# Presentation: 249208

## NUMI PRIMARY  BEAM INSTRUMENTATIONMultiwires, Loss Monitors, Toroids

- Gianni Tassotto

## MULTIWIRES

- Phenomenon : secondary emission
- Measure position and profile
- No clearing field needed
- Wire : –  0.003” AuW
-             –  48H/48V
-             – spacing: 1 mm, 0.5 mm
- Material in the beam - 8x10-5 fractional loss
- Dynamic range: 5x1010 to 4x1013 ppp
- Upgrading wire plane assembly

## MULTIWIRE UPGRADE

- Alignment - Position Repeatability - <50 um.
- Motor Drive - move in/out in 1.1 sec.
- Signal feedthroughs.
- Ceramic boards.
- Kapton flex tape.
- Considering using carbon wires to minimize beam losses. R&D effort.
- Robust limit switch assembly.
- Est. cost of new assembly $2500/ea.

## ELECTRONICS

- FNAL made 96 channel integrator
- Integration time from 5 msec - 6.5 sec
- Dynamic range: 5x1010 - 4x1013 ppp
- Noise  0.2% of full scale
-  Calibration feature to check channel response

## LOSS MONITORS

- Sealed Unit (BLM):
- Lab standards.
- IL = 10-14 Amp.
- Sensitivity (pA-hr/R).
- 9 months to fabricate.
- Cost: about $250.
- Electronics dynamic range 10-5 beam loss to full scale.

- Heliax Type (TLM):
- Various lengths & dia.
- Require ArCO2.
- Cost: $14/ft for 1 5/8”.
- Gas: $3k initial + about $50/month.
- Max cable length one monitor 430 ft.
- Electronics dynamic range 10-5 beam loss to full scale.

## BLM DETECTOR

## CALIBRATION OF BLMs

- A lot of information has been obtain from work done by F.  Krueger, R. Ford and myself at FNAL and R. Witkover at BNL:
- Sensitivity tests on new and irradiated BLMs
- Plateau at various radiation levels.
- In R. Witkover’s paper: “Choise of High Voltage Bias Polarities for the SNS BLM Ion Chambers”. Witkover tested various configurations for both positive and negative voltages. Found that the FNAL type (positive voltage to the center) offered the best response at high dose rates. Also, it included sensitivity tests.

## BLM SENSITIVITY TESTS

- See slide “Beam Sensitivity Measurements”.
- Sensitivity and plateau measurements were done using a Cs137 source (E =662 KeV) at Site 38. Typical runs were made @ 50 R/hr which equates to a very low intensity beam.

## BLM PLATEAU SERIES

- Bias	                 Current (pA) for:
- (volts)   100 R/hr      80 R/hr	60 R/hr     40 R/hr	  20 R/hr
- 2         1690.05       1412.55	1058.1         698.6	      377.675
- 3         1987.45       1573.2	1210.3         828.05	      437.9
- 4         2166.35       1747	1305.95       891.15	      463.1
- 5         2278.15       1845.65	1396.15       942.9	      479.325
- 7         2502.7         1989.35	1487.4         992.75	      496.075
- 10       2624.45       2088.15	1556.95      1026.8       501.475
- 20       2720.95       2148.45	1586.6        1035.3	      504.2
- 50       2714.25       2144.35	1584.65      1035.2	      505.825
- 100     2697.7         2132.6	1577.55      1032.8	      505.85
- 200     2687.15       2126.05	1574.85      1032.6	      506.125
- 500     2703.75       2141.85	1582.3        1037.25      507.525
- 1000   2728.8         2165.25	1608.05      1049.95      507.275
- 2000   2982.85       2341.8	1747.7        1137.2	      559.025
- 2500   3538	           2791.6	2093.05      1363.25      671.375

## TLM  DETECTORS

- We are planning to assemble a long loss monitor segment and perform sensitivity and plateau tests at site 38.
- We are also looking into the possibility of adding a small Cs137 source inside one of the caps to be used as a “heart beat”.

## TOROIDS

- Used for absolute intensity calibration.
- No material in the beam.
- Signal = 1/2 V per A.
- Accuracy: 3% absolute.
- Stability:  3%.
- Commercially available.
- Cost (Pearson Electronics)
- Detector --------$5000
- Ceramic gap ---$1000
- Electronics------$2000 Est.

## TOROID

## INTEGRATOR CHANGES

- D. Schoo is prototyping a new version of the integrator module:
- differential input.
- 16 bit converter for extended dynamic range.
- Newer op amps with better offset and drift characteristics and low leakage capacitors were added.

## SCHEDULE OF EFFORTS

- All scanners have been purchased.
- R&D work is presently underway for Multiwire, Loss Monitors, Toroid.
- Production will start after funds become available.
- Funds for Multiwire,Toroid and Loss Monitors will be available 4Q 2002 (FY2003).
- Instrumentation installation in 2004.

## CONCLUSION

- A lot of work still needs to be done:
- In the case of multiwires
- We have to finish testing the prototype, and then start assembling the final units.
- Have a much more robust system to check and verify the appropriate timing event is selected.
- For BLMs we need to perform sensitivity/saturation tests @ high beam intensities i.e., booster RDF.
- Need to develop a heart beat system for the TLMs