Beam Secondary Shower Acquisition System: Front-End RF Design Student Meeting Jose Luis Sirvent PhD. Student 19/08/2013

1. The dynamic range and the three lines Two or Three lines to cover all the needed Dyn. range (1-1e6MIPS) Scheme valid for QIE as well as ADC Technique based on splitting the signal (Detector current or Charge -> Voltage) The idea is to use 1 detector and 2 or 3 lines and sample in parallel Profile reconstruction Bunch By Bunch based on the combination of lines

1. The dynamic range and the three lines Initial proposal of architecture: 3 Signal cables (Tunnel – Detector) : 34dB, -6dB & DC 2 Power supply cables (Tunnel - Detector) 1 Splitting + Amplification in Tunnel 1 Splitting + Attenuation in Surface HV Cividec Amplifier 34dB Cividec AC-DC Splitter -6dB Cividec Diamond Detector Mini-Circuits DC-4GHz Splitter AC 40dB pCVD -6dB 12V DC Tunnel DC -6dB -12dB The proposal can be Optimized: 1. The pCVD from Cividec has high output impedance RF equipment needs to be well adapted for optimal transmission 2. Line DC could be avoided We can split in surface x3 and lowpass one output Less Installation needed -6dB Mini-Circuits DC-4GHz Splitter -32dB Cividec Attenuator -6dB -20dB Surface

1. The dynamic range and the three lines To adapt… or not to adapt? (CK50) Better frequency response if adapted in both sides, see green line

1. The dynamic range and the three lines Updated proposal: Lines well adapted Less components in the tunnel (Simpler layout) HV Cividec Amplifier 34dB Cividec Diamond Detector -6dB DC-4GHz Splitter 40dB pCVD -6dB 12V Termination 50Ω Tunnel -6dB Not yet clear: If DC measurement is necessary then -9dB splitter: Needed lines 34dB, -15dB & -35dB -12dB -6dB DC-4GHz Splitter -32dB Attenuator -6dB -20dB Surface DC Low Pass Filter Fc= 5 Hz

1. The dynamic range and the three lines Updated proposal: Lines well adapted Less components in the tunnel (Simpler layout) HV Cividec Amplifier 34dB Cividec Diamond Detector -6dB DC-4GHz Splitter 40dB pCVD -6dB 12V Termination 50Ω Tunnel -6dB Look Out!! Worst case: 1e6 MIPS in 1ns Charge = 1.6e9 C pCVD peak current =1.6A!! Needed to calculate the dissipated power per device and make wise decisions or …  -12dB -6dB DC-4GHz Splitter -32dB Attenuator -6dB -20dB Surface DC Low Pass Filter Fc= 5 Hz

2. Going back to Pspice Model of the proposed Front-End !!!

3. To shape or not to shape 1. Shaping is filtering: Band-Pass 2. A correct shaping avoids bunch pile-up (Cable effect): Recover base-line Criteria: Ti= 1/2 Tbunch (0.5e-9 for 1ns bunches)  Fc low= 2GHz Td= 1/5 Tbetween bunches (5e-9 for 25ns spaced bunches)  Fc high= 200MHz 3. Shaping “cleans” the signal: Better SNR Working Freq. Range (200e6 – 2e9 Hz)

3. To shape or not to shape By using our Matlab GUI: Observations: Shaper returns base-line (Cable independence) Shaper provides better results in fitting sigma with ADC On  Mean error: 2.95e-3% Off  Mean error: 8.55e-3% If Shaper used, not possible to use QIE10 (mean charge = 0 C) QIE10 results justified by Digitalization scheme (eqr 0.7 – 1.4%) When integrating the Pile-Up effect is more evident. Errors maybe too small ( <0.1% ) for taking a decision. Timing evaluation of ADC’s to see if possible peak detection at 40Mhz. (Synchronization Issues??)

3. To shape or not to shape Peaks With Shaper Integration With Shaper Peaks Without Shaper Peaks With Shaper Pile-Up: + 0.01% Pile-Up: - 0.0004% Integration Without Shaper Integration With Shaper 25ns bunch charge tends to 0 Not possible! Pile-Up: + 0.15%

3. To shape or not to shape Example of an Slow shaper: Band-pass 1e3 - 2e9 Hz Ti:0.5e-9 Td: 1e-3 Example of an Quick shaper: Band-pass 200e6 - 2e9 Hz Ti:0.5e-9 Td: 5e-9 In case of using a shaper this must be quick enough (bunch level) to not modify the Gaussian shape. But remember, If shaper is used not possible to use QIE10!! Option A (No problem with RH. Amplif) : Quick shaper (200e6 – 2e9 Hz) Clean signal No impact on Gaussian profile Only compatible with fast ADC’s or standard well synchronized Option B (Some developments are needed): No shaper ‘Dirty’ signal No impact on Gaussian profile (if not much noise) Compatible with QIE10 and ADC’s