Matching monitors for SPS and LHC E. Bravin 31 March 2011

Aim of the matching monitors Measure the transverse beam profiles turn by turn Maximum acquisition rate 44 kHz (SPS) Acquisition synchronous with turn clock Resolution on beam size of the order of 20%(LHC specs) around few % should be possible Beam size to measure ~1mm

The fast camera Years ago several fast cameras have been purchased (rather expensive devices) Sensitivity not sufficient for single bunches Needed the addition of image intensifiers in front (took years to get it done)(also used for bunch-by-bunch gating in LHC) Still not operational because of many hardware/software difficulties No information on radiation hardness

REDLAKE HG-100K

Other imaging options If one wants turn by turn capability there are no options other than fast cameras different models on the market, but all with the same problems – Cost – Radiation hardness – Software complexity Could use simple gated camera with one frame per injection with changing delays (gate scan) Not very practical

Profile acquisition There are more options if we reduce the scope to just measuring profiles – Segmented detector Linear CCD (up to ~500 pixels) Photo diode array (up to ~500 pixels) Segmented photomultiplier (up to 32 segments) – Acquisition Independent read-out of channels Serialized read-out of channels

Profile vs. image Two profiles (X and Y) do not provide the same information as the 2D image The additional information of 2D images is however almost never used An additional profile at 45° could in principle give the same information

Draw back of linear detectors Usually the aspect ratio of the detector if far from square Typically linear CCDs and photo-diode arrays have sizes of 5mm x 10µm Segmented photomultipliers (only one model from Hamamatsu) 32mm x 7mm If pixel height is too small requires complex cylindrical optics

Present design Based on Hamamatsu S11105 linear CMOS sensor – 512 pixels – Pixel size 12.5µm x 250µm – pixel clock ≤50 MHz (max ~ 97k profiles/s) Simple detector head Front end electronics based on CERN radiation hard components Optical data transmission using CERN module

Fast profile monitor status Electronics for head and front end done Currently being tested in the lab Using test board for readout (not done yet) Will use the new VFC for the readout in the real devices (need some FPGA programming) Optics under study – Simple solution readily available is a standard camera lens – Cylindrical setups under design/test

Fast profile monitor Camera Head Front end electronics Cylindrical lens system

SPS issue (breaking news) Yesterday the OTR in BA5 has been dismounted since it was observed that the foil was damaged (last year ?) Foil was metallised Mylar Clear signs of high temperature of the support frame Visible marks of heating on the screen support Probably cause is RF excitation

SPS OTR inside

SPS “Quattro” tank

Synchrotron light in SPS There is a SL telescope in BA5 (moved here a few years ago) Source is dipole edge Visible light only for E>~400 GeV (protons) For ions SL never seen in SPS Optical system in poor state Will be renovated next winter ?(low priority) Not planned to use it for imaging Probably not possible to do single pass even at 450 GeV? (in LHC we have the undulators)