Linac4 BPM and Phase Pickup L. Søby08/ LINAC4 Beam Position, Phase and intensity Pick-ups

Linac4 BPM and Phase Pickup L. Søby08/ Linac4 position, intensity and phase pick-up Overview Requirements and constraints Possible Pick-up types Low beta effects Acquisition system Manpower and costs Summery

Linac4 BPM and Phase Pickup L. Søby08/ Overview DTL DTL tank1DTL tank2DTL tank3 BLM SEM Grid Beam Loss Monitor Beam Current Transformer Position, Intensity and Phase pick-up Quadrupole / Dipole 32mm 103mm Is there a magnet here?

Linac4 BPM and Phase Pickup L. Søby08/ CCDTL module 1CCDTL module 2 CCDTL module 3CCDTL module 4 BLM Overview CCDTL 1-4

Linac4 BPM and Phase Pickup L. Søby08/ CCDTL module 5CCDTL module 6 CCDTL module 7CCDTL module 8 BLM Overview CCDTL 5-8

Linac4 BPM and Phase Pickup L. Søby08/ SCL module 1SCL module 2 SCL module 3 SCL module 4 BLM Overview SCL BLM ?

Linac4 BPM and Phase Pickup L. Søby08/ Pick-ups foreseen Diameter 70mm Could be of inductive type which also measures current, which would reduce the number of current transformers needed. Overview HEBT

Linac4 BPM and Phase Pickup L. Søby08/ Overview Nb. of Pick- ups Inner Diameter [mm] Available length [mm] E [MeV] β Comments DTL BPM 1 BPM + 1 dipole BPM, SEM-grid and BCT CCDTL828 Min 185 ~ Available length for magnet and BPM after 1 st module. BPM, SEM-grid and BCT SCL832 Min ~185 ? BPM’s + magnet after each module +4 BPM’s inside each module only position is required HEBT1270mm

Linac4 BPM and Phase Pickup L. Søby08/ What should be measured Absolute beam position with respect to an external reference. Relative beam intensity measured by two consecutive pick-ups. Absolute beam intensity after calibration with BCT. Absolute beam phase with respect to distributed RF reference. TOF flight between two pick-ups.  F B = 352MHz   bunch = 100ps  Int. = 10 9 /bunch  Pulse l.= 400us  I ave. = 40mA

Linac4 BPM and Phase Pickup L. Søby08/ Requirements PositionPhaseIntensity Dynamic range DTL: ± 7mm CCDTL: ± 10mm SCL: ± 10mm HEBT: ± 25mm Nominal phase advance ± 10º ?? 4-40mA Resolution0.1mm0.1º0.5mA Absolute precision0.3mm0.5º1mA Relative precision1% Time resolution2us Vacuum 10-7 Torr, NO bake out will be made Alignment jigs (on magnets)

Linac4 BPM and Phase Pickup L. Søby08/ Possible Pick-up types Area A r Due to the very small longitudinal space only Button pick-ups and Shorted strip lines are possible candidates. beta dependent

Linac4 BPM and Phase Pickup L. Søby08/ Strip line at low beta Much shorter than free space quarter wave length!! For v B << c (β=0.1) For max. response So a decrease of 60% (8dB) of the intensity signal. DTLCCDTLSCL

Linac4 BPM and Phase Pickup L. Søby08/ Transverse sensitivity at low-β Schafer theorem Transverse sensitivity varies with beta and frequency ~3.4→5dB/mm = / 3MeV. Note that the longitudinal extent of the field lines are less, and hence the frequency components are higher, on the beam tube wall closest to the beam. The amplitude of the sum signal does not change! DTLSCL

Linac4 BPM and Phase Pickup L. Søby08/ SNS Strip-line pick-up One end is shorted. 60 degree electrode angle. Prototype CCL BPM with Feed thru removed. Feed Through In mini-conflat Signal pin Beam

Linac4 BPM and Phase Pickup L. Søby08/ SNS BPM Installation & Alignment The CCL BPM will be rigidly attached to a quadrupole magnet. Up and downstream beam tube will be welded to BPM. The quadrupole magnet will have an adjustable kinematic mount. An adapter plate will be used to mount the BPM to the magnet. One side of the adapter plate will be pinned to the magnet face and the other side of the adapter plate will be pinned to the BPM mounting flange. Survey target holes are provided as alignment fiducials. Place the BPM within 1 mm and measure accurately (within 0.1 mm) where it is located. BPM mounting flange CCL Quadrupole Adapter plate BPM

Linac4 BPM and Phase Pickup L. Søby08/ Linac4 magnet and BPM At present available space is 185mm? in CCDTL and SCL. 250mm seems necessary Bellow

Linac4 BPM and Phase Pickup L. Søby08/ Acquisition system Pos= k(  )*  /  +offset Int.= c*k 1 (  )*   = k 2 *(  RF -  Beam ) TOF = S Pu /  *c  = -360*f*S Pu /  *c  Analogue or Digital I/Q down mixing is a better solution

Linac4 BPM and Phase Pickup L. Søby08/ Bergoz Analogue Front end SNS Acquisition system SNS Digital Front end with I/Q sampling 40MS/s50MHz Sample IF at 40 MHz to generate I and Q data Signal vectors calculated from I and Q

Linac4 BPM and Phase Pickup L. Søby08/ SNS Acquisition system BPM Digital Front end

Linac4 BPM and Phase Pickup L. Søby08/ Bergoz Analogue Front end SNS Acquisition system

Linac4 BPM and Phase Pickup L. Søby08/ BPM AFE Prototype Data Sheet

Linac4 BPM and Phase Pickup L. Søby08/ SNS Acquisition system AFEDFE Clock multiplier not seen. PCI

Linac4 BPM and Phase Pickup L. Søby08/ SNS 1U BPM Processor Chassis Stand alone, sends data via Ethernet

Linac4 BPM and Phase Pickup L. Søby08/ Manpower and costs CostFTEyNBTot. CostTot FTEy Design Material Construction Electronics (A + D) BI software Installation Commissioning Total 656kCHF4.4

Linac4 BPM and Phase Pickup L. Søby08/ Summary Position, Intensity, Phase, TOF and relativistic beta must be computed in front-end. Buttons or shorted stripline Pick-ups can be used. Shorted strip line pick-up’s have been intensely studied by SNS and optimized for phase linearity. The SNS designs can easily be adapted to CERN Linac4. Buttons can be ~ 10mm shorter but are non linear and correction algorithms has to be applied. Low beta transverse sensitivity must be studied. At least 250mm is needed for magnet and pick-up in CCDTL and SCL. The acquisition system should include I/Q down mixing for the phase measurement. Bergoz analogue end exists, which is compatible with SNS digital (PCI) front end. SNS digital front with rack mount PC fit our needs. Otherwise VME specific card has to be developed. LF and RF stabilized reference lines are needed for the BPM electronics.