1. Toward CDR: Plan & Perspective
Wednesday 18th July 2018
P. Abbon, F. Belloni, F. Benedetti, G. Coulloux, F. Gougnaud,
C. Lahonde-Hamdoun, P. Le Bourlout, Y. Mariette,
J. Marroncle, J.P. Mols, V. Nadot, L. Scola
C. Thomas (ESS project leader)
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Toward CDR - WM after Iphi Beam test

2. Toward CDR - WM after Iphi Beam test
IPHI test summary
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Toward CDR - WM after Iphi Beam test

3. Toward CDR - WM after Iphi Beam test
Optics: quite good results but poor skill in
pMCP
gain: no understanding of current behavior;
electron/ion: no profile measurement with electrons
ageing: no Led signal (λmin=325 nm; 3.3eV)  really poor efficiency expected anyway
polarization: Hamamatsu talk about substrate… in progress
IPM cage
Background: no efficient shielding (electrons)
Polarization: symmetric HVs have to be increased (at least ±10 kV  SC effect)
Strips + Faster
understand the signal shape (induction)  done
“trigger window” helps a lot, but only from April 9th to 12th, with good results
Faster: offset problems to measure signal efficiently and to forbid electron mode
Constant/Gaussian width  complementary profile/halo
HV trips
Test done in laboratory: no trip below 15 kV
material electric loading has to be inquired (air and vacuum with glass viewport to localize sparks or CCD camera to register)
Implementation of HV monitoring, to be tested
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Toward CDR - WM after Iphi Beam test

4. Toward CDR - WM after Iphi Beam test
FPM
Unfortunately, no signal due to low signal and high background
strips / optics: main features
Strips:
Reliability: if signal is strong enough, no need of MCP  no sensitive material in vacuum
 but, development of specific electronics and integration in EPICS will be long and expensive
Optics:
pMCP inside vacuum  less reliable
CCD camera: not radiation hard, may be counteracted with optical fiber bundle?…
 but, developments for numerous CCD camera have been already done (low investment)
Summary: comparison between strips and pMCP is not yet complete. We propose to inquire further with a new beam test at IPHI in September 2018.
18/07/2018
Toward CDR - WM after Iphi Beam test

5. 2nd IPHI tests Sept. 6th to Oct. 5th 2018 and before…
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Toward CDR - WM after Iphi Beam test

6. Toward CDR - WM after Iphi Beam test
pMCP
Ageing
The aside figure shows: light below 220 nm have less than 10-4 detection efficiency
Our Led  λmin > 320 nm
New proposition: software monitoring
Follow up the integral of the profile
Calibration wrt poorly hit cells (halo)  to be less insensitive to MCP ageing and gain fluctuations
This monitoring has be done with and without beam (beam off or integration gate shifted)
Uniformity response (thanks to J. Pancin, Ganil, private discussion)
During no beam period: feed MCP with a quite high HV  thermionic electrons are emitted, preferentially from damaged locations
 Both solution may exhibit a similar behavior
Provided by Hamamatsu
Other possibilities
Spark gap with low λ emission (<100nm), but requires low filter light (sapphire window) + space around  reproducibility?
Photodiode inside (AsGa) excited with visible light, but very low signal (+HV eventually)  outgassing, low efficiency
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Toward CDR - WM after Iphi Beam test

7. Toward CDR - WM after Iphi Beam test
IPHI tests
Test at Iphi (Bruno Pottin)
Installation in Iphi hall: week 35 (August 27th to 31st)
Week 36: power supply tests  hope to have time for beam tuning
4 weeks, 1 for each following topics
Emittance 4D (A. Dumancic),
NPM
“Artificial intelligence” (N. Chauvin),
BPMs for ESS Lund (ESS Bilbao)
No priority defined up to now, but 1 team leader during a week and user during remaining time
FPM: shielding pipe against bkgd  Cyrille & Thomas G.
Week leader: to work as low as possible for comparison to ESS and with the best beam conditioning
Ask to be leader during the last week which should be the one with the best beam tuning
Would be fine to have also X-profile tuning: welcome to FPM with low bkgd
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Toward CDR - WM after Iphi Beam test

8. Toward CDR - WM after Iphi Beam test
Test plan
Sparking effect
Increase the IPM cage HV in order to minimize the SC distortion at ESS
electron/ion
IPM cage polarization to work in both modes
 Improve the beam tuning, to reduce background
Electric field uniformity
Comsol results applied to IPHI test conditions show interesting behaviors  Florian
Check of the interferences between the 2 cages
Few measurements to confirm the electric field uniformity
Space Charge effect
Analysis has been done showing the measured beam size evolution with applied HV
Simulations are in progress to determine the SC contribution  Francesca
ESS extrapolation data
To be improved for both read-outs
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Toward CDR - WM after Iphi Beam test

9. Test beam: configuration
Not enough investigated during last beam test
Strip (constant and Gaussian shape) with, but also without MCP
without MCP for reliability test
pMCP: test of Photonis to compare with Hamamatsu
IPM measuring the dispersive (X) profile  to have a better control on beam tuning
Therefore, the foreseen installation should be:
IPM_1 (upstream)  Gaussian strips
X profile measurement to help tuning (at least at the beginning!)
May help also to sweep electron background for comparison with pMCP profile obtained on 2nd IPM
IPM_2 (middle)  Photonis pMCP
IPM_3 (downstream)  constant strips
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Toward CDR - WM after Iphi Beam test

10. Toward CDR - WM after Iphi Beam test
Future
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Toward CDR - WM after Iphi Beam test

11. High energy particle background
Background (no Linac4 since not ready), but James Storey et al. publication in IBIC2017 have seen transversal high energy particles
Rate evaluation but at CPS (Cern Proton Synchrotron – up to 25 GeV)  contact will be taken
Question: how to extrapolate synchrotron to ESS bkgd?  beam dynamics team?
Rate evaluation was asked to Mamad team beginning It is still in his program but not yet scheduled!
HV Off
HV On 1 10
100
J. Storey at al., IBIC 2017
J. Storey at al., IBIC 2017
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Toward CDR - WM after Iphi Beam test

12. Toward CDR - WM after Iphi Beam test
Material properties
Radiation hard
CCD camera  coherent optical fiber bundle
Strips  FEE (pre-amplifier) installed in the holders of the CM
Outgassing
Degraders  resistors (soldering) or serigraphy (300µA)
Validation outgassing  RGA
IPM support
Low density and strong  titanium (4.5g/cm3) for minimizing interaction with high particles background
discussion with Vacuum group tomorrow
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Toward CDR - WM after Iphi Beam test

13. Toward CDR - WM after Iphi Beam test
pMCP replacement
Hypothesis: read-out final choice is pMCP+optics+CCD
Reliability: pMCP is usually identified as the weakest point due to ageing effect and vacuum insertion
Proposition
First mounting: the entire assembly is inserted into the CF200 of the LWU
Survey can be done using the optic sight
To change the MCP: just remove the CF160 middle flange, using a N2 balloon for instance.
Before to change it, a new CF160 may be equipped in a clean room and stored in a N2 atmosphere.
Note: this system is identical for X and Y view; to switch X to Y, turn the CF160 by 180°!
pMCP storage pot: either vacuum, either N2
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Toward CDR - WM after Iphi Beam test

14. pMCP replacement: IPMY
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Toward CDR - WM after Iphi Beam test

15. pMCP replacement: IPMX
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Toward CDR - WM after Iphi Beam test

16. pMCP replacement: both IPM
IPMY: shifted wrt CF200 axis
180°
IPMX: shifted wrt CF200 axis
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Toward CDR - WM after Iphi Beam test

17. pMCP wrapping, sending & storing
Activities prior to send IPMs to Lund,
Component assembling in clean room
 Clean room class level?
IPM inserted in an airtight pot
If Strip selected  N2 or 10-2 mbar to stay clean?
If pMCP selected  10-3 mbar for storage and for test (N2 for transport)
A RGA measurement has to be done. What are the requirements in terms of outgassing molecules concentration?
Transport:
IPMs inserted in pots filled of N2
Once arrived at Lund:
Mounting of pipes and vanes provided by us,
Then, pumping to achieve the requested pressure
Remark: if strips are chosen, the flange will be simplier!
Scenarios and questions to be discussed tomorrow in detail with vacuum group
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Toward CDR - WM after Iphi Beam test

18. Toward CDR - WM after Iphi Beam test
storage
Pipes to connect all IPM pots through DN40 taps
pumping system in Saclay, and later on at ESS Lund
N2 filling
pumping system N2
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Toward CDR - WM after Iphi Beam test

19. Change request with Daresbury (1)
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Toward CDR - WM after Iphi Beam test

20. Change request with Daresbury (2)
Electric field uniformity & interferences
 Impose ground on both sides of IPMs
TOP view cross-section
SIDE view cross-section
IPMX: centered wrt CF200 axis
IPMY: shifted wrt CF200 axis
free space
for WS
grounded disks
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Toward CDR - WM after Iphi Beam test

21. Change request with Daresbury (3)
Contact NPM & Paul Aden: letter sent by Cyrille on November 22nd 2017
Proposition sent to Paul on April 16th If
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Toward CDR - WM after Iphi Beam test

22. we are here!