1. LIU Beam Wire Scanners: Status and plans for new SPS and PSB BWS
J.L. Sirvent
On Behalf of: R. Veness, F. Roncarolo, J.Emery, P. Andersson, W. Andreazza, D.Gudkov … and many others
BI/TB on uTCA, LIU wire-scanner results and AWAKE status
14/09/2017

2. Outline 1. The Pre-Series Beam Wire Scanners
2. Scanner studies on calibration bench
3. Performance with beam on parallel MDs.
3.1 SPS Prototype
3.2 PSB Prorotype
4. Plans for SPS and PSB BWS

3. BE-BI-PM Jose Luis Sirvent Blasco (jsirvent@cern.ch)
The Pre-Series Beam Wire Scanners
BE-BI-PM Jose Luis Sirvent Blasco

4. 1. The Pre-Series Beam Wire Scanners 1.1 Two different designs
SPS Type: Glass disk on opposite side of the motor Fibre optic on vacuum
PSB Type: Optimized design, compact structure on one side.
BE-BI-PM Jose Luis Sirvent Blasco

5. BE-BI-PM Jose Luis Sirvent Blasco (jsirvent@cern.ch)
Scanner studies on calibration bench
BE-BI-PM Jose Luis Sirvent Blasco

6. BE-BI-BL Jose Luis Sirvent Blasco (jsirvent@cern.ch)
2. BWS Calibration bench studies: 2.1 Scanner wire position accuracy and precision
BE-BI-BL Jose Luis Sirvent Blasco

7. 2. BWS Calibration bench studies: 2
2. BWS Calibration bench studies: 2.1 Scanner wire position accuracy and precision
Optical system to obtain practical angular-to-projected transformation.
Angular calibration of position sensors
Projection based on Scanner Mechanics:
Three parameters fit based on equation: 𝐶 𝑜 , 𝐹 𝑙 , 𝜃
Extracted residuals to determine: Precision & Accuracy
Precision: Systematic deviations , Accuracy: Random variations
𝑌= 𝐶 𝑜 − 𝐹 𝑙 cos 𝜋− 𝛼 𝑆𝑒𝑛𝑠𝑜𝑟 +𝜃
BE-BI-PM Jose Luis Sirvent Blasco

8. BE-BI-PM Jose Luis Sirvent Blasco (jsirvent@cern.ch)
2. BWS Calibration bench studies: 2.1 Scanner wire position accuracy and precision
Systematic oscillations at different speeds observed on fit residuals (very repetitive).
Different spatial frequency but similar temporal frequency (1-2 kHz). Natural vibrations?
Speed
8 m/s
20 m/s
Residuals Spread
5.5 um
11.5 um
Accuracy
10 um
Precision
2.5 um
6 um
* Operational fast BWS (PSB) show uncertainties ~100um
How this translates into BbB beam profile uncertainty?
Highly dependent on the beam measurement conditions (beam width & Speed)
𝑆𝑁𝑅 𝑥 = 𝜎 𝑏𝑒𝑎𝑚 𝜎 𝑖
𝜖 𝑆𝑡𝑎𝑡𝑖𝑠𝑡𝑖𝑐 𝑆𝑁𝑅 𝑥 , 𝑃𝑝𝑆 = 0.4 𝑆𝑁𝑅 𝑥 𝑃𝑝𝑆
*However other factors also contribute (amplitude statistics, SNRy)
BE-BI-PM Jose Luis Sirvent Blasco

9. BE-BI-PM Jose Luis Sirvent Blasco (jsirvent@cern.ch)
Performance with beam on parallel MDs
SPS Prototype
BE-BI-PM Jose Luis Sirvent Blasco

10. BE-BI-PM Jose Luis Sirvent Blasco (jsirvent@cern.ch)
3. SPS Prototype Beam Tests: 3.1 Precision on beam width determination with a COAST
Tests conditions:
Single bunch (0.23e11 Protons) at 270GeV.
Beam/Wire interceptions every 23us (SPS rev. period)
Beam continuously circulating during various hours.
Emittance (and beam sigma) growth with time.
Prototype scanner BWS V scans at 20m/s.
Reference scanner BWS V scans at 1m/s.
Analysis and processing:
Single bunch profiles parametrized as Gaussian.
Beam width precision: Spread around linear growth.
Beam centroid precision: Spread around mean value.
Scanner
BWS.51731
BWS.51740
PMT
Diam.
Speed 1 20
Points per Sigma 39
1.7
Sigma (um)
(σ %)
900 ± 28
3.0 %
800 ± 18
2.3 %
800 ± 35
4.3%
Emit. (um)
2.5 ± 0.12
4.7%
2.5 ± 0.07
3.0%
2.5 ± 0.22
8.7%
Centroid
(σ um)
94 um
48 um
66 um
BE-BI-PM Jose Luis Sirvent Blasco

11. BE-BI-PM Jose Luis Sirvent Blasco (jsirvent@cern.ch)
3. SPS Prototype Beam Tests: 3.1 Precision on beam width determination with a COAST
BE-BI-PM Jose Luis Sirvent Blasco

12. BE-BI-PM Jose Luis Sirvent Blasco (jsirvent@cern.ch)
Performance with beam on parallel MDs
PSB Prototype
BE-BI-PM Jose Luis Sirvent Blasco

13. 3. PSB Prototype Beam Tests: 3.1 Precision on beam width determination
Detectors detail
ICECAL_V3 FE detail
Beam Sigma spread comparison for prototype and operational (Ring 3 Horizontal)
LHC25 and ISOLDE beams at different energies.
Many points per sigma in both scanners : 200 – 500
Successful Prototype operation:
Similar performance for LHC25ns (Dominated by amplitude statistics in both BWS?)
Beam sigma errors Prototype ± 0,7% , Operational ±1,3% (ISOLDE).
Prototype
Operational
Beam Type
Operational
Prototype
LHC25 1.4GeV
2559 ± 31, 1.2%
2569 ± 37, 1.4%
ISO 588 MeV/c
8021 ± 125, 1.6%
8245 ± 52, 0.6%
ISO 886 MeV/c
6354 ± 88, 1.4%
6571 ± 46, 0.7%
ISO 1.39 GeV/c
5302 ± 44, 0.8%
5538 ± 38, 0.7%
ISO 1.92 GeV/c
4880 ± 53, 1.1%
5025 ± 34, 0.7%
Beam sigma measurement (um) and spread during
MD in um and %.
BE-BI-PM Jose Luis Sirvent Blasco

14. 3. PSB Prototype Beam Tests: 3.1 HDR acquisition system evaluation
Detectors detail
ICECAL_V3 FE detail
Aim: Ease BWS operation and avoid tuneable parameters (HV+Filter selection).
Prototype equipped with two secondary acquisition systems:
A) Standard: Single channel acquired on surface.
B) HDR Based on Q-PMT detector: 4 channels acquired on tunnel with ICECAL FE.
Scint. photon yield varied by 1e3:
STD  Required filter changes
HDR  Static configuration
 PMT Saturation free
BE-BI-PM Jose Luis Sirvent Blasco

15. 3. PSB Prototype Beam Tests: 3.1 Identified issues and actions
Detectors detail
ICECAL_V3 FE detail
Issue:
Not operated since then  Glass Disk was slippering into the BWS holder.
Initial calibration table not valid anymore. Incorrect beam projections.
Data shown was corrected by software (but potentially biased by this effect)
Actions:
New BWS with improved disk holder is prepared to be installed on next TS (19/09/2017)
Scanner is under testing prior to installation  Calibration and performance assessment on optical bench.
Small Scintillators to be substituted by bigger ones  Expected Improved amplitude statistics.
BE-BI-PM Jose Luis Sirvent Blasco

16. BE-BI-PM Jose Luis Sirvent Blasco (jsirvent@cern.ch)
Plans for SPS and PSB Prototypes
BE-BI-PM Jose Luis Sirvent Blasco

17. BE-BI-BL Jose Luis Sirvent Blasco (jsirvent@cern.ch)
To fill in now…
PSB Prototype:
New MDs to schedule once scanner is replaced before (if possible before EYETS)
Improved secondaries readout system (bigger scintillator and modified electronics).
SPS Prototype:
Should we specify some tests here?
Used as evaluation platform for HDR Bunch by Bunch acquisition system under design.
BE-BI-BL Jose Luis Sirvent Blasco