1. CATHI and the HIE-ISOLDE Design Study
Richard Catherall
ISOLDE Technical Coordinator
ISOLDE Users Workshop
15th – 17th December 2014

2. CATHI: Cryogenics, Accelerators and Targets for HIE-ISOLDE
A European funded Initial Training Network Program
20 Marie Curie Fellows
A project within a project
Design Study
Address the issues associated with an increase in p-beam intensity and energy
Investigate upgrades for an improvement in beam quality
HIE-ISOLDE PROJECT
High Energy Upgrade
Design Study
CATHI

3. Who was doing what? Marie Curie Fellow Michal Czapski Pol
Target material developments
Mathieu Augustin
Fra
HRS layout and magnet design, Off-line 2
Carla Babcock
Can
RFQ Cooler
Jacobo Montano
Ven
Target and Frontend Developments. Off-line 2
Serena Cimmino
Ita
Target design
Mario Hermann
Ger
Vacuum: RFQ Cooler, Dry pumps, Fast gate valves
Andrea Polato
Ventilation
Andrej Shornikov (ER)
Rus
EBIS upgrade
Leonel Morejon
Cub
Fluka Calculations
Martino Colciago
HRS Magnet controls
Martin Breitenfeld
HRS magnet design and MRTOF
Maddalena Maietta
Radioisotope propagation
Roger Barlow
Eng
HT modulator
Valentina Venturi
Beam dumps

4. Outline Infrastructure Targets and FE Beam quality Baseline Parameters
Beam dumps
Shielding
Vacuum
Ventilation
Targets and FE
Target materials
Target design
Frontend
Off-line separator
Beam quality
New RFQ Cooler
MR-TOF for ISOLDE
HRS Separator
Magnet Design and layout
EBIS electron gun

5. Base line parameters Linac 4 Booster RF upgrade
Protons/pulse
Intensity
(µA)
Energy
(GeV)
Cycle
(s)
Power
(kW)
3.3x1013
2.2
1.4
1.2
3.1
1x1014
6.7
9.3
2.0
13.3
Linac 4
Linac 4 will be able to provide 5 x 1013 ppp = 1.25 x 1013/ring
Based on 40mA from the ion source
Could possibly go beyond this value with a combination of different options
Increase in source current output
An increase in pulse length
Chopping factor
All need to be in place for testing
Booster RF upgrade
CO2/CO4 upgrade would limit protons to 1.4 x 1013/ring
Could be increased with a power amplifier upgrade after LS2
Finemet upgrade (+MOSFET amplifiers) = 2.5x1013/ring
Depends on the upgrade solution chosen
Protons/pulse
Intensity
(µA)
Energy
(GeV)
Cycle
(s)
Power
(kW)
5.0x1013
3.33
1.4
1.2
4.67
6.4x1013
4.3
6.0
1x1014
6.7
2.0
13.3

6. Beam dumps Estimations made for different heat transfer coefficients
New design based on PSB design
Valentina Venturi

7. Shielding and activation
Figure 5 : Views from the target storage geometry. Top 2D (left) and top 3D (right).
Figure 9 : Dose in µSv/h on target storage and surrounding areas. 108 stored targets situated in shelves next to opposite walls inside the storage as shown. View from top.
Simulations and Design of further shielding
Simulations for the implementation of extended target storage within the same building
Leonel Morejon

8. Dry-pump stand and test
Substitution of normal, oil sealed pumps with dry pumps and pre-filtering before storage
Primary pumping is assured by oil-sealed, rotary vane pumps. The oil efficiently traps radioactive contaminants, preventing migration past the primary pumps and into the gas recuperation system. However, we need to perform the maintenance of the primary pumps once every second year. This operation is dictated by the need to assure an efficient mechanical operation of the pump. The activity exposes the personnel to contamination by spill-out of oil and by vapour. Moreover, with 13 primary pumps operating on the vacuum of the machine, it generates approximately 70 liters of contaminated oil, which must then be stored safely in areas dedicated to radioactive waste.
We tried to implement a new scheme, where the pumps are dry and require much less maintenance, while the filtering is assured by solid absorbants in cascade. We installed a multi-roots primary pump of the last generation (Alcatel ACP28) in parallel to our normal rotary vane pump and operated it on one of the most contaminating targets, uranium carbide. Downstream to the pump, we installed two filters: one molecular sieve, 5 Angstrom, for water vapour and light molecules and one wide spectrum, active charcoal filter. Gas pumped by the primary pump is conveyed through the filters to a gas storage tank. Spectroscopy on filters in still ongoing, but it shows that the filters effectively block contamination.
Selective filtering between primary pump and dummy gas storage
Spectroscopy on filters in progress
M. Hermann, G. Vandoni

9. Ventilation NOT FEASABLE Andrea Polato Purpose of the airlocks:
Create a volume between Tunnel and Class A Laboratory in such a way to:
Avoid activated air backflows from the Tunnel to the Class A Laboratory;
Prevent the Class A Laboratory evacuation in case of Tunnel ventilation stop (and vice versa);
Enhance a more flexible pressure regulation in the two buildings;
Increase the leaktightness of the structure
Ventilation separation in progress
NOT FEASABLE
Andrea Polato

10. Progress on Infrastructure
Supplementary shielding has already been installed…mainly to reduce radiation levels in neighbouring MEDICIS lab.
Validation and implementation of extra storage will eliminate the need for unnecessary transport in the long term.
Ventilation modifications are already in progress and will contribute to a reduction in activated air release as from next year.
Still awaiting results on spectroscopy of filters from the dry pump tests.
Beam dumps are a critical item for any increase in intensity and energy and should be upgraded during LS2

11. Outline Infrastructure Targets and FE Beam quality Baseline Parameters
Beam dumps
Shielding
Vacuum
Ventilation
Targets and FE
Target materials
Target design
Frontend
Off-line separator
Beam quality
New RFQ Cooler
MR-TOF for ISOLDE
HRS Separator
Magnet Design and layout
EBIS electron gun

12. Study of prototype refractory ceramics (SiC and Al­2O3­­) with open unidirectional porosity
. The calculated thermal shock resistance is enough to survive the impact of the ISOLDE beam for all the prototypes but only S-SiC samples show enough strength to survive the impact of the HIE-ISOLDE beam. The post-irradiation study of the prototypes irradiated at RaBIT demonstrated that most of the pellets were fractured, however the fracture cause can be due to the RaBIT setup itself. The SEM analysis showed no evident evolution of S-SiC samples structure. On the other hand R-SiC samples showed presence of little grains which are probably due to the crushing impact of the beam.
Michal Czapski

13. Uncouple container and heating functions
Graphite insulation
Graphite heater
Utilization of graphite pieces
Reduction of Tantalum weight 50%
=> nuclear waste reduction
Graphite rigid connectors
Graphite flexible connectors
Ta container
Serena Cimmino

14. Prototype
Thermocouple
Insertion of a thermocouple between the heater and the container
=> Direct Temperature measurement (without calibration)
Serena Cimmino

15. Two stage extraction
Few geometrical parameters are studied in order to find an optimum electrode design:
Aperture
Acceleration gap
Tip shape
For determining the optimum intermediate electrode configuration:
Thermal tests and simulations with ion
HV insulation tests up to 5kV with respect the ion source
Extraction efficiency measurements
Ionized air conductivity measurements
Acceleration gap pressure measurements
60 kV
57 kV
Ground
Jacobo Montano

16. Two stage extraction Thermal characterization
Jacobo Montano

17. 3. A new modulator concept
Charge pump modulator
3. A new modulator concept
1) In this circuit a 400 nF buffer capacitor (C1) and the target capacitance (C2) are charged to 60 kV by a low power, high precision d.c. power supply (HVPS)
2) Immediately prior to beam impact the HVPS is disconnected from the target and the buffer capacitor using a 90 kV rated semiconductor switch (HV_Switch1). During beam impact the target capacitance is rapidly discharged to 54 kV. Then the buffer capacitor begins to re-establish voltage on the target to 99,4% of its initial value.
3) After 1 ms a feedback loop controlling an auxiliary high voltage amplifier is switch on and increases the buffer capacitor potential. This additional voltage brings the target voltage back to the required +/- 0.6 V tolerance within 5 ms.
4) Finally, when the target has recovered to a sufficient high impedance, the feedback loop is opened and the HVPS is re-connected to the target to maintain the stable 60 kV voltage.
Advantages
Modulation recovery time adjustable
Requires a single low current high precision power supply (High power supply not necessary)
A single HV switch is required (compared to C modulator which uses 3)
Roger Barlow

18. Assembly / Tank housing
Charge pump modulator
Assembly / Tank housing
Custom built tank enclosure
Tank is filled with dielectric oil
Has a second ‘skin’ for oil leak protection
Contains the modulator system, buffer capacitor bank, HV precision divider, static and dynamic load
Essex HV connector
Viewing window
Oil temp gauge
Pressure sensor
Oil filter
Filler cap
polyester or polypropylene film and capacitor paper and are impregnated and filled with a mineral oil
Capacitor bank
0.05uF 75kVdc (hivoltcapacitors)
1800mm
Tank housing
75kVdc high precision divider
VD75-20Y-BDSC-KC-BEA/PB/F (RossEngineering)
Roger Barlow
EAPPC2014: A charge-pump 60kV modulator for the ISOLDE target extraction voltage , R. A. Barlow1, B. Bleus1, A. Fowler*1, H. Gaudillet1, T. Gharsa1, J. Schipper1

19. Off-Line separator 2 Built and operated in B.275 earlier this year
Now being moved to B.3
To be used for FE modification tests, beam optics for RFQ Cooler, new magnet design tests…
Can also be used for target production/prototype testing
M. Augustin, J. Montano

20. Progress on target and FE
Post-irradiation analyses is required of the remaining irradiated samples
Graphite heat shields need to be tested further but show promising results already
Step in the right direction uniform heat distribution and for waste treatment
Further testing required for the two-stage extraction
However any modifications incur:
Modifications of the FE’s (LS2 during their replacement?)
Amendments to the target production contract
Modifications to OL separators and production protocol
HT modulator design looks promising. Implementation could be in 2016/2017
Note that new HT power supplies (compatible with the modulator design) will be delivered in October 2015

21. Outline Infrastructure Targets and FE Beam quality Baseline Parameters
Beam dumps
Shielding
Vacuum
Ventilation
Targets and FE
Target materials
Target design
Frontend
Off-line separator
Beam quality
New RFQ Cooler
MR-TOF for ISOLDE
HRS Separator
Magnet Design and layout
EBIS electron gun

22. RFQ Cooler Alignment Pressure monitoring
Internal and external alignment possibilities and done externally
Pressure monitoring
Possibility to measure gas pressure inside the electrodes
Modification of conductance
Mechanical and electrical design
Investigating mechanical support to maintain electrodes in place
Improved wiring and insulation to avoid short-circuits
Laser pumping
Modification of apertures to allow lasers to interact with ions in the bunched region
Carla Babcock

23. MR-TOF for ISOLDE Martin Breitenfeld
Can it replace a magnetic separator?
Surely not with state of the art, too small current:
1000 ions per cycle (~4ms for RFWHM=20000)
3e5 ions per 1.2s, but usually a huge fraction is contamination!
But the performance could be improved:
Higher energy inside the MR-ToF
Bigger device to reduce density
Investigations are still ongoing to improve throughput
Ion-beam composition analysis
direct feedback for target/line optimization
sampling of release curve possible
single ion sensitivity to detect lowest yields
no upper limit on half-life as with decay station
not hindered by decay branching ratio
Martin Breitenfeld

24. HRS Separator Layout
Beam emittance ε=3π.mm.mrad R = for more than 99% transmission of pure beam R ~ for 90% transmission of pure beam
Mathieu Augustin

25. New Magnet Design
Schematic view in cross section of the new HRS magnet (H-type), and partial view in 3D, featuring the pole face windings technology (picture credit to M. Breitenfeldt)
H type magnet, mechanically more stable, possibility of better pole face machining
Yoke made of laminated steel  reduction of eddy currents, allowing an increase in cycling speed (~1min VS 15min)
Poleface windings allow the adjustment of the magnetic field along the beam axis.
Martin Breitenfeld, Mathieu Augustin

26. Beam Quality Summary The new RFQ Cooler is (almost) built
To be coupled to the Off-Line 2 for testing and characterization with beam
MR-TOF is a promising tool for both experiments requiring high resolution and target characterization
Already discussed in the ISCC but WG required to further pursue design and integration
Could well be an out-of-beam device
HRS: A long way from being implemented
New magnet design looks very promising
Would like to see a 90 deg “compact version” built and tested on Off-line 2 as a pre-requisite to any further decisions
REXEBIS developments should be strongly encouraged
For HIE-ISOLDE and for possibly the TSR.

27. CATHI Final Review Held on 22nd to 26th September in Barcelona
Wrap-up of all the HIE-ISOLDE – CATHI activities
The CATHI Fellows have made excellent contributions to the HIE-ISOLDE project
They will be missed!

28. Spare Slides

29. Target simulations
The use of borated polyethelyne to reduce activation
Figure 11 : Views 3D of the target wrapped ina borated polyethylene box of cm thickness.
|Table 1 : Values of activity of the air for the cases when the target is at GPS and when it is at HRS. Wrapped and Unwrapped stand for the case when the target is not covered by the polyethylene and when it is respectively. The values are normalized to a proton (ppp: per primary particle)

30. The research leading to these results has received funding from the European Commission under the FP7-PEOPLE-2010-ITN project CATHI (Marie Curie Actions - ITN). Grant agreement no PITN-GA

31. Sampling and measurement of radioactive species
Use of a tape station to
analyze ACTIVITY and evaluate the TIME OF FLIGHT of different gas species (spectroscopy);
TEST the accuracy of Monte Carlo model (time dependent mode).
On-line Sampling :
Realized along the primary pumping system, with active carbon and cellulose filters installed downstream of the turbomolecular pumps;
Spectroscopy Analysis.
To test the simulation and compare it with reality, we will use 2 methods. On one side, we will collect at a tape station located at the main switch yard the arriving neutrals. This measurement is time-resolved. In addition, it is species-resolved via a beta-spectroscopy.
At the same time, we have installed filters along the vacuum system, downstream of each turbo-molecular pump. These filters, constructed according to the same principle as our absorbants for the dry pump study, consist in a stack of cellulose and active charcoal tissue, protected by a fine metal grid. We plan to remove the filters installed on the separator’s pumps and measure them with alpha-spectroscopy, and then compare the results with the transmission probabilities computed with Monte-Carlo.
Maddalena Maietta
M. Hermann, G. Vandoni

32. Cold Line Study… Additional 4th cooled finger assembled by EB welding
Cooled line screwed on it
Thermal contact by pressure
Actual design
Proposed design
=> This solution has still to be tested and validated by a prototype
Serena Cimmino

33. Two stage extraction Extraction optics
Particle tracking (second gap)
The low energy first extraction produces large beams. The second gap focalizes the beam
Jacobo Montano

34. 3. Charge pump modulator Hardware assembly Roger Barlow
C modulator topology / Charge pump topology (Reconfigurable prototype)
Design can support up to 3 (90kV) Belkhe switches
Structure all Vetronite
Static charge for ‘on-board’ testing
Compact design
HV supplies/Amplifier
Signal feedtroughs
HV switch
Diode
Hall effect
Static charge CT
Roger Barlow

35. ISOLDE Beam Dumps Option 2
Replace existing beam dumps
Advantages
Low dose rate for installation
Take advantage to improve shielding (see next slides)
Reduction in air activation through new design
Disadvantages
Removal, storage and replacement of ~3500m3 of earth, about half of which is activated.
Handling and storage of radioactive beam dump
Still require cooling and its associated disadvantages

36. ISOLDE Beam Dumps Option 1
Insert a PSB like water-cooled beam dump in front of existing beam dumps.
Advantages:
Cheaper option
Based on known design
“easier” access
Disadvantages
Implementation and maintenance of a cooling system
Activated water
Contribution to target area air activation and consequent release to atmosphere.
High dose rate for installation

37. Shielding
Further shielding required to attenuate dose rates observed during operation and under certain conditions:
2uA of p-beam on thick ISOLDE targets (>50gcm-2)
Identified by RP in CERN-DGS RP-SN
Impact of p-beam intensity and energy increase on radiation dose rates outside the CERN perimeter to be assessed
Can be combined with an upgrade of the ISOLDE beam dumps
Requires major excavation work of activated earth

38. Shielding

39. REX-EBIS: Electron Beam Ion Source for HIE-ISOLDE
Priorities and the goal setting
Design values for EBIS application ) / available now with REXEBIS
Electron energy [kV]
150 / 5
Electron current [A]
2-5 / 0.2
Electron current density [A/cm2]
1-2x104 / 100
New EBIS – High Energy Compression and Current (HEC2) EBIS
Main challenge – produce the high compression electron beam
Goal – have a reliable design of the HEC2 electron gun on earliest possible stage
Realization – in a joint effort with BNL, based on BNL design and infrastructure
(BNL Test-EBIS), funded and manned by CERN
See presentation by A. Shornikov