CERN Accelerating science

Luminosity performances in IR8 with and without the Upgrade II of LHCb~\cite{LHCbCollaboration:2776420,CERN_LHC_schedule,triplet}.

Schematic side-view of the Upgrade II detector extracted from the Technical Design Report (TDR) published by the LHCb Collaboration \cite{LHCbCollaboration:2776420}.

3D FLUKA geometry of UX85 and US85, including the LHCb detector and the shielding wall.

3D FLUKA geometry of the shielding wall seen from the LHCb experiment side.

Transverse dose distribution at the maximum of the IP-face front coils of the indicated conventional compensator magnets. External upward vertical crossing is assumed and values are normalized to $360 \,\mathrm{fb}^{-1}$. The bottom plot shows the geometry apertures around IP8, highlighting the location of the compensator magnets and the LHCb spectrometer in red and the shielding walls in grey.

Transverse dose distribution at the maximum of the IP-face front coils of the indicated conventional compensator magnets. External upward vertical crossing is assumed and values are normalized to $360 \,\mathrm{fb}^{-1}$. The bottom plot shows the geometry apertures around IP8, highlighting the location of the compensator magnets and the LHCb spectrometer in red and the shielding walls in grey.

Transverse dose distribution at the maximum of the IP-face front coils of the indicated conventional compensator magnets. External upward vertical crossing is assumed and values are normalized to $360 \,\mathrm{fb}^{-1}$. The bottom plot shows the geometry apertures around IP8, highlighting the location of the compensator magnets and the LHCb spectrometer in red and the shielding walls in grey.

Three-dimensional dose maps plotted on a longitudinal cutaway of the right short compensator magnet for the current geometry (left) and with the addition of a tungsten shielding with a thickness of 4 cm (right). Values are normalized to $360\,\mathrm{fb^{-1}}$. Upward external vertical crossing is assumed. The scoring mesh is Cartesian with transverse and longitudinal resolution of 3 mm.

Three-dimensional dose maps plotted on a longitudinal cutaway of the right short compensator magnet for the current geometry (left) and with the addition of a tungsten shielding with a thickness of 4 cm (right). Values are normalized to $360\,\mathrm{fb^{-1}}$. Upward external vertical crossing is assumed. The scoring mesh is Cartesian with transverse and longitudinal resolution of 3 mm.

Three-dimensional dose maps plotted on a longitudinal cutaway of the right short compensator magnet for the current geometry (left) and with the addition of a tungsten shielding with a thickness of 4 cm (right). Values are normalized to $360\,\mathrm{fb^{-1}}$. Upward external vertical crossing is assumed. The scoring mesh is Cartesian with transverse and longitudinal resolution of 3 mm.

Transverse peak dose profiles on the front upper coil of the MBXWS on the left side of IP8, evaluated with a longitudinal resolution of 5 cm for different shielding options, implemented (if any) after accumulating $60\,\mathrm{fb}^{-1}$ during Run~3 and Run~4. Upward external crossing and downward polarity of the LHCb spectrometer have been assumed.

Longitudinal profile of peak power density in the superconducting coils along the triplet and the D1 on the right side of IP8 (IP1 for the red curve), which is at z=0. Values are averaged over the cable radial thickness and the azimuthal resolution is of $2^{\circ}$. Two curves, normalized to $1.5\cdot10^{34}\,\mathrm{cm}^{-2}\,\mathrm{s}^{-1}$, refer to the LHCb Upgrade II operational scenario with $\sqrt{s}=14\,\mathrm{TeV}$, external vertical crossing, and either upward (blue crosses) and downward (green squares) polarity of the LHCb spectrometer. The red curve refers to the ATLAS insertion (where no superconducting D1 is present) and an operational Run~3 scenario with $\sqrt{s}=13.6\,\mathrm{TeV}$ at $2\cdot10^{34}\,\mathrm{cm}^{-2}\,\mathrm{s}^{-1}$. The red dashed line represents the quench limit for the triplet quadrupoles and the black dashed line represents the design limit~\cite{Mokhov:613167}.

Longitudinal profile of peak dose in the superconducting coils along the triplet and the D1 on the right side with respect to IP8 (at z=0). The azimuthal and radial resolution is of $2^{\circ}$ and {3 mm}, respectively. External vertical crossing has been considered for $\sqrt{s}=14\,\mathrm{TeV}$. An integrated luminosity of $360\,\mathrm{fb}^{-1}$ is assumed to be collected half with either polarity of the LHCb spectrometer. The grey curve is for the current layout, while the black one combines $300\,\mathrm{fb}^{-1}$ with the shielding options discussed in Secs.~\ref{TAS-like} and \ref{D1} and $60\,\mathrm{fb}^{-1}$ without any mitigation measure up to the end of Run~4. The red dashed line represents the design lifetime of Q1-Q3~\cite{Tavlet} and D1, while the green one represents the design lifetime of the correctors~\cite{Corrector_limit}.

Front (left) and inside (right) view of MBXWS-TAS. The pink blocks are made of tungsten. The shielding to protect its own front coils on the vertical plane is included.

Front (left) and inside (right) view of MBXWS-TAS. The pink blocks are made of tungsten. The shielding to protect its own front coils on the vertical plane is included.

Peak power density along the superconducting coils of the Q1 on the right side with respect to IP8 (at z=0). External vertical crossing and downward polarity of the LHCb spectrometer have been assumed. The black points correspond to the ones reported in green in Fig.~\ref{fig:power_Q1-3_D1}. The red squares represent the scenario featuring an ideal MBXWS-TAS equipped of tungsten in contact with the beam pipe, over a transverse width of 10 cm. The blue triangles correspond to a more realistic MBXWS-TAS design in which a 3~mm gap is left between the pipe and the absorber, to accommodate the bakeout tape, and the absorber transverse width is increased to 24 cm. The green crosses refer to a 10 mm reduction of the vacuum aperture diameter, enabling the shielding extension at smaller radii. Resolution and normalization are as in Fig.~\ref{fig:power_Q1-3_D1}.

Peak power density along the superconducting coils of the D1 on the right side with respect to IP8 (at z=0). External vertical crossing and downward polarity of the LHCb spectrometer have been assumed. The black points correspond to the ones reported in green in Fig.~\ref{fig:power_Q1-3_D1}. The red squares represent the scenario featuring the proposed replacement of the D1 beam screen allowing for the increase of the stainless steel cold bore wall thickness by {5.5 mm}. The blue triangles are obtained extending upstream the thick cold bore up to the Q3 non-IP end. Resolution and normalization are as in Fig.~\ref{fig:power_Q1-3_D1}.

Power density distribution on the IP-face of D2 for upward (top) and downward (bottom) polarity of the LHCb spectrometer in the case of external vertical crossing.

Power density distribution on the IP-face of D2 for upward (top) and downward (bottom) polarity of the LHCb spectrometer in the case of external vertical crossing.

Longitudinal profile of peak power density in the D2 superconducting coils on the left side of IP8 (at z=0). Values are averaged over the cable radial thickness and normalized to $1.5\cdot10^{34}\,\mathrm{cm}^{-2}\,\mathrm{s}^{-1}$. The azimuthal resolution is of $2^{\circ}$. External vertical crossing has been considered for $\sqrt{s}=14\,\mathrm{TeV}$ with either upward (red points) and downward (black points) polarity of the LHCb spectrometer.

Transverse dose distribution at the longitudinal maximum in the D2 superconducting coils of the outgoing beam on the left side of IP8 for external vertical crossing. An integrated luminosity of $360\,\mathrm{fb^{-1}}$ is assumed to be collected half with either LHCb polarity.

Longitudinal profile of peak dose in the superconducting coils of the magnets of the left DS, assuming an integrated luminosity of $360\,\mathrm{fb}^{-1}$ collected half with either polarity of the LHCb spectrometer, for external vertical crossing.

Luminosity performances without Upgrade II http://lhc-commissioning.web.cern.ch/schedule/images/ LHCb-to-2037.png

Luminosity performances with Upgrade II http://cdsweb.cern.ch/record/2776420/files/LHCB-TDR-023.pdf \cite{LHCbCollaboration:2776420}

Averaged HEH fluence in the edge region between US85 and UL84 (as shown in the dashed rectangle in the right bottom insert) between -1.1 m and 1.1 m with respect to the beam height, during Run~5 after the implementation of the shielding wall (red curve) and during Run~3-4 (black curve).

\hl{LHCb-TDR Top view of shielding effectiveness given as the ratio of high energy hadron fluence at beam height with and without the wall.}

Top view of the R-factor map given as the ratio of thermal neutron fluence over high energy hadron fluence at beam height.

Power density distribution at the IP-face of short compensators MBXWS on the left side (top plot) and on the right side (bottom plot) with respect to IP8. External vertical crossing and downward polarity of the LHCb spectrometer have been assumed. Values are averaged over the return coil thickness and normalized to $400 \,\mathrm{fb}^{-1}$.

\hl{IPAC -Transverse peak dose profiles in the IP-face return upper coil of the MBXWS on the right side with respect to IP8. External vertical crossing and downward polarity of the LHCb spectrometer have been assumed.}

\hl{IPAC - Longitudinal profile of peak power density in the superconducting coils along the triplet and the D1 on the right side with respect to IP8 (at z=0). Values are averaged over the cable radial thickness and normalized to $1.5\cdot10^{34}\,\mathrm{cm}^{-2}\,\mathrm{s}^{-1}$. The azimuthal resolution is of $2^{\circ}$. External vertical crossing has been considered for $\sqrt{s}=14\,\mathrm{TeV}$ with either upward (blue points) and downward (green points) polarity of the LHCb spectrometer. The red dashed line represents the quench limit for the triplet and the black dashed line the design limit as described in~\cite{Mokhov:613167}.}

Longitudinal profile of peak dose in the superconducting coils along the triplet and the D1 on the right side with respect to IP8 (at z=0). The azimuthal and radial resolution is of $2^{\circ}$ and {3}{mm}, respectively. External vertical crossing has been considered for $\sqrt{s}=14\,\mathrm{TeV}$. An integrated luminosity of $400\,\mathrm{fb}^{-1}$ is assumed to be collected half with either polarity of the LHCb spectrometer. The red dashed line represents the damage limit of Q1-Q3~\cite{Tavlet}.

\hl{Longitudinal profile of peak power density in the D1 superconducting coils on the right side with respect to IP8 (at z=0). External vertical crossing and downward polarity of the LHCb spectrometer have been assumed. The black points correspond to the one reported in green in Fig.~\ref{fig:power_Q1-3_D1} and the red ones represent the scenario including the proposed model of the D1, in which the D1 beam screen is replaced with the Q3 one and an additional shielding of {5.5}{mm}. Resolution and normalization are the same as Fig.~\ref{fig:power_Q1-3_D1}.}

Transverse dose distribution corresponding to the maximum of the D1 for an external crossing in the vertical plane. An integrated luminosity of $400\,fb^{-1}$ is assumed to be collected half with either LHCb polarity

Dose distribution at the maximum considering a combination of the upward and downward polarity of the LHCb spectrometer