step in fabrication 6

7 Subcomponents: RF Couplers 4 kW RF Power ATLAS 4 kW Couplers

Issue of Maintaining the Clean Vacuum Space (a.k.a. Protection from the ATLAS Users) 8  80 Kelvin ~1/2 meter long liquid nitrogen cooled cold traps installed at the entrance and exit for clean cryomodules  Volatiles, water, particulates adsorb to the surface of a 2.5” cm diameter copper tube  Gate valves at the entrance and exit of the cryomodule are interlocked to cold trap ion gauges  A fast acting valve (~10 mS) will isolate experimental areas from the accelerator in the event of a vacuum accident Cold trap Fast Valve RGA Cryomodule exit valve

The First Beam Delivered with the 72 MHz Intensity Upgrade Cryomodule 9 First beam to experiment 20 Ne 6+ on Feb. 18, 2014 (Ave. Cavity Voltage 2 MV/cavity, Ave. Power per Cavity 1.3 Watts) Also of note, all cavities stable with respect to quench with E ACC >12 MV/m, average value for field emission onset, E ACC ~9 MV/m (E PEAK ~45 MV/m)

Testing at Liquid Helium Temperatures: Q versus E (Most Commonly Used Figure of Merit) 10 Present Operations 2.5 MV/cavity

11 Context and Impact: SARAF Proton/Deuteron Accelerator In operation since 2009

12 Context and Impact: MSU Re-Accelerator (ReA3) C Planned for May 2014 In operation since 2011

13 Context and Impact: ISAC-II Heavy-ion Linac, 6 Cryomodules Commissioned

Peter Ostroumov – Accelerator R&D Leader Zachary Conway – Cryomodule assembly Michael Kelly – Clean assembly, cavity testing Scott Gerbick – Electropolishing design, up-to-air system Tom Reid – Chemistry operations Ryan Murphy – High-pressure rinsing, single-cavity assembly Mark Kedzie – Vacuum systems, cryomodule assembly Sang-hoon Kim – Alignment, diagnostics Gary Zinkann – SRF Cavity Testing Brahim Mustapha – Simulation support (e.g. cavity tuning) Sergey Kutsaev – Power simulations & qualification Also Acknowledge Efforts of Steve MacDonald – Cryogenics upgrade Sergey Sharmentov – New RF Control System Team for ANL SRF Cavity/Cryomodule Work 14