Simulation and experimental study of proton bunch self-modulation in plasma with linear density gradients

We present numerical simulations and experimental results of the self-modulation of a long proton bunch in a plasma with linear density gradients along the beam path. Simulation results agree with the experimental results reported [F. Braunmller, T. Nechaeva et al. (AWAKE Collaboration), Phys. Rev. Lett. 125, 264801 (2020)PRLTAO0031-900710.1103/PhysRevLett.125.264801]: with negative gradients, the charge of the modulated bunch is lower than with positive gradients. In addition, the bunch modulation frequency varies with gradient. Simulation results show that dephasing of the wakefields with respect to the relativistic protons along the plasma is the main cause for the loss of charge. The study of the modulation frequency reveals details about the evolution of the self-modulation process along the plasma. In particular for negative gradients, the modulation frequency across time-resolved images of the bunch indicates the position along the plasma where protons leave the wakefields. Simulations and experimental results are in excellent agreement

Experimental study of extended timescale dynamics of a plasma wakefield driven by a self-modulated proton bunch

Plasma wakefield dynamics over timescales up to 800 ps, approximately 100 plasma periods, are studied experimentally at the Advanced Wakefield Experiment (AWAKE). The development of the longitudinal wakefield amplitude driven by a self-modulated proton bunch is measured using the external injection of witness electrons that sample the fields. In simulation, resonant excitation of the wakefield causes plasma electron trajectory crossing, resulting in the development of a potential outside the plasma boundary as electrons are transversely ejected. Trends consistent with the presence of this potential are experimentally measured and their dependence on wakefield amplitude are studied via seed laser timing scans and electron injection delay scan

Simulation and experimental study of proton bunch self-modulation in plasma with linear density gradients

We present numerical simulations and experimental results of the self-modulation of a long proton bunch in a plasma with linear density gradients along the beam path. Simulation results agree with the experimental results reported [F. Braunmller, T. Nechaeva et al. (AWAKE Collaboration), Phys. Rev. Lett. 125, 264801 (2020)]: with negative gradients, the charge of the modulated bunch is lower than with positive gradients. In addition, the bunch modulation frequency varies with gradient. Simulation results show that dephasing of the wakefields with respect to the relativistic protons along the plasma is the main cause for the loss of charge. The study of the modulation frequency reveals details about the evolution of the self-modulation process along the plasma. In particular for negative gradients, the modulation frequency across time-resolved images of the bunch indicates the position along the plasma where protons leave the wakefields. Simulations and experimental results are in excellent agreement

Experimental study of wakefields driven by a self-modulating proton bunch in plasma

We study experimentally the longitudinal and transverse wakefields driven by a highly relativistic proton bunch during self-modulation in plasma. We show that the wakefields' growth and amplitude increase with increasing seed amplitude as well as with the proton bunch charge in the plasma. We study transverse wakefields using the maximum radius of the proton bunch distribution measured on a screen downstream from the plasma. We study longitudinal wakefields by externally injecting electrons and measuring their final energy. Measurements agree with trends predicted by theory and numerical simulations and validate our understanding of the development of self-modulation. Experiments were performed in the context of the Advanced Wakefield Experiment (AWAKE)

Proton Bunch Self-Modulation in Plasma with Density Gradient

We study experimentally the effect of linear plasma density gradients on the self-modulation of a 400 GeV proton bunch. Results show that a positive or negative gradient increases or decreases the number of microbunches and the relative charge per microbunch observed after 10 m of plasma. The measured modulation frequency also increases or decreases. With the largest positive gradient we observe two frequencies in the modulation power spectrum. Results are consistent with changes in wakefields' phase velocity due to plasma density gradients adding to the slow wakefields' phase velocity during self-modulation growth predicted by linear theory

The effect of sex on the meat quality charachteristics of large white pigs

The total of 20 Large White (LW) pigs were used to study the effect of sex on the meat quality characteristics of the breed. All the animals were reared in similar conditions and slaughtered at 34 weeks of age. Reports indicate that males were heavier than female (34.5 kg versus 29.9 kg; p0.05). Although, sex related differences in tenderness, juiciness and flavor were not significant (p>0.05, significant differences (p Animal Production Research Advances Vol. 2 (4) 2006: pp. 258-26

The Effect of Cinnamon Extract on Spermatogenesis and

Mineral elements are important nutrients in animal diets because they participate in metabolic, enzymatic and biochemical reactions needed for sustenance, feed efficiency, growth and development of animals. According to UnderGenerally, only a fraction of the mineral ingested by an animal is effectively absorbed, while most are bound to other components such as fibre and then excreted. In this study, faecal mineral composition differentials were used as indicators of mineral uptake by pullets supplemented varying levels of plantain ash in their daily rations for nine weeks. Plantain stalk and root base samples were collected, sun dried and ashed to produce plantain stalk ash (PSA) and root base ash (PRA), respectively. Ninety six (96) day old Isa Brown pullets were reared to 15 weeks of age and thereafter divided into 2 major groups of 48 birds each. Each group was divided into 4 subgroups of 12 birds each and each subgroup divided into three replicates giving four birds per replicate in a completely randomized design. The PSA and PRA were fed to the pullets as mineral supplements to commercial grower from the 15 th to 18 th week (4 wk) and layer mashes from the 19 th to 24 th week (6 wk) at the rate 0, 1, 2 and 3 g per kg body weight so that one group received PSA and the other PRA. In each case, the zero supplementation served as control. At the 9 th week of feeding, faecal samples were collected from the groups, dried in the sun and analyzed for their mineral compositions by atomic absorption spectrophotometry. Among the macro minerals, both PSA and PRA supplementation resulted in reductions in the faecal concentrations of K and Mg, with increasing supplementation level, resulting in further reduction of faecal content of these minerals. Mg showed highly significant (P<0.05, P<0.01) regression effects for PSA and PRA, respectively. Reductions in faecal Ni and Fe concentrations were high (47.62 and 79.19%) across 1 g/kg body weight (BW) PSA and PRA supplementations, while it was 83.33% for Mn at the same 1 g/kg BW PRA supplementation. Ni (PSA) and Cr (PSA and PRA) values were significant (P<0.10) for regression effects, implying that the faecal values of these minerals could be predicted from any given quantity of plantain ash using the regression equations. PRA supplementations resulted in increasing faecal content of the two heavy metals, that is, lead and cadmium, indicating selective poor intestinal absorption of these. Plantain ash could serve as potential sources of absorbable mineral supplements and also could improve mineral uptake from commercial diets offered to pullets