# Presentation: 668801

## Timing for NUMI Beam Instrumentation 

- Gianni Tassotto

## Type of Detectors 

- BPMs - Peter Prieto
- Multiwires  - Gianni Tassotto/Dan Schoo
- BLMs and TLMs - Olson/Tassotto/Schoo
- Toroids - Aisha Ibrahim
- Res. Wall Monitor - Brian Fellenz
- OTR - Vic Scarpine - Not installed at this time.
- For location of devices refer to: http://home.fnal.gov/~dharris/pbeam_instrumentation.html

## BPM Timing - 1

***	******BPM Measurement Timing Operation***
- The NuMI BPM system must be armed for data acquisition. The TCLK $A5 event, the NuMI signature event occurring approximately 1.2 seconds before NuMI beam extraction, shall serve as the arm event. Once armed, the BPM system awaits a trigger to commence data acquisition.
- The MIBS $74 event serves as the NuMI extraction kicker timing reference; the kicker fires approximately 200 microseconds after the event. The BPM system trigger shall likewise be referenced to MIBS $74, but with a delay much less than 200 microseconds. This permits the BPM system to acquire data for a relatively long time interval that spans extraction and begins at a precise time relative to the kicker. The EchoTek boards shall be configured to collect and store data for an interval of ~440 microseconds, 1024 data points at 430 nanoseconds per point.
- The BPM system offers the user the choice of two modes for determining the location (time) of the desired beam signal in the acquired data stream. The modes are called: Software Beam Triggered Mode and the Kicker Relative Timing Mode

## BPM Timing - 2

**Software Beam Triggered Mode**** **
- Operation in the Software Beam Triggered mode is comparable to a self-triggered analog acquisition mode. A hardware trigger is required, but the accuracy of that trigger need be only at the level of ~100 microseconds relative to the beam signal itself. A software algorithm “finds” the beam signal within the acquired data. The “edge-finding” algorithm determines the index of the value in the data array corresponding to the rising edge of the beam signal and reports the data for the earliest signal detected as “Batch 1”.Then data for subsequent batches is reported assuming pre-determined batch-to-batch index offsets (currently assuming batch center spacing of eighty-six 53 MHz periods). The algorithm is robust against variable number of batches in range of one to six and does tolerate missing batches within a train.
- This mode offers timing robustness that is highly desirable for early commissioning until operational timing of the entire NuMI system has stabilized and will serve as a fall-back option anytime accurate timing settings might be confused in operations. This mode offers the highest probability of reporting useful beam position measurements the first time beam is sent down the beam line.
- A shortcoming of this mode is that it always identifies the earliest beam observed as Batch 1. It is unable, for instance, to determine that Batch 1 might be empty and that the earliest beam actually comes in a time slot independently defined as Batch 2.

## BPM Timing - 3

**Kicker Relative Timing Mode**** **
- Operation in the Kicker Relative Timing mode is predicated on the condition that the positions of all batches, up to six, lie at fixed locations in time relative to the kicker fire signal on the beam-synch clock and that the BPM trigger is set to a known, accurate, and precise time relative to the same reference.
- The BPM trigger must be set and fixed in time relative to the beam signal at each receiver to an accuracy of approximately plus or minus 200 nanoseconds. The BPM system then simply uses fixed index offsets from the beginning of the acquired data array to select the data to report as Batch 1, 2, etc. Data for each batch is assumed to exist in the acquired data array at a known and fixed position relative to the first point.
- The time of arrival of the beginning of beam relative to the kicker event in normal circumstances will be determined empirically. But once it is determined, then this will fix Batch 1 in time. Batches 2 through 5 or 6 will follow Batch 1 by intervals of 1.6 microseconds. It is left to the user to assure that the relative timing between kicker, BPM trigger, and beam remain fixed.
- Operation in this mode enables users to be able to compare the position of any batch with other values (archived by the application program) for that same batch.  This mode is straightforward and simple to implement, but is not robust to variations in kicker delay, beam synch clock distribution, and operator set-up.

## Multiwires

- A total of 10 (University of Texas built) multiwires are installed in the pretarget area. For detectors details see Sacha Kopp’s paper: _[www.](http://www.hep.utexas.edu/~kopp/minos/sem/docs/BIW04-SEM-paper.pdf)__[hep](http://www.hep.utexas.edu/~kopp/minos/sem/docs/BIW04-SEM-paper.pdf)__[.](http://www.hep.utexas.edu/~kopp/minos/sem/docs/BIW04-SEM-paper.pdf)__[utexas](http://www.hep.utexas.edu/~kopp/minos/sem/docs/BIW04-SEM-paper.pdf)__[.edu/~kopp/](http://www.hep.utexas.edu/~kopp/minos/sem/docs/BIW04-SEM-paper.pdf)__[minos](http://www.hep.utexas.edu/~kopp/minos/sem/docs/BIW04-SEM-paper.pdf)__[/](http://www.hep.utexas.edu/~kopp/minos/sem/docs/BIW04-SEM-paper.pdf)__[sem](http://www.hep.utexas.edu/~kopp/minos/sem/docs/BIW04-SEM-paper.pdf)__[/docs/BIW04-SEM-paper.pdf](http://www.hep.utexas.edu/~kopp/minos/sem/docs/BIW04-SEM-paper.pdf)_
- Pages E41and W115 show a complete list of scanners from which the set of NuMI scanners can be looked at. Page W115 also shows the time delay feature.
- Scanners require a Start, a Sample and a Stop pulse. Pretarget scanners PM101 through PMTGT and hadron scanners have no delay capability at this time. They have been modified to require only 5 sec after the sample pulse before they starts integrating. Scanner HADM has 10,000 pF input capacitor, all others have 100 pF capacitors.
**Start up configuration:** A set of values could be: $A5, $A9, and $FE, where $A5 is NuMI Reset for Extracted Beam, $A9 is the Reflected MIBS Event $74, and $FE is a non event.  Note: MIBS $74 initiates the process of extracting MI beam toward the NuMI beamline. Detected MIBS $79 results in issuance of TCLK $A9. Actual extraction of beam is 200 sec after MIBS $79.
- The Gain could be set initially to 10 and later, after the beam intensity is increased, to 1. The Duration could be set to 10 msec or more and then slowly reduced to a minimum to increase the signal-to-noise ratio. The next page shows the settings for M101.
- Hot Wires:Without beam the voltage displayed by the scanner should be < 1 V of full scale (10 V). If two or more wires are shorted together the display could be saturated. To remove hot wires from the display go to page E41. Make sure that Remove Hot Wires is on YES, then click on Edit Hot Wires, enter the wire(s) to be disabled per plane and then restart the plot.

## Loss Monitors

- A total of 49 BLMs and 4 TLMs have been installed in the pretarget area.
- The loss monitor timing devices have been setup on page E38 - sub LOSS - sub 4.
- The timer references are for the user to setup.
- The hold delay should be set to about 5 mSec after the loss occurs. This allows the log integrator signal to peak after the loss. Timing can be checked by simply fast time plotting a loss monitor and adjustments made accordingly.
- At startup the following time events could be used:
- 	- $A9 with 0 delay for Reset
- 	- $A9 with 5 msec delay for Hold
- Next page shows a copy of page E38.

## Toroid Intensity Monitor Integrator

- Full-scale of 5e13 ≈ 10V
- With 16-bit readout: LSB of 76uV ≈ 4E8
- Integrator Time Constant: 3.3msec
- TOR101 & TORTGT both have gates, set to 13.1usec currently
- This can be modified by opening the board and resetting BCD switches from 0.1usec to 99.9 usec.

## Timing for Toroid Integrator

- •	 Trigger’s rising edge causes the integration gate to open.
- Any beam captured within this window is integrated
- A larger gate provides ample time to “see” all beam signal
- A smaller gate helps to control noise as well as the sample/hold droop rate of the integrator
- 4usec is need to digitize intensity into modules’ 16-bit digital buffer.
- The 16 bit digital readout is converted back into an analog signal for infinite sample and hold MADC readout.
- Intensity value is held until the next triggering event (i.e. next extraction or reset).
- The toroids will have to be calibrated to optimize the timing parameters before beam is delivered to NuMI.

## Example of Timing of RR Toroid

**Ignore Ch4 (Green)**
**Ch2 – Integration Gate**
**Ch3 – Beam signal**

## ACNET Devices

- E:TOR101 & E:TORTGT are 14-bit MADC readouts of integrated intensity
- E:TR101D & E:TRTGTD are 16-bit C284 readouts of integrated intensity
- LSB: 76uV ≈ 4E8
- E:TS101D & E:TSTGTD (MIBS $74) are the timing channels used to TOR101, TORTGT respectively

## Numi Resistive Wall Current Monitor

- The monitor is used as a longitudinal beam profile monitor located at the start of the Numi beam line [location 101]. It has a gap impedance of 1.124 ohms with a bandwidth of 7KHz to 1000MHz.
- The output signal is brought upstairs using 7/8” heliax cable. The cable is terminated at rack MI60303 where a Tektronix TDS 3054B scope is located to display the output from the wall monitor.
- The Tektronix scope will be triggered from a camac 479 card [E:NRWMT]. It will have an Ethernet network connection to allow the user to control and display the scope from a PC [Node name: NumiRWCMscope, IP address: 131.225.23.245].

## NuMI Resistive Wall Current Monitor Drawing