# Presentation: 905042

## Accelerator Physics Issues

-  Shekhar Mishra
- Sept 17-19, 1996
- Main Injector DOE Review

## Accelerator Physics Issues

-  Lattice  Results from Previous Reviews
-  Recent Results
-  **Magnet Data analysis**
-  **Dipoles and Quadrupole Placement**
-  **Lattice Calculations**
-  Comments on Impedance Issues
-  Conclusions

## Introduction

- All the Lattice calculations performed for Main Injector have been done using thin element tracking code TEAPOT (Talman et al.)
- These calculations includes:-
-  Strength variations in the dipoles and quadrupoles.
-  Measured higher order multipoles.
-  Misalignment of the magnetic elements and BPM.
-  p/p
-  RF
- The tune of the Main Injector is adjusted to 26.425, 25.415.
- The chromaticity is (-5,-5) below transition and small positive above.
- Using these calculations and harmonics correctors in the  Ring, we have developed a correction scheme.

## Magnet Data Analysis

- _Dipole Strength Analysis_
-  The FMI Dipole Strength has changed during the production of the dipoles, due to change in steel properties.
-  Dipoles magnets have been divided into following groups according to their strength.
-  R&D Magnets : - After machining
-     3 IDA and  IDB  (+12 Units)
-     3  IDC and IDD.  (+30 Units)
-  Pre Run 4 Steel :-
- 25 IDA              (-35 Units)
- 19 IDB              (-35 -10 Units)
-  Run 12 Steel:- (60 % Run 12 Steel)
- 1 IDA                (+12 Units)
- 6 IDB                (+12 Units)
-  Rest Nominal Magnets  (~170 Magnets)

## Magnet Data Analysis ...

- _Quadrupole Data Analysis_
- We have Build 35 IQC(100”) and 52 IQD(116”) new quadrupole magnets. These magnets will be placed in the Dispersion suppresser region.
-  Sigma of the strength variation is 7 units at injection and 5 units at 120 GeV.
-  Systematic strength difference between IQC and IQD is 17 units.   (25 Units was allowed, see MI Note 110, ``Study of the long and short quadrupole strength match’’ , C. S. Mishra)
-  Normal octupole component in these quadrupoles are about 5 Units.
-  Main Injector will also use 128 quadrupoles recycled from Main Ring. We have good measurements of a handful of these magnets.

## Dipole Multipoles at Injection

- _Multipole_		_Mean__	_	_sigma_
- _	_                                (in Units)
- b1			-0.3		0.6
- b2			-0.7		0.2
- b3			0.03		0.1
- b4			0.2		0.1
- b5			-0.02		0.1
- b6			0.2		0.2
- b7			0.3		0.4
- b8			0.7		0.5
- a1			-0.6		0.4
- a2			-0.06		0.3
- a3			-0.4		0.1
- a4			0.0		0.2
- a5			-0.6		0.2
- a6			-0.04		0.3
- a7			-0.6		0.2
- a8			0.0		0.4

## Quadrupole Multipole at Injection

- _Multipole_			_Mean_		_Sigma_
- _	__	__	__	_     (in Units)
- b0				-1.1		5.4
- b2				0.0		1.3
- b3				6.2		1.0
- b4				0.05		0.5
- b5				-1.7		0.3
- b6				0.2		0.6
- b7				1.4		0.6
- b8				-0.1		0.1
- b9				-0.8		0.1
- a2				0.5		1.4
- a3				-1.95		1.4
- a4				-0.4		0.3
- a5				0.5		0.4
- a6				-0.6		0.4
- a8				-0.05		0.1
- a9				-0.05		0.1

## Dipole Magnet Placement

- Placement of the Dipole magnets in the FMI ring has been determined by shuffling on the dipole strength.
- Criteria of the dipole placement:-
-  No sizable closed orbit error in the injection and extraction section.
-  The dipole selection should not introduce a closed orbit error larger than due to misalignment error.
- We had designed the dipole correctors to correct closed orbit error due to 10 units of random dipole strength error.
- After the assignment of 210 dipoles, which includes varieties of dipole strength, we have achieved relatively smaller closed orbit error.

## Quadrupole Placement

-  The Placement of the New Main Injector Quadrupole has been determined by the strength of the magnet.
-  The octupole component of the quadrupole is correlated with its strength and no special sorting on the octupole component is performed.
-  In the design of FMI we had developed a quadrupole placement scheme using a Monte Carlo Technique. Which was performed to keep small.
-  We have assigned New quadrupoles in FMI using the above scheme and have kept the beta function variations to about 2%.
*In the placement of both the dipoles and quadrupoles we have paid close attention to spares and how a magnet will be replaced in case of failure.*

## Comments on Impedance Issues

- FMI is a designed to be a low impedance machine in order to achieve high beam intensity.
-  Impedance & Instability Threshold Estimates in the Main Injector I, Martens and Ng, MI Note 103.
-  Beam Instabilities in Main Injector, W. Chou, F3TAC.

## Impedance ....

- The impedance of an abort kicker has been measured. It is made of ferrite that houses a 2.2 m-long ceramic tube in center. In the Range from 100 kHz to 500 MHz |Z/n| is less than 0.01 ohm, which is well within the budget.

## Conclusions

-  Dipoles and Quadrupole Magnet data has been analyzed.
-  The dipole assignment and placement in the ring is well underway. 210 assigned and 185 installed.
-  The dipole strength variation is _not_ a serious problem. We will not need any special or stronger horizontal corrector to correct the closed orbit error.
-  All the new long quadrupoles have been assigned for placement in the ring.
-  The dynamical aperture of the FMI is large.
-  More measurements of the impedance will be carried out when other Kickers and Lambertson magnets will be available.